Abstract: An air conditioning system having a cooling mode and a free-cooling mode. The system having a refrigeration circuit having a compressor and a pump; a suction pressure sensor for measuring a suction pressure of the compressor; a discharge pressure sensor for measuring a discharge pressure of the compressor; a controller for selectively operating in the cooling mode by circulating and compressing a refrigerant through the refrigeration circuit via the compressor or operating in the free-cooling mode by circulating the refrigerant through the refrigeration circuit via the pump; and a recover-refrigerant sequence resident on the controller, the recover-refrigerant sequence being configured to pump the refrigerant in a portion of the refrigeration circuit not used in the free-cooling mode to remaining portions of the refrigeration circuit used in the free-cooling mode when the controller switches from the cooling mode to the free-cooling mode.

Abstract: In a refrigerating air conditioning system using refrigerant such as CO2 used in a supercritical area, a highly efficient refrigerating air conditioning system is provided by adjusting the amount of refrigerant in a radiator which contributes to the efficiency of the system stably and quickly. During heat utilizing operation, the superheat at the exit of an evaporator is controlled to a predetermined value by controlling the opening of an expansion valve provided on the upstream side of the evaporator, and an expansion valve is controlled so that the state of refrigerant in a connection pipe on the high-pressure side becomes a supercritical state. In this state, a flow rate control valve is controlled to change the density of the refrigerant stored in a refrigerant storage container and the amount of refrigerant existing in the radiator is adjusted.

Abstract: A refrigerant compressor assembly for a refrigeration circuit controls the temperature within a temperature controlled space. The refrigerant compressor assembly includes a first unloading valve, a first valve actuator, and a first valve control system that adjusts the first valve actuator via a pulse-width-modulated signal, a second unloading valve, a second valve actuator, and a second valve control system that adjusts the second valve actuator via a pulse-width-modulated signal. The refrigerant compressor assembly also includes a third unloading valve. The first valve actuator is coupled to the first and third unloading valves and controlled by the first valve control system. The unloading valves selectively allow or resist fluid flow from higher to lower pressure areas within the refrigerant compressor assembly.

Abstract: An energy efficient and highly versatile electrically-powered air conditioning and heating system for mobile vehicles. Multiple variable-speed compressors operate in series and parallel modes giving an exceptionally wide range of operating capacity making the system suitable for combined on-highway and no-idle use in trucks. In series mode, the single-stage compressors function like a two-stage compressors for increased energy efficiency. A unique power control and storage system has multi-voltage input and output capability without the use of DC-DC or DC-AC converters. A battery management system is incorporated which is compatible with all advanced battery technologies and offers cell-level charge and discharge control.

Abstract: A system and method of controlling a compressor rack having a plurality of variable capacity components is provided. A variable capacity component is selected from the plurality of variable capacity components as a designated variable capacity component. The designated variable capacity component is operated by varying a capacity of the designated variable capacity component. Each variable capacity component of the plurality of variable capacity components, except for the designated variable capacity component, is operated at a fixed capacity corresponding to one of a maximum and a minimum capacity of the variable capacity component.

Abstract: A compressor inlet pressure estimation apparatus for a refrigeration cycle system is disclosed. An electronic control unit 14 uses Tefin_lag(N) as an actual corrected temperature Tefin_AD(N) during a period Tp1 included in the timing t1 to t2. During a period Tp2 included in the timing t1 to t2, Tefin_fwd(N) is used as the actual corrected temperature Tefin_AD(N). Thus, a highly accurate corrected temperature Tefin_AD(N) can be determined over the on period (t1 to t2) of a compressor 2. In addition, Tefin_fwd(N) is used as the actual corrected temperature Tefin_AD(N) during the off period (t2 to 3) of the compressor 2. As a result, a highly accurate corrected temperature Tefin_AD(N) can be determined over the whole period including the on and off periods of the compressor 2. In this way, a highly accurate estimated value Ps_es(N) of the refrigerant inlet pressure of the compressor 2 can be determined.

Abstract: A heat pump system includes a first heat exchanger, a second heat exchanger in fluid communication with the first heat exchanger, a scroll compressor in fluid communication with each of the first and second heat exchangers, and a flash tank in fluid communication with each of the first and second heat exchangers and the scroll compressor. A first capillary tube is disposed between the first heat exchanger and an inlet of the flash tank and a first valve is disposed between the first heat exchanger and the first capillary tube to control refrigerant to the first capillary tube.

Abstract: Climatic test chamber (10) for carrying out a sequence of specified test cycles and cooled by means of at least a refrigerating circuit (100, 200, 410) including a variable-speed compressor (120, 210, 410). During the steps of the test cycles in which said chamber (10) is held at a minimum set temperature, the compressor (120, 210, 410) operates at the minimum rotating speed thereof and the refrigeration capacity is used to cool a cold storage medium. The cold stored by the cold storage medium is then recovered to subcool the refrigerant medium during the cooling-down steps in which the compressor (120, 210, 410) operates at the maximum rotating speed thereof.

Abstract: Methods of controlling air conditioning and HVAC units using a thermostat for a discrete-speed unit that include changing speed based on how long the unit operates at a particular speed. Speed may be increased if a unit operates for longer than a predetermined time at a particular speed, and speed may be reduced if the unit operated for less than a specific amount of time during the prior run. In different embodiments, single-stage thermostats may control units that operate at three speeds, and two-stage thermostats may control units that operate at three to five or more speeds. In addition, in some embodiments, outdoor coil temperature may be measured and considered in determining speed. Further, in some embodiments, maintaining continuous or repeated operation at a boost speed may be avoided. Energy savings and noise reduction may result.

Abstract: A system to equalize pressure connected to a compressor for use in HVAC&R system is provided. The system includes a component in fluid communication between a high pressure side and an intermediate pressure side of the compressor. The component is configured to permit flow of refrigerant between the high pressure side and the intermediate pressure side at least when the compressor is not in operation.

Abstract: A method of controlling compressor for refrigerator and apparatus thereof are disclosed to control an operation of the compressor by optimum efficiency by changing freezing capacity of the compressor. The apparatus controls a rotation direction of the compressor installed in the refrigerator and changes the freezing capacity of the compressor in accordance with the rotation direction of the compressor, thereby effectively controlling the operation of the compressor.

Abstract: In a refrigeration unit including a variable performance compressor driven by an inverter motor, a sensor is configured to detect a physical amount corresponding to a refrigerant pressure on the high-pressure side of a refrigerant circuit. A measured value of the physical amount is compared with a first reference value corresponding to a first predetermined pressure of the refrigerant and a second reference value corresponding to a second predetermined pressure lower than the first predetermined pressure. A protective operation can start if the comparison result indicates that an actual refrigerant pressure is higher than the first predetermined pressure. The performance of the compressor can be gradually lowered if the comparison result indicates that an actual refrigerant pressure is between the first predetermined pressure and the second predetermined pressure.

Abstract: The transcritical refrigeration system is provided with a main compressor and booster compressor that is made to operate in parallel with the main compressor only during pulldown conditions. A single, two stage compressor is provided with valving which is controlled so as to provide for the two stages operating in series in normal operation and for operating in parallel during pulldown conditions.

Abstract: The present invention relates to a method for controlling a vehicle air-conditioner, which can prevent undershoot of an evaporator by performing a maximum capacity control or controlling an discharge capacity of a compressor through the outputting of an discharge capacity control value of the compressor directly before the stop of the air conditioner, and can improve the pleasant feelings of the passengers by preventing delay of response, which converges into the target temperature of the evaporator due to the delay of the decrease of the temperature of the evaporator.

Abstract: A refrigerating device is provided which can improve COP when a required load is 50% of a maximum load or below. When the load required of a common evaporator is 50% or less, a control unit stops a second compressor and controls the volume of a first compressor. Accordingly, it becomes possible to improve COP when the required load is equal to or below 50% as compared to the case of controlling the first and second compressors simultaneously to a low volume.

Abstract: A method comprises monitoring an operating parameter of a refrigeration system that includes a first condensing unit having a first control module and a second condensing unit having a second control module, the first and second condensing units each having at least one compressor. The method also includes controlling, with the first control module, the at least one compressor of the first condensing unit based on the monitoring. The method also includes controlling, with the first control module, the at least one compressor of the second condensing unit based on the monitoring. The first control module controls the at least one compressor of the second condensing unit by communicating with the second control module via a communication link.

Abstract: A refrigerant cycle is provided with a multi-port compressor or compressor stages connected in series, and multiple condensers. A single evaporator communicates with the plurality of condensers. At least one of the plurality of condensers receives fully compressed refrigerant while the other condensers receive refrigerant at intermediate pressure. A control can optionally direct refrigerant to the condensers to achieve desired system heat rejection characteristics and operating conditions. One or multiple reheat coils may be associated with the evaporator and are arranged either in series or in parallel to provide a desired dehumidification function and reheat stages. One or several of the intermediate pressure condensers may be utilized for the reheat function as well.

Abstract: The invention provides a refrigeration system with a compressing unit, and a method of controlling a refrigeration system. To facilitate a better control, the capacity of the compressing unit is controlled based on a predicted future cooling demand rather than an actually determined cooling demand. The invention further provides a system wherein a cost value for changing the cooling capacity of the system is taken into consideration.

Abstract: A stability control algorithm is provided for a centrifugal compressor. The stability control algorithm is used to control a variable geometry diffuser and a hot gas bypass valve (when provided) in response to the detection of compressor instabilities. The stability control algorithm can adjust the position of a diffuser ring in the variable geometry diffuser in response to the detection of a surge condition or a stall condition. The diffuser ring in the variable geometry diffuser can be adjusted to determine an optimal position of the diffuser ring. The stability control algorithm can also be used to open a hot gas bypass valve in response to the detection of continued surge conditions.

Abstract: A scroll compressor is provided with injection tubes which extend through an upper shell and into a fixed scroll member. The injection tubes are fixed relative to the fixed scroll member, and may be press-fit or otherwise secured. This arrangement simplifies the provision of injection ports into a scroll compressor.

Abstract: A system for controlling a centrifugal gas compressor (108) in an HVAC, refrigeration or liquid chiller system (100) in which flow of gas through the compressor is automatically controlled to maintain desired parameters within predetermined ranges so as to prevent stall and surge conditions within the system. A variable geometry diffuser (119) in the compressor controls the refrigerant gas flow at the discharge of the compressor impeller wheel (201). This arrangement reduces mass flow, decrease/eliminate flow-reducing stall, and increases the operating efficiency of the compressor at partial load conditions. The variable geometry diffuser control in combination with a variable speed drive (VSD) (120) increases the efficiency of the compressor at partial system loads, and eliminates the need for pre-rotation vanes at the inlet of the centrifugal compressor.

Abstract: A refrigeration system comprises a plurality of compressors and a plurality of condensing units comprising a first condensing unit having a first control module and at least one additional condensing unit having an additional control module. Each condensing unit has at least one compressor of the plurality of compressors. A communication link is connected to the first control module and at least one additional control module. The first control module controls the plurality of compressors based on communication with the at least one additional control module via the communication link.

Abstract: A system and method includes a compressor operable in a refrigeration circuit and including a motor, a current sensor detecting current supplied to the motor, a discharge line temperature sensor detecting discharge line temperature of the compressor, and processing circuitry receiving current data from the current sensor and discharge line temperature data from the discharge line temperature sensor and processing the current data and the discharge line temperature data to determine a capacity of the refrigeration circuit.

Abstract: A method for controlling a multi-unit air conditioning system adapted to cool or heat room spaces while passing a refrigerant in one direction or in a reverse direction is disclosed. In the method, which is applied to a multi-unit air conditioning system including at least three compressors, when a compressor re-operation is repeatedly carried out after all of the compressors have been turned off, to turn on again at least one of the compressors, repetition of the compressor re-operation is carried out for a predetermined number of different orders in such a manner that at least one of the compressors is turned on first in an associated order of the repeated compressor re-operation.

Abstract: An air conditioner having two compressors enables, when one compressor is started, the phase advance capacitor for the other compressor to be temporarily separated and used in parallel with the phase advance capacitor for the one compressor. These compressors can have an increased starting torque without using a starting capacitor.

Abstract: An air conditioner has a controller that controls the operation of a refrigerant circuit that has a compressor, a condenser, an expansion valve or orifice tube, and an evaporator. The condenser receives a compressed refrigerant from the compressor and condenses the refrigerant to either a liquid phase or a saturated liquid-vapor phase. The condensed refrigerant is then passed through the expansion valve or orifice tube to expand the refrigerant and to delivery the refrigerant to the evaporator. When the compressor is first started, various sounds and vibrations are created that may be unpleasant to humans. Also, if the engine is cold, then the compressor may have liquid refrigerant that can increase the torque needed to start the compressor. The controller pulses the compressor between ON and OFF operating states to reduce or eliminate these sounds and/or manage the start up torque of the compressor.

Abstract: What is disclosed is a system designed to extract water moisture from the atmosphere, highly purify and condition the extracted water, and provide optional carbonation of the extracted water for human consumption. In one embodiment, the device collects water-vapor condensation from filtered intake air, then subjects the condensate to a series of purification filters and to a sterilization process in order to produce drinking water, while also providing a means to combine the purified water with CO2 gas to facilitate dispensing carbonated water and/or carbonated drinks.

Abstract: A refrigeration system for a transport refrigeration unit and a method of operating the refrigeration system for cooling a temperature controlled cargo space are disclosed. The refrigeration system includes a primary refrigerant circuit including a refrigerant compression device, a motor for driving the compression device; a variable speed drive for varying the speed of operation of the compression device; and a controller operatively associated with the variable speed drive and the compression device. The controller controls the cooling capacity of the refrigeration system by selectively controlling the speed of said compression device in a first continuous run mode of operation and by selectively powering on and powering off said compression device in a first cycling mode of operation.

Abstract: A system and method of controlling components of a refrigeration system includes determining a desired rate of change of a refrigeration system operating parameter, using historical data to predict an expected rate of change of the operating parameter for cycling each component, calculating an appropriateness factor for each component corresponding to a difference between the expected rate of change for the component and the desired rate of change, ranking the components based on the appropriateness factor, and selectively cycling at least one component based on the ranking.

Abstract: A refrigeration device includes a switching valve control section for outputting a switching signal for controlling a four-way switching valve to a predetermined switching state when starting a compression mechanism; and a switching determination section which, when starting only a first compressor as a start-up of the compression mechanism, outputs a low differential pressure signal if a differential pressure between a high-pressure port and a low-pressure port in the four-way switching valve falls below a determination value in a determination operation after the switching signal being outputted by the switching valve control section. After the switching determination section outputs the low differential pressure signal, a capacity control section starts a second compressor.

Abstract: A capacity control algorithm for a multiple compressor liquid chiller system is provided wherein the speed and number of compressors in operation are controlled in order to obtain a leaving liquid temperature setpoint. In response to an increase in the load in the chiller system, the algorithm determines if a compressor should be started and adjusts the operating speed of all operating compressors when an additional compressor is started. In response to a decrease in the load in the chiller system with multiple compressors operating, the algorithm determines if a compressor should be de-energized and adjusts the operating speed of all remaining operating compressors when a compressor is de-energized.

Abstract: The present invention provides a configuration in which a compressor can be controlled using an inverter in an air conditioner where only a signal related to ON/OFF of the compressor is output from a control terminal. An operation controller for a compressor is configured so that the compressor can be controlled using an inverter based on an ON signal output from a control interface of an air conditioner. Specifically, a target value of at least one of an outlet air temperature, an evaporation temperature and a condensation temperature, and a suction pressure and a discharge pressure of the compressor is corrected according to a duration of the ON signal or a duration of the OFF state thereof, thereby controlling the frequency of the compressor.

Abstract: A method of controlling an air conditioning system of the type having a variable capacity compressor circulating refrigerant through a condenser, an expander, an evaporator and returning to the compressor. Sensors are disposed to sense a refrigerant condition selected from one of pressure and temperature on one or both the compressor high pressure and low pressure side; and, in the event of an overload condition, the sensors generate a control signal that effects operation of an actuator for moving a member in the compressor to vary the compressor capacity to the lowest capacity output. Alternatively, the generated control signal may vary the compressor speed.

Abstract: An air conditioner includes a fixed displacement-type first compression mechanism and a variable displacement-type second compression mechanism independent from each other in a refrigeration cycle, and further includes second compression mechanism displacement control means, compression mechanism operation switching control means, an evaporator for refrigerant, a condenser, a blower, evaporator temperature detection means, and evaporator target temperature calculation means. When the refrigeration cycle is operated only by the first compression mechanism, referring to a temperature (Teva) detected by the evaporator temperature detection means, a temperature (Toff) calculated by the evaporator target temperature calculation means and a predetermined value A, if a condition of Teva?Toff?A is satisfied, both compression mechanisms are operated simultaneously.

Abstract: Disclosed herein is an apparatus for controlling the capacity of an air conditioner and a control method using the same. The capacity control apparatus is configured in such a fashion that a 3-way or 4-way direction-switching member and a low-pressure equalizing solenoid valve are provided at a refrigerant path of the air conditioner having a pair of first and second compressors, so that the compression capacity of the air conditioner is adjusted into three stages of 100%, 60%, and 40% using the first and second compressors, enabling easy variable-capacity operation. This has the effect of considerably reducing energy consumption and of preventing wear of the first and second compressors via a rapid compensation of a pressure unbalance between both the compressors.

Abstract: A system and method in a commercial refrigeration system for compensating for events. A commercial refrigeration system includes a controller that predicts a first change in cooling capacity required based on at least one anticipated system event. The controller also predicts a second change in cooling capacity required based on at least one anticipated system event during a period of time. The controller compares the first and second changes in cooling capacity and implements a change in cooling capacity based on a relationship between the first and second changes in cooling capacity.

Abstract: A vehicle air conditioning system includes a pressure reducing device that is operatively coupled to a condenser downstream therefrom. An evaporator is operatively coupled to the pressure reducing device downstream therefrom. A refrigerant flow booster is operatively coupled to the evaporator downstream therefrom and a compressor is operatively coupled to the refrigerant flow booster downstream therefrom, the compressor also being operatively coupled to the condenser upstream therefrom. The refrigerant flow booster increases the flow of gaseous refrigerant to the compressor, in particular, when the compressor is operating at slower speeds.

Abstract: A system and a method for operating a variable-displacement compressor are provided wherein a volume of a compression chamber of at least one cylinder is varied during a compression cycle, wherein during the cycle the at least one cylinder is alternately coupled to a low pressure side and a high pressure side of the compressor. A first thermodynamic state of the low pressure side and a second thermodynamic state of the high pressure side can be estimated and a current compression ratio ( v in v out ) of the compressor can be estimated. Accordingly, a compressor displacement (D) as a function of the compression ratio ( v in v out ) can be calculated. From this, a compressor torque (M) depending on the calculated displacement (D) can be computed, and the compressor torque (M) can be provided to a control unit for operating the compressor or an engine coupled to the compressor.

Abstract: An apparatus for summing capacities of outdoor units in a multiple air conditioner comprises self-capacity storage devices mounted in outdoor units, respectively, for storing self-capacities of the outdoor units and outputting the self-capacities of the outdoor units when necessary, an outdoor unit capacity summing part mounted in one outdoor unit of the outdoor units for receiving the capacities of the outdoor units outputted from the respective self-capacity storage devices to calculate the total capacity of all the outdoor units, and a control device for receiving the result of the calculation performed by the outdoor unit capacity summing part to control the operation of the multiple air conditioner. The possibility of incorrect input of the capacities of the outdoor units is eliminated, and therefore, more accurate control of the multiple air conditioner is accomplished.

Abstract: Multi-type air conditioner including a plurality of compressors, a plurality of temperature sensors mounted in the plurality of compressors for sensing temperatures in the compressors respectively, and an equalizing pipe in communication with the plurality of compressors, for uniform distribution of oil among the plurality of compressors according to the temperatures sensed at the plurality of temperature sensors respectively, thereby distributing oil among the compressors uniformly at an exact time point at which the oil is distributed among the compressors non-uniformly, not only to permit improvement of the performance of the compressors, but also to permit improvement performance of the air conditioner having the compressors.

Abstract: To provide a refrigerating apparatus that can control the supercooling degree of liquid refrigerant irrespective of changes in circulating refrigerant amounts in a refrigeration cycle, a refrigerating apparatus includes a refrigeration cycle having one or more compressors or inverter compressor, a condenser, an expansion valve, and an evaporator; a liquid introduction circuit that guides decompressed refrigerant obtained by extracting one part of high pressure liquid refrigerant from the refrigeration cycle and decompressing, to a supercooling heat exchanger provided in the refrigeration cycle to perform heat transfer between the decompressed refrigerant and high pressure liquid refrigerant, and then introduces the refrigerant into refrigerant for intake into the compressors or inverter compressor or an intermediate pressure part of these compressors; a controller controlling shutdown of the compressors or driving frequencies of the inverter compressor based on suction pressure detection values with respect t

Abstract: An air conditioning system and control method to allow individual zone thermostats to directly control a variable capacity compressor and adaptively adjust the indoor supply air volume to meet zoning demands, without using static pressure or flow sensors or entering a set of pre-defined air flow values for each zone into a controller. The method controls an air conditioning system that is able to receive signals or commands from individual zone thermostats and give priority to a highest demand zone/thermostat. For example, a priority thermostat can be used to directly control the variable capacity compressor via an indoor controller and outdoor controller.

Abstract: An exemplary computer system includes an enclosure, a cage, a plurality of floppy disk drives, hard disk drives, and optical disk drives received, a system power supply, and a plurality of vibration absorbers. The enclosure includes a bottom wall. The cage is attached to the bottom wall of the enclosure and receives the disk drives, the hard disk drives, the optical disk drives and the system power supply therein. The vibration absorbers are disposed between the bottom wall of the enclosure and the cage.

Abstract: A multi-stage compressor is provided that reliably prevents liquid compression in a higher stage compression mechanism and also prevents compression efficiency degradation resulting from overheating of injection refrigerant and from the lubricating oil being raised up together with the injection refrigerant. An injection circuit is branched into a plurality of circuits. A first circuit thereof is communicatively connected to an inside space of a closed housing that is at the same side as the higher stage compression mechanism with respect to an electric motor, and a second circuit is communicatively connected to an inside space of the closed housing that is opposite from the higher stage compression mechanism with respect to the electric motor. The first circuit and the second circuit are provided with a switching mechanism for switching the injection circuit to the first circuit or the second circuit according to the dryness of the injection refrigerant.

Abstract: A pulse width modulation control is provided for a suction valve located on a suction line. When the flow rate through a refrigerant system needs to be reduced, the suction valve is rapidly cycled from an open position to a closed position. A bypass line connecting compressor discharge to compressor suction with a bypass valve and a discharge valve positioned on the discharge side of the compressor are also provided. When the control closes the suction valve, it also closes the discharge valve to prevent the refrigerant to backflow into the bypass line, and, at the same time, the control opens the bypass valve. Opening of the bypass valve reduces discharge pressure, leading to reduction in compressor power consumption and subsequent operating efficiency gain.

Abstract: A capacity control algorithm for a multiple compressor liquid chiller system is provided wherein the speed and number of compressors in operation are controlled in order to obtain a leaving liquid temperature setpoint. In response to an increase in the load in the chiller system, the algorithm determines if a compressor should be started and adjusts the operating speed of all operating compressors when an additional compressor is started. In response to a decrease in the load in the chiller system with multiple compressors operating, the algorithm determines if a compressor should be de-energized and adjusts the operating speed of all remaining operating compressors when a compressor is de-energized.

Abstract: A variable capacity automotive refrigerant compressor is provided with a pressure equalization passage between the crankcase volume and the suction passage in the manifold to prevent a pressure imbalance between the two that could otherwise cause a reduction in crankcase lubricant retention during extended periods of system inactivity.

Abstract: A sub-engine (30), a compressor (40) driven by the sub-engine (30), and a refrigeration circuit (70) connected to the compressor (40) and operable in a vapor compression refrigeration cycle are provided, and the interior of a refrigerator (13) of a refrigerated vehicle (10) is cooled. A rotational speed control unit (91) for linearly controlling fluctuations in the rotational speed of the sub-engine (30) such that the refrigeration capacity grows or declines in response to a refrigeration load is provided. A battery (51) for storing electric power and an electric generator (50) for generating electric power by the rotational drive of the refrigerating engine (30) to store the generated electric power in the battery (51) are provided. A fan motor (7a) for the refrigeration circuit (70) is selectively connectable to the electric generator (50) and the battery (51) such that power is fed from one of the electric generator (50) and the battery (51) to the fan motor (7a).

Abstract: A refrigeration system comprises a refrigerant circuit (10) in which a compressor (21), an outdoor heat exchanger (24) and an indoor heat exchanger (33) are connected to operate on a refrigeration cycle, and an oil recovery container (40) connected to the suction side of the compressor (21), and carries out a recovery operation for circulating refrigerant through the refrigerant circuit (10) to recover oil into the recovery container (40). The refrigeration system further comprises: a compressor control section (50) for stepwise increasing the operating capacity of the compressor (21) in an initial stage of the recovery operation so that the refrigerant temperature in the low pressure side of the refrigerant circuit (10) reaches or exceeds a predetermined value; and a fan control section (70) for continuously driving an indoor fan (33a) at least during a time period when the compressor (21) is driven.

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.