Research On The Technology Of Waste Heat Depth Recovery Of Flue Gas From Commercial Gas Cooking Ovens

When the air source heat pump water heater needs defrosting in winter,it has the problem that the heat source is insufficient and the heating capacity is insufficient.Through investigation,it is found that in the kitchen of the public canteen,the flue gas of the widely used commercial gas cooking ovens has a large amount of waste heat and a centralized flue,which has a good recovery condition.Based on a university canteen as the research object,this paper discussed on the dining room scale,using commercial gas cooking ovens flue gas waste heat for air source heat pump water heater defrost the feasibility of the energy required,a method for deep recovering of the flue gas waste heat from a commercial gas cooking ovens was presented,a heat pump hot water system based on the deep recovery of flue gas waste heat was designed,the optimum design method of two-stage waste heat depth recovery unit was discussed.This study expanded the defrosting idea of air source heat pump water heater and had certain practical significance to improve the utilization rate of heat energy in commercial gas cooking ovens.The main research content includes:(1)Through research,obtain the general situation of a university canteen,the number of designers of hot water demand was determined based on the turnover of each typical period of the year,and the air source heat pump water heater was selected for the canteen with the standard design method,which provided the data basis for the research.(2)Aiming at a commercial gas cooking ovens in service in the canteen,under the condition of actual use,carried on the thermal performance and characteristics of flue gas waste heat potential test and analysis,analyzed the commercial gas cooking ovens heat efficiency and flue gas waste heat potential change rule of different gear,and analyzed the difference between the measured data with the national standard value,to provide guidance for recovery of flue gas waste heat depth in commercial gas cooking ovens.(3)This paper discussed the application of flue gas waste heat in commercial gas cooking ovens to suppress frosting and defrosting of air source heat pump water heater,the energy balance theory of defrosting program was analyzed.From the perspective of deep recovery of flue gas waste heat in commercial gas cooking ovens and joint operation with heat pump water heater for hot water production throughout the year,a direct heat pump hot water system based on the deep recovery of flue gas waste heat in commercial gas cooking ovens was designed.In this paper,the load distribution scheme of deep recovery and two-stage waste heat recovery heat exchanger for commercial gas cooking ovens was theoretically analyzed.The energy-saving of the system under the design condition was analyzed.(4)For the two-stage waste heat recovery device in the designed heat pump hot water system,using the mean temperature difference method,using the method of average temperature difference,the mathematical model of heat transfer and flow resistance on both sides of finned tube was established.In order to meet the heat transfer capacity and the allowable installation space as the limiting conditions,in order to reduce the flue gas side pressure drop as the goal,optimized the two levels of waste heat recovery unit design,by controlling the non-critical influence parameters(wing ratio,the net surface ratio,fin efficiency),the selection of key design parameters of two-stage waste heat recovery heat exchanger(base pipe diameter,mass flow rate of narrowest surface)and the design method were given.