Modelling Of A Liquid Desiccant Air Dehumidification System With Solar Regenerator

The energy consumption of the air conditioning system accounts for 50-80% of the total energy consumption of buildings in China.It is of great significance for economic development and energy conservation to take effective energy saving measures in the air conditioning system.The basic task of air conditioning system is the temperature and humidity of air conditioning.There are great differences in temperature and humidity regulation between civil and industrial buildings.The living environment of the civil buildings is only designed to meet human comfort,however,industrial buildings not only to meet the comfort requirements of the human body,but also to meet the technical requirements.Many industrial products require constant temperature and humidity of the environment,some of which requires a very low air humidity from the viewpoint of the special industrial processes.This is more stringent requirements for outdoor wet air.In this dissertation,a dehumidification air conditioning system of industrial buildings has been taken as an example.The main goal of the dissertation is to study the application of liquid desiccant air dehumidification based on solar regenerator in low temperature and low humidity indoor environment.In this study,the basic concepts,development and application status of solution dehumidification technology have been investigated,and the physical properties of LiCl and other commonly used hygroscopic solutions are collected.The dehumidifier and regenerator are the most important components in liquid desiccant system.In this study,the heat and mass transfer model of the two components have been developed based on the finite difference method.Firstly,the heat and mass transfer model of the adiabatic type cross flow dehumidifier has been developed based on the principles of energy and mass conservation The influences of the variables such as the temperatures and mass flow rates of air and solution on the dehumidifying performance have been analyzedunder different working conditions.As for the solution side,increasing the solution mass flow rate and mass concentration can have a favorable effect on the amount of unit desiccant dehumidifying unit;while the inlet solution temperature has little effect on the dehumidification efficiency.As for air parameters,a higher air inlet velocity and high humidity can increase the performance of the liquid desiccant dehumidification.No obvious influence of dehumidification capacity was observed when varying the air inlet temperature.According to the simulation results,the variables are arranged as follows according to the effect degree on the dehumidification efficiency: solution concentration >> solution mass flow rate >> air mass flow rate >> air humidity >>solution temperature >> air temperature.The effect of the geometric size of the dehumidifier on the dehumidification efficiency is also discussed.Secondly,the mathematical model of countercurrent regenerator has been established.The outlet variables of the regenerator are calculated by means of the finite difference method.The effects of these variables such as temperature and mass flow rates of the solution and air on the regeneration performance have been analyzed.The regeneration efficiency has a nonlinear relation with the solution concentration,flow rate,temperature and air flow rate,while the regeneration capacity has a linear relation with the air humidity and solution mass flow rate.It is found that the air temperature has little effect on the regeneration performance.The simulation results show that the solution inlet temperature and the concentration have the most significant influence on the regenerator performance,then the amount and the regeneration efficiency increased accordingly with the increase of the height of regenerator regeneration unit.Finally,the liquid desiccant air dehumidification system with solar regenerator was been designed for a Ji'nan marble factory based on the simulation results.In this project,the ground source heat pump provides the heating and cooling source and the solar collector with an auxiliary electric heater provides the regeneration heating source.The heat pump cop and the energy consumption of the system have been calculated under the design conditions.The operating cost has been analyzed and compared with the traditional dehumidification air conditioning system.The results show that the energy saving of the designed liquid desiccant air conditioning system is 30% compared to the traditional cooling dehumidification.