Performance Analysis And Experimental Study Of Liquid Desiccant Air Conditioning System

At present, under the backdrop of the global energy crisis, building energy saving especially in the field of HVAC, should not be neglected. With the excellent energy saving effect and air handling ability, the temperature and humidity independent control system(THICS) has been proposed as a new concept and attracted wide attention. Among them the liquid desiccant system owns the most significant effect of energy saving and the best ability of humidity control.After summarizing the liquid desiccant air conditioning systems proposed by the predecessors and considering the feasibility, simplicity and input-output ratio, this paper proposes a pre-cooling full fresh air liquid desiccant air conditioning system. In summer, the outside air with high temperature and high humidity is sent to dehumidifier after pre-cooled by high-temperature water. After dehumidification and cooling, air should be sent to the specified room. Temperature of the desiccant solution is regulated by vapor compression refrigeration system, generative heat is provided by condensing waste heat. This air conditioning system makes full use of the dehumidifying capacity of solution and the reliability, stability of vapor compression refrigeration. The main work of this paper:Firstly, a physical model of dehumidifier/regenerator is established, outlet parameters are resolved with numerical solution and the longitudinal distribution rule of air and solution state parameters are also found. Based on the program designed with MATLAB, heat transfer efficiency and mass transfer efficiency along with the change of inlet parameters are acquired.Secondly, experimental platform of liquid desiccant air conditioning is set up and research is conducted on the unit. The effect that the inlet parameters exert on the outlet parameters of conditioned air and regeneration air is gotten. The error between experimental data and software calculation results is within 10%.For the whole unit, air parameters have more influence on the performance than solution parameters. When the air mass flow, temperature and moisture content increases, the three performance coefficients of the unit all improve.Finally, based on the second law of thermodynamics, exergy analysis is carried out on the unit and exergy destruction of every part is calculated. It is found that the largest exergy destruction occurs in condenser and evaporator and some improving methods are also given.