A climate-control system can be used to heat or cool a space. The climate-control system may include first and second vessels between which refrigerant and co-fluid may be circulated. The refrigerant may be absorbed into the co-fluid within the first vessel at a first rate. The refrigerant may desorb from the co-fluid within the second vessel at a second rate. Ultrasonic energy may be used to adjust the second rate to substantially match the first rate.

This method for producing a lubricating oil composition includes: a step of dissolving fullerenes in a base oil mainly composed of a multiply alkylated cyclopentane oil or an ionic liquid containing an imide as a negative ion to obtain a fullerene solution; and a step of producing fullerenes adduct by subjecting the above-described fullerene solution to a heat treatment in a non-oxidizing atmosphere.

This method for producing a lubricating oil composition includes: a step of dissolving fullerenes in a base oil mainly composed of a multiply alkylated cyclopentane oil or an ionic liquid containing an imide as a negative ion to obtain a fullerene solution; and a step of producing fullerenes adduct by subjecting the above-described fullerene solution to a heat treatment in a non-oxidizing atmosphere.

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.

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.