Modelling, simulation and thermal analysis case study in Natal, Brazil

In this paper, a methodology is developed to evaluate the performance of a solar system composed of a Stirling engine and a solar dish. There are four models to be assessed: theoretical model of solar irradiation, model of parabolic solar dish, thermal model of receiver and prediction model of Stirling engine performance. A case of study will analyse a city named Natal-RN, located in Rio Grande do Norte state, Brazil. This city has high annual rates of solar irradiation. Tonatiuh software is used to evaluate parabolic dishes applying the Monte Carlo Ray Tracing method. Furthermore, a prediction model of Stirling engine performance is reformulated using 26 engines data. This reformulation allows error reduction in the prediction of four parameters when compared with the original Iwamoto's model: 40.0% in the maximum output power, 31.0% in the output power at maximum efficiency, 12.1% in the engine speed at maximum output power and 55.8% in the engine speed at maximum efficiency. The behaviour of the system, NS03T Stirling engine and solar dish, is assessed using experimental data of a Brazilian program named SONDA. At Natal-RN, it is noticed that the maximum output power reached by NS03T is higher than 1.6 kW and its global efficiency is higher than 19% between 12 h and 15 h, reaching 26% at 11 h. This values are referent to April, which is the month that represents the average solar characteristics during the year of 2015.