The Air And Solution In Three Kinds Of Flow Modes About Heat And Mass Transfer Research In Internally Heated Regenerator

The enormous development of the 21 st century in our country, with the satisfaction of material life and pursuing the quality of life, people gradually make air-conditioning become necessity of residential buildings from commercial use. With the background of energy conservation and emissions reduction strongly advocated in the country, air-conditioning system need to reduce energy consumption further, meantime provide comfortable working and living environment.Two main tasks of air-conditioning are cooling and dehumidification, but in some cases half of total cooling energy can be consumed on dehumidification. Comparing with solid desiccant, taking advantage of liquidity of desiccant solution, can not only realize the continuous dehumidification and regeneration process, but also utilize low grade energy to regenerate, still hold great potential at energy storage, thus in recent years has been received the widespread attention from experts and scholars. The performance of the regenerator directly linked with the system can whether meet requirements of technical demands and users satisfaction, therefore the regenerator has become one of the key equipments in the whole solution dehumidification system. Commonly used regenerator is the adiabatic type with packed tower, packed tower regenerator has larger heat and mass transfer area, but it does not exchange heat with the outside, as the regeneration process happening, the temperature of desiccant solution is gradually lower, result in the amount of regeneration quickly decreasing. The internally heated regenerator as a research hotspot now, compared with the adiabatic regenerator, its use stable heat source continuously provide heat. It can also make the solution keeps at a certain temperature in heat and mass transfer process, improve both the amount of regeneration and regeneration efficiency.The research on the internally heated regenerator is relatively lack, thus purpose, content and method of this paper is put forward. According to the introduction of liquid desiccant system with heat and mass theoretical analysis of the internal heat regenerator, factors on influence of heat and moisture transfer can be concluded, and influence about flow modes should be focused researched, so fair current, adverse current and cross flow is chosen as representatives of flow modes to analyze heat and mass transfer theory and simulate research two aspects. A new two-dimensional model and assumed conditions, control equations and boundary conditions corresponding to the new model is presented and received the numerical simulation results of three flow modes, using summer average temperature and ventilation relative humidity as the outdoor air parameters on behalf of the city Harbin, Lanzhou, Guangzhou, Kunming in the severe cold, cold, hot summer and warm winter, moderate area. The amount of regeneration, regeneration efficiency, total heat efficiency, as well as exergy efficiency four aspects are calculated and analyzed of simulation results, also specific advices about internal heat regenerator on engineering application are given from three factors the economy, outdoor air temperature and humidity. The main conclusions are as follows:(1) Through the discussion of grid independence and compared with previous experimental data, the new mass transfer model about internally heated regenerator is concluded to be reasonable in this paper;(2) According to four cities outdoor air parameters established numerical models, the three flow modes results can be calculated using formulas about the amount of regeneration, regeneration efficiency, total heat efficiency and exergy efficiency. Adverse current can be concluded that is the most optimal the amount of regeneration, regeneration efficiency, total heat efficiency and exergy efficiency, cross flow secondly, and fair current is the worst.(3) According to the theoretical analysis of the internal heat regenerator heat and mass transfer, factors of influencing transfer process can be concluded that is including air temperature, moisture content, flow velocity, desiccant solution concentration, temperature, flow velocity and flow mode of two fluids. From temperature and moisture content of outdoor air analyzing simulation results, the amount of regeneration and regeneration efficiency is concluded both increasing with the increase of outdoor air temperature, and with the increase of outdoor air moisture content, the amount of regeneration and regeneration efficiency is concluded both decreasing; also moisture content has larger effect than temperature. Because cross flow occupies smaller area than adverse current, also has advantage to be installed in series, thus without high amount of regeneration and regeneration efficiency, cross flow can be chosen instead of adverse current device. According to building climate types in the using area, indoor exhaust air can be utilized instead of outdoor air under the condition of high temperature and high humidity climate.