Research On Temperature & Humidity Independent Control Air-conditioning System Operation In Hot-humid Area

With the development of economic and technological, energy and environmental issues become increasingly prominent. With the requirements of indoor environment improvement, temperature and humidity independent control (THIC) air-conditioning system will be widely used. Studies have shown that THIC air-conditioning system has many advantages, such as temperature and humidity of indoor air can be controlled separately, heat and moisture angle scale can be handled over a large range, high temperature cold source is more efficient. Many designers and researchers is not comprehensive understanding about the actual application process, the main running issues and the solution. In this paper, based on the full investigation and the measured data, the running main problem and operating results of THIC air-conditioning system in hot-humid areas will be discussed. Use experimental methods research condensation of terminal devices, and then propose the condensation control system design method, finally analysis the system running adjustment method.Through the multiple-site case study I found that, whether it is dry fan coil or radiant cooling at the end will produce condensation during THIC air conditioning system operating in hot-humid area. The operation adjustment method is unreasonable.The annual electricity consumption of THIC air-conditioning in an office building independent shows that THIC air-conditioning system has energy-saving advantages.From measured energy consumption every day of each unit of the THIC air-conditioning, energy consumption characteristics of the system are found. Dehumidification unit accounts for more than fifty percent of electricity consumption of the entire air conditioning system and the performance of dehumidification unit has the greatest effects on the system, followed by high-temperature chillers. The measured data show that during THIC air-conditioning system operating temperature and humidity of indoor air maintain a good level and low concentration of carbon dioxide is beneficial to human health compared with conventional air conditioning system.Condensation on the surface of the capillary tube being discussed in a variety of conditions based on the radiant cooling ceiling air-conditioning system. Analysis showed that outdoor air infiltration flux through cracks will not lead to condensation on capillary tube surface, but condensation risk. When the doors and windows open, outdoor air intrusion can cause condensate even form droplets. It takes some time from condensed water to droplets on the surface of capillary tube, so if the doors and windows closed on time, after a period of time the condensed water or water film will disappear automatically by evaporation. The distribution of indoor air dew-point temperature is uneven and part of capillary surface has condensation risk when the air-conditioning system is working.To prevent condensation on the capillary tube surface, anti-condensation control system should be installed. Dehumidification unit should be started in advance about an hour to reduce the dew-point temperature to a certain level. As the ceiling floor has cool storage capacity, if the air-conditioning system shut down earlier for an hour the levels of indoor air temperature and humidity still meet the thermal comfort requirements.The content of the thesis provides practical information for the design and operation of THIC air-conditioning system and provides the basis for application in hot-humid area.