Air conditioning system employing dual cycle

Claim 2

In an air conditioning system, an air conditioning unit comprising a compressor and an expander, the compressor and expander including a housing having an inner wall defining chamber means with rotor means rotatable therein, the rotor means having vanes for compression and expansion connected to a common shaft, the compressor and expander each having an inlet port and an outlet port, a primary heat exchanger connected between the compressor outlet port and the expander inlet port, a secondary heat exchanger between the expander outlet port and the compressor inlet port to form a closed loop, the heat exchangers being isolated from one another, the loop being charged with a main refrigerant in the form of a gas which is non-condensing at temperatures and pressures encountered in the unit so that upon driving of the rotor means the gas (1) is compressed and heated in the compressor, (2) releases heat in the primary heat exchanger, (3) is expanded and cooled in the expander, and (4) absorbs heat in the secondary heat exchanger, an auxiliary refrigerant in the loop, the auxiliary refrigerant being one (a) having an appreciable heat of vaporization and (b) capable of existing substantially in the liquid state at the pressure and temperature in the primary exchanger and in the vapor state in the secondary heat exchanger, the primary heat exchanger having an associated sump for collection of liquid auxiliary refrigerant while permitting the non-condensing gas to pass freely into the expander, a spray nozzle at the inlet of the secondary heat exchanger, a conduit connected to the sump and terminating at the spray nozzle so that liquid auxiliary refrigerant collected in the sump is sprayed into the gas discharged from the expander for vaporization at the secondary heat exchanger for absorption of additional heat therein, the auxiliary refrigerant being present in such excess amount as to collect in the sump to a reliably high level under normal running conditions to insure that auxiliary refrigerant entering the conduit is in liquid form.

Claim 3

In an air conditioning system, an air conditioning unit comprising a compressor and an expander, the compressor and expander including a housing having an inner wall defining chamber means with rotor means rotatable therein, the rotor means having vanes for compression and expansion connected to a common shaft, the compressor and expander each having an inlet port and an outlet port, a primary heat exchanger connected between the compressor outlet port and the expander inlet port, a secondary heat exchanger between the expander outlet port and the compressor inlet port to form a closed loop, the heat exchangers being isolated from one another, the loop being charged with a main refrigerant in the form of a gas which is non-condensing at temperatures and pressures encountered in the unit so that upon driving of the rotor means the gas (1) is compressed and heated in the compressor, (2) releases heat in the primary heat exchanger, (3) is expanded and cooled in the expander, and (4) absorbs heat in the secondary heat exchanger, an auxiliary refrigerant in the loop, the auxiliary refrigerant being one (a) having an appreciable heat of vaporization and (b) capable of existing substantially in the liquid state at the pressure and temperature existing in the primary heat exchanger and in the vapor state and the pressure and temperature in the secondary heat exchanger, a separator-sump interposed between the primary heat exchanger and the expander inlet port including a separator which permits the non-condensing gas to pass freely to the expander while intercepting and diverting auxiliary refrigerant in liquid form and including a sump for collecting the diverted auxiliary refrigerant, a spray nozzle at the inlet of the secondary heat exchanger having a conduit for coupling the same to the sump so that auxiliary refrigerant in liquid form is drawn from the sump sprayed into the gas discharged from the expander for evaporation at the secondary heat exchanger for absorption of additional heat therein, the auxiliary refrigerant being present in such excess amount as to collect in the sump to a reliably high level under normal running conditions to insure that the auxiliary refrigerant entering the conduit is in liquid form.

Claim 4

In an air conditioning system, an air conditioning unit comprising a compressor and an expander, the compressor and expander including a housing having an inner wall defining chamber means with rotor means rotatable therein, the rotor means having vanes for compression and expansion connected to a common shaft, the compressor and expander each having an inlet port and an outlet port, a primary heat exchanger connected between the compressor outlet port and the expander inlet port, a secondary heat exchanger between the expander outlet port and the compressor inlet port to form a closed loop, the heat exchangers being isolated from one another, the loop being charged with a main refrigerant in the form of a gas which is non-condensing at temperatures and pressures encountered in the unit so that upon driving of the rotor means the gas (1) is compressed and heated in the compressor, (2) releases heat in the primary heat exchanger, (3) is expanded and cooled in the expander, and (4) absorbs heat in the secondary heat exchanger, an auxiliary refrigerant in the loop, the auxiliary refrigerant being one (a) having an appreciable heat of vaporization and (b) capable of existing substantially in the liquid state at the pressure and temperature existing in the primary heat exchanger and in the vapor state and the pressure and temperature in the secondary heat exchanger, a separator-sump interposed between the primary heat exchanger and the expander inlet port including a separator which permits the non-condensing gas to pass freely to the expander while intercepting and diverting auxiliary refrigerant in liquid form and including a sump for collecting the diverted auxiliary refrigerant, a spray nozzle at the inlet of the secondary heat exchanger having a conduit for coupling the same to the sump so that auxiliary refrigerant in liquid form is drawn from the sump sprayed into the gas discharged from the expander for evaporation at the secondary heat exchanger for absorption of additional heat therein, the auxiliary refrigerant being present in such excess amount as to collect in the sump to a reliably high level under normal running conditions to insure that the auxiliary refrigerant entering the conduit is in liquid form.

Claim 5

In an air conditioning system, an air conditioning unit comprising a compressor and an expander, the compressor and expander including a housing having an inner wall defining chamber means with rotor means rotatable therein, the rotor means having vanes for compression and expansion connected to a common shaft, the housing providing a path for cooling fluid fed by a cooling connection, the compressor and expander each having an inlet port and an outlet port, a primary heat exchanger connected between the compressor outlet port and the expander inlet port and having an associated separator sump for drainage of liquid thereto, a secondary heat exchanger between the expander outlet port and the compressor inlet port to form a closed loop, the heat exchangers being isolated from one another, the loop being charged with a main refrigerant in the form of a gas which is non-condensing at temperatures and pressures encountered in the unit so that upon driving of the rotor means the gas (1) is compressed and heated in the compressor, (2) releases heat in the primary heat exchanger, (3) is expanded and cooled in the expander, and (4) absorbs heat in the secondary heat exchanger, an auxiliary refrigerant in the loop, the auxiliary refrigerant being one (a) having an appreciable heat of vaporization and (b) capable of existing substantially in the liquid state at the pressure and temperature existing in the primary heat exchanger and in the vapor state at the pressure and temperature in the secondary heat exchanger, the separator-sump being so constructed as to permit the non-condensing gas to pass freely to the expander while auxiliary refrigerant is collected therein in liquid form, a spray nozzle at the inlet of the secondary heat exchanger, a first conduit connected to the sump for conducting liquid auxiliary refrigerant therefrom to the spray nozzle so that liquid auxiliary refrigerant is sprayed into the gas from the expander for evaporation at the secondary heat exchanger for absorption of additional heat therein, the auxiliary refrigerant being present in such excess amount as to collect in the sump to a reliably high level, a second conduit connected to receive auxiliary refrigerant from the sump and for feeding it to the cooling connection, and means for controlling the relative flow in the conduits so that the rate of flow in the second conduit is only a small fraction of the rate of flow in the first conduit.

Claim 6

In an air conditioning system, an air conditioning unit comprising a compressor and an expander, the compressor and expander including a housing having an inner wall defining chamber means with rotor means rotatable therein, the rotor means having vanes for compression and expansion connected to a common shaft, the housing providing a path for cooling fluid fed by a cooling connection, the compressor and expander each having an inlet port and an outlet port, a primary heat exchanger connected between the compressor outlet port and the expander inlet port and having an associated separator sump for drainage of liquid thereto, a secondary heat exchanger between the expander outlet port and the compressor inlet port to form a closed loop, the heat exchangers being isolated from one another, the loop being charged with a main refrigerant in the form of a gas which is non-condensing at temperatures and pressures encountered in the unit so that upon driving of the rotor means the gas (1) is compressed and heated in the compressor, (2) releases heat in the primary heat exchanger, (3) is expanded and cooled in the expander, and (4) absorbs heat in the secondary heat exchanger, an auxiliary refrigerant in the loop, the auxiliary refrigerant being one (a) having an appreciable heat of vaporization and (b) capable of existing substantially in the liquid state at the pressure and temperature existing in the primary heat exchanger and in the vapor state at the pressure and temperature in the secondary heat exchanger, the separator-sump being so constructed as to permit the non-condensing gas to pass freely to the expander while auxiliary refrigerant is collected therein in liquid form, a spray nozzle at the inlet of the secondary heat exchanger, a first conduit connected to the sump for conducting liquid auxiliary refrigerant therefrom to the spray nozzle so that liquid auxiliary refrigerant is sprayed into the gas from the expander for evaporation at the secondary heat exchanger for absorption of additional heat therein, the auxiliary refrigerant being present in such excess amount as to collect in the sump to a reliably high level, a second conduit connected to receive auxiliary refrigerant from the sump and for feeding it to the cooling connection, and means for controlling the relative flow in the conduits so that the rate of flow in the second conduit is only a small fraction of the rate of flow in the first conduit.

Claim 7

In an air conditioning system, an air conditioning unit comprising a compressor and an expander, the compressor and expander including a housing having an inner wall defining chamber means with rotor means rotatable therein, the rotor means having vanes for compression and expansion connected to a common shaft, the housing providing a path for lubricating fluid fed by a lubricant connection, the compressor and expander each having an inlet port and an outlet port, a primary heat exchanger connected between the compressor outlet port and the expander inlet port, a secondary heat exchanger between the expander outlet port and the compressor inlet port to form a closed loop, the heat exchangers being isolated from one another, the loop being charged with a main refrigerant in the form of a gas which is non-condensing at temperatures and pressures encountered in the unit so that upon driving of the rotor means the gas (1) is compressed and heated in the compressor, (2) releases heat in the primary heat exchanger, (3) is expanded and cooled in the expander, and (4) absorbs heat in the secondary heat exchanger, an auxiliary refrigerant in the loop, the auxiliary refrigerant being one (a) having an appreciable heat of vaporization and (b) capable of existing substantially in the liquid state at the pressure and temperature existing in the primary heat exchanger and in the vapor state in the secondary heat exchanger, a sump associated with the primary heat exchanger for collecting auxiliary refrigerant in liquid form while permitting the non-condensing gas to pass freely to the expander inlet port, a quantity of lubricating oil in the loop miscible in the liquid refrigerant in the sump to form a lubricating fluid, a spray nozzle at the inlet of the secondary heat exchanger, a first conduit connected to the sump for conducting liquid auxiliary refrigerant therefrom to the spray nozzle so that liquid auxiliary refrigerant is sprayed into the gas from the expander for evaporation at the secondary heat exchanger for absorption of additional heat therein, the auxiliary refrigerant being present in such excess amount as to collect in the sump to a reliably high level, a second conduit connected between the sump and the lubricant connection for feeding lubricating fluid to the latter, and a booster pump interposed in at least the second conduit for augmenting the pressure in such conduit.

Claim 8

In an air conditioning system, an air conditioning unit comprising a compressor and an expander, the compressor and expander including a housing having an inner wall defining chamber means with rotor means rotatable therein, the rotor means having vanes for compression and expansion connected to a common shaft, the housing providing a path for lubricating fluid fed by a lubricant connection, the compressor and expander each having an inlet port and an outlet port, a primary heat exchanger connected between the compressor outlet port and the expander inlet port, a secondary heat exchanger between the expander outlet port and the compressor inlet port to form a closed loop, the heat exchangers being isolated from one another, the loop being charged with a main refrigerant in the form of a gas which is non-condensing at temperatures and pressures encountered in the unit so that upon driving of the rotor means the gas (1) is compressed and heated in the compressor, (2) releases heat in the primary heat exchanger, (3) is expanded and cooled in the expander, and (4) absorbs heat in the secondary heat exchanger, an auxiliary refrigerant in the loop, the auxiliary refrigerant being one (a) having an appreciable heat of vaporization and (b) capable of existing substantially in the liquid state at the pressure and temperature existing in the primary heat exchanger and in the vapor state in the secondary heat exchanger, a sump associated with the primary heat exchanger for collecting auxiliary refrigerant in liquid form while permitting the non-condensing gas to pass freely to the expander inlet port, a quantity of lubricating oil in the loop miscible in the liquid refrigerant in the sump to form a lubricating fluid, a spray nozzle at the inlet of the secondary heat exchanger, a first conduit connected to the sump for conducting liquid auxiliary refrigerant therefrom to the spray nozzle so that liquid auxiliary refrigerant is sprayed into the gas from the expander for evaporation at the secondary heat exchanger for absorption of additional heat therein, the auxiliary refrigerant being present in such excess amount as to collect in the sump to a reliably high level, a second conduit connected between the sump and the lubricant connection for feeding lubricating fluid to the latter, and a booster pump interposed in at least the second conduit for augmenting the pressure in such conduit.

Claim 9

In an air conditioning system, an air conditioning unit comprising a compressor and an expander, the compressor and expander including a housing having an inner wall defining chamber means with rotor means rotatable therein, the rotor means having vanes for compression and expansion connected to a common shaft, the housing having a path for cooling-lubricating fluid terminating in inlet and outlet connections, the compressor and expander each having an inlet port and an outlet port, a primary heat exchanger connected between the compressor outlet port and the expander inlet port, a secondary heat exchanger between the expander outlet port and the compressor inlet port to form a closed loop, the heat exchangers being isolated from one another, the loop being charged with a main refrigerant in the form of a gas which is non-condensing at temperatures and pressures encountered in the unit so that upon driving of the rotor means the gas (1) is compressed and heated in the compressor, (2) releases heat in the primary heat exchanger, (3) is expanded and cooled in the expander, and (4) absorbs heat in the secondary heat exchanger, an auxiliary refrigerant in the loop, the auxiliary refrigerant being one (a) having an appreciable heat of vaporization and (b) capable of existing substantially in the liquid state at the pressure and temperature existing in the primary heat exchanger and in the vapor state in the secondary heat exchanger, a sump associated with the primary heat exchanger for collecting auxiliary refrigerant in liquid form while permitting the non-condensing gas from the primary heat exchanger to pass freely to the expander in liquid form, a quantity of lubricating oil in the loop miscible in the liquid refrigerant in the sump to form a lubricating fluid, a spray nozzle at the inlet of the second heat exchanger, a first conduit connected to the sump and terminating at the spray nozzle so that liquid auxiliary refrigerant is sprayed into the gas discharged from the expander for vaporization at the secondary heat exchanger for absorption of additional heat therein, a second conduit fed by the sump and terminating at the inlet connection, and a third conduit for returning the cooling-lubricating fluid from the outlet connection to the sump, a positive displacement booster pump being interposed in series with at least the second conduit for metering the flow of fluid through the cooling-lubricating path.

Claim 10

In an air conditioning system, an air conditioning unit comprising a compressor and an expander, the compressor and expander including a housing having an inner wall defining chamber means with rotor means rotatable therein, the rotor means having vanes for compression and expansion connected to a common shaft, the housing having a path for cooling-lubricating fluid terminating in inlet and outlet connections, the compressor and expander each having an inlet port and an outlet port, a primary heat exchanger connected between the compressor outlet port and the expander inlet port, a secondary heat exchanger between the expander outlet port and the compressor inlet port to form a closed loop, the heat exchangers being isolated from one another, the loop being charged with a main refrigerant in the form of a gas which is non-condensing at temperatures and pressures encountered in the unit so that upon driving of the rotor means the gas (1) is compressed and heated in the compressor, (2) releases heat in the primary heat exchanger, (3) is expanded and cooled in the expander, and (4) absorbs heat in the secondary heat exchanger, an auxiliary refrigerant in the loop, the auxiliary refrigerant being one (a) having an appreciable heat of vaporization and (b) capable of existing substantially in the liquid state at the pressure and temperature existing in the primary heat exchanger and in the vapor state in the secondary heat exchanger, a sump associated with the primary heat exchanger for collecting auxiliary refrigerant in liquid form while permitting the non-condensing gas from the primary heat exchanger to pass freely to the expander in liquid form, a quantity of lubricating oil in the loop miscible in the liquid refrigerant in the sump to form a lubricating fluid, a spray nozzle at the inlet of the second heat exchanger, a first conduit connected to the sump and terminating at the spray nozzle so that liquid auxiliary refrigerant is sprayed into the gas discharged from the expander for vaporization at the secondary heat exchanger for absorption of additional heat therein, a second conduit fed by the sump and terminating at the inlet connection, and a third conduit for returning the cooling-lubricating fluid from the outlet connection to the sump, a positive displacement booster pump being interposed in series with at least the second conduit for metering the flow of fluid through the cooling-lubricating path.

Claim 11

In an air conditioning system, an air conditioning unit comprising a compressor and an expander, the compressor and expander including a housing having an inner wall defining chamber means with rotor means rotatable therein, the rotor means having vanes for compression and expansion connected to a common shaft, the compressor and expander each having an inlet port and an outlet port, a primary heat exchanger connected between the compressor outlet port and the expander inlet port, a secondary heat exchanger between the expander outlet port and the compressor inlet port to form a closed loop, the heat exchangers being isolated from one another, the loop being charged with a main refrigerant in the form of a gas which is non-condensing at temperatures and pressures encountered in the unit so that upon driving of the rotor means the gas (1) is compressed and heated in the compressor, (2) releases heat in the primary heat exchanger, (3) is expanded and cooled in the expander, and (4) absorbs heat in the secondary heat exchanger thereby completing a reverse-Brayton cycle, an auxiliary refrigerant in the loop, the auxiliary refrigerant being one (a) having an appreciable heat of vaporization and (b) capable of existing substantially in the liquid state at the pressure and temperature existing in the primary heat exchanger and in the vapor state in the secondary heat exchanger, means including a sump associated with the primary heat exchanger for collection of liquid auxiliary refrigerant while permitting the non-condensing gas to pass freely to the expander, means including a conduit for conducting liquid auxiliary refrigerant from the sump to the secondary heat exchanger resulting in evaporation for absorption of additional heat therein and thereby completing a reverse-Rankine cycle.

Claim 12

In an air conditioning system, an air conditioning unit comprising a compressor and an expander, the compressor and expander including a housing having an inner wall defining chamber means with rotor means rotatable therein, the rotor means having vanes for compression and expansion connected to a common shaft, the compressor and expander each having an inlet port and an outlet port, a primary heat exchanger connected between the compressor outlet port and the expander inlet port, a secondary heat exchanger between the expander outlet port and the compressor inlet port to form a closed loop, the heat exchangers being isolated from one another, the loop being charged with a main refrigerant in the form of a gas which is non-condensing at temperatures and pressures encountered in the unit so that upon driving of the rotor means the gas (1) is compressed and heated in the compressor, (2) releases heat in the primary heat exchanger, (3) is expanded and cooled in the expander, and (4) absorbs heat in the secondary heat exchanger thereby completing a reverse-Brayton cycle, an auxiliary refrigerant in the loop, the auxiliary refrigerant being one (a) having an appreciable heat of vaporization and (b) capable of existing substantially in the liquid state at the pressure and temperature existing in the primary heat exchanger and in the vapor state in the secondary heat exchanger, means including a sump associated with the primary heat exchanger for collection of liquid auxiliary refrigerant while permitting the non-condensing gas to pass freely to the expander, means including a conduit for conducting liquid auxiliary refrigerant from the sump to the secondary heat exchanger resulting in evaporation for absorption of additional heat therein and thereby completing a reverse-Rankine cycle.

Claim 13

The combination as claimed in claim 1 or claim 2 or claim 3 or claim 4 or claim 5 or claim 6 in which the inner wall of the chamber means is eccentric with respect to the shaft and in which the vanes are radially mounted on the rotor means to sealingly engage the inner wall to define enclosed compartments which become smaller in the compressor and larger in the expander for positive compression and expansion as the shaft rotates.

Claim 14

The combination as claimed in claim 1 or claim 2 or claim 3 or claim 4 or claim 5 or claim 6 in which the compressor and expander are in the form of turbines having their rotor vanes coupled to a common shaft.

Claim 15

The combination as claimed in claim 1 or claim 2 or claim 3 or claim 4 or claim 5 or claim 6 in which the sump is at a lower level than the primary heat exchanger for constant gravity drainage from the primary heat exchanger into the sump of auxiliary refrigerant in liquid form.

Claim 16

The combination as claimed in claim 1 or claim 2 or claim 3 or claim 4 or claim 5 or claim 6 in which the secondary heat exchanger is so constructed and arranged with respect to the compressor that any auxiliary refrigerant still in liquid form in the secondary heat exchanger flows therefrom with the stream of gas to the compressor to perform a sealing function therein.

Claim 17

The combination as claimed in claim 5 in which a lubricant heat exchanger is interposed in the third conduit, the lubricant heat exchanger being thermally associated with the primary heat exchanger.

Claim 18

The combination as claimed in claim 2 or claim 3 in which the separator-sump has a housing enclosing a vertically elongated chamber, having an inlet at the top and an outlet at the bottom, an inlet pipe coupled to the inlet and a stand pipe coupled to the outlet, the pipe being axially alined and spaced from one another, the stand pipe extending from the bottom of the chamber, a major portion of the height thereof to form a surrounding reservoir, means for creating a vortex in the inlet pipe for the purpose of centrifugal discharge of droplets of liquid auxiliary refrigerant entrained in the entering stream of gas for retention of the liquid auxiliary refrigerant in the reservoir while the gas passes freely through the stand pipe and into the expander.

Claim 19

The combination as claimed in claim 1 or claim 2 or claim 3 or claim 4 or claim 5 of claim 6 in which means are provided sensitive to the existence of liquid auxiliary refrigerant in the sump for insuring that auxiliary refrigerant in liquid form only flows from the sump for passage to the secondary heat exchanger.

Claim 20

The combination as claimed in claim 1 or claim 2 or claim 3 or claim 4 or claim 5 or claim 6 in which the non-condensing gas is air.

Claim 21

The combination as claimed in claim 4 or claim 5 in which the booster pump is in series with both the first and second conduits.

Claim 22

The combination as claimed in claim 1 or claim 2 or claim 3 or claim 4 or claim 5 in which the auxiliary refrigerant is sufficiently volatile to evaporate substantially completely in the secondary heat exchanger.

Claim 23

The combination as claimed in claim 1 or claim 2 or claim 3 or claim 4 or claim 5 or claim 6 in which the auxiliary refrigerant is taken from the group comprising: Trichloromethane, Dichloromethane, Methyl iodid, Methanol, Carbon disulfide, 1,1-Dichloroethene, 1-Bromoethylene, Acetaldehyde, Methyl formate, Ethyl bromide, Propylamine, 1,2-Butadiene, 2-Butyne, Cyclobutane, tert-Butyl chloride, Diethylamine, Tetramethylsilane, Isoprene, 1,3-Pentadiene, Tiglaldehyde, 1-Pentene, 2-Methyl-2-butene, 2-Methyl-1-butene, Cyclopentane, Pentane, 2-Methylbutane, 2-Methylpentane, 3-Methylpentane, 2,2-Dimethylbutane, 2,3-Dimethylbutane.

Claim 24

The combination as claimed in claim 1 or claim 2 or claim 3 or claim 4 or claim 5 or claim 6 in which the auxiliary refrigerant is taken from the group comprising: Boron trichloride, Bromine pentafluoride, Chlorine dioxide, Digermane, Molybdenum hexafluoride, Nitrogen tetroxide, Nitrogen pentoxide, Silicon tetrachloride, Iodosilane, Trichlorosilane, Trisilane, Disilasane.

Claim 25

The combination as claimed in claim 1 or claim 2 or claim 3 or claim 6 in which there is a charge of lubricating oil in the loop which circulates with the main and auxiliary refrigerants.

Claim 26

The combination as claimed in claim 1 or claim 2 or claim 3 or claim 4 or claim 5 or claim 6 including an auxiliary spray nozzle at the inlet of the compressor, and an auxiliary conduit connected to the sump and terminating at the auxiliary spray nozzle so that droplets of liquid auxiliary refrigerant are sprayed into the gas discharged from the second heat exchanger and entering the compressor.

Claim 27

The combination as claimed in claim 1 or claim 2 or claim 3 or claim 4 or claim 5 or claim 6 including a thermostat associated with one of the heat exchangers, the thermostat having a responsive element and an output member, and adjustable valve for controlling the rate of flow of liquid refrigerant from the sump, the output member of the thermostat being coupled to the valve so that a change in the temperature at the responsive element brings about a corrective change in fluid flow, and hence in the heat rate, for maintenance of a substantially predetermined temperature at the responsive element.

Claim 28

The combination as claimed in claim 1 or claim 2 or claim 3 or claim 4 or claim 5 or claim 6 including a regenerative heat exchanger having first and second fluid channels sealed with respect to one another yet thermally coupled together, the channels being interposed at the respective outlets of the primary and secondary heat exchangers.

Claim 29

The combination as claimed in claim 4 or claim 5 in which means are interposed between the sump and the second conduit for increasing the relative concentration of oil flowing through the second conduit.

Claim 30

The combination as claimed in claim 4 or claim 5 in which means are interposed between the sump and the first conduit for increasing the relative concentration of the auxiliary refrigerant flowing through the first conduit and means are interposed between the sump and the second conduit for increasing the relative concentration of oil flowing through the second conduit.

Claim 31

The combination as claimed in claim 1 or claim 2 or claim 3 or claim 4 or claim 5 or claim 6 in which there is sufficient non-condensing gas confined in the loop so that the partial pressure of the non-condensing gas in the secondary heat exchanger is about at atmospheric level.