Abstract: The technology of using heat pump to convert the heat energy of air or air-conditioning water into the heat energy of domestic hot water has been well applied in developed countries. In this paper, the structure and working principle of heat pump are introduced, Applications.
Key words: heat pump, heat exchange, domestic hot water, air conditioner
1 Introduction
In order to protect the natural environment and improve people's living standards, developing and utilizing green energy (non-polluting natural energy such as solar energy, geothermal energy, etc.) should be a new technology actively promoted by the construction hot water discipline. Discussed in this article is through the heat pump using air or air conditioning water heat as a living hot water heat source technology.
2, the working principle of heat pump
Heat pump work is the use of "air conditioning" principle, the air or water heat transfer out, but with the air conditioner is not the heat emitted to the outside but transferred to the water, to achieve the purpose of heating water, while creating air-conditioning (or cold water ), Remove excess moisture in the air. The amount of heat supplied during operation of the heat pump is greater than the amount of heat it takes from the air or water due to the fact that the plenum surface of the heat pump also converts electrical energy into heat output without contamination of the fuel or gas heating equipment. Heat pump development and application in the United States has more than two decades of history, more than 50,000 systems in use. Applications in Hong Kong have more than a decade of history and are used on multiple systems. Several years in Shenzhen have also been applied. According to the different sources of energy, the heat pump can be divided into water and water series, gas and water series and Other types. Figure 1 shows the structure and working process of heat pump with air as energy source. After the refrigerant is gasified, the refrigerant is pressurized by a compressor and sent to a pool water heat exchanger through a three-way valve (this type of heat pump is generally used for heating the pool pool and dehumidifying the air). High-temperature gaseous refrigerant is liquefied by pool cooling Then flow to the collector. The liquid refrigerant evaporates in the low-pressure evaporation coil through the expansion valve. When the refrigerant evaporates, it absorbs a large amount of heat and cools the air flowing through the outside. After the refrigerant is gasified, it is pressurized by the compressor and then flows through the three-way valve to the pool water heat exchange Device. Air-conditioning chilled water enters the evaporative heat exchanger, and the liquid refrigerant evaporates in the low-pressure evaporation coil to absorb the heat energy of the chilled water and reduce the chilled water temperature. The gasified refrigerant is pressurized by the compressor and returned to the condensing heat exchanger, liquefied in the condensing coil to release heat and heat the domestic water.
3, engineering application examples
On the evaporative heat exchanger side, the chilled water returns to the heat pump via the circulation pump, lowering the water temperature by 4 degrees per cycle. On the evaporative heat exchanger side, hot water is also circulated through the water pump into the heat pump, which increases the water temperature by 5 degrees per cycle. When the hot water tank temperature reached 65 degrees, the compressor stopped working. To increase the heat pump efficiency, the first hot water tank is used as a preheating tank, and the heat pump only provides basic heat load. The second hot water tank with heating elements serves as the last means of heating the water. The volume of the second hot water tank is calculated according to the amount of heat required for the entire building for overhaul by the heat pump or air conditioning system. Gold Coast Hotel Hong Kong is a five-star hotel, the original design of the use of oil-fired hot water boiler, after the Hong Kong Environmental Protection Department and the requirements of the power sector using heat pumps and volume electric heaters combined heating. The hotel has a total selection of four hot water heat pump, of which two per tandem installation, and the use of the original heat exchanger (3 for the guest room, two for the kitchen) as the second-level hot water tank. Total demand by the hotel total heat capacity of 5 sets of electric water heaters. Due to the space constraints of underground equipment, the total heating capacity of 4 heat pumps can not meet the total demand. During the peak water supply, 2-3 sets of electric water heaters need to be put into operation. The hotel has embarked on the renovation of the second phase of work, and then installs four sets of gas-water heat pump for the dehumidification of the pool plus the air and to supplement the shortcomings of domestic hot water heat pump.
4 Conclusion
As a new non-polluting environmental protection equipment, heat pump has been widely used in developed countries and regions. China has entered the WTO and successfully bid for the 2008 Olympic Games. Green Olympics and Science and Technology Olympics have been recognized by the International Olympic Committee Recognized. In the next seven years of construction, heat pumps in the hot water system and air conditioning system will be widely used.
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