Project CategoryMain project classification
Application of air-cooled heat pump in villa air-conditioning system
1 Building Overview
平米；地下一层有保姆室、棋牌室、多功能室，共计 58 平米空调面积。 A villa has two floors on the ground, mainly including air-conditioned areas such as living room, dining room, bedroom, study, children's room, dressing room, etc., totaling 192 square meters; the basement floor has a nanny room, chess and card room, and multi-function room, totaling 58 square meters of air-conditioned area. The cold load index method is used to calculate the cold load of the project. The factors affecting the air conditioning load are:
① the function of the room; ② the indoor lighting and the number of people; ③ the thermal insulation effect of the envelope structure; ④ the influence of geographical location and climate. 左右，总冷负荷 55KW 。 Due to the villa's high requirements for air conditioning comfort, the designed refrigeration load per unit area is about 220W / m2 , and the total cooling load is 55KW . Because traditional hot and cold water units require special maintenance, this solution was directly rejected. The preliminary plan is plan one: air-cooled heat pump module air-conditioning system and plan two: variable frequency multi-line air-conditioning system.
2 scheme comparison
/ 热水，由管路系统输送到空调房间的末端设备，在末端装置处冷 / 热水与室内空气进行热量交换产生冷 / 热风。 2.1 Air-cooled module air-conditioning system The air-cooled heat pump module is an air-water system. The unit uses air as a cold and heat source, so that the indoor host generates air-conditioning cold / hot water, which is transported to the end equipment of the air-conditioned room by the pipe system. The cold / hot water at the device exchanges heat with the indoor air to generate cold / hot air. / 热量，但却是分散处理个房间负荷的空调系统形式。 Although it belongs to the centralized cooling / heat generation, it is a form of air conditioning system that disperses the load of each room. / 热量，因此，该系统可通对每个房间的空调进行单独调节以满足每个房间不同的需求。 The fan coil is generally installed at the end of the indoor air conditioner of the system. Generally, the fan speed can be adjusted or the amount of water passing through the coil can be adjusted by a bypass valve, so as to adjust the cold / heat quantity sent into the room. The air conditioning of each room is individually adjusted to meet the different needs of each room.
Advantages of this system: Because the water with larger specific heat is used as the carrier of the cold quantity, the temperature difference of the supply air is smaller, and the temperature field and the humidity field are more uniform, so the human body is comfortable. The other is that the initial investment costs are relatively low.
Disadvantages of this system: high requirements for water system installation and insulation, inadequate installation, prone to water leakage problems.
2.2 Variable frequency multi-line air conditioning system A variable frequency multi-line air conditioning system is an outdoor unit connected to multiple indoor units. Through the frequency conversion technology, the refrigerant circulation of the compressor and the refrigerant flow into the indoor heat exchanger are controlled in time to meet the indoor cold and heat. Load-demanding direct evaporative air conditioning system. The air-conditioning system works under conditions where the ambient temperature and indoor load are constantly changing. The variable-frequency multi-line air-conditioning system can use an indoor temperature sensor to control the electronic expansion valve on the refrigerant pipeline, and perform variable-frequency speed control on the refrigeration compressor of the outdoor unit or change the compression. The number of running machines, the number of cylinders, the opening degree of the throttle valve, etc., change the refrigerant flow rate of the system, thereby adjusting the capacity of the air conditioning system, so that the air conditioning system can work stably in the best working state.
Advantages of the system: Because the refrigerant evaporates directly, the energy efficiency is relatively high; with automatic fault detection, it is convenient for maintenance. Automatic conversion of heating and cooling modes, automatic wind speed conversion, can achieve centralized management and separate control at the same time.
Disadvantages of the multi-line system: the greenhouse gas emissions are greatly increased; the installation requirements are high; if a refrigerant pipe leak occurs, it is difficult to find the leak point, it is not easy to maintain, the supply air temperature difference is large, and the human body is not comfortable enough (this is the general use of fluorine machines phenomenon). The other is the higher initial investment costs.
2.3 Comparison results The fresh air treatment of the two schemes must be considered separately. 50% 左右。 Cost As far as this example is concerned, the air-cooled heat pump module machine (Carrier vortex water machine) is about 50% lower than the variable frequency multi-connection (Daikin multi-connection) . Under the influence of price factors, owners tend to prefer air-cooled heat pump modules.
，对大气臭氧层没有任何破坏作用，配置涡旋压缩机使机组更高效节能。 The scroll air-cooled heat pump chiller in this example uses the high-efficiency chlorine - free refrigerant HFC-410A , which does not have any damaging effect on the atmospheric ozone layer. The scroll compressor is configured to make the unit more efficient and energy-saving. The built-in hydraulic module integrates necessary hydraulic components such as pumps, expansion tanks, safety valves, automatic air release valves, flow switches, etc., which greatly saves equipment installation space and is easy to install.
一台，空调末端采用卧式暗装风机盘管。 According to the specific conditions of the project and the intention of the owner, the solution 1 air-cooled module air-conditioning system was selected. A Carrier digital scroll cold water heat pump unit 30RH032 was used. The end of the air conditioner was a horizontal concealed fan coil unit. 9.7KW ；制热输入功率 10.1KW 。 Host cooling input power is 9.7KW ; heating input power is 10.1KW .
3 Several problems in the design and construction of air-cooled heat pump module air conditioning system
0 ℃时，需要对室外侧空气盘管换热器翅片采取除霜措施。 3.1 Solve the problem of inefficient heating of air-cooled heat pumps in winter. In the winter, when the air-cooled heat pump units are operating in thermal conditions, the outdoor air coils need to be replaced when the unit's evaporation temperature is lower than 0 ℃ due to the low outdoor temperature. Heater fins are defrosted. The heat pump unit uses Carrier's patented intelligent defrost control logic to optimize the cut-in time of the defrost cycle and avoid unnecessary heat loss.
℃时，甚至无法开机，这是恶劣天气对机组的影响。 In addition, when the air temperature is lower than zero, the efficiency of the unit will decrease, and when the ambient temperature is lower than -5 ° C, it will not even be able to start up. This is the impact of the severe weather on the unit. One of the design schemes uses a plate heat exchanger, which solves the problem that the air conditioner does not turn on in cold winter weather.
It enters the plate heat exchanger through the branch of domestic hot water supplied by the boiler, exchanges heat with the air-conditioning circulating water in the plate heat exchanger, and transfers heat to the air-conditioning circulating water. This greatly improves the effectiveness. The addition of a small boiler can solve the effects of severe weather on the outdoor unit of the air conditioner and provide a variety of functions such as heat sources and domestic hot water for the indoor end devices.
3.2 Installation Precautions In order to prevent the main unit from being short-circuited by airflow, the main unit should be installed outdoors with good ventilation conditions, smooth air intake, and unobstructed exhaust air. In addition, the horizontal distance above the heat pump unit and the air intake side should also be noted. 2 米以上，机组距离主体建筑（或较高的女儿墙）保持 3 米以上。 For the distance between units and the distance between units and walls, many production units have clear requirements in the design manual: the distance between units should be more than 2 meters, the unit is away from the main building (or higher daughter wall) ) Keep more than 3 meters. In addition, shelters such as rain shelters should not be set on several groups to prevent exhaust short circuit. If there is an obstruction on the upper part of the unit, in order to ensure a fixed amount of exhaust, measures must be taken to make the exhaust clear and avoid backflow. According to the principle of the limited suction and suction speed field calculation, when the horizontal distance of the air intake side is close to the height of the unit, the intake air can be unblocked and the mutual interference of the intake air between the units is reduced.
管并保证水平段有 5% 的坡度，固定牢靠且无挠弯现象。 In order to ensure that the condensate pan is free of water and leakage, the end of the air conditioner after installation must be horizontal and free of skew; there must be a rubber shock absorber or rubber between the mounting bracket and the unit with good vibration damping; U-PVC pipes should be used for the condensate pipes, and the horizontal section should have a slope of 5% , which should be firmly fixed and free of bending. In order to prevent condensation from dripping during summer use, vertical risers should be vertical and all condensate outlet pipes should be fixed and heat insulation measures taken. Condensate drainage shall be installed with water-sealed elbows in accordance with design requirements, and shall be set in accordance with the requirements of relevant specifications or unit instructions. Drainage test must be done after installation to ensure smooth drainage.
3.3 Water system pressure balance For larger systems, special attention must be paid to the pressure balance when designing the water system, otherwise the problem of uneven cooling distribution is prone to occur. The combination of three or less units can be connected by different programs or the same program. The combination of four or more units should be connected by the same program. For this example, the system is small and pressure balance is easier to ensure.
At present, although small air-cooled heat pump air conditioning systems are widely used in domestic air conditioners and small commercial air conditioners due to their own advantages, in order to take full advantage of them, we must also strive to optimize and improve their design and value the construction quality.
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Article source: http://jimesale.com Tan Yuming 13751461639