The Application Research And Characteristic Analysis Of Air-Conditioning Systme Of Radiation And Convection

At present, radiant cooling and heating have been wildly used in China. However, insufficient cooling capacity problems appear in many areas with heavy cooling demand. To solve this problem, this paper introduces a coupled air-conditioning system of radiation and convection which is based on temperature and humidity independent control. Double-cold-source fresh air handling unit is used to improve system efficiency and all humidity load is taken by fresh air. This paper analyzes the coupled air-conditioning system of radiation and convection from applicability, energy-saving and comfort which are of most concern to people and also provides theoretical foundation for engineering application.Firstly, this paperproposes a coupled air-conditioning system of radiation and convection which combines high temperature cooling system, double-cold-source fresh air handling unit, dry fan coil units, radiant cooling system and dedicated outdoor air. Indoor dehumidification model is analyzed, debamidification air capacity and pre-dehumidification time are calculated. Operational modes are proposed and their operational conditions are analysed. A control strategy is proposed in this paper for this coupled air-conditioning system.Secondly, all-year hourly dynamic air conditioning load is analyzed to study the rationality and feasibility of the coupled air-conditioning system of radiation and convection by using DeST. Energy consumption of the three different air-conditioning systems are calculated using the temperature frequency method. By comparing calculation results, energy saving of the coupled air-conditioning system is obtained. Meantime, comfort of the coupled air-conditioning system combined with dry fan coil units is also compared with other two systems and it turns out that comfort of coupled air-conditioning system combined with dry fan coil units is the best out of three systems.At last, the coupled air-conditioning system of radiation and convection is studied by simulation analysis. Airpak is used to establish six physical model with different composition form of air-conditioning systems. By simulating the room model with floor radiation or ceiling radiation only, insufficient cooling capacity problems occurred in these rooms, therefore, dry fan coil units are needed to work as auxiliary cooling equipment. Composition system of radiation panel and fan coil units installed on the ceiling or on the floor are simulaited respectively. Results show that cooling capacity of coupled air-conditioning system combined with radiant cooling and dry fan coil units meets the requirement of indoor cooling demand. However, when radiant panel and dry fan coil units are installed on the same side, their impact on human thermal comfort are smallest and temperature distribution in the room is more uniform. The composite system of radiant ceiling and a ceiling-installed dry fan coil unit is the best. The relability of the physical model are verified by experimental data of the room with radiant ceiling and a ceiling installed fan coil unit.The study on the coupled air-conditioning system of radiation and convection provides theoretical basis for the practical application of this system.