Simulation And Experimental Study Of Solar-driven Hollow Fiber Membrane Solution Dehumidification System

Solution dehumidification system is a highly efficient solution to overcome the high energy consumption of traditional compression refrigeration air conditioning system and achieve independent control of temperature and humidity.Solar-powered hollow fiber membrane solution dehumidification system uses solar energy to regenerate solution for efficient energy use.The dehumidifier uses hollow fiber membrane components to effectively avoid problems such as gas-liquid entrainment and mold contamination of the air,so the membrane solution dehumidification system represents the development direction of solution dehumidification.To date,feasibility studies and performance evaluations of solar-driven hollow fiber membrane solution dehumidification systems have been limited.For this reason,in this paper,the operational performance of the solar-driven hollow fiber membrane solution dehumidification system is studied based on the TRNSYS platform by building a system experimental bench and then completing experimental tests and analyzing the system performance for different operating conditions.The main research contents of this paper are as follows.(1)A solar-powered hollow fiber membrane solution dehumidification system experimental bench was designed and built,which mainly includes the design and fabrication of hollow fiber membrane modules,solar collector selection,casing heat exchanger design and fabrication,and related measurement instruments selection.After building the system test bench and analyzing the time-by-time solar collector efficiency,the time-by-time dehumidification capacity of the dehumidifier and regenerator,and the time-by-time COP of the system,the study of air flow rate,air relative humidity,solution flow rate,cooling water temperature and cooling water flow rate on dehumidification performance and the study of air flow rate and solution flow rate on regeneration performance were completed.The results showed that the time-by-time dehumidification of the system ranged from 0.152 g/s to 0.228 g/s,the regeneration from 0.127 g/s to 0.358g/s,and the COP of the system varied from 0.278 to 0.784.Changing the air flow rate and the relative humidity of air has the greatest effect on the dehumidification amount,and the dehumidification efficiency of the system under this condition is between 0.418 and 0.602,which is comparable to the dehumidification efficiency of the direct contact dehumidifier with the dehumidification amount of 0.160 g/s～0.287 g/s.(2)A system simulation model based on the TRNSYS platform was constructed to further analyze the system performance.After establishing the heat and mass transfer and flow control equations for the hollow fiber membrane coupling,the hollow fiber membrane dehumidifier and regenerator modules were built based on TRNSYS;and verified by the experimental data on July 17,2020,the relative errors are all within ±15%and the accuracy of the simulation model is high.(3)A simulation model of solar-driven hollow fiber membrane solution dehumidification compound evaporative cooling system was established based on the TRNSYS platform,and Beihai,Nanning,Guilin and Hechi in Guangxi were selected based on the solar radiation intensity and outdoor air parameters to study the operational performance and practicality of the system in Guangxi region.The results show that Beihai has the highest dehumidification efficiency and regeneration efficiency,and Beihai also has the highest solar energy ratio of 38.1% in the air-conditioning season;while the total system energy consumption of Beihai is the lowest 6061 k Wh,Nanning is the second lowest 6702 k Wh,Guilin is 6908 k Wh,and Hechi is the highest 7110 k Wh,so the system performance plays better in the area with sufficient solar radiation and hot and humid climate.better.The predicted average PMV of indoor personnel in the above four cities are between 0 and 0.5 and the monthly average percentage of dissatisfied people PPD are below 11%,which proves that the system can improve the indoor heat and humidity environment and human comfort in Guangxi.The total energy consumption of this system is 45.1%,39.4%,37.7% and 36.5% lower than the total energy consumption of refrigerated dehumidification system in four cities of Beihai,Nanning,Guilin and Hechi,with static payback periods of 1.74,1.98,2.06 and 2.19 years,respectively.