Study On Thermal And Humidity Environment Control Of Special Underground Space At Hengyang City

With the rapid development of modern society economic and the level ofurbanization, urban ecological environment deterioration, many large andmedium-sized cities’ development is restricted by disorder functions layout. In orderto relieve tension among the population, resources, environment, development andutilization of underground space is paid more attention by the domestic and overseas.Underground space is warm in winter and cool in summer, but the humidity and airquality is not satisfactory. Through a large number of measurements, this article doresearch on the thermal and humidity environment control strategy of undergroundspace, specific studies include:(1)The air temperature and humidity of civil defense engineering,semi-submerged library and outdoor in a college at Hengyang was measured for ayear. Results indicate that the underground space is warm in winter and cool insummer, and the temperature is stable, In summer, the average temperature is22.5℃,in winter, the average temperature is17.1℃; In summer, the relative humidity is closeto the saturated most time, and during the winter the fluctuations of relativehumidity is far less than outdoors. The characteristic of temperature and humidity insemi-underground space is between between the civil defense engineering andoutdoor climate conditions. In summer, the average temperature is31℃, in winter, theaverage temperature is13℃, and humidity fluctuations is more gentle than outdoor.The good heat conservation of soil is beneficial to maintain the thermal and humidityenvironment of underground space.(2)Two indoor air environment control strategies was compared, and the idealefficiency of two control strategies were calculated and analyzed. The ideal efficiencyof combined temperature-humidity control system is27%of independenttemperature-humidity control system. Independent temperature-humidity controlsystem can achieve a good temperature and humidity and air quality, has a simple technological process, is more suitable than combined temperature-humidity controlsystem for underground space environment.(3) Several dehumidifying methods for air conditioning system were described.Through the comparison, liquid absorbent dehumidification(LiCl) has good thermalperformance and stability, low irreversible loss, improve conditions for low grade heatutilization, is helpful to the improvement of air quality, is more suitable forindependent temperature-humidity control system than other dehumidification mode.Fresh air supply unit based on liquid absorbent dehumidifying(LiCl) is more suitablefor underground space environmental control.(4) A model of an underground office was established, boundary conditions ofmodel were obtained through calculation and analysis. Appropriate treatments wasselected. The temperature and humidity distribution of under three different exhaustmethods were simulated. Base on the measurement, through numerical simulation,concluded the effect for three types of exhaust air ventilation: up-exhaustdown-supply> down-exhaust up-supply> up-exhaust up-supply. The temperature andhumidity with up-exhaust down-supply under hot weather and high humidity insummer were simulated, concluded that the temperat and humidity also can meet therequirement of human comfort.