Study On The Experimental Method And The Influence Factors Of The Heat Transfer Efficiency Of Micro Pulsating Recuperator

In order to meet the requirements of portable electronic products growing demand for electricity, micro energy system using hydrocarbon fuel quickly becomes the trend of the development of a new generation of portable power supply, because of its great advantages in terms of energy conversion. The micro swing engine has the advantages of miniaturization, the characteristic of high energy density, is the future trend of portable power supply. However, engine exhaust takes away most of the heat generated by the combustion, so thermal efficiency of the micro swing engine the is very low. For this reason, the introduction of regenerative technique is necessary to improve the engine performance. The obvious characteristics of the recuperator suitable for micro swing engine are the small flow and the pulse characteristics of cold and hot air, which is different from the conventional recuperator. This paper designed experimental platform for the micro pulsating recuperator, and do experimental and numerical study on the heat transfer efficiency of it.At first, this paper analyses the operation difficulty of the micro swing engine brought by the recuperator. This paper solves this problem by improving its structure and using hybrid cycle. By analyzing the working cycle of the engine, the real gas flow condition of the recuperator is obtained. In order to simulate the inlet and outlet conditions of the micro pulsating recuperator, the test bench and test measurement scheme are designed in this paper. Now the working frequency of the test bench is up to 25 Hz, and the hot air temperature can be increased to 700?.Refer to the literature, it can be known that the leakage of the engine has a great influence on the engine. In order to Analysis of leakage problem, a mathematical model of leakage is established in this paper. And several sealing methods were designed on the test bench. The results show that: because of the tiny size of the engine, the quality of leak flow in engine accounts for most of the total mass of the gas inside the engine; by changing the leakage slot size and the operating frequency of the engine, the leakage in the engine can be suppressed effectively; a new type of reverse jet multistage groove sealing technology were proposed. Through numerical calculation, validator sealing effect is better, and it can suppress the leakage flow to reach more than 12%.The single air intake and the pulse frequency can influence the heat transfer efficiency of the regenerator. So this paper analyzed these two factors by numerical simulation. The research shows that: due to the effects of these two factors on the flow field in the heat exchanger, the heat transfer capability of the regenerator is enhanced. And the heat transfer efficiency of the regenerator is decreased due to the increase of the heat energy and the decrease of the heat transfer time. But the drop is not big. Also found that the heat transfer efficiency of the regenerator is lower than that of steady flow. The reason is the axial heat conduction of the wall.Then the test is carried out to study the influence factors of heat exchanger efficiency. Now the working frequency of the test bench is up to 25 Hz, and the hot air temperature can be increased to 700?. During the testing stage, it is found that the leakage of the pulse stream generator is serious, the pressurization is low, the serious influence of the leakage problem is verified, and the frequency of operation is verified. Selects two sealing method and experiment is used in test bench. It is found that the oil sealing can play a better role in sealing, labyrinth sealing can suppress the leakage flow, but the effect is poor. Then the heat transfer efficiency test of micro pulse type heat exchanger was carried out. Because of the heat dissipation and test pipeline heat conduction, the measured heat transfer efficiency is low. After considering the influence of both, experimental heat efficiency reaches about 60%, in line with the expected results. And The numerical simulation results are verified by the experimental results.