Parabolic Trough Collector Performance in a Hot Climate

Abstract

Kuwait receives annual total radiation of roughly 5,280 MJ/m2 with nearly 3,347 h of sunshine. The potential for reduction of greenhouse gas emissions motivates widespread of renewable energy systems. In the research reported in this paper, a numerical model is developed to study the effect of different collector parameters and operating conditions on the performance of parabolic trough solar collector (PTSC) in Kuwait climate. The proposed model considers all thermal losses which have been neglected in existing models. New equations were developed and used in the present model as well as reviewing the equations for convective heat transfer losses. The effects of heat conduction in the collector tube wall and mixed convection in the inner tube neglected in previous studies are included in the proposed model. In addition, a case study is presented to examine the feasibility of integrating renewable energy systems in existing buildings. Solar energy absorption system is considered in the research reported in this paper to satisfy cooling load of an existing building. The program conducted on an existing institutional building intending to convert it into near-net-zero energy building. The 2-story building under consideration is the main building at the College of Technological Studies, Kuwait. Computer software is adapted to simulate the performance of different solar system components. The economic calculations for the present study are based on lifecycle savings method. In addition, a numerical model is developed to assess the environmental impacts of building integrated renewable energy systems. The present results indicate that convection loss from the absorber tube to supporting structures is the largest between the other losses. The integrated parabolic trough collectors (PTC) satisfy nearly 73% of the building cooling load under all climatic conditions of Kuwait. The annual avoided CO2 emission at the optimum conditions is about 980 t/year which confirms the environmental impacts of these systems in Kuwait. The solar system net cost is almost equal to the current cost of producing electricity in Kuwait.