Building HVAC (HVAC application)

 

1. Industry background

 

In 2008, the temperature in most parts of the country was higher than in previous years. The traditional peak season for air-conditioning sales was "cold." At the same time,

The deep adjustment and shrinking of the domestic real estate market also directly led to a decrease in air-conditioning transactions. In the second half of 2008, the global macroeconomic environment changed suddenly. The US subprime mortgage crisis triggered a global financial crisis. The export business of China's air-conditioning products was frustrated. The domestic market became more competitive and the market space could not be enlarged. The huge inventory pressure triggered a price war, and the air-conditioning market continued to be sluggish, and sales fell all the way, encountering the coldest "winter" in history. HC D&B's research terminal sales monitoring data shows that in 2008, the annual sales of air conditioners reached 21.168 million units, a decrease of 7.6% from 2007; sales reached 59.68 billion yuan, a decrease of 2.3% from 2007.

 

After the rapid market growth in previous years, China's central air-conditioning industry had to slow down in 2008 due to the impact of the economic environment. Industry insiders estimate that in 2007, the total sales of China's central air-conditioning industry was about 30 billion yuan; in 2008, the total sales of China's central air-conditioning industry was about 32 billion yuan, and the total growth rate of the industry was only 7% at most. The data is far below the 20% to 30% in previous years.

 

In 2008, Daikin adjusted its market strategy, focusing on terminal market demand and consumer experience as a strategic focus for sales. Therefore, although the growth in large-scale construction projects was limited, in general, Daikin basically maintained the same year-on-year level as in 2007. Growth rate, in China, especially in the markets around East China, achieved good results, reaching a growth rate of 14%. Among domestic brands, Midea, Gree, and Haier still maintain good market growth and market share. In 2008, the total domestic and foreign sales of Midea's central air conditioners were approximately 5 billion yuan (including large units, heat pump water heaters, and small and medium-sized central air conditioners), of which the domestic market sales reached 3.3 billion yuan, and the domestic sales increased by more than 30% year-on-year; in 2008 , Gree’s domestic sales of central air conditioners exceeded 2.5 billion yuan. The relevant person in charge of Haier revealed that the overall sales performance of Haier central air-conditioning in 2008 maintained a steady growth.

 

In 2008, the central air-conditioning market maintained a relatively flat growth, but in the first half of 2009, the central air-conditioning industry will encounter greater challenges. The downturn in the economy and real estate market will lag behind until the first half of 2009 and continue to affect the development of central air-conditioning enterprises. The government introduced a 4 trillion yuan fund to stimulate domestic demand, which has little effect on the central air-conditioning market, especially the small and medium-sized central air-conditioning market. Be cautious about the central air-conditioning market.

 

Two industry application status

 

The HVAC industry mainly includes: central air-conditioning, constant pressure water supply, building ventilation systems, heating, etc. This industry has a large number of fans, pumps, air compressors and other equipment, and the use of variable frequency speed control for load regulating flow has obvious effects. Especially in the past two years, the exhaust systems of high-end hotels, office buildings, and apartments in large cities in China have adopted variable frequency speed regulation, and the large number of applications of heat exchange units have made this industry very active in the field of frequency converters. Inverters are not only effectively used in large-scale ventilation, air-conditioning, heating and other systems, but also in household appliances, such as household air conditioners, refrigerators and other household appliances.

 

Three application prospects of building HVAC industry

 

Relative to the saturation state of the ordinary household air-conditioning market, central air-conditioning is currently developing rapidly in China. Statistics show that with the rapid development of China's urban construction and the continuous heating up of the real estate industry, China's central air-conditioning market has seen an annual growth rate of more than 12% in recent years. It is predicted that the market capacity of China's central air-conditioning market may reach 35-40 billion yuan by 2010. In major cities such as Beijing, Shanghai, and Guangzhou, the demand for central air-conditioning is increasing at a rate of 50% every year.

 

The rapid development of my country's central air-conditioning industry in recent years has largely benefited from the huge development of the real estate industry. China’s fixed asset investment is showing a steady growth trend. Among all the growth, real estate investment has the largest year-on-year growth rate, and the scale of office and commercial buildings in real estate investment has risen; it has also been set up in many new investment and construction of civil buildings, especially high-rise buildings. In recent years, commercial buildings, hotels, commodity wholesale markets, sports and cultural entertainment centers, multi-functional office buildings and other buildings built in recent years have mostly adopted central air conditioning systems, which has led to the rapid growth of the central air conditioning market.

 

Due to the continuous overheating of the real estate market in the past two years, the state has carried out macro-control. The real estate market will be greatly affected in 2008, which will affect the HVAC industry to a certain extent.

 

Four application examples of Easy Drive 3100 in the building HVAC industry

 

1. Central air conditioning system

 

The cooling load of most buildings is always in a dynamic change during the year. The central air conditioner is at the maximum cooling load only for dozens of days in a year. Every morning and evening, every season alternates, changes in the external environment will affect it in real time The cooling load of central air-conditioning. Generally speaking, the design of central air-conditioning system is driven by the maximum power of the maximum cooling load design, so the actual cooling capacity does not match the maximum power output of the system, which actually causes huge energy waste and increases equipment operation Costs reduce the competitiveness of enterprises. Therefore, frequency converters with energy-saving effects are more and more widely used in the central air-conditioning industry.

 

The frequency conversion speed control system used in HVAC is generally composed of sensors, transmitters, regulators, controllers, frequency converters, motors and controlled equipment.

 

Frequency converters are mainly used in central air-conditioning for fan and water pump loads such as fans and cooling towers. Since the energy adjustment of the absorption unit in the refrigeration unit is controlled by the method of controlling the circulation of the lithium bromide solution, the frequency converter will be widely used. The absorption unit includes direct combustion, steam, hot water, etc., typical customers There are Yuanda, Shuangliang and so on.

 

Simple frequency conversion processing often saves limited power and the effect is not obvious. In recent years, with the development of automation control technology and the rapid development of computer software technology, intelligent control equipment combining fuzzy control theory and frequency conversion technology has been successfully developed in central air conditioning energy saving technology. It can be based on the end of central air conditioning The load changes and the refrigeration operating conditions of the air-conditioning host automatically optimize the circulating water pump in real time, and automatically adjust the pump operating frequency, so that the system water flow changes synchronously with the air-conditioning load changes, so that the water pump is in the best energy-saving working state. Under the premise of normal load usage requirements, the purpose of reducing power consumption is achieved.

 

2. Constant pressure water supply system

 

In some new buildings and renovation projects, variable-frequency constant-pressure water supply has replaced water supply equipment such as high-level water tanks and pressure tanks. The start-up is stable, and the starting current can be limited to the rated current, thus avoiding the impact on the power grid when starting; The average speed is reduced, which can prolong the service life of pumps and valves; it can eliminate the water hammer effect during starting and stopping. Its energy saving, convenience and sanitation are obvious to all. The advantage of variable frequency constant pressure water supply is that it can not only ensure sufficient water pressure; the technology of one frequency conversion cycle with multiple pumps has been known for a long time, and the energy saving effect of this type of application is very significant. Therefore, the frequency converter is more and more widely used in the field of constant pressure water supply.

 

Frequency converters are also used in building fire protection systems. The fire-fighting water in the fire-fighting water piping system should always maintain a certain value of pressure. Pumps 1 and 2 are low-power stabilized pumps, and pumps 3 and 4 are high-power fire pumps. Normally, pumps 1 and 2 work alternately. No. 1 (2) pump and the frequency converter and the pressure sensor installed on the pipeline form a closed loop system. The pump speed always tracks the set fire pressure value, so it can guarantee the usual stable fire pressure requirement value. When a fire alarm opens the fire hydrant, the water flow switch is pushed by the water flow to send out a signal, and the No. 3 or No. 4 fire pump is activated through the control box (No. 3 and No. 4 are standby for each other).

 

3. Building exhaust system

 

The ventilation system is aimed at the load as a fan. Because some need to communicate with the building automation system, there are requirements for the communication protocol of the inverter, and the number of inverters for this type of application is large.

 

The exhaust air volume requirement of the exhaust exhaust fan is calculated according to the air change standard, and it must meet the principle of "maximum demand". But in fact, the exhaust air demand of an environment is not a fixed number. For example, in underground garages, in different periods of time and in different situations, the amount of parking is changing, that is, the amount of emissions is also changing. So we can add an inverter to the fan to change the fan speed and change the exhaust air volume.

Use the CO2 sensor to detect the air quality in the garage and control the output of the inverter so that the fan speed (exhaust air volume) always corresponds to the index. The fan does not need to always run at the highest speed to exhaust air, which saves energy and reduces noise pollution .

 

If it is a fan used for exhaust air and fire fighting, there is no need for a two-speed fan to meet the requirements of different exhaust air volumes, and the required exhaust air speed can be obtained by frequency conversion speed regulation. It can also save a set of cumbersome linkage control system.

 

4. Heating system

 

In the heating system, the frequency converter mainly adjusts the water and air volume of energy-consuming loads such as circulating pumps, make-up pumps, and boiler rooms’ blowers and circulating pumps, which can make the heating quality of the heating network stable and efficient, and can effectively avoid The problem of overcooling and overheating of local heating network can also eliminate the noise generated by the air door of the induced draft fan. The heat exchange unit takes the plate heat exchanger as an example. The main engine is basically imported from the Nordic countries. In the domestic power distribution control system, the power is mostly below 75KW.

 

In the future, the central air-conditioning system will basically use frequency converters, and the rapid development of the HVAC equipment market will also drive the rapid growth of frequency converter applications in the HVAC industry.

 

_In short, the HVAC industry has relatively low technical requirements for frequency converters, but the amount of inverters used is relatively large; with the improvement of urban specifications and the country's requirements for energy conservation and emission reduction, it is showing a further upward trend! For inverters, it is an industry with great development potential.