Abstract: A refrigeration system and a lubricating method thereof. The refrigeration system (100) includes: a compressor (110), a condenser (120), an evaporator (130), and a lubrication circuit (200), the lubrication circuit including a post-lubrication flow path (230,240,260) connected from the compressor into the condenser and the evaporator respectively; and a pre-lubrication flow path (210,220,250) connected from the condenser and the evaporator into the compressor respectively; wherein after flowing from the condenser via the pre-lubrication flow path to the compressor for lubrication, a part of refrigerant for lubrication can flow back to the evaporator via the post-lubrication flow path; or after flowing from the evaporator via the pre-lubrication flow path to the compressor for lubrication, the part of refrigerant for lubrication can flow back to the condenser via the post-lubrication flow path.

Abstract: A system may include a first compressor, a second compressor, a first heat exchanger and a second heat exchanger. The first compressor has a first inlet and a first outlet. The second compressor is a sumpless compressor and has a second inlet and a second outlet. The second compressor provides working fluid discharged from the second outlet to the first compressor. The first heat exchanger is disposed upstream of the second compressor and provides working fluid to the second compressor. The second heat exchanger is disposed upstream of the first compressor and provides working fluid to the first compressor.

Abstract: A compressor with a touchdown bearing and a supply line for injecting a working fluid toward the touchdown bearing, and a vapor compression system incorporating the same are provided. The supply line injects working fluid approximately continuously when the compressor is operational. The compressor includes a magnetic bearing for levitating the rotating shaft when the compressor is operational. The touchdown bearing is used to support the rotating shaft when the compressor is shutdown. The touchdown bearing may be disposed, at least partially, between a pair of races. The injecting of the working fluid may cause the touchdown bearing to rotate between the races. The injecting of the working fluid may help mitigate a buildup of a debris between the touchdown bearing and the races.

Abstract: A cooling system drains oil from low side heat exchangers to vessels and then uses compressed refrigerant to push the oil in the vessels back towards a compressor. Generally, the cooling system operates in three different modes of operation: a normal mode, an oil drain mode, and an oil return mode. During the normal mode, a primary refrigerant is cycled to cool one or more secondary refrigerants. As the primary refrigerant is cycled, oil from a compressor may mix with the primary refrigerant and become stuck in a low side heat exchanger. During the oil drain mode, the oil in the low side heat exchanger is allowed to drain into a vessel. During the oil return mode, compressed refrigerant is directed to the vessel to push the oil in the vessel back towards a compressor.

Abstract: A refrigeration system includes a dedicated defrost-mode compressor that delivers high pressure, high temperature refrigerant to one or more evaporators to defrost the evaporators.

Abstract: A refrigerant replacement method for a refrigeration apparatus is intended to replace a first refrigerant charged into a refrigerant circuit of the refrigeration apparatus with a second refrigerant. The second refrigerant is used together with a refrigerating machine oil having a higher additive content by percentage than another refrigerating machine oil to be used together with the first refrigerant. The method includes: a refrigerant recovery step of recovering the first refrigerant from the refrigerant circuit; an oil charging step of additionally charging a refrigerating machine oil having a predetermined additive content by percentage into the refrigerant circuit; and a refrigerant charging step of charging the second refrigerant into the refrigerant circuit. The predetermined additive content by percentage is higher than the additive content by percentage of the refrigerating machine oil to be used together with the second refrigerant.

Abstract: An oil separator to separate oil from oil and refrigerant mixture. The oil separator includes inlets to allow entry of the oil and refrigerant mixture into the oil separator. The mixture flows and strikes on center of the one or more walls of the oil separator. The mixture then flows towards demister pads for filtration. The oil is separated from the mixture and exits the oil separator from the oil outlet. The refrigerant separated from the mixture escapes through the refrigerant outlet.

Abstract: A water-cooled heat exchanger with oil separator having integrated refrigerant distribution, the oil separator, including: an exterior shell having opposite end walls defining a first interior, and a first and second opening fluidly communicative with the first interior; a plurality of baffles operably coupled to and extending from at least a first opposite end wall, each baffle including a first support member generally parallel to a second support member, each operably coupled in a generally perpendicular orientation, to at least the first opposite end wall, and a crossmember operably coupled between a first and second support member, the crossmember having a width dimension that is less than the width of the first support member and the second support member, forming an orifice between the crossmember and the at least first opposite end wall; and a distributor integrated within the exterior shell to define a second interior within the first interior.

Abstract: A silencing device and a compressor having the silencing device are disclosed. The silencing device has a housing. An air inlet and an air outlet are provided to the housing. An air flow channel is provided in the housing for allowing air communication between the air inlet and the air outlet. An oil hole is provided in the housing for discharging oil from the housing. An oil guide part is arranged on the outside of the housing and at a position downstream of the oil hole in the moving direction of the oil, such that the oil drips from the housing after flowing from the oil hole to the oil guide part.

Abstract: An automatic oil level retention system for a compressor and a method for controlling a same, including: a normal oil return mode and an auxiliary oil return mode. When a lubricating oil liquid level monitored by a liquid level detection unit in real time is above a required liquid level height, the system initiates only the normal oil return mode; and when the lubricating oil liquid level monitored by the liquid level detection unit in real time is below the required liquid level height, the system initiates the auxiliary oil return mode, and the auxiliary oil return mode is closed and the normal oil return mode is initiated after the lubricating oil liquid level monitored in real time is lifted above the required liquid level height.

Abstract: The present invention provides a method for producing a refrigerating machine oil, comprising blending a hydrocarbyl hydrogen phosphite having an acid value of 100 mgKOH/g or less with a lubricating base oil or an oil composition containing a lubricating base oil, and a refrigerating machine oil obtained by the method.

Abstract: A rotary machine includes a rotor that includes an impeller cap that regulates the movement of an impeller fixed to a rotary shaft that extends in an axial direction about the axis; a housing that covers a rotor; and an inlet guide vane that has a plurality of movable blades that extend from the housing toward an inner side in a radial direction and disposed at intervals in a circumferential direction, in which a blade tip portion, which is a tip end of the movable blade in the radial direction, is disposed on the outer side in the radial direction with respect to an outer peripheral surface of the impeller cap, and the position of at least a part of the blade tip portion in the axial direction overlaps the position of the impeller cap in the axial direction.

Abstract: A heating, ventilation, and/or air conditioning (HVAC) system includes a cooling circuit, a reheat circuit, a recovery circuit, and a control system. The cooling circuit includes a condenser, a compressor, an evaporator, and a three-way valve, and the HVAC system is configured to circulate refrigerant through the cooling circuit in a cooling operating mode. The reheat circuit includes a reheat heat exchanger, the compressor, the evaporator, and the three-way valve, and the HVAC system is configured to circulate refrigerant through the reheat circuit in a reheat operating mode. The recovery circuit extends between the condenser and the compressor and includes a recovery valve. The control system is configured to send a first signal to the three-way valve to switch the HVAC system between the cooling operating mode and the reheat operating mode and a second signal to the recovery valve to recover refrigerant from the cooling circuit at a subsequent time based on the first signal.

Abstract: A cooling system for a data center includes an evaporative condenser, a pump cabinet and a heat exchange terminal. The pump cabinet has a first branch and a second branch, the first branch including a liquid storage tank and a fluorine pump. An input end of the liquid storage tank is connected to an output end of the evaporative condenser, an output end of the liquid storage tank is connected to an input end of the fluorine pump, and an output end of the fluorine pump is connected to an input end of the heat exchange terminal. The second branch includes a compressor with an input end connected to an output end of the heat exchange terminal and an output end connected to an input end of the evaporative condenser.

Abstract: A compressor arrangement includes two or more compressors (16a, 16b) arranged in a fluidly parallel configuration and a lubricant sump (38) containing a volume of lubricant operably connected to the two or more compressors. A lubricant sump pressure (P) is greater than a lubricant cavity pressure of each compressor (Pa, Pb, Pc) of the two or more compressors at all operating conditions of the two or more compressors. An equilibrium lubricant line (40) connects the lubricant sump to the two or more compressors to convey lubricant from the lubricant sump to a lubricant cavity (42) of each compressor of the two or more compressors.

Abstract: An oil separator and an air conditioning system provided with the oil separator are disclosed by the present disclosure. The oil separator comprises: an inlet (20) configured to receive a refrigerant; a duct (10) through which the refrigerant flows, the duct having a circumferential wall and comprising: a first section comprising a first muffler adjacent to the inlet, the first muffler (60) comprising a chamber (11) defined by a first wall (13) of the first section and designed to have a length dimension (L) in a length direction of the duct and a depth dimension (H) intersecting the length dimension; and a second section downstream of the first section, a second wall (23) of the second section being provided with a second muffler (70); and an oil separation assembly (80,90) through which the refrigerant passing through the duct passes. The present disclosure has a simple and reliable structure and is easy to implement.

Abstract: A refrigeration cycle cools a battery. A controller controls a refrigerant flow rate flowing through a battery cooling system so as to adjust a temperature of the battery. The controller adjusts the refrigerant flow rate flowing in the battery cooling system so that the oil retained in the battery cooling system is flushed toward the compressor. The battery cooling system has a plurality of parallel systems. Electric expansion valves as flow adjusting valves are controlled so as to intermittently provide an oil-back operation. In the oil-back operation, the flow rate of the refrigerant flowing through a part among the plurality of parallel systems is increased more than a flow rate of the refrigerant flowed by a temperature control unit.

Abstract: An evaporator (2) is provided with a casing (5), a refrigerant supply section (7), a first heat transfer pipe group (10), and a second heat transfer pipe group (11). The first heat transfer pipe group (10) is disposed in the lower part of the space in the casing (5) so as to be immersed in the refrigerant and comprises a plurality of heat transfer pipes (12) through which liquid to be cooled flows. The second heat transfer pipe group (11) is provided in the space in the casing (5) at a position below the refrigerant supply section (7) and above the liquid level of the refrigerant, and comprises a plurality of second heat transfer pipes (13) through which liquid to be cooled flows.

Abstract: Systems and methods for purging lubricant from a first compressor to a second compressor are provided. A control module receives a lubricant purge command, shuts the second compressor to an OFF-mode while the first compressor remains in the ON-mode, restricts working fluid from an outlet of the second compressor from flowing into the first compressor and allows compressed working fluid discharged from an outlet of the first compressor to flow into the inlet of the second compressor such that lubricant in the second compressor flows into the first compressor.

Abstract: An eductor system for a chiller assembly is provided. The system includes a first and a second eductor. The first eductor includes a first suction inlet that receives a first oil and refrigerant mixture from a plenum of a compressor, a first motive inlet that receives a first motive fluid from an oil sump, and a first outlet that discharges a first outlet mixture to the oil sump. The first outlet mixture includes both the first oil and refrigerant mixture and the first motive fluid. The second eductor includes a second suction inlet that receives a second oil and refrigerant mixture from an evaporator, a second motive inlet that receives a second motive fluid from a condenser, and a second outlet that discharges a second outlet mixture to the plenum of the compressor. The second outlet mixture includes both the second oil and refrigerant mixture and the second motive fluid.

Abstract: An oil-injected multistage compressor device that comprises at least one low-pressure stage compressor element (2) with an inlet (4a) and an outlet (5a) and a high-pressure stage compressor element (3) with an inlet (4b) and an outlet (5b), whereby the outlet (5a) of the low-pressure stage compressor element (2) is connected to the inlet (4b) of the high-pressure stage compressor element (3) via a conduit (6), characterized in that an intercooler (9) is provided between the low-pressure stage compressor element (2) and the high-pressure stage compressor element (3) in the aforementioned conduit (6) and that the compressor device (1) is also equipped with a restriction (10) for limiting the amount of oil injected in the low-pressure stage compressor element (2).

Abstract: To control operating parameters of the compressor and ensure stable operation of the air conditioning system, a cooling medium control method for a multi-connected air conditioning system includes: acquiring current operating values of target parameters of the compressor during the operation of the compressor; calculating deviation degrees of the target parameters of the compressor according to the current operating values of the target parameters of the compressor and standard operating ranges of the target parameters of the compressor; and selectively adjusting an opening degree of the outdoor expansion valve or the indoor expansion valve based on the deviation degrees; where the standard operating ranges of the target parameters are operating ranges of the target parameters specified by a normal operating state of the compressor. Here the opening degree of the indoor expansion valve or the outdoor expansion valve is adjusted in real time according to parameters of the compressor.

Abstract: A heat transport system includes: a refrigerant circuit that seals therein a fluid including HFC-32 and/or HFO refrigerant as a refrigerant and that includes: a refrigerant booster that boosts the refrigerant; an outdoor air heat exchanger that exchanges heat between the refrigerant and outdoor air; a medium heat exchanger that exchanges heat between the refrigerant and a heat transfer medium; and a refrigerant flow path switch that switches between a refrigerant radiation state and a refrigerant evaporation state; and a medium circuit that seals carbon dioxide therein as the heat transfer medium.

Abstract: A heat source unit for an air conditioner that includes a refrigerant circuit, the heat source unit includes: an external housing; and a cooling heat exchanger disposed in the external housing and that is connected to the refrigerant circuit. The external housing accommodates: a compressor connected to the refrigerant circuit; a heat source heat exchanger that is connected to the refrigerant circuit and that exchanges heat between a refrigerant circulating in the refrigerant circuit and a heat source; and an electric box. The electrical box: includes a top and a plurality of side walls; accommodates electrical components that control the air conditioner; and further includes an air passage that includes an air inlet and an air outlet. An air flow is induced through the air passage from the air inlet to the air outlet for cooling at least some of the electrical components.

Abstract: A refrigeration cycle apparatus includes a plurality of outdoor units. Each of the plurality of outdoor units includes an outdoor heat exchanger, a compressor, and a sensor to detect the quantity of refrigeration oil in the outdoor unit. A controller has a first operation mode in which a part of the plurality of outdoor units is operated and another outdoor unit is stopped; and a second operation mode in which all of the plurality of outdoor units are operated. In the first operation mode, when the operating time of an operating outdoor unit exceeds a prescribed time and the quantity of refrigeration oil in the compressor of the operating outdoor unit is equal to or larger than a prescribed quantity, the controller stops the operating outdoor unit and makes a switch to bring a stopped outdoor unit of the plurality of outdoor units into operation.

Abstract: Oleophobic and/or philic surface(s) are utilized for oil separation, direction, and/or collection in a refrigeration system. Surfaces of component(s) of a refrigeration system (compressor, oil separator, evaporator, etc.) are produced to be oleophobic or philic. The oleophobic and/or philic surfaces are utilized to direct a flow path of oil within the refrigeration system or to prevent oil connection in an area. Refrigerant phobic and/or lubricant phobic material(s) also may be utilized to help promote separation of refrigerant vapor from refrigerant liquid and/or from oil in refrigeration systems.

Abstract: A variable capacity screw compressor comprises a suction port, at least two screw rotors and a discharge port being configured in relation to a selected rotational speed that operates at least one screw rotor at an optimum peripheral velocity that is independent of a peripheral velocity of the at least one screw rotor at a synchronous motor rotational speed for a rated screw compressor capacity. A motor is configured to drive the at least one screw rotor at a rotational speed at a full-load capacity that is substantially greater than the synchronous motor rotational speed at the rated screw compressor capacity. A variable speed drive receives a command signal from a controller and generates a control signal that drives the motor at the selected rotational speed. A method for sizing at least two variable capacity screw compressors and a refrigeration chiller incorporating a variable capacity screw compressor are separately presented.

Abstract: A cooling system includes a heat exchange unit; a supply line configured to send a coolant to the heat exchange unit; a drain line configured to send the coolant drained from the heat exchange unit; a first to a nth gas-liquid separating units connected in series to a gas line in which a gas of the coolant flows; a first to a nth cooling lines extended via the first to the nth gas-liquid separating units, respectively. Both ends of the first cooling line are connected to a cooling device. The second to the nth cooling lines are provided between the drain line and a first to a (n?1)th liquid lines via the second to the nth gas-liquid separating units, respectively. The first to the nth gas-liquid separating units are respectively connected to liquid lines, and the liquid lines communicate with the supply line connected to the heat exchange unit.

Abstract: A refrigeration cycle apparatus includes: a refrigerant circuit including a compressor, a condenser, an expansion device, and an evaporator; an oil separator provided at a refrigerant discharge side of the compressor and configured to separate refrigerant and a refrigerating machine oil; a first oil return path connecting the oil separator to a refrigerant suction side of the compressor; a flow control device provided on the first oil return path and configured to reduce pressure of the refrigerant and the refrigerating machine oil; an oil reservoir provided to branch from the first oil return path between the flow control device and the refrigerant suction side of the compressor and configured to store the refrigerating machine oil; a second oil return path on which the oil reservoir is provided and through which the oil accumulated in the oil reservoir flows when being returned to the compressor.

Abstract: The purpose of the present invention is: to enable hot water at a required temperature to be supplied, even in cases when compressor load factor is low; to suppress heat dissipation from a waste-heat recovery device; and to improve waste-heat recovery rate. A waste-heat recovery system in an oil-cooled gas compressor is provided with: a compressor main body (3); an oil separator (6); gas piping (8) which supplies, to a demanded destination, compressed gas separated from oil by the oil separator; oil piping (7) which returns, to the compressor main body, the oil separated by the oil separator; and a waste-heat-recovery heat exchanger (10) which recovers heat from the compressed gas and/or the oil.

Abstract: A vehicle system includes a refrigerant loop with a specific arrangement of valves and evaporators or heat exchangers to reduce the number of valves necessary. The vehicle system includes a refrigerant loop that includes a first thermal expansion valve downstream of a condenser and upstream of a first evaporator. A second thermal expansion valve is downstream of the condenser and upstream of a second evaporator. A third thermal expansion valve is upstream of a battery chiller. This arrangement allows for the valves to be simplified such that none of the thermal expansion valve include a binary shut-off valve. A multi-flow position valve may be positioned at a location that combines the outlet of the first and second evaporators.

Abstract: A working fluid for use in a compression refrigeration, air conditioning or heat pump system, is described, which has a refrigerant composed of a fluoro-olefin, and a lubricant which is a mixture of polyol ester and a polyoxyalkylene glycol, and the polyol ester is present in an amount of at least 50% by weight based on the total weight of the polyol ester and the polyoxyalkylene glycol. A lubricant, being a mixture of a polyol ester and a polyoxyalkylene glycol, is described and comprises at least 10% by weight of polyoxyalkylene glycol based on the total weight of the polyol ester and the polyoxyalkylene glycol.

Abstract: A multi-type air conditioning device controls an evaporation temperature and a condensing temperature, depending on required capacity of an indoor unit. The air conditioning device compares a current evaporation temperature or condensing temperature with a reference value, of an evaporation temperature or an condensing temperature, corresponding to a lower limit flow rate, of a gaseous refrigerant, required for refrigerating machine oil not to accumulate in, but to flow through, the gas branch pipes, and calculates an amount of the refrigerating machine oil accumulated in a gas branch pipe which does not satisfy the lower limit flow rate. When the calculated amount exceeds a set amount, the air conditioning device performs oil collecting operation, and controls the oil collecting operation in view of a flow rate of a gaseous refrigerant in gas branch pipes.

Abstract: A closed loop performing a Rankine cycle for a motor vehicle includes a circulation and compression pump for a working fluid, a heat exchanger swept by a hot source for heating said working fluid, expansion means for expanding the hot fluid and a cooling exchanger-swept by a cooling fluid for cooling this working fluid. A method of controlling the closed loop performing a Rankine cycle for a motor vehicle includes, after detecting a vehicle accident situation, in communicating the inside of the loop with the ambient air.

Abstract: Provided is an oil level detection device to be mounted on a refrigerating and air-conditioning apparatus, the oil level detection device being configured to detect an oil level of oil accumulated inside a compressor forming the refrigerating and air-conditioning apparatus. The oil level detection device includes an oil level detection unit installed on an outer surface of the compressor and configured to detect a temperature of an installation position, a sensor output unit configured to output, to the refrigerating and air-conditioning apparatus, a signal for changing an operation state of the refrigerating and air-conditioning apparatus, and a determination unit configured to determine depletion of the oil accumulated inside the compressor based on measurement values obtained by the oil level detection unit at least after an output of the signal to be output from the sensor output unit.

Abstract: A liquid chiller system utilizing a refrigerant capable of possessing a liquid state and a gas/vapor state, the refrigerant being cycled through a closed loop assembly of a compressor, an eccentric condenser and an eccentric evaporator. The eccentric compressor has a lower integrated reservoir and the eccentric evaporator has an upper dedicated reservoir such that separate, dedicated separator or receiver vessels are not required. The eccentric condenser is positioned above the eccentric evaporator such that liquid refrigerant flows by gravity from the eccentric condenser to the eccentric evaporator.

Abstract: Provided is a highly reliable oil free screw compressor including a first sensor for detecting a temperature of lubrication oil, second sensors for detecting temperatures of intake air, and a cooling fan controller having a storage portion storing therein a set temperature of lubrication oil and a set temperature of intake air, and a computing portion for computing a control signal for increasing the speed of the cooling fan if a detected value of a temperature of the lubrication oil, delivered from the first sensor, becomes higher than the set value of lubrication oil stored in the storage portion, and computing a control signal for increasing the speed of the cooling fan if a detected value of a temperature of the intake air, delivered from the second sensor, becomes higher than the set temperature of the intake air, stored in the storage portion.

Abstract: A container refrigeration device aims to improve dehumidification performance of the container refrigeration device. The container refrigeration device is configured to perform, in accordance with a dehumidification load, first dehumidification control under which air having passed through an evaporator is heated by exchanging heat with a refrigerant in a reheat heat exchanger, and blown into an inside of a container, and second dehumidification control under which a pressure of the refrigerant discharged from a compressor and flowing into the reheat heat exchanger is caused to be higher than a pressure of the refrigerant discharged from the compressor under the first dehumidification control, and a flow rate of the refrigerant discharged from the compressor is regulated such that a temperature inside the container is within a predetermined temperature range.

Abstract: Refrigerating machine oil is reliably returned to a compressor, regardless of whether the oil is miscible or immiscible with a refrigerant. A first refrigerant channel includes a compressor, a condenser, a first flow control valve, a refrigerant storing container, a second flow control valve, and a first evaporator are connected in that order. A refrigerant outlet of the first evaporator is connected to a suction refrigerant inlet of an ejector. A second refrigerant channel includes a compressor and a second evaporator connected in that order. A refrigerant inlet of the second evaporator is connected to a mixed refrigerant outlet of the ejector. A third refrigerant channel branching off from a halfway point of a pipe connecting a refrigerant outlet of the radiator and the first flow control valve includes a third flow control valve and a motive refrigerant inlet of the ejector are connected in that order.

Abstract: A refrigeration system that induces lubricant-liquid refrigerant mixture flow from a flooded or falling film evaporator by means of the lubricant-liquid refrigerant mixture flow adsorbing heat from an electronic component.

Abstract: A refrigeration system that induces lubricant-liquid refrigerant mixture flow from a flooded or falling film evaporator by means of the lubricant-liquid refrigerant mixture flow adsorbing heat from an electronic component.

Abstract: An air conditioner and a method for controlling and air conditioner are provided. The air conditioner may include at least one compressor, a main suction passage to guide a refrigerant into the at least one compressor, at least one oil separator connected to the at least one compressor, that separates oil from the refrigerant discharged from the at least one compressor, at least one oil level sensor disposed in the at least one compressor to detect whether the at least one compressor lacks oil, a return passage to collect the oil separated from the at least one oil separator into the at least one compressor, a distribution return passage branched from the at least one return passage and connected to the main suction passage, and a valve disposed in each of the at least one return passage and the distribution return passage.

Abstract: This invention relates generally to oil lubricated helium compressor units for use in cryogenic refrigeration systems, operating on the Gifford McMahon (GM) cycle. The objective of this invention is to keep the oil separator and absorber, which are components in an oil lubricated, helium compressor, in an indoor air conditioned environment while rejecting at least 65% of the heat from the compressor outdoors during the summer. The balance of the heat is rejected to either the indoor air conditioned air, or cooling water. This is accomplished by circulating hot oil at high pressure to an outdoor air cooled heat exchanger and returning cooled oil to the compressor inlet, while hot high pressure helium is cooled in an air or water cooled heat exchanger in an indoor assembly that includes the compressor, an oil separator, an oil absorber, and other piping and control components. It is an option to reject the heat from the oil to the indoor space during the winter to save on the cost of heating the indoor space.

Abstract: Cooling devices for use with electric submersible pump motors include a refrigerator attached to the end of the electric submersible pump motor with the evaporator heat exchanger accepting all or a portion of the heat load from the motor. The cooling device can be a self-contained bolt-on unit, so that minimal design changes to existing motors are required.

Abstract: A refrigerating cycle apparatus and a method of operating the same are provided. For a refrigerating cycle having a plurality of compressors connected in series for multi-stage compression, an inner space of each compressor and a pipe of the refrigerating cycle may be connected via an oil collection pipe, and oil may be discharged into the refrigerating cycle by pressure reversal during a pressure balancing operation, so as to allow the discharged oil to be collected into a high-stage compressor or a low-stage compressor. Accordingly, an amount of oil may be uniformly maintained in each of the plurality of compressors to prevent losses due to friction and/or increases in power consumption due to a lack of oil in one or more of the compressors. The structure of a device and pipes for performing oil balancing between the compressors may be simplified to enhance efficiency of the compressors.

Abstract: An air-conditioning apparatus includes an outdoor air temperature sensor detecting an outdoor temperature; a compressor temperature sensor detecting a temperature of an outer wall of a compressor; a liquid-level and concentration detection sensor detecting a liquid surface level in the compressor and a concentration of a lubricant oil in a liquid in the compressor; an electric heater heating the compressor; and a controller that carries out preheating to the compressor by driving the electric heater when a detection value of the outdoor air temperature sensor is higher than or equal to a detection value of the compressor temperature sensor and, further, when the liquid surface level detected by the liquid-level and concentration detection sensor is higher than or equal to a predetermined level and the concentration of the lubricant oil in the liquid is lower than a preset minimum required concentration.

Abstract: The invention relates to a cooling system (2) and a method for oil separation, where a condenser unit (10) contains an oil separator (18,20), from which oil separator oil is lead through a pipeline (24) and back to the compressor (4). It is an object of the invention to collect all condensing functions and oil separation functions into a common pressure container (26). According to the invention, this objective is achieved by a system, the condenser unit and oil separator are integrated in a common pressure tank (26) that contains at least one first oil separator and at least a second secondary oil separator, which pressure tank contains a condenser container (30) which interacts with a third oil separator (22). Hereby, it is attained that condensation and oil separation are integrated in a common pressure tank.

Abstract: The air conditioning system uses an air cycle thermodynamic process. The system comprises a centrifuge. This centrifuge includes at one of its ends, an axial inlet that funnels air into a centrifugal compressor rotating in unison with the centrifuge. The air is compressed, adiabatically heated and directed to a heat exchanger mounted in the rim of, and rotating with the centrifuge. The air is accelerated with respect the centrifuge by varying the centrifuge radius or by using forward leaning impeller blades. The air is cooled by the heat exchanger and directed to an expander also rotating with the centrifuge. The air is expanded and adiabatically further cooled. The cold air exits the centrifuge through an axial outlet located at the second end of the centrifuge.

Abstract: This disclosure relates to a method for operating a combined heat and power device, wherein carbon dioxide as a refrigerant (17) is compressed in a compressor, wherein the carbon dioxide is carried along a refrigerant circuit and routed back to the compressor via a collecting vessel (5). The method is distinguished by the fact that the compressor is lubricated with a lubricant (15) which has a density of more than 1004 g/l, and that a hot gas temperature in the compressor is held below a predetermined value, above which overheating and/or ageing of the lubricant occurs.

Abstract: Disclosed is a heat exchanger of a plate type comprising an evaporator having at least one inlet and at least one outlet allowing a first medium to enter into and exit from the evaporator. The evaporator comprises a plurality of interconnected evaporation chambers disposed in parallel, having at least one common inlet and at least one common outlet allowing the first medium to enter into and exit from the evaporation chambers.