Study On Heat And Mass Transfer Properties Of Carbon Nanotube-based Consolidated Composite Adsorbent

Energy is closely related to the development and progress of human beings.The collection and utilization of energy has always been a major theme of social development.How to use energy efficiently has been paid more and more attention.The adsorption refrigeration is difficult to compare with the traditional compression refrigeration in the cooling power,but its driving mode of low grade heat energy and its final product are only water,showing the advantages of environmental protection and energy saving,which fully meet the needs of human development today.In this paper,calcium chloride with certain adsorptive capacity is combined with carbon nanotubes with high thermal conductivity and large specific surface area.The purpose is to obtain composite adsorbents with excellent heat transfer and mass transfer properties.The adsorption capacity of the adsorbents was measured by the simulated solar adsorption experiment.The factors such as the unit cooling capacity,the cooling power,the adsorption rate and the adsorption period were investigated,and the thermal conductivity of the adsorbent was measured by Hot Disk thermal constant analyzer.Finally,the adsorptive capacity and thermal conductivity of the adsorbent were comprehensively evaluated to evaluate its potential application.Combined with the composite adsorbent,the mechanism of heat and mass transfer in porous media is explored,and its physical and chemical adsorption processes are studied.Through the analysis and comparison of the experimental data,the most suitable refrigerant for this adsorbent was obtained,and the influence of the ratio of different adsorbents,the sintering temperature and the curing density on the adsorption and thermal conductivity was investigated.On this basis,the optimum preparation method for this adsorbent is proposed:after the carbon nanotubes and calcium chloride are pretreated respectively,the two ones are fully mixed with the deionized water,then the agitation of the attapulgite and the agitation at 240 degrees centigrade is added,the content of the carbon nanotubes is 1.5%,and the solidified composite under the condition of this ratio is mixed.The thermal conductivity of the adsorbent can reach 1.8238W/?m·K?.The adsorption rate of cured composite adsorbent is 21.78%higher than that of pure CaCl₂,and the unit mass refrigeration capacity can reach 416.39kJ/kg.The adsorbent has great potential in the field of solar refrigeration,which provides a reference for the study of adsorbent curing.Finally,the heat and mass transfer mechanism of the solidified composite adsorbent is explored from the angle of porous media.The heat transfer inside the solidified composite adsorbent is mainly carried out through the heat conduction mode of the carbon nanotubes and calcium chloride.The mass transfer is mainly achieved through the convective mass transfer mode.