Performance Analysis of Parabolic Trough Collector in Hot Climate

Abstract

In most existing buildings cooling and heating loads lead to high primary energy consumption and, consequently, high CO2 emissions. These can be substantially decreased with suitable energy concepts using appropriate integrated renewable systems. In the present study 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 takes into consideration the thermal interaction between absorber-envelope, and envelope-envelope for thermal radiation losses which have been neglected in existing models. A review of the equations for convective heat transfer losses was performed as well and new equations were developed and used in the present model. The effects of heat conduction in the collector tube wall and mixed convection in the inner tube, which have been neglected in previous studies, are included in the proposed model. In addition, a case study is carried out adapting parabolic trough collectors to satisfy nominal space heating load, water heating load and cooling load of a typical Kuwaiti dwelling. Finally, the environmental impact of solar heating and cooling systems under Kuwait climate conditions is investigated. Present results indicate that convection loss from the absorber tube to supporting structures is the largest among the other losses (conduction and radiation). Also, at noon time PTSC has the smallest angle of incidence and the highest efficiency and when the annulus between the receiver surface and the glass envelope is In vacuo, conduction and convection across the annulus are effectively eliminated. In addition, space heating load and domestic water heating load can be completely provided by PTSC. The minimum required collector area is about 82 m2 to supply cooling loads of a typical residential house under all climatic conditions in Kuwait. A CO2 emission reduction of about 12.3tonne/year can be achieved as a result of adapting parabolic trough solar collector to a typical Kuwaiti dwelling.