Application Research Of Heat Recovery Heat Pump Hot Water System In Restaurant Heating

With the further deepening of energy crisis and environmental pollution,more and more attention has been paid to the application of energy-saving and environmental protection products,this has prompted traditional,high-energy products to gradually withdraw from the market.In order to solve the problems of low heating efficiency and insufficient heating capacity of traditional air source heat pumps in the north of winter,this article is directed to the situation of a large amount of waste heat in the restaurant kitchen,improve the heat pump,make the heat pump effectively recover the waste heat generated by the equipment,and solve the hot water and heating needs of restaurants.According to the actual use conditions of the heat pump unit,the condensation temperature and subcooling degree of the condenser are determined to be 63℃ and 3℃,respectively.The evaporation temperature and superheat of the evaporator are 7℃ and 5℃,respectively,and then the refrigerant R407c is determined.The enthalpy under thermodynamic conditions calculates that the heat transfer of the condenser is 14.7kW,the power consumption of the compressor is 3.78kW,and the heat exchange capacity of the evaporator is 10.91kW.According to the calculation results,the main components of the heat pump unit are selected.The compressor uses a fully enclosed scroll compressor,the condenser uses a nickel-white copper casing heat exchanger,and the evaporator uses a brazed plate heat exchanger.At the same time,in order to better recycle the waste heat of the restaurant and improve the heating efficiency and heat generation of the heat pump unit,the heat pump unit adopts a double water circulation and a multi-point waste heat collection design.After the design of the heat pump unit was completed,in order to evaluate the reliability and working performance of the heat pump unit,the heat pump unit was tested at 10℃、20℃and 30℃ ambient temperature in the enthalpy difference laboratory.Experiments show that at 10℃,20℃ and 30℃ ambient temperature,the COP of the heat pump unit is 1.33,2.71 and 3.05,the heat pump capacity of the heat pump unit is 4753W,10809W and 14807W,respectively.In addition,according to the experimental measurement,the compressor current,the compressor discharge temperature and the like are all within the compressor use range,indicating that the heat pump unit can operate stably.In order to meet the demand for heating and domestic hot water in a restaurant in Changchun,the heat load of the restaurant was calculated to be 27447.78W according to the building structure and the amount of hot water used in the restaurant,and then the heat recovery heat pump hot water system of the restaurant was designed according to the heat load.The heat pump hot water system of the restaurant is mainly composed of a heat pump unit and a control unit.For the indoor temperature of the restaurant during the business hours of 20±1℃,the indoor temperature of non-business hours is not lower than 0℃,the control logic of the heat pump hot water system is aimed at the indoor temperature:When the indoor temperature is below the set value,heat pump hot water system starts heating;When the indoor temperature is higher than the set value,heat pump hot water system stops heating.Through practical application tests,it is found that when the outdoor temperature is-11℃～-1℃,by comparing the heating effect of the heat pump hot water system and the air conditioner,the average indoor temperature of the heat pump hot water system when heating alone is 19.2℃,when the air conditioner is separately heated.The average indoor temperature is 21.83℃,and the heat pump hot water system can replace the air conditioning heating.At the same time,the average heating rate of the heat pump hot water system alone is 184.66 kWh than that of the air conditioner alone.Compared with the air conditioner alone,the average energy saving rate is 44.71%.When the outdoor temperature is-22℃～-12℃,by comparing the heating effect of air conditioning alone heating and air conditioning,heat pump hot water system collaborative heating found:the average indoor temperature of air conditioning alone heating is 19.61℃,air conditioning,heat pump hot water system synergy the average indoor temperature during heating is 20.29℃.At the same time,the air-conditioning and heat pump hot water system co-heating has an average daily saving of 169.66 kWh compared with air-conditioning alone.Compared with air-conditioning alone,the average energy saving rate is 20.87%.When the air conditioner is heated separately,the heat pump hot water system only supplies hot water to the restaurant.The test was carried out separately.When the outdoor average temperature is-11℃～-1℃ and-22℃～-12℃,the air meter reading and water meter reading data of the heat pump hot water system are collected according to the test.The data obtained the average energy saving rate of the heat pump hot water system relative to the electric water heater is 67.14%.This paper tests the operation of the heat pump hot water system from February 1,2018 to April 15,2018.During the test,the outdoor temperature varies from-24℃ to 3℃,and the meter reading of the heat pump hot water system during the test.Data such as water meter readings and heat meter readings were collected.According to the test data,the average energy efficiency ratio of the heat pump hot water system in the restaurant was 2.56,and the average heat capacity of the single heat pump unit was 11.12 kW.The actual test shows that the heat recovery heat pump hot water system can provide hot water and heat for the restaurant by recycling the waste heat generated by the restaurant equipment.The energy saving effect is obvious,and it has broad application prospects for the waste heat recovery.