Analysis of refrigerant-charged solar collectors with phase change.

The model accounts for the thermal nonequilibrium vapour generation process along fully charged collector tubes. The local vapour generation rate is determined by solving the steady one-dimensional two-phase energy conservation equations in finite difference form along the flow path. Calculations have been made for a system fully charged by R11, with temperature-dependent thermophysical properties. The effect of solar insolation, for a controlled pressure system, on the vapour quality, and circulation rate is presented and discussed.