【 Weak current College 】 air-cooled heat pump air conditioning system design methods

<br> <br> Air conditioning load and capacity of <br> <br> Air conditioning load including air conditioning air-conditioning cooling load and thermal load. Air conditioning cold (hot) load means indoors air parameters are maintained in the State of .design parameters, the unit of time to the building of internal demand, cold (heat). This is a parameter of Interior design, Interior personnel, equipment, thermal, and the amount of saturated, envelope properties, outdoor air environmental parameters (including temperature ., humidity, airflow speed, etc.), the solar radiation intensity, and many other factors influencing variables. Let the air conditioning system properly provide cold (hot), to meet the design calculation state building requirements and adapt buildings air conditioning cold (hot .) load and its changing needs is a fundamental aim of air-conditioning design. <br> <br> In the air conditioning system design process, the cooling load calculation is the first step. Calculation of air conditioning load should include the design and calculation .of air conditioning load identification and analysis of various time slots load; second, the capacity of the device must meet the design and calculation of air conditioning cold (hot) load requirements; in addition the device's configuration should be adapted to the characteristics of air conditioning .load changes. In order to air-source heat pump type water chiller for cooling of the air conditioning system design, heat pump units of capacity is necessary to take into account the various parts of the building while using coefficient, also taking into account the actual .heat pump and cooling capacity will vary from the actual quantity of heat equipment spacing restrictions cause poor ventilation, some air short circuit (this part of the output loss accounted for 5% or so) which is affected, and the outdoor heat exchanger surface area of .ash and attenuation of surface dirt, equipment and other factors, the selected heat pump unit shall be considered a safety factor. <br> <br> Expressed by the formula: Q = β β 1? 2? QD. <br> <br .> Type: Q-heat pump in the design of refrigeration (heating), KW <br> <br> QD-design calculation load, KW <br> <br> Β 1 - use coefficients, by specific engineering, General 0.75 ~ 1.0 .<br> <br> Β 2 - safety factor, generally take 1.05 ~ 1.10 <br> <br> In addition, the heat pump unit must meet the system requirements for cooling in summer and to satisfy the system requirements for heating in winter. .Different supplier of heat pump rated cooling capacity, rated heating capacity of parameters, and the regional air-conditioning outdoor design parameters are not necessarily consistent. Nanjing, the General vendor heat pump rated working conditions and actual identical or similar, general air dry-bulb .temperature is 35 ° c, the air conditioning frozen water in and out of the water temperature is 12 ° c, respectively 7 ℃. While the winter heating of rated working conditions for the outdoor air temperature 7-8 ° c, into and out of .the water temperature is 50-55 degrees centigrade. This condition and Nanjing area in winter and air conditioning system design is very different from the calculation temperature. Nanjing climate characterized by cold winter and hot summer. For General Office and hotel complex, consisting mainly of .winter air conditioning heat load calculation of heating design is about summer air-conditioning cooling load calculation and design of 70-85%-in the heat pump unit selection, you should review the heat pump unit corresponds to the local conditions of meteorological parameters, the .calculation of real output. If the heat pump in the design of outdoor parameters of cooling capacity is larger than the design calculation of cooling load and thermal load heating equals, you should choose the heat load for heat pumps. Conversely, if the cooling capacity to .meet the design cooling load calculation requirements, the quantity of heat is greater than the required heat, can be considered part of the selection of forced-air cooling type water chiller, part of the selection of air-cooled heat pump units to reduce investment. .In General, the summer cooling loads the selected heat pump and can meet the requirements of the winter heating. <br> <br> Unit type and number of <br> <br> Air-cooled heat pump chiller is different depending on the compressor .can be divided into the scroll compressor, heat pump, piston-type heat pump units and screw-type heat pump units; press unit structure size, combined size of heat pump unit can be divided into integral heat pump unit and modular heat pump unit. .Integral heat pump unit and the modular nature of the heat pump units without distinction, the so-called modular heat pump is a heat pump unit consists of several sets of heat pump units (independent refrigeration circuits, independent of evaporation, condensation, independent of the .framework, and even has a separate control panel) in parallel, the unit or any combination of flexibility, a unit of failure does not affect the rest of the unit of work. <br> <br> Domestic heat pump production enterprise to manufacture modular .heat pump units, while the integral heat pump units visually is a combo unit, an overall framework, although internal can have more than one compressor, even with more than two refrigeration circuit, but they are not subdivided between General. Modular heat pump unit's main .advantage is the low noise, small vibration, because the system total refrigeration circuit, in winter the temperature effects on the system when the water temperature. Preparation of system interoperability. In addition, the heat pump unit is generally placed on the roof, modular heat .pump unit due to the modular, flexible, all unit size is small, the weight is light, with transportation, lifting, easy installation. If the project is large, modular heat pump units are due to the number of refrigeration units, but the point .of failure, the possibility of maintaining a large quantity, and efficiency of the rated operating conditions are slightly lower than the integral unit. In addition, because of the modular heat pumps generally use the plate heat exchanger, the higher the water quality requirements, the .units of the hydraulic balance between the requirements are higher. To sum up, on a smaller system, or on the size, weight, hoisting, and other special occasions, modular heat pump has its advantages. <br> <br> As for the .piston heat pump units and screw-type heat pump units, in theory, screw-type heat pump unit of moving parts, less maintenance, high efficiency, low noise. But because of the heat pump for a large part of the noise originates from the .fan, and compressor noise can add enclosures, lower, so actually screw heat pump noise ratio piston heat pump noise slightly lower (approximately 3-5dB (A)). In addition, for the thermal resistance of the heat pump units, mainly in the .outdoor heat exchanger, heat pump efficiency by two for area and other factors, from an engineering perspective, screw-type heat pump and heat pump piston-type differences in efficiency is limited, but the price of screw-type heat pumps-heat pump above .the piston. <br> <br> Question on refrigerants, conditional as possible selection of environmental impact small systemREFRIGERANT R134a, R407C, such as, optimization, such as R407C, followed by the prices from the refrigerant R134a; consider, currently the cheapest is .R22. <br> <br> The location of the heat pump unit <br> <br> The location of the heat pump unit are the following: first, it is placed at the top of the podium and the second is placed at the .top of the Tower, the third is placed on the windowsill, the fourth is placed higher indoor height. Considering the hoisting and subsequent replacement of the heat pump is placed at the top of the podium. When the heat pump on the skirt of the roof ., it is necessary to assess its main building and the surrounding environment, the larger the heat pump unit (≥ 200RT), standalone noise in 75 ~ 85db (A) to the left. Necessary additive noise barriers, or in the main building on unit .side to avoid the door, do double window or high quality hollow glass replace ordinary flat glass Windows. Layout of the window sill of the heat pump unit is often called independent configuration of each floor, separate measures of places is limited to smaller heat pump units ., should use side side exhaust. Use heat-pump unit on should install guide duct as side exhaust. Even if the room has a higher clearance, the heat pump unit placed in the Interior is not desirable, subject to conditions limit must be set in .the room, the room should have voices wind can use, to have sufficient wind area, and air exhaust through the duct systematically drained outdoors to prevent airflow short circuit. Plus run-in duct, the fan should be adjusted accordingly to avoid resistance increases reduce .ventilation rates. Ideal method or the heat pump unit on top of the Tower, the heat pump unit with good ventilation and noise-reduced to minimum. <br> <br> It should be noted that the heat pump can not be near the residence .or other noise requirements higher room layout, not close to the residence (rooms) above or below arrangement of heat pump and water pump. Heat pump units use a spring damper vibration isolation, shock absorber type and layout is determined by the calculation of points. .Heat pump unit and relying on parapet is greater than the distance of the main building, unit 3m spacing of not less than 3m, conditional upon distance should increase. Heat pump units arranged in addition to the impact on the surrounding environment, good ventilation, you .should also consider pipeline layout, equipment installation and subsequent replacement and other factors, conditions allow 1 to 2 units location, leaving room for future development, and for equipment installation and replacement considered sufficient load conditions. <br> <br> The selection and arrangement .of the pump <br> <br> The number of suitable water pump and heat pump unit corresponds to the number of computers. Heat pump and water pump of the connection methods to use one-to-one series, heat pump and water pump linkage .. Heat pump unit number, the pump can stick Pro heat pump, water pump with waterproof performance with sound absorbing hood rain; the quantity of heat pump units, a small centralized water pump suitable for indoor use. Spare pump can be used to not install .the temporary replacement. If the pump adopts the first water pumps in parallel with the parallel phase of heat pump units, a series of parallel heat pump unit number not more than 6, and should have a reliable hydraulic balance measures. This connection should be arranged .in nearby water pump and heat pump room, can also be placed in the basement, the number of the pump should consider 1 ~ 2 spare pump. When selecting pump specifications, as selected low-speed pump, in order to reduce noise, water pump .flow according to the system required flow 1.1 times select, the delivery lift of pump should be equal to the system required to overcome the resistance of the total. Pump power consumption should control the output of the heat pump 1 / 30. Pump layout to have .space, conditions for 1 ~ 2 pumps installation location for development. The pump should also have reliable isolation measures. <br> <br> Terminal equipment choices (level) <br> <br> Summer operating conditions, the heat pump rated for return .water temperature 7 ° c respectively, and 12 degrees centigrade, and the general air conditioner rated operating conditions, the selection and calculation of air conditioners and other forms of air conditioning systems. In winter conditions, the heat pump system at the rated temperature (outdoor .air 8 ℃), the heat pump rated for return water temperature 47 ° c, respectively in 42 degrees centigrade. But when the outdoor temperature is low, the heat pump system of water supply temperature generally remained at 39-40 ¡ .æ. The water temperature conditions significantly lower than the rated boiler heating system for the return water temperature (60 ° c and 50 ° c), that is lower than average performance parameters given in the table and out of the water temperature rating (also respectively .60 ℃ and 50 ° c), water temperature, air conditioner heat emission there are significant differences. Some scholars so that heat pump system for terminal equipment should be selected in summer condition calculation on the basis of the results has been enlarged. But according to .our calculations, Nanjing heat pump air conditioning system can be used at the end of the summer cooling condition of compute results. This is because Nanjing general building heating load is less than the summer cooling cooling load, in addition, the same air conditioners, 60 .° c inlet temperature of the heating of water greater than 7 ℃ obvious condition of cooling capacity. In winter when temperature 35 ℃, inlet water temperature down to 39 ~ 40 ℃, a / c cooling capacity to meet the requirements of the indoor heating. .In addition, it is customary to the mid-range parameter select air conditioners, in itself, have a certain margin. If the heat pump system with 4 or more refrigeration circuit, defrosting on water temperature will not cause significant fluctuation, it does not affect .the indoor temperature fluctuations. But when the heat pump system with only 1 ~ 2 circuits, to reduce the cream to indoor temperatures, conditional, air conditioner and stopping control and water temperature synchronization, such as when the water temperature below 35 ° c, air .conditioner fan to spin down, when the water temperature is higher than 35 ° c fan recovery operation. This will effectively improve indoor comfort. <br> <br> <br>.