Hvac systems 2023

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Date:2022/06/21

What is HVAC?
Energy saving technology
Energy saving and environmental protection

What is HVAC?

HVAC is an air conditioner with heating, ventilation and air conditioning functions. Since the main functions of HVAC include:

The three aspects of HVAC are referred to as HVAC (Heating, Ventilating and Air Conditioning), and the comprehensive abbreviation of these three functions is HVAC.
HVAC refers to the system or related equipment responsible for heating, ventilation and air conditioning in a room or vehicle. The design of HVAC systems is applied to thermodynamics, fluid mechanics, and fluid machinery, and is an important branch of mechanical engineering.

Frequency conversion and flow technology of air-conditioning water system

The cooling load of the central air conditioner varies with the ambient temperature and the area used. The water pump motor of the constant flow water system is basically running at full load, resulting in the phenomenon of large flow and small temperature difference. In view of the problems of low efficiency and high energy consumption, the frequency converter of the air-conditioning water system is used to control the operation of the chilled water pump motor, so that the flow of chilled water changes in direct proportion to the cooling load, and has achieved good energy-saving effects and significant economic benefits. When choosing a frequency converter, the main consideration is the matching ability of the motor power, and at the same time, factors such as high reliability, convenient operation and reasonable price should be considered. After about 30 years of technological innovation, frequency converters have become the mainstream of motor speed regulation and play an important role in various industries. With the development of the full digital control mode of the frequency converter, its precision and reliability are very high. The advantages of high performance, good stability, strong storage capacity, and strong logic operation capacity will be more prominent, the economic benefits will be more significant, and the scope of application will be wider.

Cool and heat storage, low temperature air supply, large temperature difference technology

The air-conditioning cold storage utilizes the difference in time-of-use electricity prices to store "cheap energy" during the trough period of the power grid, and releases the stored cold energy during the peak cooling period to meet the air demand adjustment load. According to the cold storage medium, there are three ways: water cold storage, ice cold storage and eutectic salt cold storage.

Advantages of ice storage:

①The capacity of the chiller is reduced by 38%
②The power of air-conditioning equipment is reduced by 27%
③The annual saving of operating costs is 371,000 yuan. Ice slurry is a solid-liquid two-phase solution containing suspended ice particles, also known as fluid ice and binary ice. Ice particles are on the order of millimeters to centimeters, and alcohol and salt inhibitors are usually added to lower the freezing point.

The application advantages of ice slurry technology are:

1: The latent heat of phase transition is large, and low-temperature sensible heat can be used (the melting heat of ice is 335KJ/kg, and the specific heat capacity of water is 4.18KJ/kg.℃)
2: Good fluidity, can be pumped anywhere
3: The ice melting and cooling speed are fast, and the thermal response is fast
4: Adopt cold storage strategy to reduce system operating costs and improve refrigeration reliability

District cooling, heating and power and distributed energy technologies

The district cooling system, similar to the urban central heating system in the north, is produced by a special refrigeration station in a certain scale area, and transported to each cooling building through the frozen water pipe network, thereby providing refrigeration and air conditioning. service system.
The district cooling system can be regarded as a large-scale central air-conditioning system, and its users can include apartments, office buildings, hotels, shopping malls, institutions, hospitals and residences. The district cooling system is suitable for places with high cooling load density and large annual cooling load coefficient, such as industrial buildings, densely populated urban business districts, etc. The district cooling system consists of three parts: the central refrigeration station and the cold storage. Water distribution network, cold water users. Central refrigeration stations produce chilled water in various ways. Its equipment includes refrigerators and auxiliary equipment, cold storage equipment, heat exchange equipment and control devices. The chilled water pipe network transports chilled water produced by the central refrigeration station to various users. Cold users are buildings that require refrigeration and air conditioning, equipped with terminal cold and heat exchange equipment.

Compared with traditional central air conditioners and split air conditioners, district cooling has the following features and advantages:

1) High energy efficiency
2) At the same time, the utilization factor is small, and the installed capacity of the refrigeration host is small
3) Reduce operation management personnel and improve maintenance quality
4) obvious advantages in environmental protection
5) Conducive to the use of cold storage technology
6) Improve architectural aesthetics and space utilization

Comfortable and energy-saving air conditioning technology such as ground source heat pump

Ground source/water source heat pump air conditioners use water as the carrier. Through the ground source heat pump unit system, the geothermal heat energy (groundwater or soil heat energy) is transferred to the interior of the building for heating in winter, and the heat in the building can be transferred out in summer. Heat is transferred to the shallow layers of the earth through a system of heat pump units. Make full use of groundwater or underground soil at a constant temperature all year round.

It has the following characteristics:

(1) Energy saving 30%~60%
(2) High efficiency and environmental protection
(3) Both winter and summer
(4) Up to 25 years of service life
(5) Reduce investment risk and save initial investment

Characteristic principle

HVAC is a household central air conditioner, and its biggest feature is that it can create a comfortable indoor environment. The general split air conditioner in the home can only solve the heating and cooling problem, but not the air treatment process. With HVAC, things are different.
The air treatment process has the following steps: First, after the air comes in, in addition to introducing fresh air, the air can also be cooled and then filtered. , mainly can capture very small particles of dust, generally speaking, it can capture dust of one micron, and most of the dust in the range is bacteria, virus, smoke or odor, so it can be filtered out; in addition, a humidification device is added. This humidifier can produce about 40% relative humidity in the humidification of our room, which is very comfortable.

Energy saving technology

1. Optimal selection of heat source system

In the energy-saving design process of the HVAC system, the heat source system should be reasonably selected according to the actual situation of the engineering building. In general, the common types of heat sources in the Chinese market are: heat pumps, thermal power plants, regional boiler rooms, small boilers, direct-fired lithium bromide absorption hot water units, etc. Power plants generally have the highest operating efficiency, followed by heat pump technology. The heat pump mainly uses a large amount of renewable, low-grade energy contained in nature as a heat source, such as surface water, solar energy, atmosphere, geothermal, etc., and absorbs heat energy from the environment through the operation of the compressor. heat source, raising the temperature and transferring it to a high temperature heat source. According to the different energy sources of the heat pump, the air source heat pump can be divided into two parts. Mainly for commercial unit heat pump air conditioners, domestic heat pump air conditioners, heat pump cold and hot water units and other ground source heat pumps represented by soil type, which can achieve at least 30% energy saving goals: direct-fired lithium-ion bromide absorption units, their heating efficiency and gas The boilers are basically similar, but for the boiler room, the application effect of the cooling storage system in the large regional boiler room is better than that of the small boiler.

2. Promote the use of frequency conversion technology

In modern HVAC systems, the application of frequency conversion technology has a strong inevitability. Through frequency conversion technology, it can not only make up for the process problems of the air conditioning system, but also reduce energy consumption and operating costs. In general, the air conditioning system only operates at the pre-designed power rating. In the case of low load, if the equipment is still running at full load with rated power, energy waste will inevitably occur. By applying frequency conversion technology in the HVAC system, the output power of the air conditioning equipment can be adjusted according to the change of the load, and the effect of energy saving and emission reduction can be exerted. Combined with the actual load of the air conditioner, appropriately change the air flow or water flow to achieve the purpose of energy saving. On the one hand, the variable air volume system uses the terminal device of the air conditioning system to realize the compensation mechanism for the indoor load, optimizes the adjustment of the air supply, and keeps the indoor temperature appropriate; compared with the constant air volume system, the variable air volume system can save about 50% energy; The variable water volume system mainly adjusts the temperature by controlling the water volume, which saves more electricity than the constant current system. With the promotion and use of industrial inverters in my country, by optimizing the air volume, water volume and the adjustment of the host, the matching operation with the air conditioning load can be realized.

3. Reduce the energy consumption of heat medium

In the HVAC system, energy-saving engineering design should pay attention to the energy consumption of each link. Taking the specific design and actual working conditions as the starting point, an integrated air-conditioning energy-saving system is formed. Among them, the heat medium transmission system is an important part of HVAC, and its heat energy transmission mode and material selection have an impact on energy saving. In the heat medium transmission system, the selection of insulation materials such as directly buried pipes can realize the prefabrication and insulation of hot water, thereby reducing the possible losses in the process of heat energy transmission. In addition, the computer system can comprehensively test the heating status of the air-conditioning system, intelligent pipe network, balance valve, etc. can be used to optimize the flow configuration of the pipe network, strengthen management countermeasures, so as to improve the operation efficiency and achieve the purpose of energy saving. In the energy-saving design of the air-conditioning system, the power transmission system can also be applied to optimize the design and construction of the power system and improve the energy-saving efficiency of the air-conditioning system. The power system should select power supply pipelines with good load characteristics, high operating efficiency, large temperature difference and large rheological speed, rationally and effectively use power equipment, improve transmission efficiency, and build a good air-conditioning operating system. It can be used to optimize the flow configuration of the pipe network and strengthen the management countermeasures, so as to improve the operation efficiency and achieve the purpose of energy saving. In the energy-saving design of the air-conditioning system, the power transmission system can also be applied to optimize the design and construction of the power system and improve the energy-saving efficiency of the air-conditioning system. The power system should select power supply pipelines with good load characteristics, high operating efficiency, large temperature difference and large rheological speed, rationally and effectively use power equipment, improve transmission efficiency, and build a good air-conditioning operating system. It can be used to optimize the flow configuration of the pipe network and strengthen the management countermeasures, so as to improve the operation efficiency and achieve the purpose of energy saving. In the energy-saving design of the air-conditioning system, the power transmission system can also be applied to optimize the design and construction of the power system and improve the energy-saving efficiency of the air-conditioning system. The power system should select power supply pipelines with good load characteristics, high operating efficiency, large temperature difference and large rheological speed, rationally and effectively use power equipment, improve transmission efficiency, and build a good air-conditioning operating system. In the energy-saving design of the air-conditioning system, the power transmission system can also be applied to optimize the design and construction of the power system and improve the energy-saving efficiency of the air-conditioning system. The power system should select power supply pipelines with good load characteristics, high operating efficiency, large temperature difference and large rheological speed, rationally and effectively use power equipment, improve transmission efficiency, and build a good air-conditioning operating system. In the energy-saving design of the air-conditioning system, the power transmission system can also be applied to optimize the design and construction of the power system and improve the energy-saving efficiency of the air-conditioning system. The power system should select power supply pipelines with good load characteristics, high operating efficiency, large temperature difference and large rheological speed, rationally and effectively use power equipment, improve transmission efficiency, and build a good air-conditioning operating system.

4. Reasonably determine the air conditioning method

For the HVAC system, the comfort level of its application mainly depends on the comprehensive influence of factors such as wind speed, humidity, air humidity, average ambient radiant temperature, and people's perception of the environment. Therefore, the selection of various combined environmental parameters will produce different thermal comfort effects: for example, the energy consumption generated by the air conditioning system will also be different due to the different thermal and humid environments. In winter, if the traditional air-conditioning method is selected to increase the indoor temperature, the heat and moisture exchange between the human body and the environment is carried out through the air, and the required air humidity is relatively high. In this case, the heat loss of heating the fresh air and the heat loss of the maintenance structure are relatively large; if the application results of the new hot and humid environment can be applied, the air conditioning operation mode can be optimized, and the radiant heat can be improved, which can significantly reduce the air humidity. 18℃~20℃, obviously the energy-saving effect of the new air-conditioning operation mode is more objective. In the same way, when using the air conditioning system in summer, the new air conditioning operation mode is more suitable. The application of this healthy, comfortable and energy-saving new air-conditioning operation mode can not only meet the needs of a high-level life, but also achieve the goal of energy conservation and emission reduction, which is in line with the low-carbon development trend. - Carbon economy. Optimizing air conditioning operation, increasing radiant heat and significantly reducing air humidity. 18℃~20℃, obviously the energy-saving effect of the new air-conditioning operation mode is more objective. In the same way, when using the air conditioning system in summer, the new air conditioning operation mode is more suitable. By applying this healthy, comfortable and energy-saving new air-conditioning operation mode, it can not only meet the needs of high-level living, but also achieve the goal of energy saving and emission reduction, which is in line with the low-carbon development trend. - Carbon economy. Optimizing air conditioning operation, increasing radiant heat and significantly reducing air humidity. 18℃~20℃, obviously the energy-saving effect of the new air-conditioning operation mode is more objective. In the same way, when using the air conditioning system in summer, the new air conditioning operation mode is more suitable. By applying this healthy, comfortable and energy-saving new air-conditioning operation mode, it can not only meet the needs of high-level living, but also achieve the goal of energy saving and emission reduction, which is in line with the low-carbon development trend. - Carbon economy. In the same way, when using the air conditioning system in summer, the new air conditioning operation mode is more suitable. By applying this healthy, comfortable and energy-saving new air-conditioning operation mode, it can not only meet the needs of high-level living, but also achieve the goal of energy saving and emission reduction, which is in line with the low-carbon development trend. - Carbon economy. In the same way, when using the air conditioning system in summer, the new air conditioning operation mode is more suitable. By applying this healthy, comfortable and energy-saving new air-conditioning operation mode, it can not only meet the needs of high-level living, but also achieve the goal of energy saving and emission reduction, which is in line with the low-carbon development trend. - Carbon economy.

5. Optimize hot and cold energy recovery

At present, in-depth research is being carried out on the recovery of cold and heat energy in the HVAC system to improve the efficiency of the recovery of cold and heat energy in the air conditioning system and achieve the goal of energy saving on the premise of ensuring energy utilization. efficiency. Through waste heat recovery, the exhaust energy can be better utilized, the fresh air can be pre-cooled or preheated, the load can be reduced, and the energy-saving of the air-conditioning system can be realized; the waste heat recovery can be divided into two parts: total heat recovery and sensible heat recovery. The recovery equipment is generally a plate-type total heat exchanger, a wheel-type total heat exchanger, and a plate-type sensible heat exchanger.

Energy saving and environmental protection

The shortage of energy, the rapid changes in the global environment and the frequent occurrence of various related hazards have made energy conservation and environmental protection the mainstream of today's era and deeply rooted in the hearts of the people. Since then, energy saving and environmental protection have entered all walks of life and become the darling of the new era. In the HVAC industry, energy saving and environmental protection have also become an industry trend.
HVAC is an energy-intensive industry. In the context of energy conservation and environmental protection, a low-carbon and environmentally friendly lifestyle has a profound impact on the HVAC market. A reporter from Refrigeration Express learned in an interview that with the continuous development of the HVAC industry, the product layout is quietly changing. Low-carbon energy saving has become the basic demand of HVAC products. HVAC companies continue to adopt advanced technologies to improve the energy efficiency of air-conditioning products, develop energy alternatives and the utilization of renewable energy, and develop new refrigerants.