Research On Thermal Environment Of An Air-conditioning Student Apartments At Night In Chongqing

The dormitory is the main place for students to learn and live, therefore the thermal enviroument will directly affect the students’ physical and mental health and learning efficiency. Air conditioner can greatly improve the thermal comfort, but the thermal enviroument under air conditioning is rather unknown. And the air conditioner has big power, a huge number of residential air conditioners consume a lot of energy in operation, it is a great challenge not only for our electric energy supply, but also for the environment.Experimental research of thermal environment has practical significance for the dormitories which installed split air-conditioning. The experimental study is conducted in this paper on hostels thermal environment working conditions under the control of air conditioning, monitoring the main parameters of the dormitory environment, using Lin Zhongping’ sleeping thermal comfort models to calculate the thermal environment evaluation index in different locations while air conditioner set at different temperature and in different running mode.First, the main parameters for indoor environment under the control of air conditioner has been monitored for a long time in summer and winter respectively – including air temperature, wall temperature, relative humidity and the concentration of carbon dioxide, to get the main parameters of the environment under different temperatures and different operating settings of air conditioning. The outlet and return air temperature of indoor unit and outdoor unit is also been monitored to understanding the operation method of the air conditioner. The outlet air temperature of indoor unit will affect indoor air temperature, the change models of outlet air temperature has been obtained by fitting.Second, several thermal environment evaluation index and it’s calculation methods has been introducted. Professor Fanger’s thermal comfort equation and a series of assumptions and amendments made to adapt them in the sleepping environment by Lin Zhongping also have been retrospected, and using the research results of Lin Zhongping to evaluate the indoor environment in winter and summer. Calculation the two thermal environment evaluation index to evaluate the sleep environment: the Operative Temperature and PMV values. Found that the difference of PMV index was little while the fan turned on or not. In response to this situation, the PMV value when the fan turned on is recalculated under the amendments of the working thermal resistance for different wind speed.This paper draws the following conclusions:1) Under the action of air conditioning the vertical and horizontal temperature difference of in indoor air increase, the vertical temperature difference is greater than the horizontal difference. In summer, the vertical temperature difference is less than in winter`s; the horizontal temperature difference is greater than in winter`s.2) When air conditioning heating(or refrigeration), the impact of the change of the set temperature for indoor air temperature change rate of measuring points is limited. Before the air conditioning unit start-stop, under different set temperature, air temperature at various measuring points are very close.3) After using air conditioning, indoor air relative humidity decreased obviously both in summer and winter but it is still in reasonable range, the bed position relative humidity is between 55% ~ 65%.4) Indoor CO2 concentration is less affected by the air conditioning set temperature and operation mode but mainly affected by the indoor personnel number. When there are 1, 2, 3 or 4 people, the indoor CO2 concentration level respectively is 600 ~ 800 PPM, 1100 ~ 1300 PPM, 1500 ~ 1800 PPM and 1800 ~ 1900 PPM. The operation of the indoor machine fan can take away the CO2 which is produced by respiration, so it is beneficial to improve indoor air quality, but when stop running air conditioning the CO2 concentration will rise.5) Under the action of air conditioning, the PMV value of sleep area can reach-1 ~+1, but sometimes the PMV value can also exceed this range.