Mixed gas refrigeration method

Claim 1

A method for selecting a fluid mixture for use in a closed loop Joule-Thomson refrigeration system, said method comprising: selecting a temperature range and a pressure range over which a closed loop Joule-Thomson refrigeration system will be operated; selecting a plurality of component fluids, each said component fluid having known enthalpy values over said selected temperature range and said selected pressure range; selecting a plurality of combinations of said component fluids to formulate a plurality of fluid mixtures; calculating enthalpy values for each said fluid mixture at a plurality of data points over said temperature range and said pressure range; calculating a theoretical heat transfer rate achievable in a counterflow heat exchanger with each said fluid mixture, over said selected temperature and pressure range; calculating a theoretical Joule-Thomson refrigeration power achievable with each said fluid mixture, over said selected temperature and pressure range; calculating a performance ratio of said theoretical refrigeration power to said theoretical heat transfer rate, for each said fluid mixture; and selecting the fluid mixture having the highest said performance ratio as the best performing fluid mixture for a closed loop Joule-Thomson refrigeration system over said temperature range and said pressure range.

Claim 2

A method for selecting a fluid mixture for use in a closed loop Joule-Thomson refrigeration system, said method comprising: selecting a temperature range and a pressure range over which a closed loop Joule-Thomson refrigeration system will be operated; selecting a plurality of component fluids, each said component fluid having known enthalpy values over said selected temperature range and said selected pressure range; selecting a plurality of combinations of said component fluids to formulate a plurality of fluid mixtures; calculating enthalpy values for each said fluid mixture at a plurality of data points over said temperature range and said pressure range; calculating a theoretical heat transfer rate achievable in a counterflow heat exchanger with each said fluid mixture, over said selected temperature and pressure range; calculating a theoretical Joule-Thomson refrigeration power achievable with each said fluid mixture, over said selected temperature and pressure range; calculating a performance ratio of said theoretical refrigeration power to said theoretical heat transfer rate, for each said fluid mixture; and selecting the fluid mixture having the highest said performance ratio as the best performing fluid mixture for a closed loop Joule-Thomson refrigeration system over said temperature range and said pressure range.

Claim 9

A method of operating a miniature refrigeration system, said method comprising: providing a miniature closed loop refrigeration system having a compressor, a counterflow heat exchanger, and a Joule-Thomson expansion element; selecting a pressure range of operation for a fluid mixture to be used in said closed loop refrigeration system, said pressure range having a high end no greater than 420 psia; selecting a temperature range of operation for said fluid mixture to be used in said closed loop refrigeration system, said temperature range having a low end no greater than 183K; selecting a plurality of component fluids, each said component fluid having known enthalpy values over said selected temperature range and said selected pressure range; selecting a plurality of combinations of said component fluids to formulate a plurality of fluid mixtures; calculating enthalpy values for each said fluid mixture at a plurality of data points over said temperature range and said pressure range; calculating a theoretical heat transfer rate achievable in a counterflow heat exchanger with each said fluid mixture, over said selected temperature and pressure range; calculating a theoretical Joule-Thomson refrigeration power achievable with each said fluid mixture, over said selected temperature and pressure range; calculating a performance ratio of said theoretical refrigeration power to said theoretical heat transfer rate, for each of said plurality of fluid mixtures; selecting the fluid mixture having the highest performance ratio; compressing said selected fluid mixture to said high end of said selected pressure range and a high end of said selected temperature range; cooling said compressed fluid mixture in said heat exchanger; and isenthalpically expanding said fluid mixture in said expansion element from said high end of said selected pressure range to a low end of said selected pressure range, to cool said fluid mixture to said lower end of said selected temperature range.

Claim 10

A method of operating a miniature refrigeration system, said method comprising: providing a miniature closed loop refrigeration system having a compressor, a counterflow heat exchanger, and a Joule-Thomson expansion element; selecting a pressure range of operation for a fluid mixture to be used in said closed loop refrigeration system, said pressure range having a high end no greater than 420 psia; selecting a temperature range of operation for said fluid mixture to be used in said closed loop refrigeration system, said temperature range having a low end no greater than 183K; selecting a plurality of component fluids, each said component fluid having known enthalpy values over said selected temperature range and said selected pressure range; selecting a plurality of combinations of said component fluids to formulate a plurality of fluid mixtures; calculating enthalpy values for each said fluid mixture at a plurality of data points over said temperature range and said pressure range; calculating a theoretical heat transfer rate achievable in a counterflow heat exchanger with each said fluid mixture, over said selected temperature and pressure range; calculating a theoretical Joule-Thomson refrigeration power achievable with each said fluid mixture, over said selected temperature and pressure range; calculating a performance ratio of said theoretical refrigeration power to said theoretical heat transfer rate, for each of said plurality of fluid mixtures; selecting the fluid mixture having the highest performance ratio; compressing said selected fluid mixture to said high end of said selected pressure range and a high end of said selected temperature range; cooling said compressed fluid mixture in said heat exchanger; and isenthalpically expanding said fluid mixture in said expansion element from said high end of said selected pressure range to a low end of said selected pressure range, to cool said fluid mixture to said lower end of said selected temperature range.

Claim 15

A method for selecting a fluid mixture for use in a closed loop Joule-Thomson refrigeration system, said method comprising: selecting a temperature range of 150K to 270K, and a pressure range of 1 bar to 21 bar, over which a closed loop Joule-Thomson refrigeration system will be operated; selecting a plurality of combinations of component fluids from among the group Ar, CH 4 , C 2 H 4 , C 3 H 4 , Kr, N 2 , NF 3 , 1-pentene, Isobutane, Isopentane, Propylene, R14, R22, R23, R32, R124, and R142b to formulate a plurality of fluid mixtures; calculating enthalpy values for each said fluid mixture at a plurality of data points over said temperature range and said pressure range; calculating a theoretical heat transfer rate achievable in a counterflow heat exchanger with each said fluid mixture, over said selected temperature and pressure range; calculating a theoretical Joule-Thomson refrigeration power achievable with each said fluid mixture, over said selected temperature and pressure range; calculating a performance ratio of said theoretical refrigeration power to said theoretical heat transfer rate, for each said fluid mixture; and selecting the fluid mixture 7% R22, 7% R23, 20% R142b, 55% Krypton, and 11% NF 3 as having the highest said performance ratio as the best performing fluid mixture possible, over said temperature range and said pressure range, among said fluid mixtures formulated from said component fluids, for use in said closed loop Joule-Thomson refrigeration system, wherein said molar percentages have a range of +/-10%.

Claim 16

A method for selecting a fluid mixture for use in a closed loop Joule-Thomson refrigeration system, said method comprising: selecting a temperature range of 150K to 270K, and a pressure range of 1 bar to 21 bar, over which a closed loop Joule-Thomson refrigeration system will be operated; selecting a plurality of combinations of component fluids from among the group Ar, CH 4 , C 2 H 4 , C 3 H 4 , Kr, N 2 , NF 3 , 1-pentene, Isobutane, Isopentane, Propylene, R14, R22, R23, R32, R124, and R142b to formulate a plurality of fluid mixtures; calculating enthalpy values for each said fluid mixture at a plurality of data points over said temperature range and said pressure range; calculating a theoretical heat transfer rate achievable in a counterflow heat exchanger with each said fluid mixture, over said selected temperature and pressure range; calculating a theoretical Joule-Thomson refrigeration power achievable with each said fluid mixture, over said selected temperature and pressure range; calculating a performance ratio of said theoretical refrigeration power to said theoretical heat transfer rate, for each said fluid mixture; and selecting the fluid mixture 7% R22, 7% R23, 20% R142b, 55% Krypton, and 11% NF 3 as having the highest said performance ratio as the best performing fluid mixture possible, over said temperature range and said pressure range, among said fluid mixtures formulated from said component fluids, for use in said closed loop Joule-Thomson refrigeration system, wherein said molar percentages have a range of +/-10%.

Claim 17

A method for selecting a non-toxic fluid mixture for use in a closed loop Joule-Thomson refrigeration system, said method comprising: selecting a temperature range of 150K to 270K, and a pressure range of 1 bar to 21 bar, over which a closed loop Joule-Thomson refrigeration system will be operated; selecting a plurality of combinations of component fluids from among the group Ar, CH 4 , C 2 H 4 , C 3 H 4 , Kr, N 2 , 1-pentene, Isobutane, Isopentane, Propylene, R14, R22, R23, R32, R124, and R142b to formulate a plurality of fluid mixtures; calculating enthalpy values for each said fluid mixture at a plurality of data points over said temperature range and said pressure range; calculating a theoretical heat transfer rate achievable in a counterflow heat exchanger with each said fluid mixture, over said selected temperature and pressure range; calculating a theoretical Joule-Thomson refrigeration power achievable with each said fluid mixture, over said selected temperature and pressure range; calculating a performance ratio of said theoretical refrigeration power to said theoretical heat transfer rate, for each said fluid mixture; and selecting the fluid mixture 7.5% R22, 7.5% R23, 20% R142b, and 65% Krypton as having the highest said performance ratio as the best performing non-toxic fluid mixture possible, over said temperature range and said pressure range, among said fluid mixtures formulated from said component fluids, for use in said closed loop Joule-Thomson refrigeration system, wherein said molar percentages have a range of +/-10%.

Claim 18

A method for selecting a non-toxic fluid mixture for use in a closed loop Joule-Thomson refrigeration system, said method comprising: selecting a temperature range of 150K to 270K, and a pressure range of 1 bar to 21 bar, over which a closed loop Joule-Thomson refrigeration system will be operated; selecting a plurality of combinations of component fluids from among the group Ar, CH 4 , C 2 H 4 , C 3 H 4 , Kr, N 2 , 1-pentene, Isobutane, Isopentane, Propylene, R14, R22, R23, R32, R124, and R142b to formulate a plurality of fluid mixtures; calculating enthalpy values for each said fluid mixture at a plurality of data points over said temperature range and said pressure range; calculating a theoretical heat transfer rate achievable in a counterflow heat exchanger with each said fluid mixture, over said selected temperature and pressure range; calculating a theoretical Joule-Thomson refrigeration power achievable with each said fluid mixture, over said selected temperature and pressure range; calculating a performance ratio of said theoretical refrigeration power to said theoretical heat transfer rate, for each said fluid mixture; and selecting the fluid mixture 7.5% R22, 7.5% R23, 20% R142b, and 65% Krypton as having the highest said performance ratio as the best performing non-toxic fluid mixture possible, over said temperature range and said pressure range, among said fluid mixtures formulated from said component fluids, for use in said closed loop Joule-Thomson refrigeration system, wherein said molar percentages have a range of +/-10%.

Claim 19

A method for selecting an environmentally safe fluid mixture incorporating freons, for use in a closed loop Joule-Thomson refrigeration system, said method comprising: selecting a temperature range of 150K to 270K, and a pressure range of 1 bar to 21 bar, over which a closed loop Joule-Thomson refrigeration system will be operated; selecting a plurality of combinations of component fluids from among the group Ar, CH 4 , C 2 H 4 , C 3 H 4 , Kr, N 2 , NF 3 , 1-pentene, Isobutane, Isopentane, Propylene, R14, R23, R32, and R124 to formulate a plurality of fluid mixtures; calculating enthalpy values for each said fluid mixture at a plurality of data points over said temperature range and said pressure range; calculating a theoretical heat transfer rate achievable in a counterflow heat exchanger with each said fluid mixture, over said selected temperature and pressure range; calculating a theoretical Joule-Thomson refrigeration power achievable with each said fluid mixture, over said selected temperature and pressure range; calculating a performance ratio of said theoretical refrigeration power to said theoretical heat transfer rate, for each said fluid mixture; and selecting the fluid mixture 7.5% R32, 7.5% R23, 20% R124, and 65% Krypton as having the highest said performance ratio as the best performing environmentally safe fluid mixture possible, over said temperature range and said pressure range, among said fluid mixtures formulated from said component fluids, for use in said closed loop Joule-Thomson refrigeration system, wherein said molar percentages have a range of +/-10%.

Claim 20

A method for selecting an environmentally safe fluid mixture incorporating freons, for use in a closed loop Joule-Thomson refrigeration system, said method comprising: selecting a temperature range of 150K to 270K, and a pressure range of 1 bar to 21 bar, over which a closed loop Joule-Thomson refrigeration system will be operated; selecting a plurality of combinations of component fluids from among the group Ar, CH 4 , C 2 H 4 , C 3 H 4 , Kr, N 2 , NF 3 , 1-pentene, Isobutane, Isopentane, Propylene, R14, R23, R32, and R124 to formulate a plurality of fluid mixtures; calculating enthalpy values for each said fluid mixture at a plurality of data points over said temperature range and said pressure range; calculating a theoretical heat transfer rate achievable in a counterflow heat exchanger with each said fluid mixture, over said selected temperature and pressure range; calculating a theoretical Joule-Thomson refrigeration power achievable with each said fluid mixture, over said selected temperature and pressure range; calculating a performance ratio of said theoretical refrigeration power to said theoretical heat transfer rate, for each said fluid mixture; and selecting the fluid mixture 7.5% R32, 7.5% R23, 20% R124, and 65% Krypton as having the highest said performance ratio as the best performing environmentally safe fluid mixture possible, over said temperature range and said pressure range, among said fluid mixtures formulated from said component fluids, for use in said closed loop Joule-Thomson refrigeration system, wherein said molar percentages have a range of +/-10%.

Claim 21

A method for selecting a fluid mixture for use in a closed loop, pre-cooled Joule-Thomson refrigeration system, said method comprising: selecting a temperature range and a pressure range over which a closed loop, pre-cooled Joule-Thomson refrigeration system will be operated; selecting a plurality of combinations of component fluids to formulate a plurality of fluid mixtures; calculating enthalpy values for each said fluid mixture at a plurality of data points over said temperature range and said pressure range; calculating a theoretical heat transfer rate achievable in a counterflow heat exchanger with each said fluid mixture, over said selected temperature and pressure range; calculating a theoretical Joule-Thomson refrigeration power achievable with each said fluid mixture, over said selected temperature and pressure range; calculating a performance ratio of said theoretical refrigeration power to said theoretical heat transfer rate, for each said fluid mixture; selecting the fluid mixture having the highest said performance ratio; selecting a revised temperature range having an upper limit below the boiling point of one of said component fluids used in said selected fluid mixture; eliminating said component fluid having said boiling point above said upper limit of said revised temperature range, to derive a revised fluid mixture as the best performing fluid mixture possible, among said fluid mixtures formulated from said component fluids, for use in said closed loop, pre-cooled Joule-Thomson refrigeration system, wherein said revised mixture is pre-cooled to said upper limit of said revised temperature range.

Claim 22

A method for selecting a fluid mixture for use in a closed loop, pre-cooled Joule-Thomson refrigeration system, said method comprising: selecting a temperature range and a pressure range over which a closed loop, pre-cooled Joule-Thomson refrigeration system will be operated; selecting a plurality of combinations of component fluids to formulate a plurality of fluid mixtures; calculating enthalpy values for each said fluid mixture at a plurality of data points over said temperature range and said pressure range; calculating a theoretical heat transfer rate achievable in a counterflow heat exchanger with each said fluid mixture, over said selected temperature and pressure range; calculating a theoretical Joule-Thomson refrigeration power achievable with each said fluid mixture, over said selected temperature and pressure range; calculating a performance ratio of said theoretical refrigeration power to said theoretical heat transfer rate, for each said fluid mixture; selecting the fluid mixture having the highest said performance ratio; selecting a revised temperature range having an upper limit below the boiling point of one of said component fluids used in said selected fluid mixture; eliminating said component fluid having said boiling point above said upper limit of said revised temperature range, to derive a revised fluid mixture as the best performing fluid mixture possible, among said fluid mixtures formulated from said component fluids, for use in said closed loop, pre-cooled Joule-Thomson refrigeration system, wherein said revised mixture is pre-cooled to said upper limit of said revised temperature range.

Claim 23

A method for selecting a fluid mixture for use in a closed loop, pre-cooled Joule-Thomson refrigeration system, said method comprising: selecting a temperature range of 150K to 270K, and a pressure range of 1 bar to 21 bar, over which a closed loop, pre-cooled Joule-Thomson refrigeration system will be operated; selecting a plurality of combinations of component fluids from among the group Ar, CH 4 , C 2 H 4 , C 3 H 4 , Kr, N 2 , 1-pentene, Isobutane, Isopentane, Propylene, R14, R22, R23, R32, R124, and R142b to formulate a plurality of fluid mixtures; calculating enthalpy values for each said fluid mixture at a plurality of data points over said temperature range and said pressure range; calculating a theoretical heat transfer rate achievable in a counterflow heat exchanger with each said fluid mixture, over said selected temperature and pressure range; calculating a theoretical Joule-Thomson refrigeration power achievable with each said fluid mixture, over said selected temperature and pressure range; calculating a performance ratio of said theoretical refrigeration power to said theoretical heat transfer rate, for each said fluid mixture; and selecting the fluid mixture 7.5% R22, 7.5% R23, 20% R142b, and 65% Krypton as having the highest said performance ratio; selecting a revised temperature range of 150K to 245K having an upper limit below the boiling point of R142b; and eliminating R142b from said selected fluid mixture, to derive the revised fluid mixture 20% R22, 20% R23, and 60% Krypton, for use in said closed loop, pre-cooled Joule-Thomson refrigeration system, wherein said revised mixture is pre-cooled to 245K, wherein said molar percentages have a range of +/-10%.

Claim 24

A method for selecting a fluid mixture for use in a closed loop, pre-cooled Joule-Thomson refrigeration system, said method comprising: selecting a temperature range of 150K to 270K, and a pressure range of 1 bar to 21 bar, over which a closed loop, pre-cooled Joule-Thomson refrigeration system will be operated; selecting a plurality of combinations of component fluids from among the group Ar, CH 4 , C 2 H 4 , C 3 H 4 , Kr, N 2 , 1-pentene, Isobutane, Isopentane, Propylene, R14, R22, R23, R32, R124, and R142b to formulate a plurality of fluid mixtures; calculating enthalpy values for each said fluid mixture at a plurality of data points over said temperature range and said pressure range; calculating a theoretical heat transfer rate achievable in a counterflow heat exchanger with each said fluid mixture, over said selected temperature and pressure range; calculating a theoretical Joule-Thomson refrigeration power achievable with each said fluid mixture, over said selected temperature and pressure range; calculating a performance ratio of said theoretical refrigeration power to said theoretical heat transfer rate, for each said fluid mixture; and selecting the fluid mixture 7.5% R22, 7.5% R23, 20% R142b, and 65% Krypton as having the highest said performance ratio; selecting a revised temperature range of 150K to 245K having an upper limit below the boiling point of R142b; and eliminating R142b from said selected fluid mixture, to derive the revised fluid mixture 20% R22, 20% R23, and 60% Krypton, for use in said closed loop, pre-cooled Joule-Thomson refrigeration system, wherein said revised mixture is pre-cooled to 245K, wherein said molar percentages have a range of +/-10%.

Claim 25

A method for selecting a fluid mixture for use in a closed loop, pre-cooled Joule-Thomson refrigeration system, said method comprising: selecting a temperature range of 150K to 270K, and a pressure range of 1 bar to 21 bar, over which a closed loop, pre-cooled Joule-Thomson refrigeration system will be operated; selecting a plurality of combinations of component fluids from among the group Ar, CH 4 , C 2 H 4 , C 3 H 4 , Kr, N 2 , 1-pentene, Isobutane, Isopentane, Propylene, R14, R22, R23, R32, R124, and R142b to formulate a plurality of fluid mixtures; calculating enthalpy values for each said fluid mixture at a plurality of data points over said temperature range and said pressure range; calculating a theoretical heat transfer rate achievable in a counterflow heat exchanger with each said fluid mixture, over said selected temperature and pressure range; calculating a theoretical Joule-Thomson refrigeration power achievable with each said fluid mixture, over said selected temperature and pressure range; calculating a performance ratio of said theoretical refrigeration power to said theoretical heat transfer rate, for each said fluid mixture; and selecting the fluid mixture 7.5% R22, 7.5% R23, 20% R142b, and 65% Krypton as having the highest said performance ratio; selecting a revised temperature range of 150K to 245K having an upper limit below the boiling point of R142b; and eliminating R142b from said selected fluid mixture, to derive the revised fluid mixture 25% R22, 25% R23, and 50% Krypton, for use in said closed loop, pre-cooled Joule-Thomson refrigeration system, wherein said revised mixture is pre-cooled to 245K, wherein said molar percentages have a range of +/-10%.

Claim 26

A method for selecting a fluid mixture for use in a closed loop, pre-cooled Joule-Thomson refrigeration system, said method comprising: selecting a temperature range of 150K to 270K, and a pressure range of 1 bar to 21 bar, over which a closed loop, pre-cooled Joule-Thomson refrigeration system will be operated; selecting a plurality of combinations of component fluids from among the group Ar, CH 4 , C 2 H 4 , C 3 H 4 , Kr, N 2 , 1-pentene, Isobutane, Isopentane, Propylene, R14, R22, R23, R32, R124, and R142b to formulate a plurality of fluid mixtures; calculating enthalpy values for each said fluid mixture at a plurality of data points over said temperature range and said pressure range; calculating a theoretical heat transfer rate achievable in a counterflow heat exchanger with each said fluid mixture, over said selected temperature and pressure range; calculating a theoretical Joule-Thomson refrigeration power achievable with each said fluid mixture, over said selected temperature and pressure range; calculating a performance ratio of said theoretical refrigeration power to said theoretical heat transfer rate, for each said fluid mixture; and selecting the fluid mixture 7.5% R22, 7.5% R23, 20% R142b, and 65% Krypton as having the highest said performance ratio; selecting a revised temperature range of 150K to 245K having an upper limit below the boiling point of R142b; and eliminating R142b from said selected fluid mixture, to derive the revised fluid mixture 25% R22, 25% R23, and 50% Krypton, for use in said closed loop, pre-cooled Joule-Thomson refrigeration system, wherein said revised mixture is pre-cooled to 245K, wherein said molar percentages have a range of +/-10%.

Claim 27

A method for selecting a fluid mixture for use in a closed loop Joule-Thomson refrigeration system, said method comprising: selecting a temperature range of 120K to 270K, and a pressure range of 1 bar to 21 bar, over which a closed loop Joule-Thomson refrigeration system will be operated; selecting a plurality of combinations of component fluids from among the group Ar, CH 4 , C 2 H 4 , C 3 H 4 , Kr, N 2 , NF 3 , 1-pentene, Isobutane, Isopentane, Propylene, R14, R22, R23, R32, R124, and R142b to formulate a plurality of fluid mixtures; calculating enthalpy values for each said fluid mixture at a plurality of data points over said temperature range and said pressure range; calculating a theoretical heat transfer rate achievable in a counterflow heat exchanger with each said fluid mixture, over said selected temperature and pressure range; calculating a theoretical Joule-Thomson refrigeration power achievable with each said fluid mixture, over said selected temperature and pressure range; calculating a performance ratio of said theoretical refrigeration power to said theoretical heat transfer rate, for each said fluid mixture; and selecting the fluid mixture 43% Ar (+/-7.5%), 13% Kr (+/-5%), 11% R14 (+/-5%), 2% R22 (+/-5%), 14% R23 (+/-5%), 4% R124 (+/-5%), and 13% Isopentane (+/-5%) as having the highest said performance ratio as the best performing fluid mixture possible, over said temperature range and said pressure range, among said fluid mixtures formulated from said component fluids, for use in said closed loop Joule-Thomson refrigeration system.

Claim 28

A method for selecting a fluid mixture for use in a closed loop Joule-Thomson refrigeration system, said method comprising: selecting a temperature range of 120K to 270K, and a pressure range of 1 bar to 21 bar, over which a closed loop Joule-Thomson refrigeration system will be operated; selecting a plurality of combinations of component fluids from among the group Ar, CH 4 , C 2 H 4 , C 3 H 4 , Kr, N 2 , NF 3 , 1-pentene, Isobutane, Isopentane, Propylene, R14, R22, R23, R32, R124, and R142b to formulate a plurality of fluid mixtures; calculating enthalpy values for each said fluid mixture at a plurality of data points over said temperature range and said pressure range; calculating a theoretical heat transfer rate achievable in a counterflow heat exchanger with each said fluid mixture, over said selected temperature and pressure range; calculating a theoretical Joule-Thomson refrigeration power achievable with each said fluid mixture, over said selected temperature and pressure range; calculating a performance ratio of said theoretical refrigeration power to said theoretical heat transfer rate, for each said fluid mixture; and selecting the fluid mixture 43% Ar (+/-7.5%), 13% Kr (+/-5%), 11% R14 (+/-5%), 2% R22 (+/-5%), 14% R23 (+/-5%), 4% R124 (+/-5%), and 13% Isopentane (+/-5%) as having the highest said performance ratio as the best performing fluid mixture possible, over said temperature range and said pressure range, among said fluid mixtures formulated from said component fluids, for use in said closed loop Joule-Thomson refrigeration system.

Claim 29

A method for selecting a fluid mixture for use in a closed loop Joule-Thomson refrigeration system, said method comprising: selecting a temperature range of 100K to 260K, and a pressure range of 1 bar to 21 bar, over which a closed loop Joule-Thomson refrigeration system will be operated; selecting a plurality of combinations of component fluids from among the group Ar, CH 4 , C 2 H 4 , C 3 H 4 , Kr, N 2 , NF 3 , 1-pentene, Isobutane, Isopentane, Propylene, R14, R22, R23, R32, R124, and R142b to formulate a plurality of fluid mixtures; calculating enthalpy values for each said fluid mixture at a plurality of data points over said temperature range and said pressure range; calculating a theoretical heat transfer rate achievable in a counterflow heat exchanger with each said fluid mixture, over said selected temperature and pressure range; calculating a theoretical Joule-Thomson refrigeration power achievable with each said fluid mixture, over said selected temperature and pressure range; calculating a performance ratio of said theoretical refrigeration power to said theoretical heat transfer rate, for each said fluid mixture; and selecting the fluid mixture 50% Ar (+/-10%), 10% CH 4 (+/-5%), 18% C 2 H 4 (+/-5%), 5% NF 3 (+/-5%), and 17% R142b (+/-5%) as having the highest said performance ratio as the best performing fluid mixture possible, over said temperature range and said pressure range, among said fluid mixtures formulated from said component fluids, for use in said closed loop Joule-Thomson refrigeration system.

Claim 30

A method for selecting a fluid mixture for use in a closed loop Joule-Thomson refrigeration system, said method comprising: selecting a temperature range of 100K to 260K, and a pressure range of 1 bar to 21 bar, over which a closed loop Joule-Thomson refrigeration system will be operated; selecting a plurality of combinations of component fluids from among the group Ar, CH 4 , C 2 H 4 , C 3 H 4 , Kr, N 2 , NF 3 , 1-pentene, Isobutane, Isopentane, Propylene, R14, R22, R23, R32, R124, and R142b to formulate a plurality of fluid mixtures; calculating enthalpy values for each said fluid mixture at a plurality of data points over said temperature range and said pressure range; calculating a theoretical heat transfer rate achievable in a counterflow heat exchanger with each said fluid mixture, over said selected temperature and pressure range; calculating a theoretical Joule-Thomson refrigeration power achievable with each said fluid mixture, over said selected temperature and pressure range; calculating a performance ratio of said theoretical refrigeration power to said theoretical heat transfer rate, for each said fluid mixture; and selecting the fluid mixture 50% Ar (+/-10%), 10% CH 4 (+/-5%), 18% C 2 H 4 (+/-5%), 5% NF 3 (+/-5%), and 17% R142b (+/-5%) as having the highest said performance ratio as the best performing fluid mixture possible, over said temperature range and said pressure range, among said fluid mixtures formulated from said component fluids, for use in said closed loop Joule-Thomson refrigeration system.