Research On Comprehensive Energy-saving Technology Of Kitchen Canteen In Restaurant

With the adjustment of the national energy structure,in order to achieve the strategic goal of sustainable development,as a high-calorie and low-emission clean energy,natural gas entered the Chinese energy market quickly and developed rapidly.With the vigorous development of the catering industry in recent years,the amount of natural gas used in the catering industry has also shown a steady growth trend.But a large amount of waste heat,residual moisture and pollutants are concentrated in the kitchen,which has a negative impact on the health of the staff and the comfort of the working environment.Therefore,in order to improve the energy utilization rate in the kitchen and reduce the impact of heat dissipation on the environment of the kitchen,this paper conducted a survey of the kitchens of five hotels in Chongqing in order to find out the flue gas emissions and energy consumption in the Chinese kitchen.After that the energy-saving potential is evaluated.The heat exchanger was used as the main heat exchange component to design a systematic and complete flue gas heat recovery system and device for Chinese kitchen.Then this paper proposes to use the high-temperature exhaust flue gas in the kitchen to drive the lithium bromide absorption heat pump to produce hot water for use in kitchen,and the theoretical thermal calculation is carried out for the heating and cooling conditions of the heat pump unit.At last,the economic analysis and comparison of the two projects are made by the dynamic investment payback period method.The main conclusions are as follows.There is a large amount of recoverable waste heat in the high-temperature flue gas.Therefore,recovering the heat in the flue gas and lowering the flue gas temperature can improve the thermal efficiency of the cooker.When the latent heat recovery is not considered,the thermal efficiency of the cooker can be increased by 10% to 30% according to the theoretical calculation and the temperature of the exhaust gas.High-temperature flue gas is used to drive the absorption heat pump to get hot water.The heat calculation is carried out without the loss considered,the heating coefficient can reach 1.778,and the theoretical heat recovery volume is 1.5 times of the heat exchanger.In addition,the thermal calculation of the absorption heat pump refrigeration conditions is carried out,and the cooling capacity can meet the summer cooling load demand of the hotel restaurant.The dynamic investment payback period of the flue gas heat recovery project with heat exchanger is less than one year,and heat recovery project with absorption heat pump has a payback period of nearly 15 years due to its large initial investment.From the perspective of economy,the flue gas heat recovery project with heat exchanger is more suitable for the waste heat recovering in the hotel kitchen than heat recovery project with absorption heat pump,but the cooling capacity of the absorption heat pump refrigeration condition can satisfy the restaurant cold load,so the absorption heat pump has an advantage in function.