Study On Deep Heat Recovery And Heat Transfer Of Flue Gas And Analysis Of System Operation Characteristics On Heat Pump

The exploitation and utilization of energy has always been the most critical factor in the process of human development.The world's demand for energy is constantly increasing,so it is very urgent to develop new energy and vigorously carry out energy conservation and emission reduction.After combustion of gas boiler,a large amount of flue gas will be generated,and there is a large number of recoverable waste heat in the flue gas.Therefore waste heat recovery of flue gas is an effective way to improve energy utilization efficiency,reduce vapor emission in the flue gas,and reduce haze phenomenon.However,the current recovery technology can only recover the sensible heat of flue gas and a small amount of latent heat,and the recovery of latent heat is the key to improve the recovery of residual heat.In this paper,GWHE heat transfer and technology in combined with heat pump technology to recover waste heat of flue gas,and the recovered heat can be directly used for heating or heating domestic water.The specific research contents of this paper are as follows:First of all,through the field research of flue gas exhaust temperature and flue gas composition,the principle of depth analysis pf low temperature flue gas heat recovery,calculate the recycled flue gas down to different temperatures of heat,and then puts forward GWHE heat exchanger and heat pump technology with the combination of flue gas waste great recovery system,analysis the advantages and dis advantages of different types of heat exchanger,selected GWHE heat exchanger in the form of a tube and shell heat exchanger.Secondly,establish GWHE three-dimensional model,using the k-epsilon equation,considering the flue gas condensation in the exchanger process,selection of the evaporation condensation model of the Mixture model,according to the experiment measured the volume fraction of each component is set,the simulation analysis of different baffle spacing and flow velocity on the effects of the heat pipe heat exchanger is analyzed flow velocity,the baffle spacing and the outlet temperature of the flue gas outlet temperature.water outlet temperature,heat transfer coefficient and condensed water quality as well as the relationship between the pressure drop ratio.The heat transfer characteristic and the resistance characteristic of the heat exchanger are considered comprehensively to select the condition with the best heat transfer efficiency.It is found by simulation that when the gap between baffles is constant,the smoke exhaust temperature decreases with the increase of water flow velocity,the heat transfer coefficient increases,the condensation water increases,and the pressure drop increases.When the water flow velocity is constant,the smoke exhaust temperature of the flue gas increases with the increases of the gap between baffles,the heat transfer coefficient decreases,the condensation water decreases and the pressure drop decreases.However,by analyzing the relationship between water flow velocity,baffle spacing and the ratio of heat transfer coefficient and pressure drop,the heat transfer characteristics and resistance characteristics were considered together.When the baffle spacing was 138 mm and the water flow velocity was 1m/s,the heat exchanger could obtain better heat transfer sufficiently small pressure drop.Finally,the heat pump system in Trnsys simulate,using the tube and shell heat exchanger modules,water source heat pump units,water pump modules,calculator modules,controller module,water tank module heat pump flue gas waste heat recovery system is established,and according to the selection of equipment type of sample parameter settings,and carries on the corresponding simulation,after internal connection of simulation to get the COP of a heat pump units,power and water of pass in and out of the condenser and evaporator temperature,temperature difference analysis of the operation characteristics of the flue gas waste heat recovery heat pump system,analysis found that the COP of the heat pump unit in the system has just started when the maximum is 4.23,as the domestic water heating process,the COP of heat pump units to reduce gradually,source side in and out of the level of the difference in temperature of 3.38?,the level of load side in and out of the difference in temperature of 4.46?,during system operation,in and out of the water temperature difference of condenser and evaporator are relatively stable,and the lowest evaporator inlet water temperature at the beginning of the heating,as heating gradually rise,but compared with condenser inlet water temperature,the evaporator inlet water temperature change in small,no significant influence on heat pump COP.