A solar simulator numerical modeling for heat absorption phenomenon research in a parabolic trough collector

The development of renewable solar technologies determines the constant need to improve and increase their energy efficiency. Determination of solar systems performance characteristics must take place under given conditions set by proper standards. Due to unstable weather conditions, including temperature and solar radiation, it is necessary to simulate the laboratory conditions' radiation. For these purposes, so-called solar radiation simulators are being constructed. This article presents the results of solar simulator modeling for parabolic trough collectors testing. A new approach presented here proposes to use reflectors placed parallel on one plane to simulate both, total radiation and direct radiation used in parabolic concentrator tests. The methodology adopted from the normative approach for evaluating the quality of the simulator is presented. The methodology used for solar radiation simulators was modified to test concentrators in constant, repeatable conditions. The analysis was carried out not only to assess the energy distribution on the plane area but also to assess the energy reaching the tubular absorber external surface. The optical engineering ray tracing software, based on Monte Carlo Method, was used for the analysis. A selection of appropriate light sources, quantity, type, and arrangement of reflectors and their coatings was carried out. Metal-halides and xenon arc lamps were considered as sources. The distribution of radiation intensity on the analyzed surface was determined for two cases, 22 reflectors and 4 reflectors. The analyzed area was 1 square meter. The evaluation index has been defined to determine the quality of the energy distribution. The influence of the simulator distance on the amount of energy reaching the absorber surface was also analyzed. An estimation of the required financial outlays for analyzed constructions of the simulator was performed. Research has shown that in terms of maintaining the energy field's homogeneity and the price for the entire radiation simulator, it is more reasonable to construct a simulator consisting of 22 reflectors. The construction of such a simulator seems to meet the assumptions required for the correct operation of the radiation simulator. Novelty statement Paper's novelty is the methodology to identify and evaluate solar radiation simulators to simulate heat radiation for parabolic trough collectors. The paper specifies the evaluation index and the way of its interpretation, which determines the radiation distribution on the simulated surface, which is crucial in this issue. In a better and more accurate way, this factor assesses the energy field in terms of quality. Modifying the normative measurement approach of solar radiation on a flat surface, we propose the analysis of concentrated radiation by performing optical analyses using software which are based on the Monte-Carlo method. The location of light sources on the plane surface is a new approach for PTC testing.