Optimization Of Heat Pump Driven Liquid Desiccant Fresh Air System

The heat pump driven liquid desiccant(HPLD)fresh air system is more and more widely used,but at present,the research on environmental adaptability and performance optimization of HPLD fresh air system is not sufficient.This paper takes the conventional HPLD system as the research object and then study the above problems through the methods of project measurement,numerical simulation and experimental research.Based on the analysis of system environment adaptability,the combined application form of HPLD system was proposed,the performance optimization of the combined dehumidification system and the matching optimization of HPLD system components were carried out.Then,a liquid desiccant prototype was built and its operation performance was tested.The specific research contents are as follows:Firstly,the mathematical models of the core components and the calculation of medium physical parameters,those involved in the HPLD system,were established,and the accuracy of the models were verified by experiments.Futhermore,based on the above models,performance analysis model of HPLD system was established.Secondly,the environmental adaptability of HPLD system was discussed through the HPLD products performance measurement and system performance analysis.Under the research conditions,the air temperature increased 1 ?,the system coefficient of performance(COP)decline rate was 0.7%,and when the air moisture content increased 1g/kg,the system COP decline rate was 4.1%.The increase of air moisture content caused a significant reduction in the system COP,so the system's adaptability to the change of fresh air humidity was poor.Thirdly,in order to expand the environmental adaptability of the HPLD system,two combined dehumidification systems,cooling dehumidification combined with liquid desiccant,and two-stage liquid desiccant combined,were put forward,and the optimal values of fresh air parameters between the combined dehumidification systems were analyzed.The results were that the optimum inter-stage fresh air parameters state of the cooling dehumidification and liquid desiccant combined system were that temperature was 19.8 ? and moisture content was 13.3 g/kg,and in the two-stage liquid desiccant combined system,the optimum inter-stage fresh air parameters state were that temperature was 27 ? and moisture content was 14.0g/kg.Under the optimal design conditions,compared with the single HPLD system,the COP of the cooling dehumidification and liquid desiccant combined system and the two-stage liquid desiccant combined system increased by 48.1% and 61.6% respectively.Finally,the system component matching design method was studied.The matching optimization of prototype components,including evaporator,condenser,dehumidifier and regenerator,were carried out,and the prototype test and electrical system were designed.Then,the HPLD experimental prototype was built and the performance test was carried out.The test results were as follows: under the design conditions,the supply air temperature was 16.8 ?,the moisture content was 7.81 g/kg,and the system COP was 3.11.Both supply air state and system performance were good,which verified the feasibility of the combined dehumidification scheme and the accuracy of the component matching optimization method.And under variable conditions,the supply air temperature and moisture content increased with the increase of fresh air flow rate and regeneration air flow rate;the change of fresh air flow rate and regeneration air flow rate had little effect on the system liquid concentration and the decrease of those were beneficial to improve the system performance.In this study,the combined application form of the heat pump driven liquid desiccant fresh air system and parameter optimization scheme between combined systems are proposed,and the system component matching design optimization method is established.These research results have reference value for the design and production of liquid desiccant products,and promotes the application of heat pump driven liquid desiccant fresh air system.