Design of the Collector of a Solar Dish-Stirling System: A Case Study

A pilot parabolic solar dish-Stirling system was designed and set up in Kerman, Iran, based on initial evaluations. The objective of this paper was to mathematically model this system to improve its performance by taking the design main factors of the collector into account. To analyze the performance of the system a thermodynamic model was developed to predict the thermal efficiency of the dish-Stirling engine based on factors such as fluid and mechanical friction, finite regeneration process time, and heat transfer, including the effects of cycle internal and external irreversibilities. The power output of the Kerman pilot was measured midday in mid-June, and it was in a good agreement with the mathematical model. Based on the results obtained by the model, the power output of the Kerman pilot in the middle days of all months in a year were predicted and then compared with the output results obtained using an improved system with an appropriately designed concentration ratio. The results showed that, in the middle of June, the maximum power output of a system with an improved concentration ratio of 2499.8 was about 1.66 times higher than that of the original Kerman pilot with a concentration ratio of 625. This system enhancement resulted in 3.56 times higher annual energy production. Moreover, the effects of the dish diameter on the system performance and the annual energy production were studied. Results showed that the annual energy production increased from 1.945 to 6.74 GWh/year when the dish diameter was increased from 3 to 5 m.