Carbon dioxide absorption heat pump

• US 6,374,630 B1
• Filed: 05/09/2001
• Issued: 04/23/2002
• Est. Priority Date: 05/09/2001
• Status: Expired due to Term

• Current Assignee: California Institute of Technology
• Original Assignee: United States Of America As Represented By The Administrator Of The National Aeronautics And Space Administration
• Inventors: Jones, Jack A.
• Primary Examiner(s): Bennett, Henry
• Assistant Examiner(s): JIANG, CHEN WEN
• Application Number:
  US09/853,931
• Time in Patent Office: 349 Days
• Field of Search: 623/242, 624/76, 624/83, 621/01, 621/02, 621/11, 621/12, 165/104.12
• US Class Current: 62/476
• CPC Class Codes: C09K 5/047 for absorption-type refrigeration systems
• CPC Class Codes: F25B 15/02 without inert gas F25B15/004, F25B15/006, F25B15/008, F25B15/12, F25B15/14, F25B15/16 take precedence
• CPC Class Codes: F25B 2309/061 with cycle highest pressure above the supercritical pressure
• CPC Class Codes: Y02A 30/27 Relating to heating, ventilation or air conditioning [HVAC] technologies
• CPC Class Codes: Y02B 30/62 Absorption based systems
• CPC Class Codes: Y02P 20/10 Process efficiency

Abstract

A carbon dioxide absorption heat pump cycle is disclosed using a high pressure stage and a super-critical cooling stage to provide a non-toxic system. Using carbon dioxide gas as the working fluid in the system, the present invention desorbs the CO₂ from an absorbent and cools the gas in the super-critical state to deliver heat thereby. The cooled CO₂ gas is then expanded thereby providing cooling and is returned to an absorber for further cycling. Strategic use of heat exchangers can increase the efficiency and performance of the system.

Claims

1. A process for delivering heat comprising the steps of:

providing a solution of carbon dioxide dissolved in an solution;

increasing the pressure of the solution;

increasing the temperature of the solution;

boiling off carbon dioxide from the solution at the increased pressure and temperature;

cooling the carbon dioxide in a super critical state across a temperature range and delivering heat thereby;

expanding the carbon dioxide; and

returning the expanded carbon dioxide to the solution.

2. The process of claim 1 wherein the solution comprises alcohol and carbon dioxide.

3. The process of claim 1 wherein the solution comprises Isobutyl Acetate and carbon dioxide.

4. The process of claim 1 wherein the solution comprises Amyl Acetate and carbon dioxide.

5. The process of claim 1 wherein the solution comprises carbon dioxide and an absorbent, said absorbent having a normal boiling point (1 atm.) of greater than 50°

C.

6. The process of claim 1 wherein the pressure throughout the system is positive relative to an ambient pressure.

7. The process of claim 1 wherein the increase in the pressure of the solution results in a pressure of at least 500 PSI.

8. A heat pump system wherein the super critical cooling of carbon dioxide alone is used to deliver heat comprising:

a solution of carbon dioxide in an absorbent;

a pump for pressurizing a quantity of the solution to an elevated pressure;

a heater for heating the quantity of the solution;

a channel for directing carbon dioxide gas absorbed from the heated quantity of said solution to a super-critical cooling apparatus where heat is removed only from the carbon dioxide gas in a super critical state;

an expansion valve for reducing the pressure of the cooled carbon dioxide gas; and

a channel for directing the expanded cooled carbon dioxide back into the solution.

9. The heat pump of claim 8 further comprising a first heat exchanger for exchanging heat between said carbon dioxide gas and said quantity of solution.

10. The heat pump of claim 9 further comprising a second heat exchanger for exchanging heat between said cooled carbon dioxide gas and said expanded carbon dioxide gas.

11. The heat pump of claim 8 wherein the absorbent comprises alcohol.

12. The heat pump of claim 8 wherein the absorbent comprises Isobutyl Acetate.

13. The heat pump of claim 8 wherein the absorbent comprises Amyl Acetate.

14. The heat pump of claim 8 wherein the absorbent has a normal boiling point (1 atm.) of greater than 50°

C.