Carbon dioxide refrigerant system

1. A compressor including a refrigerant and a lubricant, wherein the lubricant comprises at least one compound selected from the group consisting of:

wherein in each of the above formulae R′, R″, and R may be the same, or R′, R″, and R may be different, and each of R′, R″, and R are selected from the group consisting of a linear or branched C1 to C10 alkyl group, an unsaturated linear or branched C1 to C10 alkyl group, a C1 to C10 alkylene group, and an aromatic group;

wherein in Formulae (5), (6), (8), and (12), a, b, and c are an integer in the range of 1 to 10;

wherein in Formula (7), x is an integer in the range of 1 to 10;

wherein Formula (11) represents a 1,a-(dialkylamino)benzene-type compound where “a” may be 2, 3, or 4; and

wherein Formula (13) represents a 1-(dialkylamino)-a-alkyl benzene-type compound where “a” may be 2, 3, or 4.

2. The compressor according to claim 1 , wherein the lubricant includes at least one compound having Formula (7).

3. The compressor according to claim 2 , wherein x equals 2.

4. A climate-control system comprising:

a compressor compressing a carbon-dioxide refrigerant;

an absorber disposed downstream of the compressor and receiving a mixture of the carbon dioxide refrigerant and a co-fluid;

an expansion device in fluid communication with the absorber and disposed downstream of the absorber; and

a desorber in fluid communication with the expansion device and disposed downstream of the expansion device,

wherein the co-fluid is at least one compound selected from the group consisting of

wherein in each of the above formulae R′, R″, and R may be the same, or R′, R″, and R may be different, and each of R′, R″, and R are selected from the group consisting of a linear or branched C1 to C10 alkyl group, an unsaturated linear or branched C1 to C10 alkyl group, a C1 to C10 alkylene group, and an aromatic group;

wherein in Formulae (5), (6), (8), and (12), a, b, and c are an integer in the range of 1 to 10;

wherein in Formula (7), x is an integer in the range of 1 to 10;

wherein Formula (11) represents a 1,a-(dialkylamino)benzene-type compound where “a” may be 2, 3, or 4; and

wherein Formula (13) represents a 1-(dialkylamino)-a-alkyl benzene-type compound where “a” may be 2, 3, or 4.

5. The climate-control system according to claim 4 , further comprising an ultrasonic transducer configured to transmit a vibration to the carbon-dioxide refrigerant and the co-fluid at a location downstream of the expansion device and upstream of the compressor, wherein the ultrasonic transducer is attached to the desorber and transmits vibration to the carbon dioxide refrigerant and the co-fluid within the desorber to increase a rate of desorption.

6. The climate-control system according to claim 5 , further comprising a control module in communication with the ultrasonic transducer and for controlling operation of the ultrasonic transducer to adjust the rate of desorption.

7. The climate-control system of claim 6 , wherein the control module controls operation of the ultrasonic transducer based on a rate of absorption of the refrigerant into the co-fluid.

8. The climate-control system of claim 7 , further comprising a first sensor measuring a first parameter of a mixture of refrigerant and co-fluid within the absorber and a second sensor measuring a second parameter of the mixture of refrigerant and co-fluid within the desorber, the first and second sensors communicating with the control module.

9. The climate-control system of claim 8 , wherein the control module determines the rate of absorption based on data received from the first sensor and determines the rate of desorption based on data received from the second sensor, and wherein the control module controls operation of the ultrasonic transducer based on a difference between the rate of absorption and the rate of desorption.

10. The climate-control system of claim 9 , wherein the control module controls operation of the ultrasonic transducer to match the rate of desorption with the rate of absorption.

11. The climate-control system of claim 5 , wherein the ultrasonic transducer is disposed within the desorber.

12. The climate-control system of claim 5 , wherein the ultrasonic transducer is in contact with the refrigerant and co-fluid within the desorber.

13. The climate-control system of claim 5 , wherein the ultrasonic transducer is mounted to an exterior surface of the desorber.

14. The climate-control system of claim 4 , further comprising a heat exchanger having a first coil and a second coil, the first coil receiving a mixture of refrigerant and co-fluid from the absorber, the second coil receiving the mixture of refrigerant and co-fluid from the desorber, wherein the mixture of refrigerant and co-fluid within the second coil absorbs heat from the mixture of refrigerant and co-fluid within the first coil.

15. The climate-control system of claim 4 , wherein a liquid-vapor separator and an agitation vessel are disposed between and in fluid communication with the compressor and the absorber.

16. The climate-control system of claim 4 , wherein the co-fluid includes at least the compound having Formula (7).

17. The climate-control system according to claim 16 , wherein x equals 2.