Quantitative Evaluation,Dehumidification And Regeneration Performance Of A Novel Carbon-based Shutter System

In summer,parts of southern China are in a humid environment for a long time,resulting in high relative humidity in the indoor environment,which will affect people’s normal life and production activities.This requires a convenient and effective dehumidification method to regulate the indoor hot and humid environment.Generally,dehumidification methods can be divided into cooling dehumidification,solid adsorption dehumidification,liquid absorption dehumidification and membrane dehumidification.The solid adsorption dehumidification is the most widely used because of its simplicity and efficiency.The factors that have a greater impact on the performance of the solid dehumidification system mainly include solid dehumidification materials and optimization of the system structure.In this paper,activated carbon fiber cloth(ACFC)and coconut shell activated carbon(CAC)were used as alternative solid dehumidification materials to compare and analyze the water vapor adsorption kinetics,water vapor adsorption isotherms,cyclic adsorption and desorption performance and thermogravimetric curves of saturated samples adsorbed.The pore structure characteristics,surface chemical properties and thermal stability of the two materials are characterized and analyzed by automatic specific surface and aperture analyzer,fourier infrared transform spectrometer,thermogravimetric analyzer and the more excellent performance dehumidification materials are used to construct a dehumidification shutter system.On this basis,we optimized the design and built a set of dehumidification shutter system that is regenerated by solar air collection.The system combined curtains and dehumidification system that has the advantages of dehumidification,shading and purification of indoor air.When the humidity content in the room is too high,the dehumidification shutter would put down to absorb the moisture in the room.When the dehumidification process was completed,the dehumidification shutter was collected into the regeneration pipe,and the hot air generated by the solar air collector was used to regenerate the dehumidification shutter.The experiment explored the changing law of the dehumidification performance of the dehumidification shutter with the change of indoor humidity and indoor environment temperature,and the regeneration performance of the dehumidification shutter under natural outdoor conditions was explored.The thermal comfort index of the indoor environment before and after dehumidification process was calculated.The main research conclusions are as follows:(1)The BET specific surface areas of activated carbon fiber cloth and coconut shell activated carbon were 1425 m~2/g and 986 m~2/g,respectively,and the corresponding total pore volumes were 0.748 cm~3/g and 0.554 cm~3/g,respectively.The pore volume percentage of activated carbon fiber cloth was higher than the pore volume percentage of coconut shell activated carbon,which resulted in a higher water vapor adsorption rate and greater water vapor adsorption capacity of the activated carbon fiber cloth.The number of surface functional groups of coconut shell activated carbon was more than that of activated carbon fiber cloth,so the activated carbon fiber cloth exhibited higher thermal stability,which was advantageous for multiple adsorption-desorption cycles of the adsorbent.The water vapour adsorption rates for ACFC at 298K,313 K,and 328 K were higher than those of CAC.The equilibrium adsorption capacities of ACFC at 298 K,313 K,and 328 K were 353.5 mg/g,296.0 mg/g and229.4 mg/g,respectively,while the corresponding amounts for CAC were only 214.2mg/g,135.5 mg/g and 132.6 mg/g,respectively.Owing to the surface functional groups of CAC,the isosteric heats of adsorption of CAC were higher than those of ACFC for the same adsorption amounts.The peak desorption temperatures for ACFC and CAC were 322 K and 316 K,respectively,indicating that both could be regenerated by low-grade heat sources such as solar energy.In summary,the water vapor adsorption capacity of activated carbon fiber cloth was better than that of coconut shell activated carbon.(2)This paper verified the dehumidification and regeneration performance of the dehumidification shutter system through experiments.First,the dehumidification shutter system was placed in an indoor controlled environment for dehumidification and regeneration.Under the conditions of indoor temperature of 295 K,298 K and 303K,the dehumidification efficiency of the dehumidification shutter system was 37.2%,36.8%and 40.1%,respectively.The dehumidification time at these three temperatures was 204 min,155 min and 105 min,respectively.As the temperature increases,the dehumidification time was continuously shortened,which was the same as the trend of the adsorption rate of activated carbon fiber cloth with time.As the temperature rises,the thermal movement speed of molecules in the dehumidifying material was accelerated.When the initial absolute humidity of the indoor environment was 19.012g/kg,20.714 g/kg and 21.832 g/kg,the dehumidification efficiency of the system was35.4%,36.8%,and 36.9%,respectively,and its dehumidification efficiency was continuously increasing.This could be seen from the change trend of the adsorption isotherm.At a regeneration air flow of 150 m~3/h,the regeneration temperatures were324 K,330 K,341 K,and 348 K,respectively,and the corresponding regeneration efficiencies were 47.58%and 64.52%,75.60%,76.37%,respectively.The regeneration time was 47 min,39 min,37 min and 30 min,respectively.The regeneration efficiency increases with the increase of the regeneration temperature.When the regeneration air flow rates were 50 m~3/h,100 m~3/h,and 150 m~3/h.,respectively.And the regeneration efficiencies were 75.60%,56.65%and 63.01%,respectively.And the regeneration time was 64 min,59 min and 37 min,respectively.A flow rate of 150 m~3/h was the best regeneration performance.Outdoor regeneration capacity under sunny and cloudy conditions were 0.206 g/m~3 and 0.169 g/m~3,respectively,indicating that solar irradiance has a greater impact on the regeneration system of the system.From the above dehumidification regeneration experiment results,it could be seen that the dehumidification efficiency of the dehumidification shutter system was maintained above 35%.When the regeneration temperature was maintained at about 343 K,the regeneration efficiency of the system coula be above 65%.