Umoya ocindezelwe ufakwa ku-pre-cooler (ngohlobo lokushisa oluphezulu) ukuze kukhishwe ukushisa, bese ugelezela kusishintshi sokushisa ngokushintshana kokushisa nomoya obandayo okhishwa ku-evaporator, ukuze izinga lokushisa lomoya ocindezelwe lingene ku-evaporator. i-evaporator yehlisiwe.