Application of Compressible Heat Pump Water Heaters in Central Hot Water System
Heat pump hot water unit is an emerging hot water manufacturing equipment in recent years. It is electrically powered, easy to install, short construction period, small footprint, no fuel storage sites, no slag transport costs and waste treatment costs, without Special duty personnel, for concentrated water supply system in urban areas, compression heat pump hot water unit showed a clear advantage [1]. On the other hand, the heat pump can absorb high-energy, environment-friendly and non-polluting technologies [2] by absorbing natural energy, waste heat, annual heat supply and cooling in summer. Heat pump hot water unit heating power of 300% or more, the same output, heat pump hot water unit input power only electric boiler 1/3 to 1/4, the pressure on the power supply capacity is not large, the cost of producing hot water only Electric boiler 1/3 to 1/4. Heat pump hot water unit can also use the energy storage device, the use of night trough electric system to obtain a certain temperature of hot water, stored in the insulation tank, for peak use, play peak load effect. In recent years, with the improvement of energy saving and environmental protection requirements in our country, heat pump hot water unit has been widely used in central heating water system, especially in the area south of the Yangtze River valley in China, energy saving effect is very significant. 1, Project Overview A hotel in Shenzhen 221 sets of rooms, all day hot water supply hot daily peak at 8 to 11 pm. According to occupancy 300 people, guesthouse guest hot water according to national standard daily 200L / person calculation, about 60t / d hot water, a larger amount. The original design of the roof with four vertical gas boiler, the use of two loop circuit for hot water: two above the 21st floor, high pressure cycle; 21 below two, low pressure cycle. In order to reduce costs, save energy and improve the hotel environment, the hotel decided to transform the central hot water system, the transformation program using 5 Nanjing Huadian Hot Springs Heating Technology Co., Ltd. production of heat pump hot water unit, the transformation of the hotel's original hot water The original supply system remains the same, the original gas boiler as an emergency equipment, gas room for the back to the main water pipe, the original water pipe is still functioning in the new system, the original system for the total back to the supervisor connected to the heat pump hot water Unit for, back to the charge in the middle plus a heat storage tank, to facilitate the reduction of equipment selection capacity. The system also uses automatic control, according to the need to set the water temperature. New equipment layout in the roof, does not affect the appearance, no noise interference. 2, the design parameters of the selected (1) cold water temperature: summer 20 ℃ transitional season 17.5 ℃ winter 15 ℃ (2) heat pump hot water outlet temperature 55 ℃, indoor hot water outlet temperature 40 ℃ (3) peak price 0.8 yuan / KWh, storage ice price 0.3 yuan / KWh 3, selection Heat pump hot water unit selection according to climatic conditions, the average daily water consumption and water temperature, the user's rehydration temperature comprehensive consideration, select the model. Unit working hours generally take about 70% of the time. As the energy efficiency ratio of the unit is affected by the ambient temperature, the most adverse conditions and the initial investment cost need to be taken into consideration when selecting a model [3]. 1 winter heat load Qn = 60 × 1000 × 4.187 × (40-15) × (1 + 0.1) = 6908.6MJ = 1919.04KWh (0.10 is the system heat loss coefficient and 15 is the water temperature.) 2 excessive season heat load Qn = 60 × 1000 × 4.187 × (40-17.5) × (1 + 0.1) = 6217.7MJ = 1727.13KWh 3 summer heat load Qn = 60 × 1000 × 4.187 × (40-20) × (1 + 0.1) = 5526.8MJ = 1535.23KWh Table 1 heat pump hot water unit energy efficiency ratio Table 2 heat pump hot water unit main technical performance parameters Under normal operating conditions the parameters according to the standard <Q / 3201HDRQ-01-2002>, cold water 18 ℃, hot water 55 ℃, dry bulb temperature 55 ℃, wet bulb temperature 12 ℃ According to the winter heat load and unit performance parameters at ambient temperature 7 ℃ conditions, a Taiwan HAM096 heat pump water heater output power 21.4kw, 5 total output power of 107kw, 18 hours a day operation to meet the needs of thermal load. 4, economic analysis (1) thermal efficiency and calorific value of the heat source Table 3 heat source heat value table (2) two ways to heat the cost of 1 ton of water To 1,000 kilograms (1 ton) 15 degrees of cold water, heated to 40 degrees hot water, the need for 25,000 kcal of heat, for example, the cost of two heat sources. (1000 × 25 = 25000 kcal). Table 4 fee schedule Note: The gas is provided by your hotel now 13 yuan / cubic meter. (3) cost calculation Calculated on the basis of winter heat load, the use of heat pump hot water system for hot water, low trough electricity 8 hours a day, producing 27t of hot water, electricity was 67.23 yuan, 10 days a day peak use, hot water production 33t , Electricity is 219.45 yuan, a total of 286.68 yuan. And the hotel originally used gas boiler heating water costs 1154.4 yuan a day. After the renovation of the hotel can save running costs of 867.72 yuan a day, saving operating costs more than 310,000 yuan each year. (4) Comparison of day-to-day operation and maintenance costs of heat pumps and gas boilers The reason why this new energy-saving product of heat pump can be widely used in central water heating system quickly is mainly because of its advantages of energy saving, environmental protection, safety and comfort, which are favored by more and more users. Its daily maintenance costs are also lower than the conventional hot water system, mainly in the following aspects. 1 heat pump hot water unit by the hot water tank, you can always use hot water, without someone switch machine and maintenance. Saving a boilerman costs more than a gas boiler. 2 heat pump hot water unit maintenance include: the machine shell, evaporator heat sink cleaning. Mainly to clean the evaporator heat sink dust, gas boilers to gas as a fuel, are flammable, explosive dangerous goods, with insecurity. 3 heat pump hot water unit can be placed in outdoor roof and other places, does not affect the work efficiency. The gas boiler regularly by the technology, safety supervision and inspection, accreditation. 4 heat pump hot water unit using electric energy to clean the air, will not cause air pollution. Gas boiler gas combustion, the flue gas emissions still contain sulfur dioxide, nitrogen oxides, carbon monoxide and other harmful gases, long-term emissions, will pollute the surrounding environment. 5 heat pump hot water unit using parallel operation of units, respectively, separate control, if one of the failure, does not affect the normal operation of other units. 6 heat pump hot water unit life of up to 15 years, converted, lower than the cost of using gas boilers. 5, concluding remarks Through the above analysis, we can further recognize the heat pump hot water unit in the central hot water system application prospects. After the project was put into operation, the investment cost of the equipment was recovered within one year and was praised by the owners. As a result of the hotel in the life cycle of the heat pump water heater can save costs more than 470 million, energy saving effect is very obvious. Heat pump hot water unit of this new energy-saving products will become the first choice of China's central hot water system. references 1 Jiang Nengzhao, editor. Heat pump technology for air conditioning and its application [J] Beijing: Mechanical Industry Press, 1997 About the Author Liu Jun, male, born in 1976, a native of Pucheng, Shaanxi province, graduated from Baotou Iron & Steel Institute, specializing in heating, ventilating and air-conditioning engineering. He is a bachelor's degree and assistant engineer and is mainly engaged in heat net design, heat pump heating and energy saving. Rotating Anode Tube,The Xray Tube,Rotating Anode X-Ray Tube,Standard Rotating Anode X Ray Tube Wenzhou Kangyuan Electronics Co Ltd , https://www.kangyuanelectronic.com
2 Jiang Yiqiang. Air source heat pump hot and cold water unit selection [J]. HVAC, 2003,33 (6): 30-33
3 Nanjing Huadian Hot Springs Heating Technology Co., Ltd. electrician heat pump hot water unit technical manual, 2003