Research On The Performance Of A Solution Dehumidification Air-conditioning System Coupled With A Heat Pump Cycle

liquid desiccant air-conditioning system can use low-grade heat source to drive solution regeneration,and effectively avoid the shortcomings of traditional heat pump air-conditioning system,such as low system performance,poor thermal humidity ratio adaptability.More and more researchers pay attention to liquid desiccant airconditioning system.This paper presents a liquid desiccant air conditioning system with coupled heat pump cycle,which decouples the heat and humidity load and optimizes the indoor heat and humidity environment.In winter,liquid desiccant solution is used to reduce the air humidity entering the evaporator,effectively restrain the frosting of the outdoor evaporator of the heat pump air conditioner,improve the relative humidity of indoor air supply and indoor thermal comfort by using the solution regeneration process;in summer,the solution circulation is used to treat indoor wet load,and the selected evaporation temperature of the system can reach 15-18 ? after the thermal and humidity decoupling,and the system performance coefficient can be achieved In addition,the high temperature and low humidity air supply ensures the operation of the evaporator under dry conditions,avoids the growth of bacteria in the evaporator,and avoids the reheat loss in the traditional air conditioning condensation and dehumidification.At the same time,the condensation heat released by the heat pump system is used to drive the solution regeneration,and the energy utilization efficiency is improved.In this paper,the theoretical and Experimental Research on the liquid desiccant air conditioning system of coupled heat pump cycle is carried out.In this paper,the regenerator,which is the key equipment of the system,is first tested and studied.An internal heated counter flow regenerator is built.Li Cl desiccant solution is used as the regeneration solution,The regenerating performance of the internal heated counter flow regenerator is compared with the preheating type counter flow regenerator.The effects of air inlet temperature,flow rate,solution inlet temperature,flow rate and internal heat source working medium inlet temperature on the regenerating performance of the system are studied.The regeneration performance of internally heated regenerator and the preheating type regenerator are compared under different air inlet temperatures.The results show that increasing the inlet air temperature,regeneration solution temperature,internal heat source temperature,inlet air flow rate and regeneration solution flow rate can improve the regeneration capacity of the system,while increasing the inlet air temperature and internal heat source temperature will lead to the decrease of the regeneration thermal efficiency of the system,and increasing the regeneration solution temperature can greatly improve the regeneration performance of the system;under the test conditions,the regeneration of the internal heat regenerator The regeneration quantity and regeneration thermal efficiency of the regenerator are better than those of the preheated regenerator.Secondly,the mathematical models of heat and mass transfer of internal heat and preheating countercurrent regenerator are established based on the test conditions.The accuracy of the regeneration model is verified by the test data.The influence of the key parameters of each cycle on the regeneration performance of internal heat and preheating countercurrent regenerator is analyzed and compared,and the test law is verified.The different internal heat distribution ratio is compared Analysis of regeneration performance of internal heat regenerator.The results show that the regenerator with preheating solution and internal heat source has higher regeneration performance,and there is the best internal heat distribution ratio under different liquid gas ratio and water gas ratio,which makes the regenerator's regeneration thermal efficiency reach the maximum.The best ratio decreases with the increase of liquid gas ratio,and increases with the increase of water gas ratio.Under the simulated working condition of the total heat of the system is fixed: when the internal heat distribution ratio is greater than 0.5,the influence of water gas ratio on regeneration capacity and thermal efficiency is not significant;when the internal heat ratio is less than 0.5,reducing the water gas ratio can significantly improve the thermal efficiency of regeneration.Finally,a liquid desiccant air-conditioning system with coupled heat pump cycle is built,and the typical working conditions in winter in Nanjing are studied.The influence of various adjustable inlet parameters of the system on the operation performance of the system is analyzed.The results show that: the dehumidification performance and the overall operation coefficient of the system increase with the increase of the temperature and humidity in the outer space of the room;the regeneration performance and the overall operation coefficient of the system increase with the location The increase of temperature and humidity at the inlet of the air conditioning system is gradually reduced.Reducing the temperature and humidity at the inlet of the indoor supply air can effectively improve the system performance;excessive dehumidification and regeneration solution flow have no obvious impact on the system performance,and will lead to "liquid carrying" of outlet air,which should be reasonably concerned to meet the requirement of system economy;Comparing the performance of liquid desiccant air conditioning system with coupled heat pump cycle and traditional air source heat pump combined system,When the outdoor temperature in Nanjing is below-1 ? in winter,the liquid desiccant air conditioning system with coupled heat pump cycle can always restrain the frosting of outdoor evaporator.Under different fresh air ratio conditions,the overall operating coefficient COP of the system is much higher than that of the traditional air source heat pump power humidification composite system,and the performance COP of the new system increases with the increase of fresh air ratio and tends to be flat.