Study Of The Oscillation In A Static Gas Wave Refrigerator

Natural gas will become the fastest-growing demand energy of the global energy consumption.High-performance expansion refrigeration equipments suited for operating condition of high pressure are needed urgently for natural gas' expansion refrigeration technology.The static gas wave refrigerator is a new type of expansion refrigerator,in which the self-induced jet oscillator is used to generate oscillation jet's periodical injection into receiving tubes with one-closed end.In the receiving tube,gas waves are produced owing to the interaction between the driving gas and the driven gas.Energy is rapidly transferred from the driving gas to the driven gas by means of propagation of the gas waves,which result in temperature increase of the latter and then heat dissipates to environment across the tube wall. Static gas wave refrigerator has no moving parts and its seal is simple.Hence,its use is not confined by the condition of high pressure.However,the refrigeration efficiency of the jet-oscillation refrigerator is at a low level presently,and it could not satisfy the requirement of natural gas's industrial production.Performance and mechanism of the multiple static gas wave refrigerator are investigated in the current paper supported by Chinese 863 National Program Foundation" Study on new technology of combined utilization of natural gas's pressure energy (No.2006AA05Z216).The self-induced jet oscillator is a key component of static gas wave refrigerator and it is developed on the basis of jet's wall-attaching effect which is also called Coanda effect.Firstly, this paper numerically simulates the properties of wall-attaching jet and analyses the flow field of wall-attaching jet.Effects of the element's geometrical sizes and operating conditions are simulated numerically,and emphasis is placed on analysis of geometrical properties and pressure distribution properties together with their relationship.It is concluded that the deflection characteristics of the jet flow is associated with the pressure on both sides of the jet. Component geometry and operating conditions will affect the pressure distribution of the jet on both sides,and the straight wall has an optimum value for the jet's wall-attachment.The receiving tube is the place of refrigeration.The gas and wave's motion and propagation in the receiving tube are studied.As the wave sweeps,the pressure,density and temperature of the gas rise rapidly.After the incident,wave will be reduced because of friction in the process of dissemination.Before the arrival of the wave,the gas in the receiving tube is moving towards the open end direction,and it is in the phase of exhausting.Under the action of the waves and injecting gas,the velocity of the gas decreases suddenly,and then turns to the direction of the injecting gas.The application shows that the multi-tube gas wave refrigerator is more effective than the double-tube gas wave refrigerator.The jet-oscillation refrigerator works on the basis of the jet oscillator.The frequency modulation of the jet's oscillation and decreas of total pressure loss of the jet passing the oscillator are important approach to improve the performance of the refrigerator.Therefore this paper develops the jet oscillator for multi-static gas wave refrigerator based on the study of jet oscillator and the receiving tube,transforms the sonic oscillator and feedback oscillator for multi-static gas wave refrigerator.This paper numerically simulates the oscillation availability and frequency of the static gas wave refrigeration.As a conclusion,the jet oscillates only in a certain range of geometrical sizes and operating conditions.This paper does experiments on the multi-static gas wave refrigerator based on the numerical simulation and studys the effects of the element's geometrical sizes and operating conditions.In conclusion,matching the other parameters,as the inlet pressure rises,the temperature drop also rises.The temperature drop also rises as the inlet temperature rises.Matching with the oscillation frequency,the length of the receiving tube,diameter of the nozzle and the pressure ratio,there is a best injecting frequency.If the gas is generted by a high frequency oscillator-a feedback oscillator,as the frequency to drive the gas in the receiving tube is also high,so higher temperature drop can be realized as to the sonic oscillator.