Carrier Corporation

Thomas J Dobmeier

Michael F Taras

Alexander Lifson

Kevin J Porter

Garret J Malone

Ruddy C Bussjager

Peter H Kopp

Howard H Fraser, Jr

Thierry Jomard

Dennis R Penge

Mark R Rabbia

Mark B Rabbia

Howard Fraser

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.

Control scheme for multiple operating parameters in economized refrigerant system

A refrigerant system is provided with a variable speed drive for at least one of its fluid-moving devices, wherein the variable speed drive is provided by an automated mechanical drive. In the disclosed embodiment, one of the pulleys for driving the fluid-moving device has a variable diameter to vary the speed at which the fluid-moving device is driven. The pulley may include two plates that are biased in one direction by a spring or permanent magnet force, and in an opposed direction by a hydraulic or electro-magnetic force. A control adjusts the amount of hydraulic or electro-magnetic force delivered to the plates to achieve a desired speed for the fluid-moving device.

Automated drive for fan and refrigerant system

An inventive method of preventing unpowered reverse rotation in a compressor includes the steps of placing a solenoid valve at a location near compressor discharge. The valve is preferably actuated soon after the power to the motor is cut off, blocking the flow of refrigerant from expanding back toward the compression chambers of the compressor. The compressor is disclosed as a scroll compressor, but may also be a screw compressor. These two types of compressors are susceptible to undesirable unpowered reverse rotation when compressed refrigerant re-expands through the compression elements from the compressor discharge into the compressor suction. By blocking the flow of refrigerant, this unpowered reverse rotation is prevented. A high pressure switch can be positioned directly upstream of the solenoid valve to immediately stop the compressor if the valve malfunctions and blocks the flow of refrigerant during normal compressor operation. This high pressure switch will prevent the continued operation of the compressor with the blocked discharge line by sending a signal to a control to cut the power to the compressor motor. A pressure differential switch can be utilized in a similar manner to avoid undesirably high pressure differentials across the valve. Also, the valve itself may be equipped with the flow bypass that opens when pressure differential across the valve exceeds a safe limit.

Valve for preventing unpowered reverse run at shutdown

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.

Flash tank for heat pump in heating and cooling modes of operation

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.

Fluid diode expansion device for heat pumps

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.

Refrigerant subcooling by condensate

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.

Refrigerant system with controlled refrigerant charge amount

A refrigerant system is operable in either a heating mode or cooling mode. The system is also provided with an economizer cycle that will function in either heating mode or cooling mode. A pair of economizer heat exchangers are positioned adjacent to an air conditioning economizer expansion device, and a heat pump economizer expansion device, respectively. A control for the system will control the opening either the air conditioning economizer expansion device or the heat pump economizer expansion device, dependent on whether economized operation is desired, and whether the system is in cooling or heating mode. Thus, a pair of heat exchangers are utilized, with one being selected for economizer operation dependent on whether the system is in cooling or heating mode.

Dual economizer heat exchangers for heat pump

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.

Refrigerant system pressure control for storage and transportation

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.

Monitoring refrigerant charge

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.

Control of multi-circuit economized system

An air conditioning or refrigeration system includes an expansion device that has a plurality of operating positions. When the expansion device is in a fully open position, the expansion device provides an indication to a system controller regarding that position. The controller responsively determines if the fully open position of the expansion device is caused by an undesirably low amount of refrigerant charge in the system. In one example, the controller rules out other possible reasons for the expansion device being in the fully open position. In one example, the controller automatically shuts down appropriate portions of the system to avoid any component damage that may result from having too low refrigerant amount in the system.

Expansion device with low refrigerant charge monitoring

A method for operating a vapor compression system includes the steps of providing a vapor compression system having a compressor circuit including a compressor having an inlet port and an outlet port, a circuit incorporating the compressor, a condenser, an evaporator and an expansion device for sequentially generating a cooling refrigerant for cooling a stream of air so as to provide a dehumidified cooled stream of air, and a reheat refrigerant for heating the dehumidified cooled stream of air to provide a reheated dehumidified stream of air; controlling discharge pressure from the compressor outlet so as to increase discharge pressure from the compressor outlet. Furthermore, system dehumidification performance is improved in terms of latent capacity boost, undesired sensible capacity reduction, latent efficiency enhancement, and recovery of supply air temperature to a desired level.

Control scheme and method for dehumidification systems at low ambient conditions

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.

Refrigerant cycle with tandem economized and conventional compressors

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.

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Phoenix, NY, United States of America

Thomas J Dobmeier