Weak current College】 【air source for the application of hot and cold water unit.

<br> Abstracts: air-source heat pump chiller in local can be used as one of the air conditioning system and heat source is applied to each kind of project; in General, the summer load selected heat pumps can meet the demand for frozen quarter .load, can not separate auxiliary heater; heat pump system of annual energy consumption is lower than cold water unit plus boiler air conditioning system; the use of heat pump works should give full consideration to the characteristics of refrigeration and heating, due regard should be paid .to the effects of noise and vibration and the corresponding measures. <br> <br> First, an overview <br> <br> In accordance with the norms, the heat pump is defined to be able to achieve the evaporator and condenser function to .convert refrigerators. We can also be called a heat pump is based on the principle of reverse Carnot cycle, can be used both to refrigeration and can be used to heat supply of the unit. A variety of categories with heat pump, if the same heat .pump evaporator and condenser heat transfer media category, heat pumps can be divided into: air-air heat pumps, air-water heat pumps, water-water heat pumps, water-air heat pumps, soil-air heat pumps and soil-water heat .pump, table 1 lists the currently works on the application of four heat pump. Which the air-water heat pump, air-source heat pump type water chiller in engineering more widespread. <br> <br> Table 1: classification of heat pump .unit <br> <br> Classification of air-air heat pump air-water heat pump-water-water heat pump-water-air heat pump unit <br> Characteristics in outdoor air heat from inside the cold air, hot air to air .heat from air conditioning systems in cold water or hot water in the environment (water, River, River, sea water, etc.) as sources of heat from the hot and cold water to the environment, water, heat circulating water, the necessary preparation .of indoor heat and cold wind <br> Sample household, air conditioning, VRV, MRV, ECO and multi-split air conditioner air-source heat pump chiller, hereinafter referred to as an air-source heat pump water source heat pumps-heat pump .chiller-cold and hot air blower group hereinafter referred to as water-loop heat pumps <br> <br> <br> Heat pump unit of research, production and application, in the 1970s began in the United States and other developed countries embarked on .the path of healthy development. In 1980, China in Shanghai to design and production of the first to R12 for refrigerants, the compressor power 55KW air-water heat pump units, and put into practical application. Always to the end of the 1980s, air .source heat pump chiller research, production and application in China will have a faster development. Initially, the application of heat pump works mainly as no conditions set the boiler or premium rates too expensive or free space for freezing room construction, are available for only a .few imported brands of units, unit compared to a single form, often of piston compression integral air-source heat pump unit. Over the past few years with heat pump works, whether geographically or in architectural features and scale, has a great breakthrough, heat .pump brands, types of space to expand both the number of imported brands, there are many domestic brands, piston compression heat pump units and screw unit, a one-piece unit and modular heat pump units, a single unit with cooling capacity ranging from 3RT .-400RT, and unit of refrigeration, heating performance, quality, reliability, etc. all have significantly improved. <br> <br> 2. heat pump characteristics <br> <br> Air-source heat pump hot water unit has the following .characteristics: <br> <br> 1. air conditioning system and heat source in one, and on the building roof, you do not need to set up special refrigerated room, boiler room, also eliminates the chimney and cooling water pipes of building space .. <br> <br> For busy section and harder for city buildings, or unconditionally set the boiler room building, air source heat pump chiller is undoubtedly a more appropriate choice. <br> <br> 2. no cooling water system, cooling .water system power consumption, no cooling water consumption. <br> <br> Air conditioning system as water-cooled chillers, water loss not only the evaporation losses, there is water damage, bleaching effluent losses, loss of anti-freezing drainage, summer .is enabled in system flush losses, dilution losses, chemical cleaning, all these losses total about cooling water circulation water 2-5%, depending on the nature of water chillers, equivalent unit refrigeration capacity of loss amounts to 2-4t/100RT · h .. Us some serious lack of cities is a rather impressive number. In addition, a significant part of the project in part load case cooling water circulation amount remains unchanged. Or depending on the host running the number, the corresponding number. Our previous economic comparison .very little attention to this point. <br> <br> 3, because no boiler, without the corresponding fuel supply system, smoke-free air, cooling water, systems security, hygiene, compact. <br> <br> For warm road .professional, the boiler room is most likely a security risk, in addition, cooling water formation in the case of Legionella infection has been reported from a security point of view of health, air source heat pump has obvious advantages. <br> <br> .4, system equipment less, centralized, operation, maintenance and management is simple and convenient. Some small systems can be done through indoor air blower plate tube of start-up and shutdown control heat pump switch. <br> <br> 5, - .stand-alone capacity 3RT from 400RT, specifications, engineering adaptability, to refine the classification system, layered, chunking, set by user unit independent system. <br> <br> COP 6, summer run cold water unit value is relatively low, lower .power consumption, savings in energy consumption in winter operation. For a cold winter and hot summer city general building, the heat pump system of annual energy consumption is lower than cold water unit plus boiler of air conditioning systems, but at the current price of energy ., the heat pump system with year-round operation costs higher than cold water unit plus boiler. <br> <br> 7, higher cost. As the air conditioning system and heat source of investment in equipment, air-source heat pump chiller cost .higher than water-cooled unit plus boiler scheme system integrated cost you 20-30%, as the only operator and heat source equipment, heat pump prices around the water cooler + boiler 1.5-1.7 times. <br> <br> 8, air .source heat pump chiller perennial exposed outdoor, operating conditions worse than water cooled chiller, their life is to short than water-cooled chillers.BR> <br> 9. heat pump noise is large, the environment and the adjacent room has a certain influence .. Heat pumps are usually directly on the podium or top roof, vibration noise effect, directly affects the stick-o-room and around some of the rooms. Reasonable location settings and vibration noise measures in place, heat pump noise can basically eliminated. < .br> <br> 10, air source heat pump performance with outdoor climate change significantly. Outdoor air temperature is higher than 40-45 ° c or below-10 to-15 ° c, heat pump is not working properly. <br> < .br> 3. heat pump output and climate <br> <br> The rated operating conditions, temperature of 35 ° c, water 7 ° c, air source heat pump summer cooling performance coefficient COP value around 3.0, winter (air 7 ℃, .water 45 ℃), excluding the loss of defrosting, heating coefficient value also in 3.0 COPH, air source heat pump performance of refrigeration, heating and outdoor climate has a direct relationship, air source heat pump chiller cooling capacity with the outdoor temperature, unit power .with outdoor environment temperature. When the outdoor air temperature to 40 ℃, the cooling capacity generally declined 5-7%. Air source water chiller-upper limit of normal refrigeration temperature usually 40-45 ° c, individual brand with condenser fan speed control system .step by step, the best allows outdoor temperatures of up to 50 ℃. It should be noted that, unlike with cooling towers, cooling condition of relative humidity on the adverse effects of air-source heat pump didn't, instead, relative humidity, .favorable for cooling. Cities of the relative humidity is high, so in fact air cooling and water cooling in the cooling effect of difference, than people imagine. <br> <br> Air-source heat pump chiller with heating characteristics of a more complex .when the coil surface temperature below the dew point temperature of air, air dew, coil surface phase change heat transfer occurs, increase heat pump heating capacity, but when the coil surface temperature is lower than the air temperature of freezing point (0 ° c) ., if the relative humidity in the air while achieving a certain degree, coil surface is frosting, if not timely cream, cream layer will become more influence of thick, open air actual liquidity, and hinder the coil on the heat to be frozen, the .compressor has low downtime. Correspond to a different face of wind and weather conditions, the heat pump unit outdoor side air coil on wet air there are three States, namely, Frost, dew, the dry areas (without frosting or dew). Transition curve .Frost, it and the psychrometric chart, wet-bulb temperature line. When approaching from the wind 2.5M / S, environmental temperature of 0 ° c, relative humidity is 73%, the coil on the frosting, such as wind speed increases to 4M ./ S, ambient temperature 0 ° c, relative humidity up to 82%, coil before frosting, increasing wind speed can reduce product cream. Surface wind speed 2 m / S, outdoor air dry-bulb temperature in 5 ° c, 0 -> .; 85% relative humidity is the most severe frost, when tw <-5 ℃, frosting rate slowed down, this is because at this point the air moisture content has been significantly reduced. <br> <br> Heat pump system coils on .the frosting, affect the unit's normal effective heat supply, it must be timed defrosting. At present most of the units using reverse loop to defrost, and not only this part of the compressor stop heating and for cooling operation, so the system quantity of heat .is obvious. Severe frost, average half an hour of a frost, a defrosting time is 5 minutes or so, because of the amount of heating defrosting reduce up to 17%. In addition, the outdoor temperature decreases, the heat pump unit of output .significantly reduced. 0 º c, the heat pump unit of the actual rate for rated operating conditions of 70%. -6 ° c, the output is only rated operating conditions of 62%, -10 ¡ .ã c conditions for quantity of heat is only rated operating conditions of 55%. Rain and snow cold weather on the heat pump output has significantly impacted, the effects of normal operation, some users use artificial extension of the time, pour the lukewarm water defrost ., removal of frost. Environment temperature lower than-10 ° c-15 ° c, heat pump units generally does not run correctly. <br> <br> In the summer heat and winter cold, humidity and high temperatures of the region, the .winter is less than-5 degrees centigrade 69 hours, day 8: 00-18: 00 hours the temperature is below-5 ° ca total of 7 hours. 1994 summer temperatures higher than 37 ° total 10 hours * year, 1994, winter frost .heat pump in the workplace, the respective 1613 hours and 1527 hour (heat exchanger Windward surface winds 2.0m / s), such as the daytime only and 8: 00-18: 00 hours, 1993, 1994, winter frost heat pump in the .workplace, the respective 711 hours and 653 hour (heat exchanger Windward surface winds 2.0m / s). Average meter, regional air source heat pump unit frosting time at 1500 hours, such as only run during the day, the annual cumulative time Frost in .680 hours or so as to improve coil in the face of the wind speed to 3M / S, air source heat pump unit frosting time at 1300 hours or so, as only during the day, all year round in the frosting time accumulated 600 hour. .<br> <br> <br> <br> <br>.