Abstract: A refrigeration system includes a trailer refrigeration unit including a refrigerant circuit through which a refrigerant is circulated. The trailer refrigeration unit includes a condenser. A fuel cell is configured to generate electrical power for the trailer refrigeration unit. A coolant circuit includes a radiator configured to dissipate heat generated by the fuel cell. The condenser and the radiator are positioned such that each of the condenser and the radiator receives a flow of unconditioned ambient air.

Abstract: A refrigeration system (2) comprises a condenser/gas cooler (4), an intermediate expansion device (6) and a refrigerant collecting container (8); a normal refrigeration branch (10) connecting the refrigerant collecting container (8) to the condenser/gas cooler (4) said normal refrigeration branch (12) comprising a first expansion device (12), a first evaporator (14) and a compressor unit (16) of the normal refrigeration branch (10); a freezing branch (18) connecting the refrigerant collecting container (8) to the condenser/gas cooler (4), said freezing branch (18) comprising a second expansion device (20), a second evaporator (22), and a first compressor unit (24) and a second compressor unit (26) of said freezing branch (18), the first and second compressor units (24, 26) of the freezing branch (18) being connected in series.

Abstract: A method of sanitizing pipes, etc. in a hot water supply system includes the steps of normally heating water by driving water from a water storage tank, into a heat exchanger. Typically, a water pump is stopped once the water storage tank receives a particular percentage of hot water. However, when a sanitation mode is desired, the pump is not stopped, such that the water tank becomes all, or almost all, hot water. The hot water is then delivered to the pump, and from the pump to the heat exchanger. This hot water is thus operable to sanitize pipes and the pump.

Abstract: Refrigerant is circulated through an economized refrigeration system including a compressor, a gas cooler, a main expansion device, an economizer heat exchanger and an evaporator. After cooling, the refrigerant splits into an economizer flow path and a main flow path. Refrigerant in the economizer flow path is expanded to a low pressure and exchanges heat with the refrigerant in the main flow path in the economizer heat exchanger. The refrigerant in the main flow path is then expanded and heated in the evaporator and enters the compressor, completing the cycle. An accumulator positioned between the economizer heat exchanger and the compressor stores excess refrigerant in the system, regulating the amount of refrigerant in the system and the high pressure in the system. The amount of refrigerant in the accumulator is controlled by regulating the economizer expansion device.

Abstract: A water heater is provided by a refrigerant cycle, in which the gas cooler is utilized to heat the water. A drain is incorporated into a water circuit for draining all of the water outwardly of the circuit when the system is shut down. In a preferred embodiment, a water outlet of the gas cooler is at the vertically lowermost portion of the water circuit. A drain valve is placed in this vertically lowermost location such that the water can be easily drained.

Abstract: A heat pump, and in particular a heat pump for heating a hot water supply is provided with an improved defrost mode. The defrost mode is actuated to remove frost from an outdoor evaporator that may accumulate during cold weather operation. An algorithm for operation of the defrost mode is developed experimentally by seeking to maximize the heat transfer provided by the refrigerant. A heating system condition is experimentally related to the heat transfer capacity. One then maximizes the average heat transfer capacity to determine the optimum initiation point for the defrost mode. Further, protections are included into the defrost mode. When the heat pump is utilized to heat hot water, methods are provided to prevent the water that remains in the heat exchanger from becoming unduly heated. In one method, the water pump may be periodically operated to move the water.

Abstract: An energy-efficient heat pump water heating system determines whether to energize a heat pump by interpreting readings from one or temperature sensors based on two thresholds. The heat pump is energized if the detected temperature falls below a first threshold and de-energized when the detected temperature rises above a second threshold. The thresholds may correspond to outputs of two or more sensors. Using multiple temperature thresholds improves the temperature sensing capabilities of the system, thereby improving energy efficiency by matching heat pump operation with hot water demand more closely than previously known systems.

Abstract: A water heater is provided by a refrigerant cycle, in which the gas cooler is utilized to heat the water. A drain is incorporated into a water circuit for draining all of the water outwardly of the circuit when the system is shut down. In a preferred embodiment, a water outlet of the gas cooler is at the vertically lowermost portion of the water circuit. A drain valve is placed in this vertically lowermost location such that the water can be easily drained.

Abstract: A refrigerant cycle is provided with a single three-way service valve that is utilized for draining and adding refrigerant. In the prior art, a second two-way valve was used in combination with the three-way valve. The present invention simply drains the refrigerant, and does not need to return the refrigerant. The present invention is particularly well suited for use with an environmentally benign refrigerant such as CO2.

Abstract: An improvement to the oil supply grooves in connecting rods for compressors increases surface area in an upper bearing half. The upper bearing half transmits a force from a driveshaft to the connecting rod. The lower half of the connecting rod includes an oil supply groove that extends over the majority of a circumferential extent of a bearing surface in the lower half that contacts an eccentric. On the other hand, the inner surface of the upper half does not include any large oil supply groove such that the surface area between the upper half and the eccentric is maximized.

Abstract: An accumulator acts as a buffer to prevent over-pressurization of the vapor compression system while inactive. By determining the maximum storage temperature and the maximum storage pressure a system will be subject to when inactive, a density of the refrigerant for the overall system can be calculated. Dividing the density by the mass of the refrigerant determines an optimal overall system volume. The volume of the components is subtracted from the overall system volume to calculate the optimal accumulator volume. The optimal accumulator volume is used to size the accumulator so that the accumulator has enough volume to prevent over-pressurization of the system when inactive.

Abstract: Refrigerant is circulated through a vapor compression system including a compressor, a gas cooler, an expansion device, and an evaporator. When a sensor detects that frozen water droplets form on the evaporator, a valve positioned between the discharge of the compression and inlet of expansion device is opened. Refrigerant from the discharge of the compressor bypasses the gas cooler and enters the inlet of the expansion device. The high temperature refrigerant melts the frost on the evaporator. As the frost melts, the passage of the evaporator is opened to allow air to flow through the evaporator.

Abstract: A method of sanitizing pipes, etc. in a hot water supply system includes the steps of normally heating water by driving water from a water storage tank, into a heat exchanger. Typically, a water pump is stopped once the water storage tank receives a particular percentage of hot water. However, when a sanitation mode is desired, the pump is not stopped, such that the water tank becomes all, or almost all, hot water. The hot water is then delivered to the pump, and from the pump to the heat exchanger. This hot water is thus operable to sanitize pipes and the pump.

Abstract: A hot water heating system is utilized in conjunction with a refrigerant cycle such that the water is heated in an indoor heat exchanger associated with the refrigerant cycle. Water is delivered from a water source by a pump into a first heat exchanger. A refrigerant is compressed by a compressor and also delivered into the first heat exchanger. The hot refrigerant heats the water as desired by a user of the hot water system. A water softening device softens the water passing through the heat exchanger, such that calcification does not occur. Calcification is the build-up of scale by calcium leaving solution with the water and depositing itself onto hot surfaces, such as the heat exchanger surfaces. By providing the water softening device, the problem with calcification is largely eliminated such that the efficiency of the heat exchanger will be greatly increased.

Abstract: A method of detecting and diagnosing operating conditions for a heat pump water heating system includes the steps of monitoring system operating conditions and comparing actual operating conditions to predicted operating conditions. The predicted operating conditions are based on expected pressures and temperatures given current system inputs. A difference between the actual and expected values for refrigerant pressures and temperature outside a desired range provides indication of a fault in the system. The system controller initiates a prompt to alert of the need for maintenance and direct to potential causes.

Abstract: A transcritical vapor compression system includes a compressor assembly that includes an oil separator for separating oil from refrigerant. The oil separator is disposed between a motor and a compression chamber in a sub-critical portion of the vapor compression system. Oil emitted from the drive assembly attached to the motor is substantially removed from the refrigerant before entering the compression chamber of the compressor.

Abstract: A method of detecting and diagnosing operating conditions for a heat pump water heating system includes the steps of monitoring system operating conditions and comparing actual operating conditions to predicted operating conditions. The predicted operating conditions are based on expected pressures and temperatures given current system inputs. A difference between the actual and expected values for refrigerant pressures and temperature outside a desired range provides indication of a fault in the system. The system controller initiates a prompt to alert of the need for maintenance and direct to potential causes.

Abstract: A transcritical refrigeration system includes a compressor, a gas cooler, an expansion device, and an evaporator. Refrigerant is circulated though the closed circuit system. Preferably, carbon dioxide is used as the refrigerant. A fan moves outdoor air that exchanges heat with the refrigerant across the evaporator. The speed of the fan is regulated to regulate the evaporator pressure and to adapt the evaporator to different environmental conditions to achieve the optimal coefficient of performance. During high ambient conditions, the fan speed is decreased, decreasing the refrigerant mass flowrate in the system. The energy exchange per unit mass of the refrigerant in the gas cooler increases and the work of the fan decreases, increasing the coefficient of performance of the system. During low ambient conditions, the mass flowrate of the system is low and there is more heat transfer thermal resistance on the refrigerant side at the evaporator. The speed of the fan is lowered to decrease the work of the fan.

Abstract: A heat pump system includes a compressor, a heat rejecting heat exchanger, an expansion device, and a heat accepting heat exchanger. A storage tank stores the water that cools the refrigerant in the heat rejecting heat exchanger. A mechanical interface plate positioned between a hot water reservoir and a cold water reservoir in the storage tank reduces heat transfer between the hot water and the cold water. During a water heating mode, cold water from the cold reservoir flows into the heat sink to cool the refrigerant in the heat rejecting heat exchanger. As the water exchanges heat with the refrigerant, the water is heated in the heat sink, exits the heat sink, and flows into the hot reservoir of the storage tank. During a water discharge mode, the hot water in the hot reservoir is removed from the storage tank and flows into a hot water discharge. Cold water from a water source flows into the cold reservoir of the storage tank to refill the storage tank.

Abstract: A refrigerant cycle is provided with a control for an expansion device to achieve a desired compressor discharge pressure. The system operates transcritically, such that greater freedom over compressor discharge pressure is provided. The system's efficiency is optimized by selecting an optimum discharge pressure. The optimum discharge pressure is selected based upon sensed environmental conditions, and the expansion device is adjusted to achieve the desired compressor discharge pressure. A feedback loop may be provided to sense the actual compressor discharge pressure and adjust the actual compressor discharge pressure by further refining the expansion device. The system is disclosed providing heated water based upon a demand for a particular hot water temperature.