Simulation of Concentrated Photovoltaic Cooling System

This paper reports work underway in converting a dish-Stirling system to a dish-PV system at UNLV. The existing SAIC dish–Stirling system is being retrofitted with new fixed-focus facets and an Amonix photovoltaic receiver to replace the Stirling engine/generator package. As is the case with photovoltaic systems generally, the Amonix cells being used in this application lose efficiency as their temperatures increase. To combat this effect, cooling is provided by circulating liquid through channels in the backing plate. The liquid is then pumped through an array of automotive type radiators and the excess heat is rejected to the ambient air. Reported here is the development of a numerical model for the cooling system, with specific attention being paid to the transient response. Experimental data is taken to determine the various properties of the individual components to be used in the system and this data is used in a MatLab-based simulation. The cooling system model can then be linked to a similar model for the receiver and cell assembly and the optimization functions included in MatLab can be used to select the input parameters (pump size, number of radiators, fan speed, etc.) that maximize the overall efficiency of the system. The predictions of the model can be used in the selection of the final cooling system design and the validity of the model can be checked against the actual performance of the unit.