- cooling the gas during compression by introducing a cooling substance (liquid) into the compression chamber – e.g. injected oil or water.
In ‘contact cooling’, a coolant is mixed with compressed air. Compression heat released by compressed air is absorbed directly by the coolant, and then coolant is filtered in separator.
For contact cooling, liquid spray has been increasingly applied to attain the isothermal compression due to its high heat transfer rate, large contact surface, small installation space, easy handling. Cooling liquid is injected to the compressed gas directly and absorbs the compression heat to keep the temperature at a low level, due to its high specific heat and evaporation heat.
Generally, oil is a common medium for cooling and lubrication, whereas the effect of cooling is not perfect.
Oil Cooling for Screw Compressors:
Water spray cooling is also being used for its high specific heat, small spray diameter and large evaporation heat. In this study, compression system with water spray is compared with that without water spray. Increasing flow rate of water spray can enhance cooling effect, whereas the generated pressure of water spray has little influence on cooling effect.