Liquid chiller evaporator

A closed cycle very low temperature refrigeration system comprising:

• a refrigeration unit for delivering low temperature, low pressure refrigerant to the refrigerant inlet of the evaporator, and receiving a return flow of said refrigerant at a higher temperature from the refrigerant outlet of the evaporator;
• a liquid chiller for cooling low temperature coolant, said coolant in steady state operation being cooled to outlet temperature T2 from inlet temperature T1 at a predetermined mass flow and with limited pressure drop, said liquid chiller including:
• a cylindrical outer casing having an initial internal volume, and including a coolant inlet and a coolant outlet, said coolant inlet and outlet communicating with said initial internal volume, said outer casing further including a refrigerant inlet receiving said refrigerant from said refrigeration unit and a refrigerant outlet returning said refrigerant to said refrigeration unit;
• an inner cylinder within said outer casing and having a common longitudinal axis with said casing, said inner cylinder occupying a substantial portion of said initial internal volume;
• a finned tubing of extended length connected between said refrigerant inlet and said refrigerant outlet for refrigerant flow therethrough, said finned tubing being wrapped around and contacting said inner cylinder and further occupying said initial internal volume, fins of said tubing extending toward an inner surface of said outer casing;
• in operation, coolant entering said volume at said coolant inlet flowing over said finned tubing to said coolant outlet, said cold refrigerant flowing through said finned tubing from said refrigerant inlet to said refrigerant outlet absorbing heat from said coolant,
• said outer casing and inner cylinder being constructed in materials and dimensions, and said fins and tubing being selected, to provide low mass and a coolant flow passage between the outer casing and inner cylinder around the finned tubing,
• said chiller providing rapid cool down of said coolant at start up and, in steady state operation, reducing the inlet temperature T1 of said coolant to said outlet temperature T2, at a predetermined mass flow, and with limited pressure drop and, said coolant has a kinematic viscosity of at least 10 centistokes at −80 degrees C.

A liquid chiller for cooling very low temperature coolant, said coolant being cooled to outlet temperature T2 from inlet temperature T1 at a predetermined mass flow and with limited pressure drop, comprising:

• a cylindrical outer casing having an initial internal volume, and including a coolant inlet and a coolant outlet, said coolant inlet and outlet communicating with said initial internal volume, said outer casing further including a refrigerant inlet and refrigerant outlet;
• an inner cylinder within said outer casing and having a common longitudinal axis with said outer casing, said inner cylinder occupying a substantial portion of said initial internal volume;
• a finned tubing of extended length connected between said refrigerant inlet and said refrigerant outlet for refrigerant flow therethrough, said finned tubing being wrapped around and contacting said inner cylinder and further occupying said initial internal volume, fins of said tubing extending toward an inner surface of said outer casing;
• in operation, coolant entering said volume at said coolant inlet flowing over said finned tubing to said coolant outlet, a cold refrigerant flowing through said finned tubing from said refrigerant inlet to said refrigerant outlet absorbing heat from said coolant,
• said outer casing and inner cylinder being constructed in materials and dimensions, and said fins and tubing being selected, to provide low mass and a coolant flow passage between the outer casing and inner cylinder around the finned tubing,
• said chiller providing rapid cool down of said coolant at start up and, in steady state operation, reducing the inlet temperature T1 of said coolant to said outlet temperature T2, at a predetermined mass flow, and with limited pressure drop and,
• said coolant is a liquid coolant having a kinematic viscosity of at least 0.2 centistokes at 25 degrees C. and 2 centistokes at −80 degrees C. and a pressure drop of 2 PSI or less.

A liquid chiller for cooling very low temperature coolant, said coolant being cooled to outlet temperature T2 from inlet temperature T1 at a predetermined mass flow and with limited pressure drop, comprising:

• a cylindrical outer casing having an initial internal volume, and including a coolant inlet and a coolant outlet, said coolant inlet and outlet communicating with said initial internal volume, said outer casing further including a refrigerant inlet and refrigerant outlet;
• an inner cylinder within said outer casing and having a common longitudinal axis with said outer casing, said inner cylinder occupying a substantial portion of said initial internal volume;
• a finned tubing of extended length connected between said refrigerant inlet and said refrigerant outlet for refrigerant flow therethrough, said finned tubing being wrapped around and contacting said inner cylinder and further occupying said initial internal volume, fins of said tubing extending toward an inner surface of said outer casing;
• in operation, coolant entering said volume at said coolant inlet flowing over said finned tubing to said coolant outlet, a cold refrigerant flowing through said finned tubing from said refrigerant inlet to said refrigerant outlet absorbing heat from said coolant,
• said outer casing and inner cylinder being constructed in materials and dimensions, and said fins and tubing being selected, to provide low mass and a coolant flow passage between the outer casing and inner cylinder around the finned tubing,
• said chiller providing rapid cool down of said coolant at start up and, in steady state operation, reducing the inlet temperature T1 of said coolant to said outlet temperature T2, at a predetermined mass flow, and with limited pressure drop and,
• said coolant when flowing over said finned surface has a Reynolds number of approximately 3 to 30.

A liquid chiller for cooling very low temperature coolant, said coolant being cooled to outlet temperature T2 from inlet temperature T1 at a predetermined mass flow and with limited pressure drop, comprising:

• a cylindrical outer casing having an initial internal volume, and including a coolant inlet and a coolant outlet, said coolant inlet and outlet communicating with said initial internal volume, said outer casing further including a refrigerant inlet and refrigerant outlet;
• an inner cylinder within said outer casing and having a common longitudinal axis with said outer casing, said inner cylinder occupying a substantial portion of said initial internal volume;
• a finned tubing of extended length connected between said refrigerant inlet and said refrigerant outlet for refrigerant flow therethrough, said finned tubing being wrapped around and contacting said inner cylinder and further occupying said initial internal volume, fins of said tubing extending toward an inner surface of said outer casing;
• in operation, coolant entering said volume at said coolant inlet flowing over said finned tubing to said coolant outlet, a cold refrigerant flowing through said finned tubing from said refrigerant inlet to said refrigerant outlet absorbing heat from said coolant,
• said outer casing and inner cylinder being constructed in materials and dimensions, and said fins and tubing being selected, to provide low mass and a coolant flow passage between the outer casing and inner cylinder around the finned tubing,
• said chiller providing rapid cool down of said coolant at start up and, in steady state operation, reducing the inlet temperature T1 of said coolant to said outlet temperature T2, at a predetermined mass flow, and with limited pressure drop and,
• said refrigerant is a mixed refrigerant that is approximately 22% of R-14, approximately 9% of R-23, approximately 9% of R-125, and approximately 60% of R-236fa.