Research On Optimization In Thermal Performance Test System Of Evacuated Collector Tubes

With the rapid development of science and technology,human beings have achieved unprecedented achievements in solar thermal power generation.As a focused solar thermal power generation mode,solar thermal power generation can be divided into solar dish thermal power generation,solar tower thermal power generation and solar trough thermal power generation according to the different heat collection methods.Because of its outstanding advantages,slot power has been widely used in commercial power generation systems.The principle of power generation of trough solar power system is that the solar light collected in different directions is gathered into the heat collecting tube at the center of the column through the condensing mirror of a parabolic column,so that heat is transferred to the flowing thermal mass to drive the turbine to generate electricity.Evacuated collector tube(HCE)is one of the core components in the process of the thermal power generation,the efficiency of power generation is directly influenced by its heat collecting performance.Therefore,it is crucial importance to improve the efficiency of power system through testing the performance of the tube with specific methods.The objects of studying and optimizing of this subject is the testing system for the thermal performance of evacuated collector tube,establishing the corresponding model of the thermal performance test through using the test methods of DLR and NREL,such as outdoor test(working state measurement)and indoor test(back sun measurement).Among them,the indoor test is mainly aimed at its insulation capacity,which is measured by the heat loss of the heat collecting tube.The results of heat loss test will be affected by many factors,such as the insulation at both ends,the selection of temperature sampling points,the temperature control accuracy and environmental factors.This paper from the perspective of test tube principle,firstly analyzes the technical difficulties of several important design process for measuring thermal performance test system,such as the end of the heat loss and the temperature field balance in the tube,temperature detection,energy detection,and expounds the importance of the temperature control in the process of testing the accuracy and stability of test results.Secondly,according to the test model,we design and build the corresponding hardware framework,including device selection,antiinterference design and so on.Based on this hardware,the monitoring and control software is developed with Visual Basic6.0 as the development tool,and the software is modified and perfected according to the test requirements.Then,the thermal performance test as the target,the temperature control as the core,combined with the specification of the tube testing to compare the advantages and disadvantages of several commonly used temperature control algorithm,and thus puts forward a multi-level control strategy to realize the optimization of the system.This strategy will generate a control target curve that is suitable for this test through the current control target and the state of system and provide the suitable control parameters according to the current situation of temperature increasing in real time.It can be used to accurately control the temperature of the heat collecting pipe after combining the previous two results.Finally,we proved the superiority of the optimized control strategy to control the temperature in the tube through verifying control effects of this algorithm under different test process and analyzing the corresponding test data.