Study On Thermal Environment And Energy Consumption Limit In Student Dormitory In Chongqing Based On Air Conditioning Heating

In recent years,air conditionings have been installed in student dormitory in Chongqing.Air conditioning greatly improves thermal environment in student dormitory in summer.When used for heating in winter,it is safer and has longer life compared to other heating equipment.Since there is no fresh air system,to maintain good air quality,it is necessary to keep ventilation when using air conditioning.This study has analyzed heating effect of air conditioning in the primise of ensuring ventilation during noon and night time in winter in sudent dormitory in Chongqing by questionnaire survey,measurement and simulation.The problems existing during application were analysed and some improvement measurements were supplied to make it more effective.Simulation software was used to calculation heating energy consumption limit of rooms at different location to supply a reference for the application of air conditioning in winter in student dormitory.Firstly,thermal comfort in student dormitory in winter and the window-opening and heating behavior are researched by questionnaire survey.The result shows that thermal comfort is not the factor students firstly concerned when decide wether heating equipment should be used.The main reasons why students preferred not to use air conditioning are high electric charge,bad air organization and feeling dry.Most students set the temperature above 24℃ when using air conditioning for heating in winter.Thermal environment of dormitory under non-air conditioned condition was tested to analyze if it is necessary to use heating equipment in winter in dormitory.The influence of outdoor environment,setpoint,opening area and location of rooms on thermal environment and energy consumption is analyzed in the primise of ensuring ventilation.The result shows that vertical temperature difference is large when air conditioning is used for heating.Since peple are located in the upper space of the room at night,the vertical temperature difference becomes an adventage because the temperature of sleeping area is easy to reach even exceed the setpoint and the setpoint can be lower to reduce energy consumption of air conditioning.Outdoor environment and opening area have greater effect on lower space than upper space.The effect difference of heating by air conditioning is large between terminal and middle rooms.The software PHOENICS is applied to analyse the influence of wind speed and angle on indoor temperature and velocity distribution.The effective strategies are proposed to supply a refence for the application of air conditioning at noon and night.The result shows that the higher the wind speed is,the lower the height of recirculation zone is,which can narrow the vertical temperature difference and the whole room temperature can be greatly improved.However,if wind speed is increased,the wind speed at sleeping area is also increased.Large wind speed can result in direct draft sensation,which can not meet the comfot requirement.A good thermal environment can be reached when wind angle is at 60°combined with proper wind speed.When people are mainly located in the lower space of the room at noon,wind speed can be set at 2.0m/s to meet thermal comfort requirement.When people are mainly located in the upper space of the room at night,wind speed can be set at 1.5m/s.The software DeST is applied to calculate heating energy consumption limit of rooms at different locations.When winter holiday is not considered,heating energy consumption can be reduced by about 38.5%.When the building meets the minimum requirement of energy efficiency standard,heating energy consumption can be reduced by about 16%.Room location and heat transfer between adjacent unit have significantly effect on heating energy consumption limit of rooms.Heating energy consumption limit of terminal and top room are respectively about 80% and 70% more than middle room under whole space operation mode and about 20% to 30% more than middle room under partial space operation mode.Heating energy consumption limit of middle room under whole space operation mode is nearly 60% lower than under partial space operation mode.Heating energy consumption limit of terminal and top room under whole space operation mode are about 40% lower than under partial space operation mode.