Research On The Operation Strategy And Applicability Of The Fresh Air System In Green Buildings

Under the background of energy crisis and environmental deterioration in China,,green building has been developed rapidly,and energy-saving technology as an important part of green building has been widely used and developed rapidly.The fresh air system provides the high quality indoor air quality and the comfortable indoor environment for the green building,but it consumes energy consumption in the process of providing comfortable indoor environment.Recent years,it has been found that there are many problems in the operation of green buildings,some of which have important influence on the energy consumption and overall evaluation of green buildings.Therefore,it is of great significance to study how to solve the problems existing in the fresh air system and to reduce the energy consumption of the fresh air system as far as possible under the precondition of achieving high quality indoor air quality.Based on the methods of literature investigation and project testing,the use condition and problems of fresh air system in green building are analyzed.The results show that the utilization rate of fresh air system in green Building project is 54%,and the fresh air system consumes about 30%-40% of the total energy consumption of air-conditioning system in the whole year,which indicates that the new air system technology has important significance in the process of popularizing green building.The geometrical model of green building and the numerical model of air conditioning system were established by energy-plus simulation software.The results of three simulations of temperature,load and energy consumption of the numerical model are verified by the actual test data,and the measured results are in agreement with the simulation results,and the accuracy of the model is proved.The differences and shortages between temperature control and specific enthalpy control,electronic enthalpy control and switching temperature control methods are analyzed respectively,and an optimal combination control strategy is proposed.The electronic enthalpy discriminant line is used to control the operation of the fresh air system in the high temperature region,and the low line temperature to control the operation of the fresh air system in the low temperature region.Taking Beijing as an example,the economic operation plan and energy saving effect of the fresh air system in Beijing area are obtained.According to the regional division of the enthalpy diagram,the control scheme of the fresh air system in 5 typical climatic regions was obtained.The main factors of heat recovery are temperature and humidity,the heat recovery device is only affected by the temperature difference,and the recovery effect of the whole heat recovery device is affected by the temperature difference and the enthalpy difference.Based on these two factors,the applicability of heat recovery device is judged by dividing the region on the psychrometric chart.Taking Beijing as an example,the regional division and Simulation calculation of the psychrometric chart are given,and the selection scheme of heat recovery and the energy saving effect are presented.This method provides some reference for the selection and application of heat recovery.