Experimental Study On Heat Engine And Winter Heating Based On Fresnel Solar Collector

Solar energy resources are abundant and the total amount is huge.It can meet the energy demand without affecting the environment,so it has great development potential.This paper is based on the existing small Fresnel lens-type solar thermal air tank experimental platform for optimization and modification,and conducts summer solar thermal engine optimization experiments and winter heating experiments respectively.The analysis of experimental data reveals the influence of key parameters of the experimental system on system performance,and provides a feasible idea for the rational use of solar energy.In order to optimize the heat absorption tube in the experimental system,a mathematical model of the fins outside the heat absorption tube was first established,and the mathematical model was subjected to heat transfer analysis to obtain the temperature distribution and heat transfer expression of the fins;then the Origin software is used to solve a series of expressions of fin heat dissipation.On the basis of greatly increasing heat transfer and basically meeting the experimental requirements,and considering its economy,an optimal set of fin parameters is finally obtained.According to the optimal fin parameters obtained in theoretical analysis and calculation work,a new type of heat absorption tube with fins was manufactured and customized,and the installation method of the heat absorption tube was improved.Subsequently,the optimized experimental bench was used to carry out the solar thermal engine experiment.Through detailed analysis of the experimental data,it was found that after installing the fins,the heat transfer efficiency of the first cycle increased from 0.284 % to 0.622 %,and the thermal power conversion efficiency increased from 27.68 % to 32 %,which indicates that the installation of fins can improve the working performance of the system and also fully verify the correctness of the theoretical analysis.However,the experimental results also showed that although the installation of fins can promote the heating process,the excessively high temperature of the fins will also have a certain negative effect in the cooling process,and this negative effect is especially obvious in the first cycle of the system.This shows that adding fins has advantages and disadvantages throughout the cycle.In winter,the original experimental device was transformed into a solar thermal storage air tank winter heating experiment system.The experimental results showed that when using this system for winter heating,the outlet air temperature of ventilation duct can be about 50 ° C higher than the indoor ambient temperature;the instantaneous thermal efficiency of the system can reach about 60%.This proves that using this system for heating is completely feasible and has certain significance for improving the heating problem in winter.However,it is still not to be neglected that the average solar thermal efficiency of the system is low,only about 40%,and the heat loss of the experimental air tank and flange is large,indicating that the system still has a space for optimization.It can be seen from this that when using a small Fresnel lens concentrating heat collection system to use solar energy,whether it is used as a heat engine or heating in winter,the system has a fast heat collection rate and high temperature,which has a great advamtages than other systems.In addition,if the heat storage device is used to store the waste heat of the cooling process while doing work,and the work obtained from the gas deflation process is also used during heating in winter,the efficiency of the system will be further improved.