Experimental Research On Improving The Sound Field Intensity In The Resonant Cavity Of A Micro-refrigerator

Thermoacoustic refrigerator is a new type of refrigeration device with green environmental protection and simple structure,which is in line with the development trend of new energy diversification.Thermoacoustic refrigerators are refrigeration equipment that realizes heat transfer based on the principle of thermoacoustic effect.However,at present,there are mainly problems such as low refrigeration efficiency and insufficient refrigeration capacity.Existing studies have shown that the higher the sound field intensity(sound pressure),the larger the particle displacement.The higher the cooling efficiency,the better the cooling effect.To improve the cooling efficiency of the thermoacoustic refrigerator,a strong alternating flow of gas is required,and the previous acoustic drivers have problems such as too small amplitude and insufficient driving force.The strong alternating flow of the working medium gas cannot be met,and thus the temperature drop requirement of the refrigerator cannot be met.Therefore,in response to this problem,the following research work is carried out in this paper:(1)The idea of replacing standing wave vibration with piston modal vibration of gas column is proposed.Using piston modal vibration of gas column instead of standing wave vibration can improve the longitudinal amplitude of the gas column in the resonant cavity,and then improve the working medium gas in the resonant cavity.The strength of the alternating flow,and the modal vibration of the piston of the gas column has the same properties as the standing wave,both of which are longitudinal vibrations with stable velocity nodes and pressure nodes,like other acoustic drive thermoacoustic refrigerators,as long as there is the same gas The heat transfer can be achieved by stacking the plates between the appropriate pressure anti-node and velocity anti-node,thereby achieving more efficient cooling efficiency.(2)This paper uses the high-speed motor to drive the crank-slider mechanism to push the vibrating thin plate to realize high-frequency and large-amplitude vibration,and then realize the idea of strong alternating flow of the working medium gas in the thermoacoustic refrigerator.The large-amplitude piston-type acoustic driver meets the needs of a thermoacoustic refrigerator for a powerful sound source.(3)Using the simulation software ANSYS,the free modal analysis was carried out on the air column in the resonant cavity with a length of 600 mm,a diameter of 100 mm and a wall thickness of 5mm,and the optimal excitation frequency was found to increase the amplitude of the sound pressure in the resonant cavity and improve the thermoacoustic conversion efficiency.It provides a basis for subsequent experimental research.(4)The optimized design of some key thermoacoustic components in the refrigerator is carried out,and the experimental device of the thermoacoustic refrigerator is built.According to the simulation results,the sound field strength and cooling effect in the resonant cavity of the thermoacoustic refrigerator are experimentally studied.Including the influence of the sound pressure value on each position of the resonator axial direction under different working conditions.As well as the influence of different conditions on the temperature difference between the two ends of the thermoacoustic reactor,the experimental results verify that the use of the piston modal vibration of the gas column instead of the standing wave vibration can indeed improve the sound field strength in the refrigerator resonant cavity under the driving of the fundamental frequency,which is beneficial to improve the The cooling effect of the refrigerator.