Study On Dynamic Test Method Of Lhasa Trough Solar Collectors

The solar medium temperature thermal utilization as one of the most promising energy saving technologies could be popularized as an alternative energy in the field of industrial thermal utilization.Tibet area was poor of conventional energy and rich in solar energy resources.The solar energy could effectively improve the quality of life of local residents and improve the ecological environment while it utilized efficiently.Since the solar elevation angle tracking and line focusing,it was convenient to obtain the medium temperature source of 80~400?.For thermal performance investigation,steady-state test methods that commonly employed had strict qualification conditions,which was difficult to satisfy in practice.However,the dynamic test method was only used in inland plain area.It was necessary to research on dynamic test method of thermal performance of trough collector in plateau area.Taking the experimental platform of trough solar collector system in the Energy Research and Demonstration Center of Tibet Autonomous Region as the research object,the influence of different operating parameters on the thermal performance of the collector was analyzed.Firstly,the dynamic characteristics of direct irradiance of the whole day were tested to analyze the effect of cosine loss and end loss on the heat collecting efficiency caused by the sunlight reflected by the parabolic reflector to the vacuum collector,The results showed that the cosine loss effect on thermal efficiency was obviously,and the longer the collector,the end loss reduced gradually.Secondly,based on the geographical location of Lhasa,theoretical and experimental research on factors such as concentration reflection,solar incident angle,heat transfer and heat loss,establish the dynamic test models for optical and heat transfer processes.Then the multiparameter dynamic thermal performance test model of trough collector was given,in order to accurately describe the variation characteristics between the input and output energy of the plateau trough solar collector.Finally,based on the experimental conditions of three typical meteorological environments,comparison between the predicted value of the steady state test model and the calculated value of the experimental measurement data in the American standard ASHRAE 93,the all day average thermal efficiency error predicted by the dynamic test model does not exceed ±10%.The dynamic test model reflects better predictions and was validated.This paper studied the thermal performance of the trough collector system by dynamic test analysis method in plateau area,which broken through the limitation of the steady-state method on the actual operating conditions.The method not only reduced the test time and the experimental cost,but also laid a theoretical and experimental basis for the industrialization of the plateau trough collector.Figure 44;Table 8;Reference 56.