Evacuated tube receiver used with parabolic trough collector can be characterized in terms of their heat loss and their optical efficiency. The optical efficiency of the collector involves reflectivity, transmissivity, tracking accuracy, shading by receiver tube surface, shape and absorptance of the material used. On the other hand, receiver tube heat loss includes conductive, convective and radiative losses. Here, in case of evacuated tube, major losses are through radiation, the vacuum that surrounds the outside of the tube greatly reduces convection and conduction heat loss, therefore, achieving greater efficiency than other collector. If we subtract losses from input energy, we can reach towards approximate value of the output of the system. Hence, for obtaining the heat gain for a thermal system, heat losses play an important role. For estimating heat losses, there are several laboratories’ developed methods for heat loss with respect to temperature. This paper is focused on the heat losses of the evacuated receiver tube i.e. conductive or convective heat losses and radiative heat loss. A measurement set up for the heat loss of the single parabolic trough receiver components at steady state condition has been developed by the several research laboratories such as NREL (National Renewable Energy Laboratories), DLR (German Aerospace Centre), Schott, etc. Every method has its limitation for the performance estimation of PTC receiver tube, with the deviation of <10%. At the National Institute of Solar Energy (NISE), we have tested ETC with different methods and we found the best suitable method for the testing of ETC which is developed by the German Aerospace Centre (DLR) in which the error is very low, at about ≤2%. The standardization of procedure in testing of solar thermal evacuated tube collectors is an important factor in the analysis of any concentrating and non-concentrating solar thermal systems. Keywords: Evacuated tube collector, parabolic trough collector, reflection, transmission, radiationCite this Article Avritti Srivastava, Sachin Gupta, Usha Bajpai. Analysis and Testing Methods for Solar Thermal Evacuated Tube Collector: A Review. Journal of Thermal Engineering and Applications. 2017; 4(1): 1–4p.
