Analysis On Heating Applicability Of Energy Tower Heat Pump System In Tianjin

With fewer limitations to the application environment and being well in energy conservation and environmental protection,the traditional wind cold air source heat pump is widely used among heat pump types,but it is being up against the frosting problem in winter heating conditions,which has a great influence on the energy efficiency.Energy tower heat pump is converted from traditional air source heat pump.Being different with air source heat pump,an energy tower is added in the system,which could take heat from the air depending on solution with freezing point lower than 0℃.It could well solve the problem of frosting,and then improve the COP,but the system is mainly used in winter low temperature and high humidity regions such as central China,east China,while it is not yet widely applied in Tianjin and other northern region.Based on open upstream energy tower as the research object and the principle of heat and mass transfer between air and solution in direct contact,the mathematical model is established.Then,this paper determined the model parameters through the theoretical research and engineering measured data.Next,this paper used the Matlab software to solve the model,and done the related numerical simulation analysis.At last,this paper chose a certain office building in Tianjin to calculate the running energy consumption in the heating period of energy tower heat pump system,taking the air source heat pump system as comparing object,and on the basis of efficiency and energy saving,compared the two systems.The following conclusion is obtained from the research:For energy tower heat pump system,the unit operation efficiency is mainly affected by outdoor meteorological parameters.Compared with the energy tower heat pump system currently widely used area,there are three main characteristics of outdoor meteorological parameters in Tianjin: 1.the average dry bulb temperature is lower;2.the average moisture content is lower;3.the day and night temperature difference is bigger.Among them,the lower average dry bulb temperature makes the heat pump units harder to take heat from the air,but when temperature is low,part of energy tower heat pump units maintain at a high rate,which has a positive impact on the unit running performance.In the part of the time period of heating period outdoor temperature is higher,due to the partial load rate dropped to below 0.2,makes the sharp decline in operating efficiency.The lower average moisture content also makes the energy tower heat pump system difficult to take heat from the air,and in the lower moisture content condition,the air source heat pump is relatively difficult to frost,which makes the advantages of energy tower heat pump system is reduced compared with air source heat pump system.This is also the main factors influencing the energy tower applicability in Tianjin area.The bigger day and night temperature difference mainly affects the stability of the running unit.It’s influence degree to energy tower heat pump system and air source heat pump system is similar.Obtained by calculation,the average heating period running COP difference of energy tower heat pump system and air source heat pump system in Tianjin district is 0.48,while the average EER difference is 0.05,slightly lower from Yantai,Chongqing and other regions the system is already widely used.But through the analysis of energy consumption calculation and economy during the heating period,the energy consumption of energy tower heat pump system is still 4.9% lower than the air source heat pump system and the annual cost is 1.4% lower than the air source heat pump system.As a result,the energy tower heat pump system in Tianjin has a good energy saving and popularizing value.