Study On Heat Transfer Characteristics For Parabolic Trough Solar Collector

The solar energy resources are rich in our country,and the potential for solar power is enormous.Solar-thermal power generation compared with the photovoltaic power output is relatively stable,and is suitable for the auxiliary renewable energy as a power generation.It has been paid much attention by people from all circles.According to the principle of the operation of the trough type solar collector and physical model,Analysis the influence of non-uniform heat flux density characteristics.It is necessary to set up a heat transfer mathematical model under non-uniform heat flux density.In order to study heat transfer characteristic of parabolic trough solar collector(PTC),a heat transfer mathematical model was established with the circumferentially non-uniform heat flux boundary conditions.The model putted the heat flux of absorber simplified to the rectangular distribution and the circumferential heat conduction of tube wall was considered.Compared with experimental results of the literature,the correctness of the model was validated and the results show that the maximum deviations are about 1.39% and 4.75% respectively.The heat transfer mathematical model can be used for the calculation and analysis of PTC.The heat transfer characteristics of PTC were analyzed by using the mathematical model.Meanwhile,the circumference temperature distribution of absorber surface was presented by FLUENT simulation.Results show that the heat transfer mathematical model can be used for the calculation of PTC.Fluid temperature,heat flux density and mass flow rate are the key factors influencing the heat transfer characteristics and the tube wall circumference temperature distribution for PTC.Axial and circumferential wall section of the heat tube has a larger temperature difference;the temperature difference is the cause of heat pipe thermal expansion and thermal stress influence safe operation of the collector.By hot-structure coupling analysis,change on the heat flux density distribution of the surface of tube wall,temperature distribution and the equivalent Von Mises stress change rule were obtained.Through the depiction of the maximum equivalent stress curves under various operating conditions and the analysis of simulation dates,the results show that the equivalent stress distribution was closely correlated with temperature distribution,and the maximum temperature shift changes with the value of heat flux density.Large temperature gradient location also has a larger thermal stress.