Dynamic Analysis Of Exhaust Air Heat Recovery Suitability In Chengdu

Energy consumption of air-conditioning system accounted for a large proportion of building energy consumption in China and heat recovery from exhaust air is an efficient way to reduce the load of supply air. Total heat recovery can reduce both sensible and latent heat load of supply air. Enthalpy exchanger is one common used heat recovery equipment. Usually minimum economic enthalpy difference and constant enthalpy efficiency are used in analysis of its suitability.But performance of enthalpy exchanger is affected by many factors.To know the suitability of adding enthalpy exchanger to air-conditioning system that is already built,dynamic enthalpy efficiency is used in calculating energy saving with a flat plate enthalpy exchanger in case of a certain office area in Chengdu.First deriving a mathematical model of flat plate enthalpy exchanger according to engineering method of heat and mass transfer calculation.And validate the model by testing on a certain flat plate enthalpy exchanger.Then to help engineers design and select flat plate enthalpy exchanger,use RECOP as a comprehensive evaluation index and study on influence on comprehensive performance of core height, length, channel height and average channel velocity.Build a module which can calculate dynamic enthalpy efficiency per hour in pace with the change of state of exaust and supply air in TRNSY. And the best channel height of the core is determined by analyzing its impact on flat plate enthalpy exchanger in standard condition.In the end, in case of a certain office area in Chengdu, a dynamic simulation model of air-conditioning system with adding enthalpy exchanger using dynamic enthalpy efficiency calculation method in TRNSYS is built. The on and off status of enthalpy exchanger is determined by comparing RECOP to TCOP. Results shows that fraction of annual energy saving is 28.6% with total heat recovery in both summer and winter,and payback period is 3.6 years. Fraction of annual energy saving is 25.6% with total heat recovery in summer and sensible heat recovery in winter, payback period is 4.5 years.