Abstract: In this paper, an actual design project is taken as an example. In the aspect of bathing and living hot water, an air source heat pump hot water system is introduced. The working principle and design requirements of each component are introduced. Comprehensive analysis and comparison, which concluded that: air-source heat pump hot water system to replace the boiler is indeed an economical solution. This without the need for special engine room, pollution-free and safe, the annual comprehensive energy saving rate of more than 70% of the hot water, is a practical environmental protection and energy saving technology, it is worth promoting. Keywords: air source heat pump hot water system Introduction With the economic development, energy shortage and environmental protection issues are also increasingly prominent in recent years, many hotels in Shanghai have implemented a "coal to gas (oil and electricity)," the environmental protection Policy, but it has caused hot water bath costs increased, we Baoshan Hotel winter peak alone when the cost of up to 30,000 yuan per day, how to make more and better use of natural energy, especially low-grade energy, to avoid and reduce Environmental pollution and ease of energy shortage has long been a subject of concern. Some hotels in order to reduce the cost of bathing hot water, the installation of a vacuum tube solar hot water system, direct sunlight to heat, is to solve the environmental problems, but also a corresponding part of the bath time to reduce the hot water costs, but according to Shanghai Nearly three years of meteorological data show that the city every year for nearly half a year for cloudy and rainy days, this climate or rely on electric heating tube heating, and electricity directly when the cost of heating water is higher than the boiler (per ton of water Temperature 40 ℃ up to 30 yuan), and the need to provide adequate roof lighting installation area, there are some limitations. Solar energy is the inexhaustible clean energy that nature has endowed to mankind. Taking full advantage of it to serve mankind's production and life is a long-cherished wish. Air source heat pump hot water system is ideal for the use of solar potential (air energy) one of the ways, for this reason, our hotel Peng Peng, general manager and a group of leadership decisions, instructed the Department of security in the lead manager The QC research group consisting of Ji Jianming, Ren Haijun, Yu Mingfa, Ye Guoliang, Zhang Bing and other engineers and technicians was established. In the second half of 2004, this project was explored. 1. The working principle of heat pump and heat pump Heat pump technology is the new energy technology attracting much attention in the world in recent years. At present, it is widely used in air conditioners. Pumps used in everyday life are many. Pump is a device to improve the bit energy, according to different purposes have pumps, pumps, pumps and so on. The main pump is to raise the water level or increase the pressure; air pump is mainly to increase pressure; pump is mainly used for oil supply systems and hydraulic equipment. People use the pump is also a simple injection double pump. These pumps work directly on the substance in contact. "Heat" is not matter, but rather can be widely found in all kinds of qualitative things in nature, which we think are hot carriers. The carrier can be solid (such as metal), liquid (such as water), or It is gas. Heat transfer convection, conduction and radiation. "Hot" must be carried and delivered by the carrier, the main carrier of different carriers in different ways. Heat pump as the name suggests is the pump heat device. According to the new International Refrigeration Dictionary, a heat pump is a refrigeration system that uses heat from a condenser to generate heat. Heat pump according to the working principle can be divided into vapor compression, gas compression, steam injection, absorption, electric, semiconductor and electrochemical variety. At present, the most common application is the vapor compression heat pump. Its main work is to rely on electric-driven compressor heat pump fluid in the compressor, heat exchangers, throttling devices and other components of the closed loop system, through the phase transition of the working state, the low-grade thermal energy conversion For high-grade heat. Low-end heat-absorbing cooling, high-end radiating heating, cycling back and forth is the dual effect of cooling and heating, the current more used in heating and cooling air conditioning. Heat pump system works. After the evaporator absorbs heat, the high-temperature and low-pressure superheated gas generated by the evaporation of its working medium is converted to high-temperature and high-pressure gas by adiabatic compression in the compressor, and is condensed and fixed to a low-temperature and high-pressure liquid by a condenser (releasing heat of vaporization and heating). The liquid refrigerant is decompressed adiabatic throttling to low temperature and low pressure liquid, and then into the evaporator constant pressure to absorb heat from the heat source and evaporate to become superheated vapor to repeat the next cycle. Therefore, the use of heat pump water heater heat released into the water is not directly generated by electric heating, but by the heat pump water heater to carry the heat to the water. Using a small amount of high-grade electric energy as the driving energy, low-grade heat energy is efficiently absorbed from a low-temperature heat source and transmitted to a high-temperature heat source to achieve the purpose of "pump heat." Heat pump technology is also a technology to improve energy quality, it is not the process of energy conversion, not limited by the energy conversion efficiency limit of 100%, but by the anti-Carnot cycle efficiency constraints. The handling capacity and energy input into the heat pump called the coefficient of heating performance, also known as energy efficiency (with CDP). The theoretical efficiency of: (working temperature +273) / temperature rise â–³ T. When the working temperature is 25 ℃, â–³ T is 20 ℃, the theoretical heating coefficient can reach COP = 15. In practice, however, motor efficiency = 0.95, compressor efficiency = 0.8, heat exchanger efficiency = 0.9 and system efficiency = 0.8, the total efficiency is 0.95 × 0.8 × 0.9 × 0.8 = 0.55. This means that 1KW of energy is used to carry the heat, ideally carrying up to 8.25KW of heat. 2. The advantages of air source heat pump hot water system Air source heat pump hot water system is the air as a low-grade heat source, by consulting a large number of literature that compared with conventional hot water heating system, air source hot water system has the following advantages: 2.1 rich in resources. Ninety percent of the earth's energy comes from the sun. The solar energy is huge and inexhaustible. A series of conventional energy sources such as coal and oil are the result of long-term solar energy conversion, and this is only A fairly small amount of energy. The other most of the energy is in the form of heat flow, radiant heat and other forms of presence in the air. Air source heat pump hot water system is the heat in the air and other low-temperature heat source can not be used by the latent heat and industrial waste heat removed by the pump to the water, so that the water gets hot. 2.2 technology is maturing. Internationally, the air-source heat pump water heater in the United States has a history of more than 20 years. Australia started to develop similar products 15 years ago. Although the country started relatively late, with the continuous efforts of the state and the research and production departments, the current air Source heat pump water heater production has begun to take shape, some manufacturers products have reached or exceeded the international advanced level, the air source heat pump water heater industrialization and product quality improvement for our attempts to provide the conditions. 2.3 Superior economy. Air source hot water system uses very few electrical transport several times the heat, the annual savings rate as high as 80%. 2.4 good practicality. Air source heat pump hot water system uses a volumetric heat storage, water heating in the case of short-term power outage, and the cost is lower than the conventional hot water system, continuous water supply can reduce pipeline corrosion and prolong pipeline life And to ensure clean water. 2.5 unparalleled environmental benefits. Air source heat is pollution-free energy, which is unmatched by other energy sources. As environmental pollution is worsening, it is even more important. 3 exploration process 3.1 heat pump unit selected air source heat pump hot water unit, as the name suggests, the key is the heat pump. To rely on the heat pump to the presence of low-grade heat in the air to move to the water to heat the water, the compressor is required to withstand high temperature and pressure; two require a larger surface area of ​​the evaporator, the greater the surface area in contact with air, Under the same conditions can be transported to the more energy, energy efficiency will be higher and more energy-efficient; Third, the high-performance heat removal of the working fluid (also known as refrigerant), in cold winter to cold air in low grade Of the heat collection to improve the handling to the water, the working fluid requires two state (liquid and gaseous) conversion temperature is lower than -25 ℃, at the same time be able to produce 65 ℃ hot water also requires the working fluid of the critical pressure is low, or Too high pressure is not good for the compressor or the compressor into high pressure protection and can not make hot water. Controlled by the above three and the manufacturers of products, production technology, quality assurance, after-sales service and many other factors ultimately selected by the World Solar Energy Association, China's air-source heat pump hot water heater sponsor Mr. Han Guangtian Howard Watt heat pump hot water unit due to The manufacturer of the United States Copeland compressor and similar products than the same industry increased to 1.5 times the surface area of ​​the evaporator, especially the unit is used in its own unique formula of mixed refrigerant, breaking the other brands of units with R22 or R417 and other single working medium can only be made to 55 ℃ hot water and can not adapt to the environment below -5 ℃ limit, generate 65 ℃ hot water compressor pressure is 22Kg, other brands of similar products to 55 ℃ compressor pressure exceeds This value. In order to be cautious, we established the winter demonstration that a small system of 2 tons of 65 ℃ hot water per day was installed in our hotel at the beginning of December 2004, which was relatively cold. In April 2005, the data showed that: The harsh winter with this unit made a ton of hot water total cost of 7.32 yuan, 28.93 yuan with gas boiler to save nearly 75%. 3.2 System Program Demonstration and Implementation 3.2.1 System Program Demonstration Heat pump hot water unit must be composed of the host and the water tank, circulating pump, the host heat through the loop into the water tank, the water tank heating gradually heating water system work, Directly affect the overall effect, so we call it heat pump hot water system. Commonly used system has a direct cycle and constant temperature water release two different forms. There is a direct cycle of water heating and water and uninterrupted use of water two. Constant temperature water from the heating tank and storage tank, heating tank does not have to withstand the constant pressure water temperature and water pressure uninterrupted automatic top water release two. Each of these systems has advantages and disadvantages. We analyzed the characteristics of 2T heat pump hot water system and found that in the process of heating, the lower the water temperature is, the higher the COP value is. As the water temperature increases, the COP value decreases. The same amount of water heated from 20 ° C to 50 ° C is similar to the energy consumed by the 50 ° C rise to 60 ° C. Finally, the choice of constant temperature with a heated water tank full discharge, although the control system is more complex, but every box of water is heated from the initial temperature of the cold water to set the temperature of the whole process of heating to take full advantage of the heat pump input power changes with temperature characteristics of COP Energy-saving effect is obvious. In addition, the intermittent winter work is not easy to frost. 3.2.2 The goal and direction of transformation. With the data and foundation of over 2 tons of small units overwintering, under the decision of the hotel leaders, we first selected hot water of bathrooms and canteens of hotel workers as the direction of energy-saving reform; the goal is to combine the smart card system with the bathroom and the use of nighttime low Vale price electricity, and strive to make energy-saving transformation of the annual average comprehensive savings rate of 80% (see table below). Savings after energy-saving retrofitting Energy-saving retrofit Savings Daily hot water for bathroom (tons) 50 35 15 Daily hot water in canteen 15 tons 5 Average hot water consumption (yuan) 28.93 7.0 21.93 Daily heating cost (yuan) 1880.45 315.00 1565.45 Annual heating costs (yuan) 686364.25 114975.00 571389.25 The overall savings rate of 83.25% 3.2.3 The composition of the system. According to the staff bathroom and canteen after the goal of making the daily hot water 45T, put 10% of the volume margin, our air-source heat pump hot water system Nissan hot water capacity needs to reach 50T. 3.2.3.1 Selection of 8 ho Watt JKR-10H heat pump engineering unit. Nissan hot water is 50T, by consulting the company's product information combined with the actual situation, the spring and summer and autumn three temperature and water temperature is relatively high, the maximum temperature in Shanghai up to 35 ℃, the average ambient temperature of 25 ℃, the water temperature is 20 ℃, 10 machines produce 750L of hot water at 60 ℃ per hour. It can produce 50T of hot water at 60 ℃ for 8.5 hours with 8 10 machines. The winter temperature is relatively low, the minimum temperature in Shanghai is about 0 ℃, water temperature 10 ℃, this time 10 horsepower 60 ° C hot water produced 400L, the worst case of 8 10 10 machine work 16 hours to produce 60 ℃ hot water 50T. Watt Watts parameters: Model JKR05H JKR10H Rated input power 4KW 8KW Equivalent output Heating power 16KW 32KW Production hot water temperature 55 ~ 60 ℃ 55 ~ 60 ℃ Hot water compensation speed (ambient temperature 25 ℃ Water 20 ℃ â–³ t 40 ℃ ) 350L / h 750L / h Heating coefficient Standard condition 25 ℃ About 4 Standard condition 25 ℃ About 4 Outlet size G1 "G1.5" Equipment size 820 × 820 × 1025mm 850 × 1660 × 1450mm Equipment weight 153kg 300kg 3.2 .3.2 a hot water storage tank. 50T capacity (internal part 15T and 35T independent two compartments, 35T for the hotel staff bathroom 15T for the canteen), the inner stainless steel plate, the thickness of the floor 2.0mm, advise æ´ ç©¸? .5 ~ 2.0mm, stamping to strengthen the molding, diameter 7m Long (divided into 5m and 2m) × 3m width × 2.5m high, the outer layer of glass or stainless steel stamping to strengthen the molding, two middle 10cm thick PE rubber insulation, the whole bottom 8 × 4 No. 20 channel, In the insulation layer plus 8 channel steel frame. Tank outside the north? Let éž” éž” å… whistle Yun ?? ?? straight 鸶 iliac è°¥ sets of stainless steel steam pipe silencer for backup steam boiler start-up. 3.2.3.3 Two heated water tanks are 2T capacity, Ø1.28m × 2.1m, both inside and outside the stainless steel, the middle of 50mm polyurethane filled polyurethane insulation. Three heat pump unit to a heating tank heating supply 15T heat storage tank, 5 heat pump unit to the other heating tank to supply 35T heat storage tank. 3.2.3.4 a hot water storage tank placed on the canteen roof to improve the potential. 3T capacity, Ø1.52m × 2.1m, both inside and outside the stainless steel, the middle of 50mm polyurethane filled polyurethane insulation. 3.2.3.5 hot water circulating pump 11 only. 8 sets of heat pump hot water unit with 8 sets of each with one, three small tanks with each one. 3.2.3.6 5 solenoid valve. Control two 2T heated water tank with a water inlet and a control of the heating out of the hot water to 50T with a large water tank with 3. 3.2.3.7 The total system control cabinet 1 only. Control 70KVA load capacity; with leakage, phase loss, wrong phase, overload protection; display and control of two heating tanks and 15T, 35T hot water tank temperature; display and control 15T, 35T hot water tank water level; 3.2 .4 system works. 3.2.5 system of water temperature settings. (Omitted) Whether it is a boiler or other forms of hot water, people always hope that the water temperature is as high as possible, we found that this is a study of the errors, the water temperature is too high, the water cycle capacity will be reduced, the general water quality Between 65 ℃ ~ 85 ℃ is a strong scale area, 65 ℃ below is a weak scale area, if reached above 85 ℃ will be hard into the line will hinder the hot water system within the water cycle, affecting the water temperature. International standard of living hot water is 60 ℃, bath water is 40 ℃ -45 ℃, the use of low water temperature, high-capacity approach can improve system efficiency. Therefore, we set the hot water tank heating water temperature at 56 ℃, heat pump unit final shutdown temperature is set to 58 ℃. 3.3 The implementation of the system program As the entire system program in the early stages of a rigorous demonstration and analysis, combined with our hotel has a multi-year experience in refrigeration boilers and plumbers engineering and technical personnel, with Howard Watts company multi-contact technical staff, Work together, after nearly a month's time, the entire renovation project is completed and put into operation. Now the system fully automatic operation of all normal. 4. Economic Value Analysis After the system was put into operation, we recorded a set of hydropower data from 22:00 on May 27, 2005 to 7:24 on May 28 as follows: (ambient temperature: 21 ℃; inlet water temperature: 18 ℃ ; Water temperature 56 ℃) Period electricity consumption Price Unit Price (yuan) Electricity fee (yuan) 27th 22:00 - 28th 6:00 396KWh 0.267 105.74 28th 6: 00-28 æ—¥ 7:24 66KWh 0.972 64.15 Subtotal 462KWh 169.89 Total output of hot water (ton) 50.6 Average cost per ton of hot water heating (yuan) 3.36 Hotel water unit price of 1.2 yuan / ton, sewage charges 1.5 yuan / ton In the above conditions, the system produces hot water per ton The total cost is: 3.36 + 1.2 + 1.5 = 6.06 yuan compared with the original gas boiler 28.93 yuan per ton of hot water cost savings: 28.93-6.06 = 22.87 yuan summer temperature in Shanghai up to 35 ℃, when the water temperature Up to 21 ℃, the minimum temperature in Shanghai in winter can be as low as -5 ℃, the inlet temperature is 4 ℃, but the relative time is short. To do this, we calculate the above recorded data as annual average: System annual cost savings The total is: 22.87 × 50.6 × 365 = 42.24 million 5. Existing problems and the next step intends to heat pump After the water system was put into operation, it was found that 8 heat pump units were operated within a very small area of ​​7 meters by 7 meters. In addition, the solar roof with four slope surfaces was built above, so that the air-conditioning heat exchanger (nearly 100,000 cubic meters per hour Of the wind) hit the roof slope and return to the unit, the formation of a vicious circle of cold, limiting the crew around the collection and convection of hot air, so that the best energy-saving heat pump advantages not fully demonstrated. In the meantime, we plan to add air-conditioners to eight heat pump units in the near future and introduce air-conditioners into the hotel canteens and laundries in summer. 6. Conclusion By analyzing the above project examples, we can see that the air source heat pump hot water unit is a new type of high efficiency, environmental protection and safety energy saving products. The air source heat pump hot water system gradually replaces the electricity, gas and oil hot water systems Is an inevitable trend. The product can effectively solve the current domestic departments on the energy saving, environmental protection, safety and other aspects of the more difficult issues, benefit the country and people, it is worth to promote the application.
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