INTEGRATED ENERGY MANAGEMENT SYSTEM INCLUDING A FUEL CELL COUPLED REFRIGERATION SYSTEM

Abstract

The disclosure relates to an integrated energy management system for managing thermal and electrical energy in a fuel cell coupled refrigeration system. In one example, a refrigeration cycle is driven by heat provided alternatively by a fuel cell and an electric heating device. In another example, a refrigeration cycle is driven by heat provided by a fuel cell to reduce consumption of electrical grid supplied power.

Description

CROSS-REFERENCE TO RELATED APPLICATION

The present application claims the benefit of U.S. Provisional Patent Application Ser. No. 61/492,318 filed on Jun. 1, 2011, entitled “Fuel Cell Coupled Refrigeration System for Power, Heating and Cooling Applications”, the entire disclosure of which is expressly incorporated by reference herein.

FIELD OF THE DISCLOSURE

The present disclosure relates to an integrated energy management system including control systems for use with a refrigeration system powdered by a fuel cell, and in particular a proton exchange membrane (PEM) fuel cell. The integrated energy management system is used for regulating the ambient temperature of an environment.

BACKGROUND OF THE DISCLOSURE

Heating and cooling systems of different types are commonly used to control ambient temperatures of internal spaces of buildings and vehicles and to cool refrigeration volumes such as transport trailers, refrigerators and freezers. Generally, heating and cooling systems consume electrical or mechanical energy to drive a heating and cooling cycle. Some systems, for example heat pumps, include valves adapted to switch the flow of refrigerant through heat exchangers, referred to as condensers and evaporators, so that the system can provide heating or cooling depending on the outdoor temperature. For convenience, systems configured to provide heating or cooling by changing the state of a fluid medium to transfer heat will be referred to as refrigeration systems.

Air cooling and vapor-compression are two common refrigeration systems. In air cooling systems, a fan or series of fans causes ambient air to flow over or through the target space. The air absorbs heat and transfers the heat to an external space. However, the cooling capacity depends on the air temperature of the ambient air, which can vary widely. As a result, air cooling may be unreliable, particularly in tropical and desert environments.

In a vapor-compression refrigeration system, the system transfers heat through a fluid refrigerant that is periodically cycled through a condenser and an evaporator. The cooling effect is provided when the refrigerant enters the evaporator, where the refrigerant's phase changes from a liquid-vapor mixture to a saturated-vapor at low pressure. The refrigerant then passes into a compressor where pressure of the refrigerant is increased as it is mechanically compressed and the refrigerant is transformed into a superheated-vapor. From the compressor, the refrigerant enters into the condenser where the heat picked up in the evaporator is rejected to the atmosphere, and the refrigerant changes back to a saturated-liquid. The refrigerant then returns to its initial liquid-vapor state after passing through an expansion valve. The energy input to drive the cycle is provided in the refrigerant compression stage. Vapor-compression systems are more reliable than air cooling systems but consume more energy and are generally heavier.

Accordingly, there is a need in the art for a more energy-efficient, effective means of powering refrigeration systems. It would be further advantageous if the thermal and electrical energy to be provided to a refrigeration system was provided at a highly efficient, consistent manner, with little to no gas emissions.

SUMMARY OF THE DISCLOSURE

The present disclosure is directed to generating and managing thermal energy in a fuel cell coupled refrigeration system. For example, a heat exchanger couples, directly or indirectly, to a fuel cell and a heat driven refrigeration system to transfer at least a portion of thermal energy generated by the fuel cell to the refrigeration system, thereby driving a refrigeration cycle of the refrigeration system. In some embodiments, the heat exchanger may further be coupled with an electric heating device such to transfer at least a portion of the thermal energy generated by the electric heating device to the refrigeration system as an alternative or supplemental thermal energy source from the fuel cell. A control system is coupled with the fuel cell coupled refrigeration system to form an integrated energy management system that controls operation of the fuel cell coupled refrigeration system.

In one embodiment the present disclosure is directed to an integrated energy management system for generating and managing thermal energy. The system comprises: a fuel cell operable to generate electric energy and thermal energy; an energy storage device operable to receive at least a portion of the electric energy generated by the fuel cell; a refrigeration system including a refrigerant; a heat exchanger operable to transfer at least a portion of the thermal energy from the fuel cell to the refrigeration system to heat the refrigerant; and a control system operable to control operation of the fuel cell.

In another embodiment the present disclosure is directed to a method of operating an integrated energy management system. The method comprises generating electric energy and thermal energy with a fuel cell; storing at least a portion of the electric energy in an energy storage device; and driving a refrigeration cycle of a refrigeration system with energy provided by a first source of energy and with thermal energy from the fuel cell.

It has been unexpectedly discovered that using thermal energy generated by fuel cells to drive refrigeration cycles of a refrigeration system provides both functional and financial benefits to the user, particularly homeowners. Particularly, the average energy output of the fuel cell is decreased as the electrical load of the HVAC system is decreased or eliminated, compared to the conventional electrically driven heating, ventilation, and air conditioning (HVAC) system, enabling a higher efficiency fuel cell operation. Note that fuel cell efficiency for a given fuel cell stack increases as its power level decreases. Further, surplus electrical energy generated by the fuel cell can additionally be used to power the electrical grid of a building or residence, providing alternative or supplemental electrical energy during periods when electrical costs are highest for utilities (e.g., summer months).

Further, an integrated energy management system for controlling the operation of the fuel cell coupled refrigeration system allows for further efficiency in a heating and cooling operation, thereby reducing the total energy cost to the consumer. Additionally, the integrated energy management system advantageously operates to recharge or condition any additional electrical energy storage devices and to reduce compressor load in vapor compression cycles such that the system is able to attain longer lifetimes than conventional HVAC and energy storage systems. Moreover, since the fuel cell is able to provide heat generated from the power producing electrochemical reaction, and since this heat can be used to promote cooling, these can be used to provide temperature regulation for high cost electrical components such as batteries, control systems, or power electronic devices. Furthermore, since the output power of the fuel cell is inherently direct current (DC), it can power DC or brushless DC electric motors that could power the compressor used in a vapor compression refrigeration cycle, thus further increasing the efficiency of the refrigeration system and enhancing its life.

Accordingly, the integrated energy management system of the present disclosure can be used as an upgrade or alternative to the conventional HVAC system, which is a high cost appliance, to provide for more energy-efficient heating/cooling of an environment.

BRIEF DESCRIPTION OF THE DRAWINGS

The above-mentioned and other disclosed features, and the manner of attaining them, will become more apparent and will be better understood by reference to the following description of disclosed embodiments taken in conjunction with the accompanying drawings, wherein:

FIG. 1A is a block diagram of a fuel cell coupled refrigeration system including a fuel cell, a heat driven refrigeration system, and a heat exchanger for use with an integrated energy management system according to one embodiment of the disclosure;

FIG. 1B is a block diagram of an integrated energy management system including a fuel cell, a refrigeration system, and an energy storage system according to one embodiment of the disclosure;

FIG. 2 is a schematic diagram depicting an absorption refrigeration system thermally coupled with a fuel cell for use with the integrated energy management system according to yet another embodiment of the disclosure;

FIG. 3 is a schematic diagram depicting the fuel cell coupled refrigeration system of FIG. 2 thermally coupled with an air pump directing excess heat to a heat load;

FIG. 4 is a schematic diagram depicting a vapor-compression refrigeration system thermally coupled to a liquid cooled fuel cell with an auxiliary cooling system for use with the integrated energy management system according to a yet further embodiment of the disclosure;

FIG. 5 is a schematic diagram depicting an absorption refrigeration system thermally coupled to a fuel cell and an auxiliary liquid cooling system for use with the integrated energy management system according to a further embodiment of the disclosure;

FIG. 6 is a schematic diagram depicting the ejector refrigeration system fluidly coupled to a fuel cell for use with the integrated energy management system according to yet another embodiment of the disclosure;

FIG. 7 is a schematic diagram depicting a compressor fluidly coupled to a fuel cell coupled refrigeration system for use with the integrated energy management system according to another embodiment of the disclosure;

FIG. 8 is a schematic diagram depicting a vapor-compression refrigeration system thermally coupled to a fuel cell and an auxiliary cooling system for use with the integrated energy management system according to a further embodiment of the disclosure;

FIG. 9 is a schematic diagram depicting an absorption refrigeration system thermally coupled to a liquid cooled fuel cell with an auxiliary liquid cooling system for use with the integrated energy management system according to a yet further embodiment of the disclosure;

FIG. 10 is a block diagram of a fuel cell coupled refrigeration system including a heat driven refrigeration system, a fuel cell and a battery cell stack for use with the integrated energy management system according to another embodiment of the disclosure;

FIGS. 11 and 12 are block diagrams of a fuel cell coupled refrigeration system for use with the integrated energy management system in a mobile application according to a further embodiment of the disclosure;

FIG. 13 is a graph of an exemplary range extending feature implemented with an integrated energy management system according to a further embodiment of the disclosure; and

FIGS. 14 and 15 are graphs of exemplary comfort features implemented with an integrated energy management system according to a yet further embodiment of the disclosure.

Corresponding reference characters indicate corresponding parts throughout the several views. Although the drawings represent embodiments of various features and components according to the present disclosure, the drawings are not necessarily to scale and certain features may be exaggerated in order to better illustrate and explain the present disclosure. The exemplification set out herein illustrates embodiments of the disclosure, and such exemplifications are not to be construed as limiting the scope of the disclosure in any manner.

DETAILED DESCRIPTION OF THE DISCLOSURE

The present disclosure is directed to an integrated energy management system for managing thermal and electrical energy generated in a fuel cell coupled refrigeration system. Thermal energy generated by the fuel cell can be used to drive a refrigeration cycle of the refrigeration system in an energy-efficient operation as an alternative or as a supplement to conventional electrically driven refrigeration systems. Exemplary refrigeration systems include vapor-compression, absorption and ejector refrigeration systems. The electrical energy generated by the fuel cell may be provided to an energy storage device or to electrically drive a primary or supplemental compressor in a vapor compression cycle or to generate heat through a resistance load to drive an absorption or ejector refrigeration system. Exemplary energy storage devices include batteries and capacitor banks.

These and other features of the integrated energy management systems and methods of the present disclosure, as well as some of the many optional variations and additions, are described in detail hereafter.

As used herein, the term “heat driven refrigeration system” refers to a heating and cooling refrigeration cycle that eliminates the need for a mechanical compressor and instead uses a thermal energy source to drive the cycle. Exemplary heat driven refrigeration systems include absorbent and ejector refrigeration systems.

As used herein, the term “refrigeration cycle” refers to a model of moving heat from one location (“source”) at a lower temperature to another location (“heat sink”) at a higher temperature using mechanical work or thermal work.

As used herein, the term “thermal load” refers to any component or device suitable to supply or receive heat. Exemplary thermal loads include electronic components, passenger cabins, battery compartments, electronic circuits, storage compartments, ice makers, dehumidifiers, and the like. The foregoing and later described embodiments describe heat transfer devices which may be referred to as heat exchangers (e.g., evaporators, condensers and generators).

As used herein, the term “generator” refers to a heat transfer device which thermally couples, directly or indirectly, a refrigeration system and a fuel cell such that excess heat from the fuel cell may heat the refrigerant of the refrigeration system. In one embodiment according to the disclosure, a generator includes a body. Embedded in the body are a refrigerant circuit and a heating device. The heating device is configured to heat the refrigerant in the refrigerant circuit. The body may comprise a number of integrated components. A fuel cell coupled refrigeration system may be referred to herein as a heat driven refrigeration system. Heat transfer devices may be liquid-to-liquid, gas-to-gas, surface-to-liquid and surface to gas heat transfer devices. Air is an exemplary gas.

As used herein, the term “evaporator” is a component that is thermally coupled, directly or indirectly, to a thermal load to remove heat therefrom.

The foregoing embodiments and additional embodiments of the disclosure will now be described with reference to the figures. Referring to FIG. 1A, a general embodiment of a fuel cell coupled refrigeration system 25 for use in the integrated energy management system according to the disclosure includes a heat driven refrigeration system 50 thermally coupled to a thermal load 52 and to a fuel cell 60, and a fuel cell fuel supply 64. Excess heat from fuel cell 60 is applied, via heat exchanger (i.e., generator as shown in FIG. 1A) 72, to increase the temperature of a refrigerant (not shown) flowing in refrigeration system 50 and at least partially increases the pressure of the refrigerant. Refrigeration system 50 provides or removes thermal energy to or from thermal load 52 to heat or cool thermal load 52.

As shown in FIG. 1B, generally, an integrated energy management system 10 includes fuel cell coupled refrigeration system 25, and may additionally include an additional energy source 30, an electrical energy storage device 34, a power circuit 40, an energy management system 44, and an electrical load 54. Energy source 30 provides energy through power circuit 40 to one or both of refrigeration system 50 and electrical load 54. Exemplary additional energy sources include mechanical, direct current (DC) and alternating current (AC) energy sources. Exemplary mechanical power sources include belts and gears driven by engines, hydraulic turbines and other non-electrical sources of energy. Exemplary AC energy sources include generators and an AC power grid. Exemplary DC energy sources include energy storage devices, fuel cells and solar arrays.

In one embodiment, fuel cell coupled refrigeration system 25 of the integrated energy management system 10 is comprised in a building. Energy source 30 comprises an electrical power grid (not shown) providing AC power to refrigeration system 50, in this case a vapor-compression refrigeration system, through power circuit 40. Energy management system 44 monitors thermal load 52 of refrigeration system 50 and forecasts the power requirements of refrigeration system 50 by application of known thermodynamic and energy balance principles involving temperature differential, mass and fluid flow parameters. The forecast may be based, for example, on historical trends, external ambient temperature measurements and operating profiles. An exemplary profile includes an ambient temperature setpoint and a demand formula based on the ambient temperature setpoint and an actual temperature. Energy management system 44 determines how much electrical energy and heat to produce with fuel cell 60 based on the forecast, a profile, and the availability of AC energy from the power grid.

In one example, power circuit 40 includes an inverter device, or inverter (not shown). In one variation, energy management system 44 incorporates a fuel cell control system such as fuel cell management system (FMS) 140 described with reference to FIGS. 10 and 11.

In another variation, energy management system 44 determines, based on a cost threshold of electrical energy supplied by the power grid, whether it is economical to sell electrical energy back to the power grid and, if so, operates power circuit 40 to transfer electrical energy generated by fuel cell 60 to the power grid.

In one example, the cost threshold is the peak power cost of the electrical energy supplied by the power grid. In another example, the cost threshold is a predetermined difference between the energy cost of the power grid energy and the fuel cell supplied energy.

In a further variation, power circuit 40 includes an inverter (not shown) and energy management system 44 is operable, with power circuit 40, to regulate power received from the power grid and thus manage opportunity costs. In one example, opportunity costs are managed by scheduling energy consumption. Generally, scheduling comprises controlling target temperatures and operating loads so as to minimize consumption during peak hours. The inverter provides a central DC bus. In one example, converters are provided to convert the DC voltage and AC voltage from different power sources (e.g. solar arrays, fuel cells and AC generators) to a common DC bus voltage. Power management system 44 is configured to regulate current drawn from the DC bus voltage by the refrigeration system and the electrical loads. Based on the current draw, energy storage system charge level, and refrigeration parameters, energy management system 44 determines how much energy to draw from the power grid.

In some embodiments, energy management system is similar to energy management system 178, described with reference to FIG. 11, and comprises a processing device 242 and a memory device 244 having stored therein an application 248, which when executed by the processing device 242 causes energy management system 178 to control one or more of power circuit (not shown), refrigeration system 150, 308, electrical load 104 and fuel cell 100.

In one example, the memory device 244 includes a plurality of operating profiles for controlling power circuit, refrigeration system 150, 308, electrical load 104 and fuel cell system 100. Each profile is configured to control operation of the devices in a particularized way such that energy management system 178 can change operation of the system 178 by selecting a different operational profile. Further, fuel cell coupled refrigeration system 300 may be configured with different modes of operation which may be comprised in a single profile or embodied in different profiles.

In one embodiment of multi-mode operations, a profile has a first and a second mode of operation and energy management system 178 switches between the first and second modes depending on predetermined conditions. In a cost-saving mode of operation, electrical energy produced by fuel cell 100 is converted to AC energy and supplied, together with AC energy from the power grid, to refrigeration system 150, 308. Fuel supplied by fuel cell fuel supply 105 is consumed by fuel cell 100 to produce electrical energy, which is consumed by refrigeration system 150, 308, and excess heat. The excess heat is applied to refrigeration system 150, 308 to reduce consumption of electrical energy by refrigeration system 150, 308. Exemplary fuels include natural gas and propane gas. Thus, operation of fuel cell 100 reduces consumption of electrical energy from the electrical power grid while consuming fuel cell fuel. The cost-saving mode of operation is most economical during periods of time during which the cost of energy received from the power grid is higher than the cost of energy obtained from conversion of fuel by the fuel cell.

In another cost-saving mode of operation, referring back to FIG. 1B, energy management system 44 is configured to control operation of electrical load 54. In one variation, energy management system 44 energizes electrical load 54 during periods of time in which the cost of energy from the power grid is not at a maximum. In another variation, energy management system 44 energizes electrical load 54 during periods of time in which refrigeration system 50 is not operating to reduce a peak-demand from the power grid. In a further variation, energy management system 44 energizes electrical load 54 with energy stored in electrical energy storage device 34. In one example thereof, energy management system 44 energizes electrical load 54 with energy stored in electrical energy storage device 34 during periods of time in which the cost of energy from the power grid is at a maximum. In another example thereof, energy management system 44 energizes electrical load 54 with energy stored in electrical energy storage device 34 is above a charge threshold. An exemplary profile for a grid power supplied system includes a relationship between electricity prices and demand levels and time of day. In one further example, the demand levels comprise a demand forecast.

In a reliability mode of operation, electrical energy produced by fuel cell 60 is supplied to refrigeration system 50 to operate refrigeration system 50 even if power from energy source 30 is unavailable. The DC energy from fuel cell 60 is inverted into AC energy and the AC energy is supplied to refrigeration system 50. In another example, energy source 30 supplements the DC energy supplied from fuel cell 60 to operate refrigeration system 50.

In yet another example, fuel cell coupled refrigeration system 25 is comprised in an electric vehicle and energy source 30 comprises a mechanical energy source driving the compressor of a vapor-compression refrigeration system. In a further example, fuel cell coupled refrigeration system 25 is comprised in an electric vehicle and refrigeration system 50 comprises an absorption or ejection refrigeration system.

In a further variation of the present embodiment, a first mode of operation causes energy storage device 34 to maintain a substantially full charge while a second mode causes energy storage device 34 to substantially deplete its charge. Thus, in the second mode energy storage device 34 is a net provider of electrical energy. When selected, the profile enables the system to charge in the first mode and to provide energy to the power grid in the second mode. In another variation, the profile is configured to operate the refrigeration system 50 primarily from energy source 30 when the cost of energy source 30 is low and to operate fuel cell 60 when the cost of energy from energy source 30 is high. The profile includes values for low and high cost thresholds. In a further variation, a profile includes operating schedules which enable electrical load 54 to be operated during low power grid cost periods. In a yet further variation, a profile causes refrigeration system 50 to maintain a target refrigeration parameter, e.g. temperature and/or temperature variation, near a limit of a range when it is economical to do so and near the opposite limit otherwise. For example, the profile may be defined to cool a target space to the low temperature limit of the range when grid energy costs are low and to operate near the upper temperature limit when grid energy costs are high. Thus, the refrigeration system 50 operates more during low cost periods than during high cost periods. Furthermore, the profile may cause energy storage device 34 to charge during the low cost period and discharge during the high cost period after the target space approaches the high temperature limit. The profile is selected from a plurality of profiles manually or automatically. In one variation, the user selects a new profile with a user input device (not shown). For example, a user may choose a profile to draw energy primarily from fuel cell 60 and energy storage device 34 if energy source 30 becomes unreliable even if the profile does not result in the most economical consumption. The user may then switch to a profile selected for economy when reliability of energy source 30 increases. Similarly, in a mobile application, the user may choose profiles based on anticipated traffic or terrain choices, choosing between profiles optimized for performance, economy, reliability or other characteristics.

In another variation, the profiles are conditioned such that as operating or ambient variables change, the energy management system 44 automatically selects a new profile. In one example, the energy management system 44 selects a reliability profile after it detects intermittent or unreliable supply from the power grid. In another embodiment, the energy management system 44 changes profile if, while in an economy mode, it is unable to satisfy the refrigeration target. Similarly, in a mobile application example, the energy management system 44 automatically changes from economy to performance profiles (or modes) if it is unable to reach performance targets with the economy profile (or mode).

In another variation of the present embodiment, electrical load 54 comprises a thermal heating device (not shown) thermally coupled with refrigeration system 50. Energy management system 44 cycles fuel cell 60 and the thermal heating device to heat the refrigerant alternatively with excess heat from fuel cell 60 and the thermal heater. In one embodiment, the thermal heating device is an electric heating device. One skilled in the art, however, would easily recognize that any thermal heating device as known in the art can be used as the thermal heating device without departing from the present disclosure.

Fuel cell coupled refrigeration system 25 may be comprised in a building or a mobile application. A fuel cell coupled refrigeration system such as fuel cell coupled refrigeration system 25 may be comprised in an electric vehicle to provide range extension or comfort features as disclosed with reference to FIGS. 12-13.

A method to operate an integrated energy management system is also provided herein. In one embodiment, the method comprises generating electric energy and thermal energy with a fuel cell; storing at least a portion of the electric energy in an energy storage device; and driving a refrigeration cycle of a refrigeration system, at least sometimes, with energy provided by a first source of energy and with thermal energy from the fuel cell.

In one variation, the method further comprises changing an energy ratio between the energy provided by the first source of energy and the thermal energy responsive to a variable associated with the first source of energy. By changing the energy ratio, for example by increasing fuel cell energy production and reducing supply from the first source accordingly, or vice-versa, the overall energy cost consumed by the fuel cell coupled refrigeration system can be adjusted. As the cost of energy from the first source and the fuel cell vary, due to fluctuations in pricing or efficiency, for example, the energy ratio is adjusted accordingly to minimize cost relative to what cost would be if the ratio remained unchanged. In one example, the variable is the energy cost of the energy from the first source of energy, and the changing comprises reducing the energy ratio when the energy cost of the energy from the first source of energy increases. In another example, the variable is the energy cost of the energy from the first source of energy, and the changing comprises reducing the energy ratio when the energy cost of the energy from the first source of energy exceeds a predetermined high cost level. In a further example, the first source of energy is the energy storage device and the changing comprises reducing the energy ratio when a charge level of the energy storage device reaches a predetermined low charge level.

The present integrated energy management system is applicable in stationary and mobile applications. In one variation, the method further comprises operating a vehicle including a propulsion system, an integrated energy management system including the refrigeration system and the fuel cell, and changing, by the integrated energy management system, an energy ratio between the energy provided by the first source of energy and the thermal energy responsive to a variable associated with the first source of energy. In another variation, the method further comprises operating the refrigeration system and the fuel cell with an integrated energy management system to control a building temperature, and changing, by the integrated energy management system, an energy ratio between the energy provided by the first source of energy and the thermal energy responsive to a variable associated with the first source of energy.

The present integrated energy management system is also applicable, in stationary applications, to manage interaction with a power grid. In one variation, the first source of energy is an electrical power grid, and the method further comprises, by the integrated energy management system, reducing the ratio when an energy cost of the electrical energy from the electrical power grid exceeds a predetermined kilowatt-hour cost. In another variation, described in more detail below, the ratio is increased and excess power can then be sold to the power grid.

In another embodiment, the method comprises generating electric energy and thermal energy with a fuel cell; driving a refrigeration cycle of a refrigeration system, at least sometimes, with energy provided by a power grid and with thermal energy from the fuel cell; and, at other times, providing energy generated by the fuel cell to the power grid.

The integrated energy management system of the present disclosure is also applicable, in stationary applications, to manage interaction with a power grid. In one variation, the first source of energy is an electrical power grid, and the method further comprises, by the integrated energy management system, reducing the ratio when an energy cost of the electrical energy from the electrical power grid exceeds a predetermined kilowatt-hour cost. In another variation, described in more detail below, the ratio is increased and excess power can then be sold to the power grid.

The embodiments described herein above and below are illustrative. Additional embodiments include any combination of the variations and examples provided herein. Furthermore, while the energy control concepts have been described with reference to a refrigeration system, the concepts are also applicable to systems in which thermal energy from fuel cells may be used to substitute other forms of energy. More particularly, heat from a fuel cell is provided to an appliance to reduce consumption of electrical or gas energy. In one example, the appliance is a water heater. A heat exchanger is coupled to the water heater. When the fuel cell operates, heat from the fuel cell is transferred to the water in the water heater, directly or indirectly, by the heat exchanger. An exemplary integrated energy management system includes a fluid conduit fluidly coupling the fuel cell and the water heater. In one example, a water heater system is retrofitted by inserting a heat exchange loop in the existing hot water or water heater piping. Water is circulated through, and heated in, the heat exchange loop.

In another example, a heat exchange loop is physically coupled to the water heater to heat the water indirectly such that the heated water does not contact the heat exchange loop. In one embodiment of a cost-saving method, the integrated energy management system determines use and non-use periods based on historical trends or via user programming. The integrated energy management system controls the water temperature setpoint and prevents the water heater from heating water during non-use periods. Instead, the integrated energy management system directs fuel cell heat to the water heater to raise the water temperature to the target temperature just prior to the use period. Exemplary water heaters include electric and gas water heaters.

In another embodiment of a cost-saving method, the integrated energy management system directs grid supplied energy to an electric water heater to raise the water temperature to the target temperature just prior to the use period so long as the heating period coincides with a time when grid power is below a predetermined cost threshold. Otherwise, the integrated energy management system directs grid supplied energy to the water heater to raise the water temperature to the target temperature just prior to the time when grid power is above the predetermined cost threshold. In a further embodiment of a cost-saving method, the integrated energy management system reads an on/off status of electrical or thermal loads and adapts operation of the fuel cell accordingly.

The variations and examples provided above are also applicable to other thermal and electrical loads including, for example, dishwashers, clothes washers and dryers, and other household appliances. In a further variation, the integrated energy management system operates the appliances and the fuel cell to reduce charging and discharging cycles of the energy storage device.

Typically the fuel cell coupled refrigeration systems used in the integrated energy management systems of the present disclosure include heat driven refrigeration systems including absorption refrigeration and ejector refrigeration systems. Absorption refrigeration relies on the use of a liquid media (the “adsorbent”) such as water or lithium bromide that is capable of adsorbing a large amount of a refrigerant at low temperature and pressure. The refrigerant, for example ammonia, sulfur dioxide, water or a hydrocarbon as known in the art, passes through a condenser, an expansion valve and an evaporator in the same way as in the vapor-compression system described above. The compressor is replaced by an adsorber, a pump and a generator. As the refrigerant passes through the adsorber, it is adsorbed by the adsorbent and heat is released to the environment. The refrigerant and the adsorbent then enter a pump where the pressure of the mixture increases to the generator's pressure. The mixture is heated in the generator to separate the high-pressure refrigerant from the adsorbent.

Ejector refrigeration is a refrigeration cycle that also relies on heat input rather than mechanical means to drive the cycle. The ejector refrigeration system consists of two loops, the refrigeration loop and the power loop. In the power loop, the liquid refrigerant is pumped into a generator where an external heat source (e.g., fuel cell and/or electric heating device) vaporizes the refrigerant resulting in high pressure vapor called the primary fluid. The primary fluid expands through the ejector's nozzle and increases its velocity. This creates a vacuum in the refrigeration loop which draws in the vapor from the evaporator called the secondary fluid. The secondary fluid enters the ejector's diffuser where the velocity decreases and the pressure recovers. The secondary fluid goes through a condenser where heat is rejected to the environment. The condensed liquid is partly pumped back to the generator completing the power loop. The remaining condensed liquid is drawn into an expansion valve where the pressure is lowered. The liquid enters the evaporator where the low pressure created by the primary fluid allows the secondary fluid to evaporate at very low temperature and thereby provide the cooling effect. The secondary fluid then enters the ejector completing the refrigeration cycle.

In another embodiment, a fuel cell coupled refrigeration system coupled to an energy management system is provided. In the present embodiment, the fuel cell coupled refrigeration system is also coupled to an energy storage system, forming an integrated energy management system according to one embodiment of the present disclosure. The energy storage system generates heat as it charges. The amount of heat is related to the charging and discharging rate of the energy storage system. The power generation efficiency of fuel cells, on the other hand, is inversely related to power demand. Therefore, when the energy storage system is nearly fully discharged, charging generates a relatively large amount of heat and causes the fuel cell charging the energy storage system to operate inefficiently. At the same time, however, due to the high electrical energy demanded by charging, the fuel cell generates a large amount of heat. It has unexpectedly been found that as the fuel cell generates more power to charge the energy storage system, and thus, generates more heat, more effective cooling is generated by the fuel cell coupled refrigeration system. Advantageously, the cooling effect is generated at a time that it is most needed by the energy storage system.

In one variation, the energy management system prevents substantial discharge of the energy storage system. In another variation, the energy management system cycles the fuel cell's electrical power production at a predetermined rate to maintain a desired charge level, and reduces the cycling rate when the heat load demand increases above a predetermined heat demand level. Exemplary energy storage systems include energy storage devices such as batteries and capacitors. In a further variation, the energy storage system powers heating and cooling devices under low or no load conditions. In one example, the refrigeration system cools the energy storage devices. In another example, a heating device powered by the energy storage device drives the refrigeration system under no or low load conditions.

In further embodiments, the foregoing integrated energy management system is configured to extend the range of a vehicle and/or to provide comfort heating and cooling features. In even further embodiments, the foregoing integrated energy management system includes additional heating and cooling components to transfer thermal energy, or heat, to and from thermal loads.

Referring to FIGS. 2-9, exemplary embodiments according to the disclosure of integrated energy management systems including fuel cell coupled refrigeration systems are provided. Referring to FIG. 2, in one embodiment a fuel cell coupled refrigeration system 100 comprises an absorption system 400 including a heat exchanger 152, such as an evaporator having a heat receiving surface 416, coupled to a thermal load 402, an adsorber 424, a pump 428, at least one generator 430, 432, a condenser 440 and an expansion valve 442. The system 100 also comprises an exemplary fuel cell system, illustratively fuel cell 410, thermally coupled to generators 430 and 432. Heat output by fuel cell 410 provides thermal energy to generators 430 and 432 to drive the refrigeration cycle of absorption system 400 as described above.

In one embodiment, an electric heating device 220 drives the refrigeration cycle when fuel cell 410 does not generate sufficient heat to do so. An additional unexpected advantage of coupling the electric heating device 220 and fuel cell 410 is that this allows decoupling of the thermal and electrical loads from the fuel cell. That is, when a separate electrical load provides electrical energy to electric heating device 220, heat produced from electric heating device 220 combines with heat produced by fuel cell 410 to drive the refrigeration cycle. When no separate electrical load is provided, however, electrical energy produced by fuel cell 410 can drive electric heating device 220, while heat produced from fuel cell 410 may still be used to drive the refrigeration cycle. It should be recognized that although described herein as an electric heating device, any other heating device as known in the refrigeration art can be used as a supplemental or alternative thermal energy source to the fuel cell for providing heat to drive the refrigeration cycle.

Generators 430 and 432 may be manufactured applying known heat exchange principles based on contact surface and fluid flow control to maximize the transfer of heat generated by fuel cell 410 to the fluid mixture circulating through the generator to cause the mixture to separate into its absorbent and refrigerant constituents. Another method of achieving heat transfer may be through boiling or phase change heat transfer in the generator 430, 432. Heat is transferred by heat transfer surface 416 from thermal load 402 and evaporated by the heat exchanger (evaporator) 152 thereby cooling thermal load 402. In one example, thermal load 402 is an electric vehicle battery compartment. In another example, thermal load 402 also includes a passenger cabin or compartment.

In one embodiment (not shown), fuel cell 410 also functions as a heat source for a heat load in addition to heating generators 430 and 432. A separate heat exchanger may be used to extract heat from fuel cell 410 for heating purposes. For example, in one embodiment, a dual purpose heat exchanger is provided configured with separate heat transfer conduits. One conduit extracts heat for use with refrigeration system 400 when refrigeration is required and another conduit extracts heat for heating of thermal load 402 when heating is required.

In one particularly suitable embodiment, the fuel cell comprises at least one proton exchange membrane (PEM) fuel cell designed to convert fuel such as pure hydrogen or a hydrogen-rich gas stream and an oxidant such as air in an electrochemical reaction that generates water vapor, electrical power and waste heat. Each cell includes a PEM membrane disposed between bipolar plates. Fuel cells may operate at different temperatures. Low-temperature PEM fuel cells operate between 60° C. and 80° C. High-temperature PEM fuel cells may operate between 95° C. and 180° C. and reject heat at about 150° C. Typically, absorption refrigeration can be achieved with heat at a temperature of about 60° C. Similarly, thermal compression or isochoric compression of typical air cooling system refrigerants can be achieved with heat at a temperature of about 60° C. The temperature differential between the rejected heat and the generator, which determines the heat transfer efficiency, also determines the size of the exchange surface required to transfer heat from a typical PEM fuel cell to a generator. Thus, the size of the generator to exchange heat with a low-temperature PEM fuel cell is much larger than the size of a generator used with a high-temperature PEM fuel cell to achieve the same heat transfer rate. Furthermore, at the temperatures at which the high-temperature PEM fuel cells operate, it is possible to transfer enough heat to run a compact generator utilizing the external surfaces of the fuel cells rather than having to circulate fluid through the bipolar plates. The ability to extract sufficient heat from the external surfaces simplifies and enables construction of an integrated fuel cell/generator structure.

In another embodiment, however, heat exchange may be improved by circulating fluid through the biopolar plates to increase the contact surface. This configuration enables the use of low-temperature PEM fuel cells with fuel cell coupled refrigeration systems as described in the present disclosure.

In another example, a second cooling conduit is built into the generator to construct a dual purpose generator. Independent flow control of the conduits permits the fuel cells to both heat a thermal load and refrigerate a second thermal load with the refrigeration system. In one variation, dual loop generators are used in stationary systems using lead-acid batteries to store energy generated by the fuel cells. Because temperature control can extend the life of lead-acid batteries, heating and cooling to maintain a desired temperature within a narrow band is desirable and achievable with a dual purpose generator. In another variation, described with reference to FIG. 7, a dual loop generator is used in conjunction with an auxiliary cooling loop.

Referring to FIG. 3, in another embodiment, a fuel cell coupled refrigeration system 100 is provided comprising an air pump or fan 456 forcing air to flow through fuel cell 410. The forced air absorbs heat produced by fuel cell 410 and transfers the heat to the environment or to a thermal load. For example, thermal load 454 is shown in FIG. 3 receiving heat from the forced air.

In one embodiment, an integrated energy management system is configured to control the temperature of one or more compartments (not shown). When heating is desired, the fuel cell coupled refrigeration system 100 transfers heat from fuel cell 410 to the compartments.

In some embodiments, the fuel cell coupled refrigeration systems include auxiliary cooling systems. Embodiments of fuel cell coupled refrigeration systems including auxiliary cooling systems according to the disclosure are described with reference to FIGS. 4 and 5. In FIG. 4, an auxiliary cooling system 446 includes a heat exchanger 444, a radiator 448 and a pump 452.

For example, in an electric vehicle application, pump 452 is powered by an energy storage system (not shown) which is in turn powered by fuel cell 410. A refrigerant is circulated in a cooling loop through auxiliary cooling system 446 to cool, at least partially, fuel cell 410. In one embodiment, generator 430 and heat exchanger 444 are integrated in a dual purpose generator. In an alternative embodiment, separate heat exchange components are independently coupled to the fuel cell 410. If the refrigeration system 100 is not in operation, auxiliary cooling system 446 cools fuel cell 410. If some refrigeration is desired, absorption refrigeration system 400 and auxiliary cooling system 446 may be selectively operated by an energy management system to maximize the efficiency of the fuel cell coupled refrigeration system 100. In a further embodiment, generator 430 also includes heating device 220.

In FIG. 5, an auxiliary cooling system 460 includes heat exchanger 444, radiator 448, pump 452, and a liquid cooled fuel cell 466 thermally coupled to a second heat exchanger 464. A refrigerant is circulated through cooling system 460 to cool fuel cell 466. The refrigerant may be circulated through fuel cells to draw heat from fluid channels disposed within the fuel cell bipolar plates or around their periphery. Heat is then transferred from the refrigerant to generator 430 by heat exchanger 444. Alternatively, heat is removed from the refrigerant by radiator 448. In the arrangements described with reference to FIGS. 4 and 5, the auxiliary cooling system 446, 460 supplements fuel cell thermal management utilizing a liquid refrigerant such as water, ethylene glycol, propylene glycol or mineral oil. The auxiliary cooling system 446, 460 provides operational flexibility by enabling fuel cell 410, 466 to operate independently from the absorption refrigeration system 400, 480. Auxiliary cooling is particularly useful when radiator 448 can discharge absorbed heat to a heat load (not shown).

Referring to FIG. 6, in another embodiment of a fuel cell coupled refrigeration system for use with an integrated energy management system according to the disclosure, an ejector refrigeration system 670 is provided. Ejector refrigeration system 670 comprises a refrigerant reservoir 672, expansion valve 642, heat exchanger 652, a pump 674 pumping refrigerant through the fuel cell coupled refrigeration system 500, an ejector 676 having an ejector nozzle 680, and condenser 640. The power loop includes pump 628 to pump the refrigerant therethrough and fuel cell 610 thermally coupled to heat exchangers 678 and 679. After exiting the power loop, the refrigerant is mixed with secondary fluid exiting refrigeration system 670 and heat is removed therefrom.

In a variation thereof (not shown), an auxiliary cooling system is provided as described with reference to FIGS. 4 and 5. During operation, refrigerant is pumped into the power loop from reservoir 672 to heat exchangers 678 and 679. The excess heat produced by fuel cell 610 vaporizes the refrigerant which maintains the fuel cell temperature within an optimal range, for example, at temperatures of from about 120° C. to about 150° C. The vaporized refrigerant enters ejector nozzle 680 at high pressure and is throttled to high velocity. This increase in velocity draws the secondary fluid in the refrigerant loop into ejector 676. The same refrigerant used as the primary fluid is also used for the secondary fluid. The secondary fluid first enters expansion valve 642 which opens only if below a certain pressure, for example below about 8 and 10 mbar absolute. The refrigerant flows into evaporator 652 and pump 674 before entering ejector 676. Pump 674 is added to achieve a deeper vacuum thereby causing the refrigerant to boil at lower temperature. In one embodiment, the refrigerant is water and the boiling point of the water is decreased to between 50° C. and 80° C. The fluid mixture exiting from ejector 676 is routed to condenser 640 which rejects the heat picked up by the refrigerant to the atmosphere. The refrigerant then returns to reservoir 672.

In one variation, electric heating device 700 is provided as an alternative/supplemental heat source to drive the refrigeration cycle of ejector refrigeration system 670. In one example, heating device 700 and fuel cell 610 are cycled to alternatively drive the refrigeration cycle, at least sometimes. In another example, heating device 700 and fuel cell 610 are operated concurrently, at least sometimes, to drive the refrigeration cycle. It should be recognized that by having the electric heating device 700, the fuel cell power output and heat generation can be decoupled from the heating load and the electrical load as described above, enabling greater operational flexibility.

In other embodiments of an integrated energy management system including a fuel cell coupled refrigeration system, as shown in FIG. 7, the refrigeration system 300 comprises a compressor 310. The compressor 310 may be powered by electrical energy (e.g., alternating or direct current) (not shown). In one embodiment, compressor 310 may be powered by electrical energy generated by fuel cell 314. In one variation, Q₁, such as is provided by fuel cell 314, is used to induce isochoric compression of the refrigerant to reduce an energy requirement of the compressor 310. In one embodiment, the system 300 is operable to increase a pressure of a portion of the refrigerant downstream of the compressor. In a form thereof, the pressure is increased by heating the portion of the refrigerant in a substantially constrained volume. By heating in a substantially constrained volume, pressure increases. In another embodiment, heating can also be applied in a not-substantially constrained volume so long as heating increases the pressure of the refrigerant, for example by controlling feed and discharge flow rates such that the pressure is not relieved as a result of decreased flow.

In yet another embodiment, the pressure is increased by expanding steam (not shown) generated by fuel cell 314 to compress the refrigerant. As the steam increases in a constrained space, the refrigerant is compressed and its pressure increases. Increasing the pressure reduces an energy requirement of compressor 310. Thus, for the same amount of heating or cooling demanded of refrigeration system 300, less electrical energy 312 is consumed as a result of the application of thermal energy from fuel cell 314 to refrigeration system 300. In one embodiment, fuel cell 314 is operated between 60° C. and 180° C. More particularly, in one embodiment, a low temperature PEM fuel cell is operated between 60° C. and 80° C. In another embodiment, an intermediate temperature PEM fuel cell is operated between 90° C. and 150° C. In yet another embodiment, a high temperature PEM fuel cell is operated between 100° C. and 180° C.

In one suitable embodiment, a method according to the disclosure includes retrofitting a vapor-compression refrigeration system, such as system 300, by adding generator 316 and fuel cell 314 to transfer excess heat from the fuel cell 314 to the refrigerant.

Referring to FIGS. 8 and 9, exemplary embodiments of a fuel cell coupled vapor-compression refrigeration system 1000 for use with an integrated energy management system according to the disclosure are provided. Fuel cell coupled refrigeration system 1000 includes vapor-compression refrigeration system 480 coupled to a generator 430 to heat the refrigerant. As shown in FIG. 8, generator 430 is coupled upstream of a compressor 482, between compressor 482 and condenser 440. In another variation, generator 430 is coupled downstream of compressor 482. For example, generator 430 may be coupled downstream of compressor 482 between heat exchanger 152 and compressor 482. As illustrated in FIGS. 8 and 9, vapor-compression refrigeration system 480 comprises, respectively, auxiliary cooling systems 446 and 460. In a further variation, system 480 does not include an auxiliary cooling system. In all of the above variations and examples, generator 482 compresses the refrigerant, and generator 430 raises the temperature of the refrigerant such that the energy consumed by compressor 482 is reduced when generator 430 operates relative to when it does not.

As noted above, alternative/supplemental energy sources may be included in the fuel cell coupled refrigeration systems. Referring to FIG. 10, a schematic diagram of an integrated energy management system including a fuel cell coupled refrigeration system according to an embodiment of the disclosure, including a fuel cell system 100, a heat driven refrigeration system 150, and a battery system 160, is provided to power a load 104. Fuel cell system 100 includes a fuel cell 110, a fuel cell management system (FMS) 140, and a fuel reservoir 130 containing fuel for the fuel cell 110. In the present embodiment, fuel cell system 100 includes a fluid conduit 120 thermally coupled to fuel cell 110 to extract heat therefrom and having an inlet 122 and a discharge outlet 124. When fuel cell system 100 operates, the fluid passing through fluid conduit 120 is heated and the heated fluid then flows to refrigeration system 150. In a variation thereof, a heat exchanger 152 (e.g., generator) of refrigeration system 150 is physically and thermally coupled to fuel cell system 100 to extract heat from surfaces of fuel cell 110. FMS 140 is communicatively coupled by a signal line 191 to an energy management system 178 and receives a demand signal therethrough. The demand signal causes FMS 140 to control fuel cell system 100 to provide fuel to fuel cell 110 in relation to the amount of energy required by energy management system 178 to enable an electrochemical reaction in fuel cell 110. Electrical power produced by the electrochemical reaction is provided via power lines 171 and 172 to battery system 160. FMS 140 includes a power conditioner (not shown) which converts the voltage of electrical energy generated by fuel cell 110 to a voltage compatible with battery system 160. Electrical power is provided via power lines 173 and 174 from battery system 160 to load 104. Exemplary loads include propulsion systems in mobile applications, computing systems of telecommunication systems or mobile systems, and any other compatible electrical system.

In particularly suitable embodiments, fuel cell 110 is electrically coupled in parallel with battery cell stack 162 and load 104. In this configuration, fuel cell 110 can participate in powering the electrical load 104 in conjunction with battery system 160. In cases where load 104 is lower than fuel cell 110 power output, fuel cell 110 can recharge battery cell stack 162 while providing power to load 104.

In the present embodiment, heat exchanger 152 is configured to receive heat from battery system 160. Refrigeration system 150 further includes a fluid supply line 154 fluidly coupled to inlet 122 and a fluid return line 156 fluidly coupled to discharge outlet 124. A primary fluid circulates through refrigeration system 150, fluid supply line 152, fluid conduit 120 and fluid return line 156 driven by a fluid pump (not shown) or by density changes caused by temperature variations in the refrigerant. As the primary fluid passes through fluid conduit 120 it receives heat from fuel cell 110 and then refrigeration system 150 discharges the heat to the environment or to a heat load. The heat received by refrigeration system 150 drives its cooling cycle as explained above and below with reference to FIGS. 2-9. Refrigeration system 150 also extracts heat from battery system 160 with heat exchanger 152. In one variation of the present embodiment, fluid conduit 120 is comprised by a generator (not shown), and the generator is integrated with fuel cell 110. While the fuel cell coupled refrigeration system depicted in FIG. 10 has been described with reference to a battery system, the invention is not so limited. In one variation of the fuel cell coupled system with an additional energy source as depicted in FIG. 10, the system comprises any electrical energy storage device.

In another variation of the present embodiment, the primary fluid is thermally coupled to an electric heating device 200 having a fluid conduit 203 between an inlet 202 and a discharge outlet 204. In one example, heating device 200 comprises a plurality of electric heating bands 206 configured to heat fluid conduit 203 and fluid passing therethrough. Heating device 200 is powered by power lines 175 and 176 which are supplied power by battery cell stack 162 of battery system 160 or directly by the fuel cell. A switching device 210 is controlled by energy management system 178 with a control signal supplied via a signal line 192 to engage or disengage heating device 200. Exemplary switching devices include relays and contactors.

As explained further below with reference to FIGS. 11 and 12, according to various embodiments disclosed herein it is advantageous to enable operation of refrigeration system 150 even when fuel cell system 100 is not producing electric power. At such times, battery system 160 powers heating device 200 to produce sufficient heat to drive the refrigeration cycle. When the charge level of battery system 160 is sufficiently reduced, e.g. below a no-load charge threshold, energy management system 178 engages fuel cell system 100 to recharge battery system 160, thereby also producing sufficient heat to drive the refrigeration cycle, and disengages heating device 200. In one example, energy management system 178 engages fuel cell system 100 when its charge level is below 90%. In another example, energy management system 178 engages fuel cell system 100 when its charge level is below 80%. The no-load charge threshold is a design choice dependant on the sizes and response times of the integrated energy management system components.

The no-load charge threshold can depend on application specific variables. Thus, multiple conditional no load charge thresholds may be applicable under varying conditions. In one example, after the batteries are sufficiently charged the fuel cell system is disengaged and the heating device is engaged to keep the refrigeration system working, to cool the batteries for example. Once the batteries reach a no-load charge threshold, the fuel cell system re-engages to charge the batteries, the heating device disengages, and the fuel cell heat drives the refrigeration cycle. The fuel cell system and the heating device may cycle on and off as described herein for other purposes as well.

Battery system 160 includes a battery cell stack 162 and a battery management system (BMS) 166. Battery management system 166 communicates via a demand signal on signal line 181, providing sufficient information to enable energy management system 178 to engage fuel cell 100 at an appropriate power level to charge battery cell stack 162. In one variation, BMS 166 determines, based on historical data and present voltage, a required charge rate and communicates the required charge rate and voltage to energy management system 178 via the demand signal. In another variation, energy management system 178 determines the charge rate based on a voltage signal on demand line 181. In a further variation, energy management system 178 determines the charge rate based on a voltage signal on demand line 181 and predictive information received on signal line 182 or any other signal lines as described below. Based on the required charge information, FMS 140 calculates how much current is required given the voltage output by fuel cell 110 and converts the voltage output to substantially match the present voltage of battery cell stack 162. FMS 140 adapts the DC/DC conversion ratio as the present voltage increases during charging. BMS 166 may include a pre-charge circuit suitable to receive electric energy from an external source. The functionality of the system has been described with reference to FMS 140, BMS 166 and energy management system 178 for simplicity, but the present disclosure is not to be construed as requiring three control components. The same functionality can be achieved with a single control component or with a distributed control system in which the control logic is even more distributed than in the disclosed embodiment. The control logic can be embodied in software, in hardware and in a hybrid system comprising software and hardware. Demand and control lines are described in singular form for simplicity. Demand and control lines may comprise one or more conductors transmitting one or more signals each. In one example, demand and/or control lines comprise serial communication lines communicating a variety of data types such as data representative of voltage, current, timing, faults and errors. In another example, demand and/or control lines comprise control voltages or currents, for example 0-10 volts or 4-20 milliamps, as is know in the art of control systems. The control logic may also be integrated with a control device controlling the overall operation of a mobile or stationary system coupled to the integrated energy management system.

In a further embodiment, the integrated energy management system is comprised in an electric vehicle. The electric vehicle comprises an electric propulsion system and the integrated energy management system. Exemplary propulsion systems comprise wheels or propellers driven by one or more electric motors. Exemplary motors include regenerating motors. The integrated energy management system includes a fuel cell coupled refrigeration system, such as shown in FIG. 10, to provide electric power to the propulsion system. In one variation, the refrigeration system is coupled to a thermal load of the electric vehicle and the integrated energy management system includes a comfort cycling feature. Accordingly, when the vehicle is parked, the fuel cell refrigeration system of the integrated energy management cycles to provide comfort. In one example, comfort is provided by heating an electric vehicle cabin while the propulsion system of the electric vehicle is disengaged. Heating may be provided by the fuel cells or by an auxiliary heating device powered by an energy storage system. In one example, heating is provided by the fuel cells and the no-load threshold is set below a cooling no-load threshold to enable the fuel cells to generate more heat than would be generated if an optimal efficiency threshold were chosen. In another example, comfort is provided by cooling the electric vehicle cabin while the propulsion system of the electric vehicle is disengaged. When the electric vehicle is parked, the heating device and the fuel cell coupled refrigeration system cycle and the refrigeration system cools the cabin.

An embodiment of an integrated energy management system including fuel cell coupled refrigeration system as in FIG. 10 in a mobile application is depicted in FIGS. 11 and 12. Referring to FIG. 11, an exemplary schematic diagram of an electric vehicle 300 with an energy management system 178 is shown comprising a plurality of heating sources and a plurality of cooling sources powered by fuel cell system 100, battery system 160 and refrigeration system 150. Some heating and cooling sources may be available, for example, if a vehicle is retrofitted with a fuel cell coupled refrigeration system. Battery system 160 is located in a battery compartment 304. An auxiliary heating source, denoted as heating device 306, is provided for heating a cabin 302 where a driver and passengers may be seated. Auxiliary cooling sources include auxiliary fuel cell cooling system 310 and compressor refrigeration system 308. Sensors 250-257 comprise temperature sensors T1 T3 designated to measure ambient temperature and the temperatures of battery system 160 and cabin 302. Sensors 253 and 254 comprise voltage sensors V1 and V2 designated to measure the output voltage of fuel cell system 100 and the voltage of battery system 160. Sensors 255-257 comprise current sensors A1-A3 designated to measure the current output by fuel cell system 100 and drawn by battery system 100 and load 104. Additional sensors may be provided to measure performance of auxiliary heating and cooling components. Alternatively, each auxiliary heating and cooling component may comprise an independent controller communicatively coupled with energy management system 178. Labels Q1-Q10 represent heat, i.e. energy measured in calories or British Thermal Units (BTU's), flowing through the electric vehicle. Q1 and Q6 represent heat provided to cabin 302 and battery compartment 304. Q4 and Q5 represent heat extracted from cabin 302 and battery compartment 304. Q2 and Q10 represent heat provided to heat driven refrigeration system 150. Q7-Q9 represent heat vented to the environment. Of course, heat Q7-Q9 can also be re-circulated to cabin 302 or battery compartment 304. Additional power lines may be required to power fluid circulation pumps associated with heat exchangers and refrigeration systems. In addition to sensors, energy management system 178 receives a plurality of signals on lines 181-184 and outputs a plurality of signals on lines 191-196.

Energy management system 178 further comprises a processing device 242, a memory device 244, and imbedded in memory device 244, an application 248 including a plurality of processing instructions executable by processing device 242 to engage and disengage the heating and cooling sources, the integrated energy management system and other components of electric vehicle 300. Referring to FIG. 12, in one embodiment, control signals are provided on lines 191-196 to engage the integrated energy management system components and the auxiliary heating and cooling components. As described above, the lines can comprise single and multi-conductor lines which transmit simple demand signals or establish serial or other communication protocols to exchange information with the components. In other words, control signals can be bi-directional so as to transmit control and programming data, e.g. temperature setpoint or on/off control signals, and receive performance data, e.g. temperature, volts, current, faults and any other feedback data. Furthermore, predictive input signals are provided on line 182 corresponding to a speed control of electric vehicle 300, on line 183 corresponding to a comfort control, and on line 184 corresponding to a heating/cooling (H/C) demand. As explained with reference to FIGS. 13-15, predictive signals may be utilized to provide range increasing and comfort features.

Unless otherwise expressly stated in connection with a specific use thereof, the term “memory device” includes any variation of electronic circuits in which processing instructions executable by a processing device may be embedded unless otherwise expressly stated in connection with the specific use of the term. For example, a memory device includes read only memory, random access memory, a field programmable gate array, a hard-drive, a disk, flash memory, and any combinations thereof, whether physically or electronically coupled. Similarly, a processing device includes, for example, a central processing unit, a math processing unit, a video processing unit, a plurality of processors on a common integrated circuit, and a plurality of processors operating in concert, whether physically or electronically coupled. Furthermore and in a similar manner, in the context of a processing device, the term “application” includes a single application, a plurality of applications, one or more programs or subroutines, software, firmware, and any variations thereof suitable to execute instruction sequences with a processing device.

As described above, an integrated energy management system in a mobile application may be enhanced with predictive range extension and/or comfort features. In one embodiment according to the disclosure, a plurality of profiles is obtained corresponding to a plurality of modes of operation. In one example, the integrated energy management system includes an algorithm programmed to operate so as to optimize particular profiles. Referring to FIG. 12, a graph 500 of an output profile corresponding to an electric vehicle operating in a “passing mode” is provided. A curve 510 represents a speed demand signal including substantially constant portions 511 and 513, and a constant but higher speed portion 512 representing a desired passing speed. Curve 510 is shown for illustrative purposes as a square shaped curve. A passing mode profile would naturally include some curvature representing a desired degree of acceleration/deceleration between portions 511, 513 and 512. A curve 520 represents the fuel cell system output. Curve 520 includes a constant portion 523 and a curved portion 534. A line 522 is shown above curve 520 indicating the maximum output of the fuel cell, which is also the most inefficient output level. In a range extension mode, the fuel cell operates more efficiently and the range of the electric vehicle is thereby extended by preventing operation at the maximum output. A curve 530 represents battery charge or voltage level. A line 532 is shown below curve 530 indicating the discharge threshold at which the battery system can no longer contribute a meaningful amount of power to power the vehicle. Before the battery system reaches this level, the fuel cell engages and the electric vehicle is powered, if necessary, by the fuel cell. If acceleration or high speed demand exceeds the capacity of the fuel cell, the electric vehicle will not respond to the driver's controls. Portion 533 of curve 530 represents a battery system voltage at constant speed. Since the voltage is constant, the fuel cell is powering the electric vehicle. When the speed demand increases, the integrated energy management system has two options: increase fuel cell output or supplement its output with battery power. The latter option is represented by graph 500. Portion 534 shows a decrease in battery voltage as a result of batteries outputting power. However, if option 2 continues for too long and into portion 535, the batteries will be depleted which is a situation that should be avoided. Therefore, the integrated energy management system increases the fuel cell output, indicated by portion 534, before the batteries become depleted to stabilize their voltage, as indicated by portion 536. Once speed demand decreases, the fuel cell output is maintained for a while longer to enable the batteries to recharge, as indicated by portion 537. The range extension benefit results from the ability to use the batteries to respond to an increase in demand to reduce the fuel cell power level increase required to satisfy demand. The length of portion 512 for different types of vehicles may be predicted based on electric vehicle usage history. If the battery voltage does not stabilize within a predefined time range, indicating that the predicted high speed portion 512 has been exceeded, the fuel cell output may be increased to maximum.

Referring to FIG. 13, an output profile corresponding to an electric vehicle operating in a comfort mode is provided. A pre-start comfort warm-up profile is illustrated by graph 600. A dashed line indicates the battery voltage and a solid line represents the fuel cell output. During portions 622 the fuel cell does not output power and during portions 624 the fuel cell does output power. During portion 612, the battery voltage is below its maximum level and the fuel cell does not output power, indicating that the electric vehicle is in a dormant state. At some pre-start time prior to a start up time, the fuel cell begins to charge the batteries, which is represented by portions 624 and 614. Then, the fuel cell and a heating device cycle on and off to heat the cabin. During portion 616 the battery discharges as it powers the heating device. In one example, the pre-start time is predicted based on a sequence of start-up times detected over time. In another example, the pre-start time is indicated by a user. In another embodiment, the fuel cell and a refrigeration heating device alternatively cycle on and off to drive the refrigeration cycle and cool the cabin. Cooling may begin at a pre-start time as in the foregoing comfort heating cycling process.

Referring to FIG. 14, a short-stop comfort mode of operation is illustrated by graph 700. As indicated by portions 720 and 722, a load current is initially constant indicating that the electric vehicle is operating at a constant speed, and then decreases, indicating that the electric vehicle is slowing down and eventually stopping. Portions 740 and 760 indicate that while speed is constant, the fuel cell is providing propulsion power and the battery voltage is constant. When the electric vehicle slows down, the fuel cell decreases power output, at portion 742, while the battery voltage increases, at portion 762, indicating that the fuel cell is producing more power than the electric vehicle propulsion system requires. The propulsion system may regenerate power as the brakes are applied. The fuel cell then maintains output, at 744, until the batteries are fully charged. At 764 the batteries discharge while they power a heating device to maintain operation of the refrigeration system to keep the batteries and the cabin cool. Once the batteries discharge to a predetermined level, the fuel cell and the heating device cycle as described above. In one example, the predetermined level is set to balance inefficient operation of the fuel cell and the cycling frequency to achieve cycling stability. In another example, the integrated energy management system is programmed to distinguish a short stop from a long stop, and to maintain a cabin temperature at a comfort threshold temperature for a short time. The short time may be, for example, indicative of a shopping stop. The short stop may be predicted based on travelled distance, travel profile, or GPS location, for example.

While the present disclosure has been described as having an exemplary design, the present disclosure may be further modified within the spirit and scope of this disclosure. For example, additional predictive features may be incorporated. In a method for a mobile application, for example, acceleration, passing and stopping profiles are defined for different environments such a city, highway, mountain environments based on vehicle displacement, acceleration and velocity. The integrated energy management system compares present variables to the profiles to select a profile and then utilizes the profile and other variables to optimize operation and efficiency of the vehicle. Exemplary other variables include the voltage of the batteries, desired cabin temperature, ambient temperature, and other operating parameters of the vehicle. In one example, the profiles include variable thresholds. The integrated energy management system compares profile thresholds to present values of the corresponding variables and switches profiles when the present value indicates that further operation according to the profile in place will cause a violation of a threshold. Then, the integrated energy management system switches profiles to prevent such violation.

In another example, a fuel cell coupled refrigeration system is operated based on profiles in a stationary application. Exemplary profiles are based on time of day, loads schedules, seasonal weather patterns, and schedules such as work and travel schedules. Thus, while the environment in which the refrigeration system is used, and the type of refrigeration system, define the operating variables of the system, operational control of the coupled fuel cell provides flexibility to optimize operation of the integrated energy management system at different times and for different reasons. This application is intended to cover any variations, uses, or adaptations of the disclosure using its general principles. Further, this application is intended to cover such departures from the present disclosure as come within known or customary practice in the art to which this disclosure pertains.

In view of the above, it will be seen that the several advantages of the disclosure are achieved and other advantageous results attained. As various changes could be made in the above systems and methods without departing from the scope of the disclosure, it is intended that all matter contained in the above description and shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense.

When introducing elements of the present disclosure or the various versions, embodiment(s) or aspects thereof, the articles “a”, “an”, “the” and “said” are intended to mean that there are one or more of the elements. The terms “comprising”, “including” and “having” are intended to be inclusive and mean that there may be additional elements other than the listed elements.

Claims

1. An integrated energy management system for generating and managing thermal energy, the system comprising:

a fuel cell operable to generate electric energy and thermal energy;

an energy storage device operable to receive at least a portion of the electric energy generated by the fuel cell;

a refrigeration system including a refrigerant;

a heat exchanger operable to transfer at least a portion of the thermal energy from the fuel cell to the refrigeration system to heat the refrigerant; and

a control system operable to control operation of the fuel cell.

2. A integrated energy management system as in claim 1 further comprising a heating device thermally coupled with the refrigeration system, the control system operable to cycle the fuel cell and the heating device.

3. An integrated energy management system as in claim 2 further comprising a heating device thermally coupled with the refrigeration system, the control system operable to cycle the fuel cell and the heating device to drive a refrigeration cycle of the refrigeration system alternatively with the fuel cell and the heating device.

4. An integrated energy management system as in claim 1 further comprising a plurality of operating profiles, the control system operable to select a selected profile of the plurality of operating profiles.

5. An integrated energy management system as in claim 4 wherein the selected profile is selected to control a temperature inside a compartment.

6. An integrated energy management system as in claim 1 wherein the refrigeration system comprises a compressor.

7. An integrated energy management system as in claim 6 wherein the compressor is powered, at least in part, by the fuel cell.

8. An integrated energy management system as in claim 6 wherein the control system is operable to provide electrical energy to the compressor motor from an electrical power grid, and from the inverter device to the electrical power grid.

9. An integrated energy management system as in claim 6 further comprising a heating device, the control system operable to cycle the fuel cell and the heating device according to the selected profile.

10. An integrated energy management system as in claim 6 wherein the selected profile is configured to control the fuel cell to satisfy a target refrigeration parameter and reduce a total energy cost of the energy consumed by the refrigeration system and the fuel cell.

11. An integrated energy management system as in claim 10 further including an electrical load, wherein the selected profile is configured to operate the electrical load and to reduce the total energy cost of the energy consumed by the refrigeration system, the fuel cell and the electrical load.

12. An integrated energy management system as in claim 10 wherein the selected profile includes a first mode of operation and a second mode of operation, and wherein the control system is operable to maintain a high charge level in the energy storage device in the first mode of operation and to engage the second mode of operation during times when grid supplied electrical energy costs exceed a cost threshold.

13. An integrated energy management system as in claim 1 further including an auxiliary cooling system operable to remove thermal energy from the fuel cell.

14. A method to operate an integrated energy management system, the method comprising:

generating electric energy and thermal energy with a fuel cell;

storing at least a portion of the electric energy in an energy storage device; and

driving a refrigeration cycle of a refrigeration system with energy provided by a first source of energy and with thermal energy from the fuel cell.

15. A method as in claim 14 further comprising changing an energy ratio between the energy provided by the first source of energy and the thermal energy responsive to a variable associated with the first source of energy.

16. A method as in claim 15 wherein the variable is the energy cost of the energy from the first source of energy, wherein the changing comprises reducing the energy ratio when the energy cost of the energy from the first source of energy increases.

17. A method as in claim 15 wherein the variable is the energy cost of the energy from the first source of energy, wherein the changing comprises reducing the energy ratio when the energy cost of the energy from the first source of energy exceeds a predetermined high cost level.

18. A method as in claim 15 wherein the first source of energy is the energy storage device and the changing comprises reducing the energy ratio when a charge level of the energy storage device reaches a predetermined low charge level.

19. A method as in claim 14 further comprising operating the refrigeration system and the fuel cell with an energy management system to control a building temperature, and changing, by the energy management system, an energy ratio between the energy provided by the first source of energy and the thermal energy responsive to a variable associated with the first source of energy.

20. A method as in claim 19 wherein the first source of energy is an electrical power grid, further comprising, by the energy management system, reducing the ratio when an energy cost of the electrical energy from the electrical power grid exceeds a predetermined kilowatt-hour cost.