Experiment Study On The Absorption Refrigeration System Performance Improvement With Mechanical Vibrating Effect

Lithium bromide absorption chiller powered by heat energy, do not need to consumelarge amounts of electricity, can use a variety of natural low grade heat energy, waste gasand waste heat, have the effect of environmental protection and energy saving. But due tothe low overall performance of LiBrabsorption chiller，limiting its popularization andapplication. Therefore, we must improve the performance of LiBr absorption chiller, andthe key of improving lies in the absorber, the structure and properties of absorberdetermines the efficiency of the refrigerating system. At the moment, most experts andscholars focus on the research of through the passive way of strengthening heat transfer toimprove the efficiency of the LiBr absorption chiller, butin this article,we have the researchby using active reinforcement method to strengthen the absorption process.This article first expounds the absorption process of absorber is a heat and masstransfer in the complex process of mutual coupling and restriction. With double membranetheory explains the process of absorption, it conclude that the resistance of mass transferprocess between gas and liquid two phases mainly come from gas membrane and liquidmembrane. By falling film technology can reduce the membrane resistance, so as tostrengthen the heat and mass transfer. The heat and mass transfer Strengthen theory isanalyzed, and summarized the research progress on the application ofLiBr absorptionchiller.The separation phenomenon of solution and pipe wall was analyzed based on thetheory of boundary layer separation, the results showed that when the flow speed ofsolution is equal to the maximum vibration velocity, the solution just separated from thewall, this is the separation point. Further concluded that when the vibration speed is notgreater than the flow speed of solution, increase the vibration frequency and amplitudeappropriatelycan strengthen the absorption performance in the absorber. Lead to theactively strengthen absorption concept and have experimental analysis.We set up a test bench to study the enhancement of the effect of absorptionrefrigeration and heat transfer by mechanical vibration, thetest bench is a comprehensiveexperiment system which consists of single-effect lithium bromide absorption refrigerationsystem, electric vibration and vibration control system, data acquisition system andconstant temperature water circulation system. The main technical parameters andcharacteristics, the system operation process and experimental method of experimentsystem was introduced in detail, and carried on the preliminary experiment on lowfrequency vibration condition.Under the condition of mechanical vibration analysis and absorption processmathematical model is derived, the calculation and selection of relevant physical parameters of the lithium bromide solution, experimental study on the performance in theprocess of absorption refrigeration along with the change of vibration frequency andamplitude. Through the test data processing and analysis can be seen that:In the conditionof low frequency vibration, the heat transfer effect is better than that of static in theabsorber, show that low frequency vibration is beneficial to strengthen heat transfer, butalso can improve the efficiency of refrigeration.