Energy optimization of a dish/stirling solar system for electricity generation

Abstract

Stirling cycle machines are used in both motor and receiver cycles. The Stirling cycle engine has good potential for use due to advantages such as external combustion and fuel flexibility. This study presents a Dish/Stirling system to capture solar energy for electricity generation by optimizing its energy performance. The system comprises a solar collector to convert solar energy into heat, a Stirling engine to convert heat into mechanical energy, and an alternator to convert mechanical energy into electrical energy. The Schmidt model with imperfect regeneration is used, taking into account work losses due to gas spring hysteresis. In addition, thermal losses from the solar collector are taken into account in this model. Numerical modeling was performed using MATLAB software. The impact of operational and design elements on the energy performance of the system are studied. Two objective functions were studied, namely solar electric power and solar electric energy efficiency. The results reveal that the present Dish/Stirling explores an improvement in solar electric energy efficiency of 7 % in particular in the absence of consideration of fluid friction losses. Optimum solar electric energy yield is 43.78 % at f = 18 Hz, a maximum electrical power is 10.85 kW at T_E=400 K. Finally, the heat loss due to regenerator imperfections is greatest for the paraboloidal concentrator, with a value of 0.520 kW, while the smallest loss is that due to gas spring hysteresis, with a value of 0.045 kW. This system can be used for lighting in non-electrified areas.