Basic study on new cryogenic refrigeration using CO 2 solid–gas two phase flow

Abstract

In this paper, a cryogenic refrigeration method is described, which utilizes CO 2 solid–gas two phase flow and the dry ice. The CO 2 solid–gas two phase flow is achieved by expanding liquid CO 2 and thus refrigeration process less than CO 2 triple point −56.6 °C can be available. The experimental work is divided into two parts and two experimental set-ups were designed, constructed and tested. The interest of the first experiment test is the feasibility of expanding liquid CO 2 into CO 2 solid–gas flow in a horizontal circular tube by expansion valve. The second experiment focuses on the feasibility of the refrigeration of liquid CO 2 expanding into solid–gas two phase flows used in a prototype CO 2 heat pump system. The results show that solid–gas two phase flows can be achieved by expanding liquid CO 2 by expansion valve in a closed CO 2 heat pump system loop and low temperature refrigeration below −56.6 °C is achieved in the experiments, which give greater possibility to create a cryogenic refrigeration process below −56.6 °C for food industries, bio-medical engineering, etc.