Abstract: Auxiliary refrigeration system used to refrigerate a wind turbine's gearbox (10) when the main refrigeration system (20) is inoperative due to low outside temperatures. The auxiliary equipment (30) is installed inside the nacelle and comprises a pressure limiting valve (31), an exchanger and a motor fan (M), all of them connected to a control cabinet that activates or deactivates the auxiliary refrigeration equipment (30) based on the exterior temperature Text, the temperature of the refrigerant at the outlet of the main circuit Tsc, and the gearbox temperature Tm.

Abstract: In a refrigerant circuit (11), a compressor (20) and an expander (30) are provided separately. An expander casing (34) is connected to a delivery pipe (26) of the compressor (20) and high pressure refrigerant passes through the inside of the expander casing (34). Therefore, the compressor casing (24) and the expander casing (34) are equalized in their internal pressure. An oil distribution pipe (41) for connection of an oil sump (27) of the compressor (20) and an oil sump (37) of the expander (30) is provided with an oil regulating valve (52). The oil regulating valve (52) is controlled in response to a signal outputted from an oil level sensor (51). When the oil regulating valve (52) is opened, the oil sump (27) within the compressor casing (24) and the oil sump (37) within the expander casing (34) fluidly communicate with each other whereby refrigeration oil travels through the oil distribution pipe (41).

Abstract: When during a heating operation the value calculated by an oil amount calculation section (51) is equal to or above a predetermined value, a frequency control section (52) of a controller (50) increases the operating frequency of a compressor (21) in order to recover refrigerating machine oil in a refrigerant circuit (R).

Abstract: A system has a compressor having a compression path between a suction port located to receive a working fluid and a discharge port located to discharge the working fluid. The system has means for controlling a flow of at least one of additional working fluid and lubricant responsive to changes in at least one pressure parameter.

Abstract: The compressor has a differential pressure type flow rate detector that obtains the pressure in an upstream passage and the pressure in a downstream passage to detect a refrigerant flow rate within a refrigerant passage. The detector has an accommodation chamber, and a partition body slidably accommodated within the accommodation chamber. The partition body comparts the accommodation chamber into a high pressure chamber to which the pressure in the upstream passage is introduced, and a low pressure chamber to which the pressure in the downstream passage is introduced. The compressor has an oil separator having an oil introduction passage connected to the oil separating chamber and a high pressure introduction passage introducing the pressure in the upstream passage to the high pressure chamber. The oil introduction passage introduces the oil separated from the refrigerant by the oil separator to a pressure zone other than a discharge pressure zone.

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: Disclosed is an apparatus and method for preventing liquid refrigerant accumulation in an accumulator of an outdoor unit of an air conditioner. The method includes the steps of: determining a state of a compressor; if the compressor is in standby mode or off state, turning on a four-way valve; determining whether the state of the compressor in standby mode or off state continues longer than a predetermined amount of time; and if the state of the compressor continues longer than the predetermined amount of time, closing an expansion valve. Particularly, high-pressure refrigerant flows in the closed expansion valve while low-pressure refrigerant flows in a check valve through the four-way valve.

Abstract: A controller reduces a rotational speed of a Rankine cycle from a predetermined normal rotational speed during an operation of a compressor in a predetermined state when the controller determines that a predicted refrigerant flow quantity, which is predicted by assuming that the compressor is operated in a sole operation of the Rankine cycle at the predetermined normal rotational speed of the Rankine cycle, exceeds a predetermined flow quantity. The predetermined state is a state that satisfies a predetermined condition, which relates to the sole operation of the Rankine cycle.

Abstract: In a refrigerant circuit (11), a compressor (20) and an expander (30) are provided separately. An expander casing (34) is connected to a delivery pipe (26) of the compressor (20) and high pressure refrigerant passes through the inside of the expander casing (34). Therefore, the compressor casing (24) and the expander casing (34) are equalized in their internal pressure. An oil distribution pipe (41) for connection of an oil sump (27) of the compressor (20) and an oil sump (37) of the expander (30) is provided with an oil regulating valve (52). The oil regulating valve (52) is controlled in response to a signal outputted from an oil level sensor (51). When the oil regulating valve (52) is opened, the oil sump (27) within the compressor casing (24) and the oil sump (37) within the expander casing (34) fluidly communicate with each other whereby refrigeration oil travels through the oil distribution pipe (41).

Abstract: An apparatus for optimizing an efficiency of a refrigeration system, comprising means for measuring a refrigeration efficiency of an operating refrigeration system; means for altering a process variable of the refrigeration system during efficiency measurement; and a processor for calculating a process variable level which achieves an optimum efficiency. The process variables may include refrigerant charge and refrigerant oil concentration in evaporator.

Abstract: The present invention relates to a method for controlling an air conditioner, in which operation time periods of an outdoor unit is integrated, to determined a time point when an oil recovery operation is performed, and performing the oil recovery operation only when a summed rates, or a number of indoor units accessed with communication is higher than a value preset at a control unit.

Abstract: A multiple path fluid circuit comprising a fluid reservoir and a fluid pump having an inlet in fluid communication with the fluid reservoir. The fluid pump may have an outlet in fluid communication with an inlet of a fluid cooling circuit. The fluid cooling circuit may then have an outlet in fluid communication with the fluid reservoir. The outlet of the fluid pump may also be in fluid communication with an inlet of a lubrication circuit, which may be in fluid communication with a delivery system capable of supplying a fluid to a moving component or to a component in contact with the moving component. A gas turbine engine comprising a multiple path fluid circuit is also disclosed as well as a method of utilizing a multiple path fluid circuit.

Abstract: An air conditioner including an outdoor unit including a first compressor and a second compressor connected in parallel to the first compressor, an outdoor unit connected in parallel to the outdoor unit, the outdoor unit including a first compressor and a second compressor connected in parallel to the first compressor, the outdoor units being connected in parallel to indoor units, the compressors being connected by first-compressor oil equalizing tubes and second-compressor oil equalizing tubes to feed surplus oil in the compressors, the oil equalizing tubes being connected by an external oil equalizing tube, wherein oil equalization is performed by collecting lubricant oil in the first compressor of the outdoor unit, pressurizing the collected lubricant oil by a discharge pressure of another compressor connected in parallel to the first compressor in the same outdoor unit, that is, the second compressor, and feeding the pressurized lubricant oil into the first compressor or second compressor of the other out

Abstract: There is provided a rotary compressor capable of preventing deterioration of performance following plug fixing carried out to prevent falling-off of a spring member. The rotary compressor comprises a cylinder constituting a rotary compression element, a roller engaged with an eccentric portion formed in a rotary shaft of an electric element, and eccentrically rotated in the cylinder, a vane abutted on the roller to divide an inside of the cylinder into a low pressure chamber side and a high pressure chamber side, a spring member for always pressing the vane to the roller side, a housing portion of the spring member, formed in the cylinder, and opened to the vane side and a hermetically sealed container side, a plug positioned in the hermetically sealed container side of the spring member, and inserted into the housing portion to fit into a gap, and an O ring attached around the plug to seal a part between the plug and the housing portion.

Abstract: An apparatus and a method for controlling oil of a multi-compressor installed in an air conditioner includes a microcomputer for sequentially stopping compressors installed in the air conditioner for a preset time and then sequentially operating the compressors when the preset time elapses; and oil pipes connected to the compressors and balancing oil in the compressors, so that damage of the compressors due to imbalance of refrigerating machine oil is prevented by uniformly dividing oil of a multi-compressor installed in the air conditioner.

Abstract: An apparatus for optimizing an efficiency of a refrigeration system, comprising means for measuring a refrigeration efficiency of an operating refrigeration system: means for altering a process variable of the refrigeration system during efficiency measurement: and a processor for calculating a process variable level which achieves an optimum efficiency. The process variables may include refrigerant charge and refrigerant oil concentration in evaporator.

Abstract: An apparatus for optimizing an efficiency of a refrigeration system, comprising means for measuring a refrigeration efficiency of an operating refrigeration system; means for altering a process variable of the refrigeration system during efficiency measurement; and a processor for calculating a process variable level which achieves an optimum efficiency. The process variables may include refrigerant charge and refrigerant oil concentration in evaporator.

Abstract: The object of the present invention is to provide a method of operating a refrigeration cycle which is capable of preventing oil from staying in an evaporator and ensures high coefficient of performance as well as sufficient circulation of oil. An electronic expansion valve is controlled such that during normal operation, refrigerant is always in a superheated state at the outlet of an evaporator, and the refrigerant is periodically forced to have negative superheat for a predetermined time by a superheat control device. Thus, during normal operation, the refrigerant sucked into a variable displacement compressor always has superheat, whereby the refrigeration cycle can operate with high coefficient of performance and an engine driving the variable displacement compressor can be operated at high fuel efficiency. Also, the refrigerant is temporarily controlled so as to have negative superheat.

Abstract: Disclosed is a refrigerating apparatus using a temperature sensitive expansion valve (46) as an expansion mechanism. In the refrigerating apparatus, a switching valve (7a) is disposed on the upstream side of an evaporator (45). The switching valve (7a) is closed for a while, thereby forcibly placing an outlet side of the evaporator (45) in the superheat state to increase the valve travel of the expansion valve (46). Thereafter, the switching valve (7a) is opened for liquid refrigerant to flow through the evaporator (45) so that a wettish operation is carried out. As a result of such arrangement, refrigerating machine oil that has accumulated in the evaporator (45) is reclaimed and returned to a compression mechanism (2D).

Abstract: A dual evaporator air conditioning system and method for use therewith to cool air in front and rear portions of a cabin of a vehicle. The dual evaporator air conditioning system includes primary and auxiliary HVAC units to cool the air in the front and rear portions of the cabin, respectively. The dual evaporator air conditioning system also includes a control system having cooling and non-cooling modes for each of the HVAC units. The control system automatically activates a heating element near the auxiliary evaporator in response to the auxiliary HVAC unit being in the non-cooling mode while the primary HVAC unit is in the cooling mode. The heating element heats the refrigerant in the auxiliary evaporator to prevent accumulation of liquid refrigerant and lubricating oil in the auxiliary evaporator when the auxiliary HVAC unit is in the non-cooling mode while the primary HVAC unit is in the cooling mode.

Abstract: A refrigeration circuit (1) sequentially connected to a compressor (10), a condenser (11), an electric expansion valve (13), an evaporator (17), and an intake proportional valve (21). When the freezing capability of the refrigeration device is to be suppressed, a control means (30) will restrict the intake proportional valve (21) in order to place refrigerant in a discharge side of the evaporator (17) in a wet saturated steam state, and the electric expansion valve (13) will be set to an aperture such that the refrigerant in the interior of the evaporator (17) will be placed in the wet saturated steam state.

Abstract: Disclosed is a refrigerating apparatus using a temperature sensitive expansion valve (46) as an expansion mechanism. In the refrigerating apparatus, a switching valve (7a) is disposed on the upstream side of an evaporator (45). The switching valve (7a) is closed for a while, thereby forcibly placing an outlet side of the evaporator (45) in the superheat state to increase the valve travel of the expansion valve (46). Thereafter, the switching valve (7a) is opened for liquid refrigerant to flow through the evaporator (45) so that a wettish operation is carried out. As a result of such arrangement, refrigerating machine oil that has accumulated in the evaporator (45) is reclaimed and returned to a compression mechanism (2D).

Abstract: A system for reclaiming oil from a combined refrigerant/oil liquid mixture at an evaporator takes a tap of discharge pressure refrigerant from a screw compressor. This hot refrigerant is utilized to boil off refrigerant in the combined liquid refrigerant/oil mixture in a vaporizer. The separated oil is returned to an oil sump and utilized to lubricate the compressor. The tapped discharge pressure refrigerant can be tapped from two distinct locations, and each of these taps receives a valve. The two valves are controlled based upon system conditions. The two valves are selectively opened and closed to provide the hottest temperature refrigerant to the vaporizer to achieve the maximum separation efficiency.

Abstract: A system for reclaiming oil from a combined refrigerant/oil liquid mixture at an evaporator takes a tap of discharge pressure refrigerant from a screw compressor. This hot refrigerant is utilized to boil off refrigerant in the combined liquid refrigerant/oil mixture in a vaporizer. The separated oil is returned to an oil sump and utilized to lubricate the compressor. The tapped discharge pressure refrigerant can be tapped from two distinct locations, and each of these taps receives a valve. The two valves are controlled based upon system conditions. The two valves are selectively opened and closed to provide the hottest temperature refrigerant to the vaporizer to achieve the maximum separation efficiency.

Abstract: A highly reliable refrigeration cycle having a residual refrigerant, which is designed that the refrigerating machine oil does not stagnate in the refrigeration cycle after flowing out from the compressor even if the refrigerating machine oil is weakly soluble in a refrigerant. Thus, the compressor may be prevented from the exhaustion of oil. In addition to that, even if the accumulator is removed from the cycle, a large amount of wet vapor suction into the compressor may also be avoided. A control section is provided for controlling saturated oil solubility in a liquid refrigerant in the refrigeration cycle. The control section includes a receiver and first and second flow regulators which are placed before and after, respectively, the receiver. A residual liquid refrigerant obtaining in the circulation of a refrigerant is reserved in the receiver at a high temperature so that the weakly soluble refrigerating machine oil is prevented from separating.

Abstract: A refrigeration circuit (1) sequentially connected to a compressor (10), a condenser (11), an electric expansion valve (13), an evaporator (17), and an intake proportional valve (21). When the freezing capability of the refrigeration device is to be suppressed, a control means (30) will restrict the intake proportional valve (21) in order to place refrigerant in a discharge side of the evaporator (17) in a wet saturated steam state, and the electric expansion valve (13) will be set to an aperture such that the refrigerant in the interior of the evaporator (17) will be placed in the wet saturated steam state.

Abstract: An oil holding tank (40) is communicated to the case (10c) of the compressor (10). Part of the refigerant discharged from the compressor (10) is introduced into the oil holding tank (40) so that the lubrication oil (L) is allowed to flow out from the oil holding tank (40) and the lubrication oil (L) which flows out is allowed to return to the case (10c). The presence of the lubrication oil (L) is detected from a comparison between the temperature (TK1) of the refrigerant introduced from the compressor (10) to the oil holding tank (40) and the temperature (TK2) of the lubrication oil (4) flowing out from the oil holding tank (40). On the basis of the result of the detection, it is judged whether or not the amount of the lubrication oil (L) in the case (10c) is appropriate.

Abstract: This invention increases efficiency of a refrigeration system by maximizing the cooling of the condenser and reducing unnecessary work done by the compressor. In air cooled systems it will also increase the stability of the fans by reducing fan cycling. The fan controller will utilize an algorithm that will consider the following inputs: oil pressure, compressor suction pressure, expansion valve position, compressor loading, last compressor loading change, and current fan stage. The algorithm uses fuzzy logic to characterize the inputs and generates an output that controls the system cooling fans.

Abstract: This invention increases efficiency of a refrigeration system by maximizing the cooling of the condenser and reducing unnecessary work done by the compressor. In air cooled systems it will also increase the stability of the fans by reducing fan cycling. The fan controller will utilize an algorithm that will consider the following inputs: oil pressure, compressor suction pressure, expansion valve position, compressor loading, last compressor loading change, and current fan stage. The algorithm uses fuzzy logic to characterize the inputs and generates an output that controls the system cooling fans.

Abstract: An apparatus for optimizing an efficiency of a refrigeration system comprising means for measuring a refrigeration efficiency of an operating refrigeration system: means for altering a process variable of the refrigeration system during efficiency measurement: and a process for calculating a process variable level which achieves an optimum efficiency. The process variables may include refrigerant charge and refrigerant oil concentration in evaporator.

Abstract: A refrigerant fluid is placed within a driveline component, and in particular an axle housing. This refrigerant fluid is received within a sealed reservoir such that it is sealed from the typical lubricant in the driveline component. The lubricant heats the refrigerant through a housing such that the refrigerant vaporizes within the driveline component housing, thus cooling the lubricant. The vaporized refrigerant travels to a cooling chamber mounted remotely from the reservoir. The cooled refrigerant is cooled to a liquid state, and then returned to the reservoir. Preferably the cooling chamber is positioned on the vehicle frame vertically above the driveline component.

Abstract: A highly reliable refrigeration cycle having a residual refrigerant, which is designed that the refrigerating machine oil does not stagnate in the refrigeration cycle after flowing out from the compressor even if the refrigerating machine oil is weakly soluble in a refrigerant. Thus, the compressor may be prevented from the exhaustion of oil. In addition to that, even if the accumulator is removed from the cycle, a large amount of wet vapor suction into the compressor may also be avoided. A control section is provided for controlling saturated oil solubility in a liquid refrigerant in the refrigeration cycle. The control section includes a receiver and first and second flow regulators which are placed before and after, respectively, the receiver. A residual liquid refrigerant obtaining in the circulation of a refrigerant is reserved in the receiver at a high temperature so that the weakly soluble refrigerating machine oil is prevented from separating.

Abstract: The present invention relates to the art of refrigeration and more particularly to a method of regulating the cooling process by controlling the oil pressure in a compressor. The system prevents the accumulation of the liquid refrigerant in the crankcase of the compressor. The system allows a compressor to continue to work without interruption.

Abstract: A lubricant-refrigerant composition contained within a compression refrigeration system is disclosed which comprises (A) at least one fluorine-containing hydrocarbon refrigerant containing 1 to 3 carbon atoms, further wherein fluorine is the only halogen in said fluorine-containing hydrocarbon with the proviso that 1,1,1,2-tetrafluoroethane is not the sole refrigerant; and (B) at least one lubricant comprising (1) a hydrocarbyl substituted arene, (2) a phosphate ester, (3) an organic ester of a carboxylic acid and an alcohol, (4) a perfluoropolyethylene, (5) an ether; (6) a polyether; (7) a polyalphaolefin; or (8) a mineral oil; wherein at a temperature of above −60° C. a phase separation occurs such that at least two phases are formed, said phases being a refrigerant rich phase and a lubricant rich phase, further wherein the lubricant rich phase resides below the refrigerant rich phase.

Abstract: An injector for introducing a fluid composition into an air conditioning system is provided. The injector includes a pump including an internal volume having a first opening and a second opening, and a plunger which moves within the internal volume between a first position and a second position. The first opening includes a first valve for selectively allowing the fluid composition to flow from the internal volume as the plunger moves from the first position to the second position. The second opening includes a second valve for selectively allowing the fluid composition to flow into the internal volume as the plunger moves from the second position to the first position. A hose is provided having a first end connected to the first opening, and a second end constructed for attachment to a port on an air conditioning system. A cartridge including a fluid composition is provided fluidly connected to the second opening of the pump.

Abstract: A method for operating a motor vehicle air conditioner includes starting a compressor, and lubricating the compressor with a circulating lubricant for at least a specified minimum lubricating time.

Abstract: A conduit is coupled to an oil accumulator with an orifice coupled in series with the conduit for limiting the flow of oil therethrough. A pressure sensor is coupled to the conduit for measuring the pressure in the conduit. An oil drain control solenoid valve is coupled to an electrical circuit also coupled to the pressure sensor for selectively opening the oil drain for the draining of oil into a collection tank without losing refrigerant.

Abstract: Hot gas bypass of compressed fluid is accomplished using standard components of an oil separation circuit. In this method, an electronically controlled valve, which is selectively opened and closed for returning oil accumulated in the oil separator is also selectively opened when a determination is made that hot gas bypass is desired. This electronically controlled valve is placed in the oil separator return line. When the valve is opened, hot gas is bypassed from compressor outlet into compressor inlet through the oil separator.

Abstract: An assured supply of lubricant to the compressor in a refrigeration chiller is provided by a reservoir that is connected in parallel with the main line by which lubricant is supplied to the compressor. The reservoir is connected to the main lubricant supply line in a manner such that if the lubricant supply line is blown dry, as can occur as a result of an unusual or abnormal chiller shutdown condition, a critical portion of the supply line will be refilled by the reservoir relatively very quickly which assures the immediate availability of lubricant to the compressor from that portion of the lubricant supply line when it next starts up.

Abstract: An air conditioning equipment is provided with an oil level equalizing system, which includes a plurality of low-pressure shell-type compressors communicating with a suction line through a plurality of branch portions, a plurality of connecting lines each communicating with a corresponding compressor shell at a location adjacent to a normal oil level in the shell, and an oil level equalizing line communicating with the plurality of connecting lines. The oil level equalizing system also includes a communication line, through which the suction line communicates with the oil level equalizing line at a location upstream of the plurality of branch portions with respect to a direction of flow of a refrigerant. This arrangement functions to increase the pressure within the oil level equalizing line to a value higher than that within the shell of each compressor.

Abstract: An air conditioning apparatus includes a compressor, an interior side heat exchanger, an exterior side heat exchanger, an expansion device provided between the interior side heat exchanger and the exterior side heat exchanger, a four-way valve provided between the compressor and the interior side heat exchanger and between the compressor and the exterior side heat exchanger, an oil separator provided between a delivery outlet of the compressor and the four-way valve, a first restrictor and a second restrictor provided between the oil separator and a suction inlet of the compressor, and an open-close valve provided between the second restrictor and the suction inlet of the compressor.

Abstract: An air conditioner has an outdoor unit and a plurality of room units supplied with a refrigerant from the outdoor unit. The outdoor unit and the room units are connected by a plurality of refrigerant pipes. In a recovery operation for returning refrigerator oil from the room units, the refrigerant pipes and the like to the outdoor unit, the plurality of room units are divided into a plurality of room unit groups, and the recovery operation of the refrigerant is carried out for each of the room unit groups.

Abstract: In a refrigerant circulating apparatus, a liquid accumulating container for allowing oil droplets to flow out in suspended form is connected between a condenser and a pressure reducing device. Thus, refrigerating machine oil which flowed out from a compressor can be reliably returned to the compressor, and proper lubricating and sealing functions can be maintained for the compressing elements.

Abstract: An oil separator for an evaporator in a cooling system is installed between a capillary tube and the evaporator for separating oil from the refrigerant flowing into the evaporator. The oil separator comprises an inflow member connected to the capillary tube, for receiving the oil-containing refrigerant therefrom. A refrigerant outflow member is connected between the inflow member and an inlet of the evaporator, for conducting the refrigerant upward to the inlet of the evaporator. An oil outflow member is disposed between the inflow member and an outlet of the evaporator, for conducting the oil downward to an outlet of the evaporator. The oil separator prevents oil from flowing into the evaporator, thereby preventing accumulation of the oil inside the evaporator which could reduce the amount of oil disposed inside a compressor of the cooling system.

Abstract: In an accumulator constituting a refrigerating cycle apparatus, a high liquid-level auxiliary pipe (14a) and a low liquid-level auxiliary pipe (14b), which act as oil recovery pipes, and each of which is provided with a plurality of oil recovery holes (10a), are attached to a discharge pipe (12) in positions so as to be different vertically from each other, so that lubricating oil can be surely recovered through the oil recovery holes.

Abstract: In a multi story air conditioning system having elevated compressors and varying loads, a suction line oil return arrangement comprising dual parallel suction risers having a pressure relief valve positioned in one to ensure a minimum pressure drop for oil return in the other.

Abstract: An oil level regulator is provided for controlling the oil level in the crankcase of one or more refrigeration compressors or the like. The regulator has a closed chamber for containing the oil. An inlet valve assembly extends into the chamber and includes a float-controlled valve for introducing liquid into the chamber as necessary to maintain the oil level in the chamber and compressor crankcases. The inlet valve assembly includes a vertically telescoping piston for adjusting the float valve and the oil level regulator in the regulator chamber. The piston is moveable from outside the chamber in response to rotation of a concentric stem having a bore through which oil flows into the chamber. The float valve includes a lever bracket which extends horizontally across the chamber to contact a top of a float ball. The lever bracket pivots to cause side-to-side motion of a valve needle against a valve seat to control oil flow into the chamber.

Abstract: The invention resides in improvements to refrigeration systems which rely on circulation of refrigerant gas through compression and expansion phases, and thereby discharging heat from a fluid to be cooled. The invention includes a subcooler (38) in the refrigerant loop, downstream of the refrigerant condenser (34) and a gas trap (36) between the condenser (34) and the subcooler (38), that assures temperature drop in the subcooler (38). The invention also comprehends a shut-off valve (44) between the compressor and the heat source heat exchanger (28). The invention further includes a high capacity-to-volume oil to air heat exchanger (48), for cooling the lubricating oil in the oil loop (26). Preferred refrigerant is ammonia. Incorporating the above improvements into refrigeration systems enables an overall reduction in system sizing. Such systems, having heat exchange capacity of at least 200,000 Btu/hr., up to at least 500,000 Btu/hr.

Abstract: The invention resides in improvements to refrigeration systems which rely on circulation of refrigerant gas through compression and expansion phases, and thereby discharging heat from a fluid to be cooled. The refrigeration systems of the invention include a refrigerant loop (24) and a lubricating oil loop (26). The oil loop includes a high capacity-to-volume oil to air oil cooler (48), for cooling the lubricating oil in the oil loop (26). The oil cooler includes a fan, and a variable speed drive for controlling the speed of rotation of the fan. The Preferred refrigerant is ammonia. Incorporating the above improvements into refrigeration systems enables an overall reduction in system sizing, and constancy in the temperature of the oil at the exit of the oil cooler. Such systems, having heat exchange capacity of at least 200,000 Btu/hr., up to at least 500,000 Btu/hr.

Abstract: Each compressor in a circuit has an oil pump with excess capacity relative to lubrication requirements of the respective compressor. Excess capacity is diverted to a common line which connects to each of the compressors in the circuit through a float valve. Each float valve is operated responsive to the oil level in the associated compressor such that oil diverted as excess capacity is supplied to any compressor in the circuit short of oil.