Analysis On Application Of Sewage Source Heat Pump System Of A Commercial Building In Chengdu

In recent years,building energy consumption has gradually become one of the main energy consumption,in which the HVAC energy consumption can be a major part.Heat pump technology has been widely used with more and more attention being paid to the energy saving of HVAC.This paper studies sewage source heat pump system of a commercial building,which is the first application of sewage source heat pump system in Chengdu.Firstly,the scheme of the sewage heat pump system was studied.The building’s load was computed using DesignBuilder.Based on it,equipment was sized and an operation scheme was outlined in the constant flow system and the varied flow system.Secondly,the performance of the sewage heat pump system was analyzed.The COP of heat pump units and annual energy consumption of heat pump units and pumps were computed using Trnsys.Thirdly,the sewage heat pump was evaluated comprehensively by comparing with the traditional air conditioning system.The simulation results are listed as follows:compared to the constant flow system,the annual energy consumption of heat pumps increased 4.47%,because of the value of heat pumps’COP of the variable flow system is lower;and because of using varied speed pumps,the pumps’annual energy consumption of the variable flow system is 33.2%less than that of the constant flow system;the annual total energy consumption of heat pumps and pumps of the variable flow system is 6.38%less than that of the constant flow system;compared to the traditional air conditioning system,the sewage source heat pump system costs extra 1.31million yuan in initial investment,but its annual operating costs can save 0.217 million yuan,the payback period of the investment is about 6 years,and this project can save 409 tons standard coal per year,equivalent to 993.3 tons of CO₂,SO₂ and dust.Therefore,this project has both good economic and environmental benefits.In addition,the operating cost is proportional to the price of sewage.If the sewage fee is more than 1.82 yuan/m³,the initial investment cannot be paying back in life cycle.Hence,I hope the water sector can promulgate preferential policies to support application of sewage source heat pump system.Consequently,using heat pump to recover the heat energy in sewage can not only reduce the dependence on fossil fuels,but also has good economic benefit and environmental benefit.The research of this thesis can provide a reference for the application of sewage source heat pump system in Chengdu area.