Abstract
Increasing attention has been given to carbon dioxide as an alternative substance in refrigeration and air conditioning from a framework of global environment. The refrigerating cycle with carbon dioxide becomes trans-critical cycle because of low critical temperature (31.06℃), and the operating pressure becomes essentially higher compared with other refrigerants. This paper describes boiling heat transfer and critical heat flux of carbon dioxide near critical pressure in horizontal tubes of 1.0 and 2.0mm in diameter, and observed flow patterns in 2.0mm-diameter tube are presented.
