Study On Climate Applicability And Performance Optimization Of Ventilation Heat Recovery

With the proposal of China’s dual carbon strategy of "peak carbon by 2030 and carbon neutral by 2060",The issue of carbon emission in the building field has become an important concern.To a certain extent,building energy consumption and carbon emission can be reduced through building envelope insulation and airtightness enhancement.However,while enhancing the airtightness of buildings,people need to use mechanical ventilation system to ensure indoor air quality,and the ventilation energy consumption brought by mechanical ventilation system will have a great impact on the overall energy consumption level of buildings and gradually become the focus of building energy saving.The ventilation heat recovery system uses exhaust air to pre-cool/pre-dehumidify the fresh air in summer and pre-heat/pre-humidify the fresh air in winter,which can reduce the energy consumption generated by handling the fresh air and alleviate the contradiction between improving the indoor air quality and improving the energy efficiency of the building.The heat recovery efficiency of total heat recovery system is affected by the difference between indoor and outdoor temperature and humidity,while the heat recovery efficiency of sensible heat recovery system is only related to the difference between indoor and outdoor temperature.China is a vast country,and there are obvious climate differences in different regions,and the temperature and humidity vary in each climate zone,so it is necessary to analyze the energy-saving characteristics and applicability of ventilation heat recovery system in different climate zones.In this paper,we firstly compare and analyze the energy saving and economy of using total/sensible heat recovery systems in seven typical buildings in different climatic zones in typical cities.The calculation process takes into account the impact of the incremental energy consumption of fans and the influence of frosting problem on energy saving effect of heat recovery system under low temperature condition.The results show that total heat recovery can achieve high energy saving and economic advantages in cold regions,hot summer and cold winter regions,hot summer and warm winter regions,humid severe cold regions.Sensible heat recovery is more economical in dry severe cold regions and mild regions.However,the payback period of heat recovery system in mild regions is more than 5years,which indicates it is not suitable for comprehensive promotion in such climate.The conclusion of the analysis provides a reference for the selection,operation and promotion of heat recovery system under different climatic conditions.After obtaining the type of fresh air heat recovery device suitable for Beijing area,this paper proposes a new ventilation system based on the coupling of total heat recovery device and air source heat pump,and it was installed and tested in the temporary housing of Beijing Yanqing Alpine Ski Center of 2022 Winter Olympics Games.In order to verify the feasibility of the system,the operation of the system during the Winter Olympic Games was tested remotely.The actual performance and theoretical performance of the system with the outdoor weather conditions were compared and analyzed.The test results show that the average heating COP of the heat pump in the system is between 1.6 and 2.4;the average heating COP of the whole system is between 2.1 and 2.8,and the system has a certain energy-saving effect,however,there is a certain gap between the actual operation effect of the system and the theoretical operation effect.Based on this,this paper proposes an optimization scheme of the full-temperature section ventilation heat recovery system,which can overcome the problem of low heat recovery efficiency due to the frosting problem of the total heat recovery device in the original system under low temperature conditions,so as to realize the full temperature section heat recovery.In order to verify the feasibility of the proposed full-temperature section ventilation heat recovery system,the selection and calculation of the system as well as the construction of the experimental bench were carried out,and the preliminary tests were conducted in the enthalpy difference laboratory of Beijing University of Civil Engineering and Architecture,and the analysis of the theoretical operation effect of the system under different working conditions was completed based on the test results.