Evaluation And Design Parameters Of Air Conditioning Exhaust Energy Recovery System

The energy consumption of central air-conditioning system accounts for 60% of building energy consumption in China.Reducing the energy consumption of air-conditioning system is an essential way to save building energy.Recycling the energy of cold or hot exhaust of air conditioning system to precool or preheat fresh air,can effectively reduce the fresh air load.It is an important measurement to reduce energy consumption of air conditioning system.Since the low temperature difference between cooling/heating recycle facility,greater heat exchanger are required and then the facility cost and system resistance will be increased.Thus,the reasonable arrangement of cooling and heating exhausted air is the significant and urgent issue to solve in the field of energy recycle for air conditioning.This paper studies the techno-economic comprehensive evaluation index and design parameters of air-conditioning system with cold/hot exhaust energy recovery,analyses the evaluation index and key parameters of exhaust energy recovery system and their influence on the comprehensive performance of the system,and compiles the evaluation software of air-conditioning cold/hot exhaust energy recovery system,which is expected to provide technical support for engineering designs and facility researches.First,based on the working principle and influence factors analysis,the comprehensive economic technical evaluation model of aviation heat recycle was built,the correlation between heat recycle efficiency and key influence factors such adding fan number and pressure was deduced.Then,the calculation equation of critical pressure drop was obtained,i.e.the recycled cooling/heating and adding fan pressure when system energy consumption reached a balance.In addition,the "Reference pressure drop" and investment payoff period were set as the key technical index and economic evaluation index,respectively.Second,based on the comprehensive economic technical evaluation model of exhaust energy recovery system,taking the air conditioning of office building in Beijing as an example,under the conditions of 50%-80% energy recovery efficiency and 30-90% exhaust air volume participating in heat recovery,when the air volume participating in heat energy recovery is constant,the reference critical pressure drop of the total heat recovery ratio is higher than that of sensible heat recovery,higher in winter than that in summer.The higher the efficiency of heat recovery,the greater the reference critical pressure drop;when the heat recovery efficiency remains unchanged,the larger the exhaust volume involved in the heat recovery,the lower the reference critical pressure drop.Then,the performance characteristics of various types of heat recycle facilities were analyzed.With using the built evaluation model,the thesis calculated the effects of different outdoor climatic conditions,residential regions,air conditioning buildings on the technical and economic comprehensive performances when designed heating recycle.Further,the volume of exhausted air participated in the heat recycle and the optimized scheme of heat recycle efficiency were obtained,which are supposed to the design reference for heat recycle of exhausted air.Finally,based on the comprehensive economic technical evaluation model of exhaust energy recovery system,develop the evaluation software of exhaust energy recovery system,which is built to provide the analysis tool for engineering design and equipment development evaluation.