Carbon dioxide co-fluid
A carbon dioxide/co-fluid mixture is provided for use in a refrigeration cycle in which the carbon dioxide is alternately absorbed and desorbed from the co-fluid. Suitable co-fluids are selected from the class of alkoxylated carboxylic amides, wherein the amides are cyclic or non-cyclic. It has been discovered that N-2,5,8,11-tetraoxadodecyl-2-pyrrolidinone and its homologs exhibit an advantageous property of a high rate of desorption at lower temperatures.
1. A compressor containing a lubricant, wherein the lubricant comprises a compound selected from
where m is 1 to 10; R is alkyl, alkenyl, or aryl with 1 to 26 carbon atoms; R′ is H or C 1-6 alkyl; R″ is H, methyl, or ethyl; R′″ is H, methyl, or ethyl; and at least one R″ and R′″ is H;
where m is 1 to 10; R is alkyl, alkenyl, or aryl with 1 to 26 carbon atoms; p is 1 to 3; R′ is H or C 1-6 alkyl; R″ is H, methyl, or ethyl; R′″ is H, methyl, or ethyl; and at least one R″ and R′″ is H;
where x is 1 to 4; n is 1 to 10; R′ is H or optionally substituted C 1-6 alkyl; R″ is H, methyl, or ethyl; R′″ is H, methyl, or ethyl; and at least one R″ and R′″ is H;
where y is 1 to 4; n is 1 to 10; p is 1 to 3; R′ is H or C 1-6 alkyl; R″ is H, methyl, or ethyl; R′″ is H, methyl, or ethyl; and at least one R″ and R′″ is H;
where z is 1 to 4; n is 1 to 10; R′ is H or optionally substituted C 1-6 alkyl; R″ is H, methyl, or ethyl; R′″ is H, methyl, or ethyl; and at least one of R″ and R′″ is H; and
where z is 1 to 4; n is 1 to 10; p is 1 to 3; R′ is H or optionally substituted C 1-6 alkyl; R″ is H, methyl, or ethyl; R′″ is H, methyl, or ethyl; and at least one of R″ and R′″ is H.
2. The compressor of claim 1 , wherein the lubricant comprises a compound of formula
where y is 1 to 4; n is 1 to 10; R′ is H or optionally substituted C 1-6 alkyl; R″ is H, methyl, or ethyl; R′″ is H, methyl, or ethyl; and at least one R″ and R′″ is H.
3. The compressor of claim 2 , wherein y is 2 or 4.
4. The compressor of claim 2 , wherein n is 1 to 4.
5. The compressor of claim 2 , wherein R′ is methyl.
6. The compressor of claim 2 , wherein R″ and R′″ are H.
7. The compressor of claim 2 , wherein y is 2 or 4, n is 3, R′ is methyl, and R″ and R′″ are both H.
8. The compressor of claim 1 , wherein the lubricant comprises a compound of formula
where x is 1 to 4; n is 1 to 10; R′ is H or optionally substituted C 1-6 alkyl; R″ is H, methyl, or ethyl; R′″ is H, methyl, or ethyl; and at least one R″ and R′″ is H.
9. The compressor of claim 8 , wherein x is 2 or 4.
10. The compressor of claim 8 , wherein n is 1 to 4.
11. The compressor of claim 8 , wherein R′ is methyl or C 1-3 alkyl substituted with alkylcarbamido.
12. The compressor of claim 8 , wherein R″ and R′″ are H.
13. The compressor of claim 8 , wherein x is 2 or 4, n is 3, R′ is methyl, and R″ and R′″ are both H.
14. The compressor of claim 1 , wherein the lubricant comprises a compound selected from
where m is 1 to 10; R is alkyl, alkenyl, or aryl with 1 to 26 carbon atoms; R′ is H or optionally substituted C 1-6 alkyl; R″ is H, methyl, or ethyl; R′″ is H, methyl, or ethyl; and
at least one R″ and R′″ is H.
15. The compressor of claim 14 , wherein R is alkyl.
16. The compressor of claim 14 , wherein R′ is methyl.
17. The compressor of claim 14 , wherein m is 1 to 4.
18. The compressor of claim 14 , wherein both R″ and R′″ are H.
19. The compressor of claim 14 , wherein R is alkyl with 7 to 17 carbon atoms.
20. The compressor of claim 14 , wherein the lubricant is selected from
21. The compressor of claim 1 , circulating a mixture through a climate control system, wherein the mixture comprises the lubricant and a refrigerant, wherein the refrigerant comprises carbon dioxide.
22. A cooling composition comprising carbon dioxide and a co-fluid, wherein the co-fluid is selected from compounds of formula
where m is 1 to 10; R is alkyl, alkenyl, or aryl with 1 to 26 carbon atoms; R′ is H or C 1-6 alkyl; R″ is H, methyl, or ethyl; R′″ is H, methyl, or ethyl; and at least one R″ and R′″ is H;
where x is 1 to 4; n is 1 to 10; R′ is H or optionally substituted C 1-6 alkyl; R″ is H, methyl, or ethyl; R′″ is H, methyl, or ethyl; and at least one R″ and R′″ is H; and
where y is 1 to 4; n is 1 to 10; p is 1 to 3; R′ is H or optionally substituted C 1-6 alkyl; R″ is H, methyl, or ethyl; R′″ is H, methyl, or ethyl; and at least one R″ and R′″ is H.
23. The cooling composition of claim 22 , wherein the co-fluid is selected from
24. A method of operating a refrigeration system comprising pumping the cooling composition according to claim 22 around a circuit containing in sequence a compressor, an absorber, an expander, and a desorber.