Analysis Of Thermal Performance Of Cavity Receiver In Solar Dish Stirling Engine System

The solar receiver is an important component of solar thermal power system. In solar dishstirling thermal power system, the cavity receiver applied in high temperature conditions is placed atthe focal point of the concentrator, receives the high heat flux from the condenser and then convertssolar energy into heat energy. The thermal performance of cavity receiver directly impacts on thermalefficiency and economics of the entire system.Therefore, based on the findings of internal temperaturedistribution characteristics and heat loss characteristics of the cavity receiver, structure optimization isan effective way to improve the dish solar stirling thermal power efficiency.In this paper, cavity receiver in5kW solar dish stirling thermal power system was presented.Reasonable simplifications and assumptions were carried on cavity receiver with the convective heattransfer theory and the knowledge of the radiation model to study the thermal performance of thecavity receiver. The study took temperature impact on air thermophysical properties and the diversityof heat exchanger on the setting of thermal boundary conditions into consideration. The influence ofthe operating temperature, emissivity, the inclination angle and the aperture size on the staticperformance for the receiver was investigated. Heat loss regularity and excellent structural model ofthe cavity receiver were also given. The results showed that the model with lower wall temperature,lower emissivity, higher inclination angle and approximately8ratio of the receiver bottom area toaperture area was beneficial to reducing the heat loss of cavity receiver. In addition, the impact of heatflux boundary and combined free-forced convection caused by wind was also studied.Accounting for the instability and nonuniformity of solar distribution, numerical simulation onthe dynamic thermal performance of cavity receiver was also finished. The dynamic thermalperformance trend was obtained over different time and different forms of heat source distribution.The conclusions were obtained as follows: firstly, the upper portion of the receiver was in hightemperature region, and the maximum temperature was not at the center of the upper wall. Secondly,the greater the incident radiation flux was, the higher the internal wall temperature of the receiverbecame. The higher concentrated the incident radiation heat flux distribution became, the betteruniform distribution of the internal temperature of the receiver was.This paper also studied the thermoelectric conversion characteristics of5kW sirling engine, andthe experimental system of the thermal performance about the cavity receiver was designed.