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Air source heat pump water chiller related knowledge
Air-source heat pump chiller units can be used as one of the hot and cold sources of air-conditioning systems in the local area. In general, the heat pump selected according to the summer load can meet the requirements of the load in the frozen season without the need of a separate auxiliary heater. The annual energy consumption of the system is lower than that of water-cooled units plus boilers; the heat pump project should take full account of its cooling and heating features, should pay full attention to the noise and vibration effects and the corresponding measures. I. Overview In accordance with "norms", the heat pump is defined as a refrigerator to achieve the function of the evaporator and condenser conversion. We can also call the heat pump a unit that works on the principle of inverse Carnot cycle, both for cooling and heating. There are many types of heat pump, heat pump can be divided into: air - air heat pump, air - water heat pump, water - water heat pump, water - air heat pump, soil - air heat pump and soil - water heat pump, etc., Table 1 lists the current application of more engineering four heat pump. Air-water heat pump units, that is, air-source heat pump water chiller units are more widely used in engineering. Heat pump unit classification Table 1 Classification Air - air heat pump unit Air - water heat pump unit Water - water heat pump unit Water - air heat pump unit Features Outdoor air as the heat source to obtain indoor cold air, hot air to air as the heat source to make air conditioning system Cold water or hot water Take the hot and cold water as the heat source of environmental water (groundwater, river, river, sea water, etc.) Take the ambient water and circulating water as the heat source to make the hot and cold air required in the room Examples Household, air- VRV, MRV, ECO, etc. Air-source heat pump hot and cold water unit, referred to as air-cooled heat pump water source heat pump chiller Water source heat pump hot and cold air unit Water ring heat pump heat pump unit research, production and application, Only in the 1970s did the United States and other developed countries embark on a path of sound development. In 1980, China designed and produced the first air-to-water heat pump unit with R12 as working fluid and compressor power of 55KW in Shanghai and put it into practical application. Until the end of the eighties of the 20th century, air-source heat pump hot and cold water unit research, production, application in our country had a rapid development. At the beginning, the application of heat pump project mainly to set the condition of the boiler or the land price is too expensive or no space for the construction of freezer room, available for selection only a few imported brands of units, the unit is relatively simple, mostly for the overall piston compression Air-cooled heat pump. In recent years, the use of heat pump project, both in the area or in the building function and size have a great breakthrough, heat pump unit brand, type of choice greatly expanded the space, there are many imported brands, there are many Domestic brands, there are piston compression heat pump units, there are screw-type units, there are integral units, there are modular heat pump units, single unit cooling capacity from 3RT-400RT, everything, and the unit's cooling, heating performance, quality , Reliability, etc. have significantly improved. Second, the heat pump features air-source heat pump chiller has the following characteristics: 1, air-conditioning system, a combination of hot and cold, and placed on the roof of the building, do not need to set up a special refrigeration room, boiler room, but also eliminates the chimney and cooling Water pipe occupied by the building space. For the construction of bustling city lots of land, or unconditional boiler room construction, air-source heat pump hot and cold water unit is undoubtedly a more appropriate choice. 2, no cooling water system, no cooling water system power consumption, no cooling water loss. Air-conditioning systems such as water-cooled chillers, tap water loss not only evaporation loss, drift loss, as well as blowdown losses, loss of winter antifreeze drainage, system washoff when the summer is enabled, chemical cleaning dilution loss, etc., all of these losses And the equivalent of about 2-5% of the cooling water circulation water, according to the different nature of the chiller, the equivalent unit of cooling capacity loss 2-4t / 100RT · h. This is a considerable amount for some of our severely missing cities. In addition, a considerable part of the project under partial load cooling water circulation remained unchanged. Or according to the number of host operating units, only for the appropriate number of adjustments. Our previous economy paid much less attention to this point. 3, because there is no boiler, no corresponding fuel supply system, no flue gas, no cooling water, system safety, sanitation and conciseness. For the professional heating, the boiler room is most likely to be a security risk, In addition, the formation of cooling water contamination of Legionella infections have been reported in many cases, from a health and safety point of view, air-source heat pump has obvious advantages. 4, system equipment and less concentrated, operation, maintenance and management simple and convenient. Some small systems can be used to control the opening and closing of indoor fan coil heat pump unit switch. 5, stand-alone capacity from 3RT to 400RT, complete specifications, engineering adaptability, which will help system refinement, can be layered, sub-block, sub-user units to set up independent systems. 6, COP COP value lower than water-cooled units in summer, more power consumption, saving energy consumption in winter operation. For the general building in the winter and hot summer city, the annual energy consumption of the heat pump system is lower than that of the water-cooled unit plus the boiler. However, at current energy prices, the annual operating cost of the heat pump system is higher than that of the water-cooled unit and boiler. 7, higher cost. As a cold and heat source of air-conditioning system investment in equipment, air-source heat pump water heater unit cost is higher than the water-cooled unit plus the program of the boiler system cost more than 20-30% of the cost, such as only cold and heat source equipment, heat pump The price is about 1.5-1.7 times of water-cooled machine + boiler. 8, air-source heat pump chiller units exposed to the outdoors all year round, operating conditions worse than water-cooled chillers, their life is also shorter than the water-cooled chillers. 9, heat pump unit noise, the environment and adjacent rooms have a certain impact. Heat pump usually placed directly on the podium or roof, noise isolation effect, directly affect the neighboring rooms and the surrounding use of some rooms. Reasonable location and isolation noise isolation measures in place, the impact of heat pump noise can be basically eliminated. 10, air-source heat pump performance with the obvious changes in outdoor climate. When the outdoor air temperature is higher than 40-45 ℃ or lower than -10 ~ -15 ℃, the heat pump unit can not work normally. Third, the heat pump output and climate In the rated conditions, the temperature 35 ℃, water 7 ℃, air-source heat pump summer cooling coefficient COP coefficient of about 3.0 in winter (air 7 ℃, water 45 ℃), excluding the defrosting loss, the system The COPH value of thermal coefficient is around 3.0. The cooling and heating performance of the air source heat pump is directly related to the outdoor climate. The cooling capacity of the air source heat pump chiller unit decreases with the outdoor temperature. The power consumption of the unit decreases with the outdoor temperature Increased ambient temperature. When outdoor air temperature is increased to 40 ℃, the cooling capacity will generally drop about 5-7%. Air-source chiller normal cooling maximum temperature is generally 40-45 ℃, individual brands with condenser fan speed control system, the maximum allowable outdoor temperature of up to about 50 ℃. It should be pointed out that with the cooling tower is not the same, the relative humidity in cooling conditions on the air source heat pump did not adversely affect the contrary, the relative humidity, the cooling is beneficial. The city has a relatively high summer relative humidity, so the difference between cooling effect and cooling effect is actually smaller than people think. Air-source heat pump water heating unit more complex heating characteristics, when the coil surface temperature is below the air dew point temperature, the air will be dew condensation, coil surface heat transfer occurs at this time, help to improve the heat pump unit Heating capacity, but when the coil surface temperature below the freezing point of air temperature (0 ℃ below), if empty