Abstract: A heat pump design with an economizer flash tank provides an efficient way to operate the system in both heating and cooling modes. Various expansion device types can be employed with this design. The invention enhances system performance in both cooling and heating modes of operation, through utilization of the flash tank economizer cycle, in simplistic and cost effective manner, while sustaining expansion device and entire system functionality through an appropriate refrigerant rerouting around the compressor and the flash tank.

Abstract: Refrigerant system schematics are provided with enhanced humidity and temperature control of the air supplied to an environment to be conditioned. In particular, an economizer cycle is incorporated to be utilized in a combination with a reheat coil. Proposed system configurations enhance system performance characteristics, offer more steps of unloading, especially in the reheat mode of operation, and operate at improved reliability. Additionally, due to the enhanced performance of the economizer cycle, the reheat coil size can be reduced.

Abstract: Various refrigerant system schematics incorporate the ability to bypass refrigerant around a condenser, to selectively provide refrigerant of a desired thermodynamic state to downstream system components, including a reheat coil located downstream of the condenser. In addition, the reheat coil may be utilized in combination, or independently from an economizer cycle, that is also incorporated into the system design. The economizer branch can be configured in a sequential or parallel arrangement relative to the reheat coil. Consequently, a wide spectrum of sensible and latent load demands can be satisfied. Furthermore, various schematics provide distinct benefits and flexibility in unloading and temperature and humidity control, also resulting in system performance and reliability enhancement.

Abstract: A refrigerant system incorporates at least two compressors that act in tandem to provide variable control over the refrigerant system performance. The tandem compressors can be of conventional or economized type and are configured for maximum performance utilization. Further, a reheat circuit can be incorporated into the refrigerant system at several different locations. The reheat cycle provides additional control over sensible and latent capacity of the refrigerant system, and is particularly advantageous when utilized in combination with the tandem compressors. As a result, multiple steps of unloading can be implemented in all operation regimes, the external load demands are satisfied with much greater precision, eliminating undesirable variations in temperature and humidity, system efficiency and reliability are augmented and equipment life-cycle cost is reduced.

Abstract: In disclosed embodiments of this invention, the main flow of refrigerant is subcooled by another refrigerant stream in an auxiliary heat exchanger. The auxiliary heat exchanger is either an economizer heat exchanger or a liquid-suction heat exchanger. In the case of the economizer heat exchanger, the smaller tapped portion of the refrigerant is returned into the intermediate compression stage. In the case of the liquid-suction heat exchanger, the refrigerant leaving the evaporator subcools the refrigerant in the main line as it leaves the condenser. In either case, the refrigerant approaching the evaporator is subcooled and greater cooling capacity is achieved. At the same time, the reheat function is provided by passing a stream of air over the auxiliary heat exchanger.

Abstract: Multi-circuit refrigerant systems are provided with better control over a dehumidification function. In one embodiment, system circuits have means of communication with each other through connecting lines and flow control devices operable on demand. In another embodiment, a single reheat heat exchanger is utilized for both circuits, ensuring heat transfer interaction between the circuits. In yet another embodiment, a control unit operates refrigerant circuits in such a way that if some circuits are in a reheat mode, the remaining circuits are either shut off or are in an enhanced reheat mode.

Abstract: A refrigerant cycle is provided with an economizer circuit. The amount of refrigerant passing through the economizer circuit can be gradually modulated by an expansion device whose position can be easily adjusted from fully open to fully closed or disengaged. In the past, economizer circuits have either been fully engaged or fully disengaged. Modulation of economizer flow allows for variable capacity operation. This improves unit operating efficiency, minimizes unit cycling and prevents compressor overloading at extreme of operating conditions. It also allows for head pressure and discharge temperature control.

Abstract: An air conditioning, heating or refrigeration system includes a controller that automatically determines if refrigerant amount is above or below the desired amount within the system. In one example, a sensor measures the temperature difference between sub-cooled liquid and saturated condensing temperature and provides information to the controller. The controller determines a variance between the measured and an expected value. If that variance exceeds a selected threshold, the controller automatically determines that the amount of refrigerant in the system is outside of an acceptable range.

Abstract: An expansion device for the heat pump applications consists of a flow resistance device that has a different resistance to refrigerant flow depending on the flow direction through this device. The flow resistance device has no moving parts so that it avoids the damage, wear and contamination problems of the moveable piston in the prior art. The flow resistance device is a fixed obstruction about which the fluid must flow when traveling through the expansion device.

Abstract: Multiple refrigerant circuits are operated in parallel, and each has an economizer cycle. One of the two circuits may have a greater capacity than the other. By controlling the two circuits to run in economized, conventional, bypassed, or economizer bypassed operation, the control is able to match demanded capacity. Moreover, by exercising similar technique, the control can provide better humidity control, can limit or maintain head pressure, and can avoid power consumption peaks.

Abstract: Refrigerant is circulated through a vapor compression system including a compressor, a condenser, an expansion device, and an evaporator. Cold condensate forms on the evaporator surfaces as the refrigerant accepts heat from an air stream. The cold condensate drips down from the evaporator coil and collects in a condensate pan. In one example, the cold condensate is directed into a condensate heat exchanger to subcool the refrigerant exiting the condenser. In another example, the refrigerant exiting the condenser flows through a refrigerant line located in the condensate pan. In another example, the cold condensate is sprayed on the refrigerant line exiting the condenser or on the subcooling portion of the condenser. By utilizing the condensate for further subcooling of the refrigerant, system capacity and efficiency are enhanced. Various control techniques and condensate flow methods are also disclosed.

Abstract: A hybrid dehumidification system includes a compressor, a condenser, an expansion device and an evaporator connected for flow of working fluid through a fluid circuit; a reheat coil positioned relative to the evaporator for heating at least a portion of a stream of air passing through the evaporator; and a working fluid directing system adapted to flow working fluid in at least two modes of operation selected from the group consisting of a standard cooling mode, a cooling and enhanced dehumidification mode; a dehumidification without substantial sensible capacity mode; a heating and dehumidification mode; and a dehumidification with variable sensible capacity mode.

Abstract: A refrigerant cycle is provided with tandem compressors. Only some of the multiple compressors are provided with an economized cycle, and an optional unloader valve for selectively returning flow from an economizer injection port back to suction. The present invention thus provides the economized operation capabilities and benefits for a refrigerant cycle having tandem compressors, without the complexity of providing separate economizer arrangement for each of the compressors.

Abstract: A refrigerant cycle includes economized tandem compressors. The refrigerant cycle is also provided with a common economizer circuit for all tandem compressors. Common manifolds communicate discharge, suction and economizer return flows within the refrigerant cycle to each of the tandem compressors. Also, an optional unloader function is provided for each of the compressors. Various arrangements allow enhanced operation control, improved system reliability and reduced equipment life-cycle cost.

Abstract: An air conditioning or refrigeration system includes an attached refrigerant receptacle associated with the system. During shipment or storage, the pressure within the system may exceed a selected threshold for the low pressure side. Under such circumstances, a pressure relief device automatically allows refrigerant to flow from the system into the attached receptacle, which brings the pressure within the system back to an acceptable level for the low pressure side. Various optional shutoff devices are disclosed that can be incorporated into the design to simplify receptacle removal or recycling.

Abstract: An actual superheat value in a refrigerant system is compared to an expected superheat level. If the actual superheat valve exceeds a certain predetermined value, this is an indication of refrigerant charge loss or a malfunctioning expansion device. In one example, the superheat valve is determined by comparing a difference between a saturated vapor temperature and an actual operating vapor temperature. The superheat determination can be made either at evaporator exit, economizer heat exchange exit or near the compressor discharge port.

Abstract: Several control algorithms reduce the likelihood of insufficient oil return to the compressor. One algorithm is useful in a multi-circuit refrigerant system. A control reduces the cooling capacity of one of the circuits if the number of compressor start/stop cycles becomes excessive. By reducing the capacity, the control will reduce the number of compressor start/stop cycles for a circuit. In this manner, the oil continues to circulate through the circuit, and is more efficiently returned to the compressor. Another problem area associated with a poor oil return back to the compressor is when there is low mass flow rate of refrigerant circulating through the system. Various ways of increasing the refrigerant mass flow rate are disclosed to ensure proper oil return to the compressor. Also, if oil return problems are likely due to an undesirably high oil viscosity at the vapor portion of the evaporator or suction line, then steps are taken to reduce oil viscosity.

Abstract: A refrigerant system has a controller associated with it that determines an equilibrium pressure when the system is inactive. The controller determines if the equilibrium pressure differs from an expected equilibrium pressure corresponding to a current ambient temperature and the selected refrigerant type. When the difference exceeds a selected threshold, the controller determines that the amount of refrigerant within the circuit is below a desired level. In one example, the controller provides an indication of a low charge amount. The disclosed technique allows early detection of refrigerant charge loss and differentiation between loss-of-charge and other failure modes. Consequently, system performance is enhanced, component damage is prevented, service interruptions and maintenance are reduced, exhaustive troubleshooting is avoided and potential exposure to refrigerant substances is minimized.

Abstract: A refrigerant cycle is disclosed having a number of compressors operating in tandem and supplying a compressed refrigerant to a refrigerant system. Discharge lines communicate a compressed refrigerant to a central discharge line for receiving flow from all tandem compressors. A control is operational to determine a number of compressors need to be operated or whether some compressors should be shutdown to satisfy load requirements. Shutoff valves are placed on discharge lines outwardly of the shell of the compressors. That can be shutdown during part load operation. These shutoff valves are closed when their associated compressors are stopped to prevent backflow of refrigerant from operating compressors through the shutoff compressor, and into the system suction side. Additionally, high pressure differential across the compressor internal discharge check valve is eliminated and the possibility of compressor flooding through a discharge line is reduced.

Abstract: An air conditioning system includes a supplemental storage container that allows for transferring refrigerant into or out of an air conditioning or refrigeration system based upon different operating conditions. In one example, a controller controls the operation of valves that selectively couple the storage container to the high pressure side or the low pressure side of the system. Depending on operating conditions, when it is desirable to increase an amount of refrigerant in the system, refrigerant is transferred from the storage container to the low pressure side of the air conditioning or refrigeration system. Under conditions where the amount of refrigerant in the system is above a desired amount, refrigerant can be transferred from the high side of air conditioning system to the storage container to bring the pressure within the system closer to the desired level.