| Energy plays an important role in people’s lives and provides important resources for economic and social development.Energy is one of the problems that people are facing.After experiencing the industrial revolution,the world economy has developed rapidly,but it has also brought about problems such as resource security,resource shortage,resource competition,and environmental damage caused by over-utilization.These problems will greatly threaten the development of society and even human beings’ life.Faced with the above-mentioned problems,mankind invented the adsorption refrigeration technology.Compared with the traditional vapor compression refrigeration technology,the adsorption refrigeration technology uses a relatively easy-to-use heat source as the kinetic energy,and has the characteristics of pollution-free and energy-saving.In recent years,these problems have been widely concerned.The current problem with adsorption chillers is that the system performance(COP)is low,so there is currently no large-scale commercial use.Studying the influencing factors of the performance of the adsorption refrigeration system and improving the COP of the adsorption refrigeration system are the main problems to be solved at present.In response to the above problems,the main research content and conclusions of this article are as follows:1.An adsorption refrigeration system was built,and the cycle process of the adsorption refrigeration system was analyzed,including the changing trends of various temperatures and pressures,as well as the changing trends of heating capacity and cooling capacity during a typical cycle,and the influence of heat recovery time on the system was analyzed.The results show that the heat recovery process plays an important role in the operation of the system,and there is an optimal heat recovery time to make the performance of the refrigeration system reach the best.2.The effects of hot water temperature,hot water flow,low temperature water temperature and low temperature water flow on the refrigeration capacity and COP of the adsorption refrigeration system are studied,and the primary and secondary order affecting the refrigeration capacity of the adsorption refrigeration system is hot water temperature and low temperature water.Inlet temperature,hot water flow,low temperature water flow,the primary and secondary order that affects the COP of the adsorption refrigeration system is hot water inlet temperature,hot water flow,low temperature water inlet temperature,low temperature water flow,and each factor has been analyzed to affect the adsorption refrigeration system Graph of performance impact,draw the following conclusions:(1)When the heat source temperature range is 55℃-75℃,the cooling capacity and COP of the system increase with the increase of hot water temperature,and the increasing trend is obvious.The cooling capacity increases from 5.3k W to 12.53 k W,and the COP increases from 0.36 to 0.5.It shows that increasing the temperature of the heat source can effectively improve the performance of the refrigeration system.(2)The cooling capacity of the system increases with the increase of the hot water flow,and the COP increases firstly and then decreases with the increase of the hot water flow.This shows that it is not that the larger the hot water flow,the better,but there is a maximum proper hot water flow.(3)The temperature change of low-temperature water has a significant impact on the performance of the refrigeration system.During the temperature change of 12℃-22℃,the cooling capacity and COP of the system increase with the increase of the low-temperature water temperature,and the low-temperature water temperature increases by 5℃ every time.The refrigeration capacity of the system is increased by 12%-15%,and the COP is increased by 7%-9%.Therefore,if conditions permit,the low-temperature water temperature should be increased as much as possible to ensure better performance of the system.(4)When the low-temperature water flow is changed,the cooling capacity and COP of the system are not changed significantly,indicating that changing the low-temperature water flow to increase the cooling capacity and COP of the system is not a feasible solution.3.The two-dimensional model and mathematical model of the adsorption bed were created in the CFD software,and the reliability of the model is verified.According to the simulation,the cloud diagram was obtained to analyze the temperature uniformity of the adsorption bed during the heating process.Then simulated and analyzed the influence of the height,thickness and spacing of the fins of the tube-fin adsorption bed,and the porosity of silica gel on the average temperature of the adsorption bed,and the conclusions are as follows:(1)The height of the fins has a significant effect on the heat transfer performance of the adsorption bed.The greater the height of the fins,the slower the average temperature rise rate of the adsorption bed,and the lower the final average temperature.However,considering that the height of the fins will affect the adsorption.Therefore,the height of the fins should not be too low.When the height of the fins is 10 mm,the adsorption bed has better heat transfer performance.(2)The thickness of the fin has a significant effect on the heat transfer performance of the adsorbent bed.The greater the thickness of the fin,the faster the average temperature of the adsorbent bed rises,and the higher the final average temperature,but when the thickness of the fin increases to a certain level.When the thickness is increased,increasing the thickness has little effect on the heat transfer performance of the adsorption bed.At the same time,considering that the thickness of the fins will increase the heat capacity of the metal and cause the sensible heat loss of the adsorbent bed,the thickness of the fins should not be too large.When the thickness of the fins is 0.22 mm,the adsorbent bed has better heat transfer.performance.(3)The spacing of the fins has a certain effect on the heat transfer performance of the adsorbent bed,but it has little effect.Because the distance between the fins affects the number of fins,it is still necessary to choose the appropriate distance between the fins.The distance between the fins is 2.2mm.(4)The porosity of silica gel also has a certain effect on the heat transfer performance of the adsorption bed.The smaller the porosity of silica gel,the better the heat transfer performance of the adsorption bed.This paper uses a combination of experiment and simulation to study the operational performance of the adsorption refrigeration system under different working conditions and the heat transfer performance of the adsorption bed,which provides a basis for improving the energy efficiency ratio of the adsorption refrigeration machine and the optimization of the adsorption bed. |
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