Two-phase flow performance prediction for minichannel solar collectors

High thermal efficiencies reported in the literature for non-evacuated minichannel-based solar collectors open up the possibility to explore their operation under two-phase flow conditions for low-grade steam generation and energy storage. In this article, a mathematical model is developed to analyze the performance of a minichannel solar collector under two-phase flow conditions. Six published two-phase frictional pressure drop correlations and six two-phase heat transfer correlations are utilized, and the results compared against experimental two-phase flow data from the literature. The most accurate correlations are later on used for simulating the operation of the minichannel solar collector. Results show that for two phase flow conditions, the pressure drop is found to increase dramatically with mass flux, while the outlet quality is found to remain near saturated liquid at mass fluxes higher than 54.58 kg/m(2)s. In addition, inlet temperature at saturated liquid conditions and constant mass flux did not have a significant effect on outlet quality. Applications that require low-grade steam, such as food-drying, steam-cleaning, or sterilization, among others, could benefit from the two-phase flow operation of this type of collectors.