During the period of 2000-20 10 and 10, the average annual housing construction in China was 10 million m 2, of which the urban housing construction area was 250-300 million m2. Take the sales in Shanghai in 200 1 year as an example, the new house170,000 ㎡ and the second house148,000 ㎡, about 550,000 households. According to the air conditioning consumption of 50% users, it needs 225,000 sets, and the market space is huge. Experts predict that with the improvement of people's living standards, the development of housing construction, the miniaturization of central air conditioners and the commercialization of household air conditioners, household central air conditioners will become the mainstream of air conditioners in the future.

Characteristics of 2-Household Central Air Conditioning System

A) It has the advantages of single room air conditioning. Such as reliable quality, low failure rate, flexible use, convenient installation and simple maintenance.

B) It has the advantages of central air conditioning, uniform indoor temperature distribution, no room area occupation, good coordination with decoration and low indoor noise.

c)

It has a good personality, on the one hand, it should be reflected in the personal purchase and personal use of residents, on the other hand, the layout of indoor air conditioning can be flexible and diverse, and there are many options to choose from according to the layout of the room and personal preferences.

d)

The consumer groups of household central air conditioners are not only aimed at high-consumption groups, but also at ordinary wage earners. With the large-scale production and development of air-conditioning manufacturers, its price will gradually decline, making it possible for household central air-conditioning to settle in ordinary people's families.

Analysis and comparison of several domestic central air conditioning modes

3. 1 district central cooling and heating system

There is a centralized cold and heat source station in the residential area, which sends cold and hot water to every household through the outdoor pipe network. The system has the advantages of central air conditioning, such as uniform indoor temperature distribution, no room space occupation and low indoor noise. However, the one-time investment is large, effective property management is needed, and the usual operating cost is high, so it is difficult to measure accurately, so it is used more in the original planned economy. With the cancellation of welfare housing distribution and privatization of housing, it is more and more difficult to charge for central heating and cooling system, and its market share is shrinking day by day.

3.2 Household Small Air-cooled Heat Pump Central Air Conditioning System

It consists of air-cooled heat pump unit, indoor unit, air conditioning water pipe and accessories. The outdoor unit is installed on the balcony to block the noise from the outside. The air-cooled heat pump unit is equipped with a small pressure expansion water tank, a circulating water pump and an automatic water replenishing valve. There are many forms of fan coil air conditioning terminal, which can be selected according to the owner's preference, functional use and indoor decoration.

The system has compact structure, convenient installation, less building space than the all-air system, and is easy to cooperate with decoration. The unit is equipped with a built-in expansion water tank, which makes the installation, operation and maintenance easier without damaging the appearance of the building. The air-cooled heat pump unit adopts microcomputer automatic control, which is simple to operate, and each room can be controlled independently and centrally, which is convenient, practical and easy to save electricity. If fresh air is set, it is necessary to set up a new unit, which will increase the cost.

The disadvantage of this system is that the water tray is easy to accumulate dust and breed bacteria, and there is a hidden danger of water leakage, but the water leakage is easy to find and maintain. Air-cooled heat pump unit is a three-phase power supply, which needs to be distributed separately and measured by electricity meter.

3.3 One-to-many air conditioning system (usually called household variable frequency central air conditioning system)

It consists of indoor unit and outdoor unit, refrigerant pipe, condensate pipe and accessories. As in Section 3.2, the outdoor unit is placed on the balcony, and various indoor units can be selected, but the indoor unit and the outdoor unit are connected by copper refrigerant pipes, and there is no expansion water tank and circulating pump. Single-phase current can be selected without special approval of three-phase households, which saves lines and is convenient for metering and charging.

Advantages of the system: due to the direct evaporation of refrigerant, the energy efficiency is relatively high; It has all the attributes of household air conditioning, such as ion dust filter, photocatalyst, luminous remote control, ultra-low noise and so on. The air supply of indoor unit automatically swings and guides the blades; There are many models and specifications, and there is a large choice, which can be selected according to different performance and functional requirements; Drive multiple indoor units at a time. The frequency conversion circuit can adjust the rotating speed of the compressor at any time to adapt to the total load according to the number of indoor units in operation and the load of each room, so that each indoor unit can operate efficiently, saving energy by more than 40% compared with the traditional central air conditioner, reducing the operating cost, and saving energy and economy; The outdoor unit has compact structure and flexible and convenient installation, which can save outdoor space, beautify the home environment and reduce the number of outdoor units; With automatic fault detection and convenient maintenance; The heating/cooling mode can be automatically switched, and the wind speed can be automatically changed. It has timing and night setting modes, which can realize centralized management and individual control at the same time.

Its disadvantages: the peak-valley difference of power supply is large, the efficiency of grid-connected generator is low and the energy consumption is large when it runs at low load; Greenhouse gas emissions have increased significantly; No fresh air supply, high installation requirements; If the refrigerant pipe leaks, it is difficult to find the leakage point and repair it, and its price is high. At present, Haier and Midea, domestic air-conditioning enterprises, have begun to promote this model, and the price is expected to be further lowered.

3.4 One Drag One Duct Air Conditioning System

It consists of outdoor unit, air duct air conditioning box, air supply pipe, air valve and air outlet. The refrigeration principle is similar to that of split air conditioning, and it also belongs to the direct evaporation type of refrigerant, except that the indoor unit in section 3.3 is changed into an air conditioning box with air duct. Air duct air conditioning box belongs to all-air system, waterless system and its various supporting equipment, which greatly reduces the initial investment; The indoor unit is placed in the indoor ceiling, saving room area and capital investment; The wind system is simple, so it does not need special management, and only needs regular inspection. Compared with the scheme in Section 3.2, there is no fear of water leakage, and the price is relatively low. We can give full consideration to fresh air, improve indoor air quality and keep the air fresh; The direct evaporation of cooling air saves the energy loss caused by the refrigerant water circulation process, and the evaporation temperature is higher than that of the water chiller, which improves the refrigeration efficiency of the system.

The air pressure at the air outlet of the duct air-conditioning box is relatively high, generally 80 ~ 150 Pa. Through the duct, a certain range of hot and cold air at each air outlet can be ensured to keep the indoor air flow field and temperature field uniform. Mufflers can also be configured to fully meet indoor noise requirements. Using multiple pipeline machines in large-area air-conditioned places such as shopping malls can start and stop some pipeline machines to adjust energy according to indoor load changes; However, when used in residential air conditioning, each room cannot be controlled independently, and the return air is concentrated, which affects the privacy of each room; The air duct takes up a lot of space in the building. Moreover, the air filtration ability is poor, the enthalpy drop of the treated air is small, and the dehumidification ability is not strong.

Based on the above four domestic central air conditioning modes, the author thinks that each mode has its own characteristics, and according to the specific engineering situation, economic and technical analysis and comparison, the most suitable air conditioning scheme is determined. However, at present, the author thinks that one-tow multi-air conditioning system and one-tow one-duct air conditioning system are more suitable for existing residential air conditioning. The former is difficult to popularize because of the price. It is estimated that in the next few years, with a large number of domestic air conditioner manufacturers involved in commercial air conditioners, their prices will drop and their market share will continue to rise. The latter should have a good market potential at this stage.

Several problems that should be paid attention to in the design and construction of 4-household central air conditioning system

4. 1 The indoor unit capacity of the air conditioner can be appropriately enlarged.

According to the living habits of most people in China at present, we should turn on the air conditioner when we get home from work, hoping to achieve the air conditioning effect as soon as possible; In addition, due to the lack of heat insulation treatment of the envelope, when the neighbors upstairs and downstairs do not turn on the air conditioner, the cooling capacity will be greatly lost, so the capacity of the indoor unit of the air conditioner should be appropriately increased to ensure the air conditioning effect. At the same time, the indoor unit is equipped with an adjusting device, which can adjust the air volume and refrigeration capacity as needed.

4.2 The outdoor host capacity can be reduced appropriately.

According to the living habits of most three or five households at present, it is impossible for the air conditioning terminal to run at full load at the same time. When the living room and dining room are air-conditioned, the bedroom and study are hardly or rarely opened. According to the specific situation, the host capacity can be appropriately reduced to reduce the initial investment and operating costs.

4.3 The installation quality shall be guaranteed.

Pipes should be installed tightly, and air leakage and water leakage are not allowed, especially when the refrigerant pipe leaks, it is difficult to find the leakage point, maintenance is difficult, and disputes are prone to occur. Air conditioning water pipes and refrigerant pipes can be considered to pass through beams and shear walls to save space.

4.4 When the condensed water is discharged, the pipeline shall be well insulated.

Water leakage is a common problem in family decoration, and it is also a difficult problem to solve. For air-conditioning systems, condensate discharge is the most easily overlooked, which leads to potential water leakage. Condensate water should be discharged centrally by independent vertical pipes, and the horizontal pipes should not be too long, and the slope should not be less than 0.008. Air pipes and condensate pipes, especially air conditioning pipes and refrigerant pipes, are prone to condensation and leakage due to low temperature, such as poor insulation.

5 conclusion

Household central air conditioning industry is a very new industry in China. It has gradually developed since the reform and opening up. After more than ten years of efforts, a number of high-level enterprises have been established, which has promoted the rapid development of the domestic central air-conditioning industry. I believe that in the next few years, with the rapid development of science and technology and the further standardization of the market, the domestic central air-conditioning industry will enter a brand-new new era.

References:

[1] GBJ-87, code for design of heating, ventilation and air conditioning [S]

[2] Lv Yaoqing, et al. Practical Manual for Heating and Air Conditioning Design [M]. Beijing: China Building Industry Press, 1993.

[3] Gu Xingyu, et al. Technical measures for HVAC design of civil buildings [M]. Beijing: China Building Industry Press, 1996.

Author's resume: Liu Hanhua, Jiangxi Architectural Design and Research Institute, Nanchang, Jiangxi 330046.

Liu Hanhua (1964-), male, bachelor of engineering, senior engineer, chief engineer.