Study On The Performance Of Temperature And Humidity Independent Treatment Device In High Temperature And High Humid Area

Low-latitude islands with high temperature and high humidity are far from inland and lack of energy.It is crucial to choose a suitable air process scheme for reducing energy consumption.The traditional vapor compression air conditioning system uses condensation method to cool the air below the dew point temperature,so as to realize the concentrated treatment of sensible heat load and latent heat load,but there is a high energy consumption problem.Whereas the independent treatment of temperature and humidity can reduce energy consumption.The dehumidification methods in the independent treatment of temperature and humidity are mainly composed of liquid dehumidification and solid dehumidification.The solid rotary dehumidification is widely used due to its simple structure,continuous operation and good applicability.Accordingly,this paper presents three descant cooling systems for the high temperature and high humidity low-latitude islands,respectively two-stage desiccant-wheel combined with direct evaporative cooling system,two-stage desiccant-wheel combined with indirect evaporative cooling system and two-stage desiccant-wheel combined with mechanical refrigeration systems.Local abundant solar energy acts as the regeneration heat source.The mathematical models of desiccant wheel,cooling and heat exchanger and solar heating system are established.And the desiccant-wheel performance is mainly analyzed.Firstly,the dynamic characteristics of desiccant wheel process under different operating parameters are simulated.The results show that reducing the rotational speed,increasing the air flow rate and reducing the regeneration temperature can reduce the number of cycles for the wheel to reach the stable state.The change of the calculating operation parameters will affect the parameters outside.This is slight impact the process air on the time for the wheel to reach a steady state.The influence of the parameters such as the process and regeneration air parameters,the speed of rotation on the dehumidification capacity and the dehumidification coefficient of the wheel is analyzed when the outlet parameters of the dehumidification wheel are stable.Taking an office building with an area of 200m² on the island as an example,the system total load are the indoor load and the fresh air load,in which the indoor sensible heat load is 19.8 kW and the humidity load is 7.8 kg/h.The most suitable desiccant wheel cooling system in this area is selected through simulation calculation based on the most common ventilation mode of two-stage desiccant wheel cooling system.The operating parameters of optimal system are obtained by means of simulation and comparison performance with different regeneration air temperature and system return air ratio.The result shows that the regeneration temperature of 85?,return air ratio of30%,after processing the air humidity ratio of 8.5 g/kg?a?can meet the requirements of indoor hot and humid environment.The total cooling capacity of the two-stage rotary desiccant composite mechanical refrigeration system is 57.2 kW.The cooling capacity of the chiller is 11.6 kW covering part of the sensible cooling load.The recyclable condensing heat is 15.9 kW,which is used for preheating the regeneration air so as to reduce the regeneration heat.The thermodynamic performance coefficient COP_thh of the dehumidification section is 1.32 and the COP of chiller was 4.85.