| As a new type of refrigeration, adsorption refrigeration could utilize low grade heat source such as solar energy and industrial waste heat, at the same time, the technology could solve the problems of environmental destruction that come from CFCs refrigerant. The technology has great values on both theory and application, In recent years, the research on adsorption refrigeration mainly included several aspects of adsorbent, design of adsorbent bed, optimization of adsorption system cycle in various counties of the world. As the center of adsorption refrigeration, many problems would appear when the adsorbent was put into practical application. Chemical adsorbents have the advantage of large amount of adsorption, but its thermal conductivity is low, the phenomenon of expansion and agglomeration when used for a long time will make the transform of heat and mass of adsorbent worse. The attenuation will reduce the life and reliability of adsorbent.This thesis researched the factors that influenced the performance of chemical adsorbent calcium chloride probably and corresponding way of these factors, aimed at the problems of heat and mass transform reducing and attenuation. Using the pore forming mechanism of carbonization and activation, a new type of composite adsorbent was prepared. By orthogonal experiment, the influence of different factors of preparation on the adsorbent performance has been analyzed, and the change of adsorption amount and curves also has been analyzed. Details are follows:(1) Based on the principle of controlling the volume, an experiment system of adsorption amount has been designed and built. The time relays and the electromagnetic valves ensure the independent control of electronic heater and cooling water cycle, the temperature conditions of adsorption/desorption would be obtained. The sample sink of reactor was designed to adapt for small quantity samples. The aim was to reduce the heat of reaction, requirement of heat source and reaction time. The design would accelerate the adsorption cycle and adsorbent aging. The experimental system could operation for a long time. The attenuation would be described by the change of adsorption amount.(2) The calcium chloride was selected as the chemical adsorbent of research, because of its low cost and wide source. The normal CaCl2 and CaCl2 that heated by 500℃and 600℃ were prepared to proceed the test of adsorption cycles for more than 200 times. The influence of temperature on adsorption amount of cycles and adsorption/desorption rate has been analyzed.(3) In order to research the influence of the sample sink space on CaCl2 adsorption performance, an attenuation test of CaCl2 that expansion space was restricted has been proceed and the difference to normal CaCl2 has been analyzed.(4) In order to solve the problems of expansion and agglomeration of chemical adsorbent and optimize the preparation of composite adsorbent, the wood has been impregnated in the solution of CaCl2 to increase the load because of loose and porous structure. The wood would get abundant pores according to the principle of pore forming. The experiment of four factors included concentration of CaCl2 solution, a ratio of wood to graphite, temperature and time has been designed according to the orthogonal experiment. The samples have been tested for more than 200 times. Range and Variance Analysis of the results have been proceeded to ensure the best program of composite adsorbent preparation. The influence of factors to the greatest attenuation of adsorption amount of cycles has been analyzed. The adsorption amount and curves attenuation of best and worst composite adsorbent also have been analyzed. Through the research above, the preparation method of composite adsorbent that could reduce attenuation has been provided. |
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