Energy Efficient Two-Phase Microcooler Design for a Concentrated Photovoltaic Triple Junction Cell

The potential application of an R134a-cooled two-phase microcooler for thermal management of a triple junction solar cell (CPV), under concentration of 2000 suns, is presented. An analytical model for the triple-junction solar cell temperature based on prediction of two-phase flow boiling in microchannel coolers is developed and exercised with empirical correlations from the open literature for the heat transfer coefficient, pressure drop, and critical heat flux. The thermofluid analysis is augmented by detailed energy modeling relating the solar energy harvest to the “parasitic” work expended to provide the requisite cooling, including pumping power and the energy consumed in the formation and fabrication of the microcooler itself. Three fin thicknesses, between 100 μm and 500 μm, a variable number of fins, between 0 and 9, and 5 channel heights between 0.25 mm and 3 mm, are examined for a R134a flow rate of 0.85 g/s to determine the energy efficient microcooler design for a 10 mm × 10 mm triple junction CPV cell.