Compressed air energy storage system utilizing two-phase flow to facilitate heat exchange

Abstract

A compressed-air energy storage system according to embodiments of the present invention comprises a reversible mechanism to compress and expand air, one or more compressed air storage tanks, a control system, one or more heat exchangers, and, in certain embodiments of the invention, a motor-generator. The reversible air compressor-expander uses mechanical power to compress air (when it is acting as a compressor) and converts the energy stored in compressed air to mechanical power (when it is acting as an expander). In certain embodiments, the compressor-expander comprises one or more stages, each stage consisting of pressure vessel (the “pressure cell”) partially filled with water or other liquid. In some embodiments, the pressure vessel communicates with one or more cylinder devices to exchange air and liquid with the cylinder chamber(s) thereof. Suitable valving allows air to enter and leave the pressure cell and cylinder device, if present, under electronic control.

What is claimed is: 
     
         1 . A method comprising:
 introducing a first quantity of a gas at a first temperature into a first chamber;   in a compression cycle, subjecting the first quantity of gas to compression by a first piston coupled to the first chamber;   injecting a first determined quantity of liquid into the first quantity of gas to absorb thermal energy generated by the compression cycle and thereby maintain the first quantity of gas in a first temperature range during the compression; and   transferring at least a portion of the first quantity of gas to a pressure vessel partially filled with the liquid.   
     
     
         2 . The method of  claim 1  wherein the first determined quantity of liquid is based upon one or more control parameters. 
     
     
         3 . The method of  claim 2  wherein the control parameter is calculated for the compression cycle from a measured physical property. 
     
     
         4 . The method of  claim 3  wherein the measured physical property comprises a temperature of the gas in the pressure vessel. 
     
     
         5 . The method of  claim 3  wherein the measured physical property comprises a temperature of the liquid in the pressure vessel. 
     
     
         6 . The method of  claim 2  wherein the control parameter comprises a maximum increase in a temperature of the first quantity of gas during compression. 
     
     
         7 . The method of  claim 2  wherein the control parameter comprises an amount of the liquid. 
     
     
         8 . The method of  claim 2  wherein the control parameter comprises an efficiency. 
     
     
         9 . The method of  claim 2  wherein the control parameter comprises a power input to the piston. 
     
     
         10 . The method of  claim 2  wherein the control parameter comprises a speed of the piston. 
     
     
         11 . The method of  claim 2  wherein the control parameter comprises a force on the piston. 
     
     
         12 . The method of  claim 1  wherein the piston is solid, liquid, or a combination of solid and liquid. 
     
     
         13 . The method of  claim 1  wherein the first temperature range is reflected by a change in a temperature of the first quantity of gas from a first temperature to a second temperature below a boiling point of the liquid. 
     
     
         14 . The method of  claim 1  further comprising placing the liquid in the pressure vessel in communication with a heat exchanger. 
     
     
         15 . The method of  claim 1  further comprising placing the liquid in the pressure vessel in communication with a pump. 
     
     
         16 . The method of  claim 1  further comprising placing the liquid in the pressure vessel in communication with a hydraulic motor. 
     
     
         17 . The method of  claim 16  wherein the hydraulic motor comprises a motor/pump. 
     
     
         18 . The method of  claim 1  wherein the transferring comprises actuating a valve when a pressure in the chamber exceeds a pressure in the pressure vessel by a predetermined amount. 
     
     
         19 . The method of  claim 18  wherein the valve is electronically actuated. 
     
     
         20 . The method of  claim 18  wherein the valve is hydraulically actuated.