HVAC knowledge

HVAC knowledge

1. The expansion water tank is used in the heating system to store the expansion water after the system is heated, and plays the role of exhaust in the natural circulation up-and-down system. In addition, it can also play the role of constant heating system pressure.

　　2. The air environment elements controlled by air conditioning include air temperature, relative humidity, air velocity, pressure, air cleanliness, noise, etc.

　　3. The air conditioning system is mainly composed of four basic parts: air handling equipment, fans, air ducts, and air supply and return ports.

　　4. The air conditioning system can be mainly divided into centralized air conditioning system, semi-centralized air conditioning system and local air conditioning system.

　　 5. The most commonly used type of semi-centralized air conditioning system is the fan coil system. The fan-coil air conditioning system consists of three parts: fan-coil unit, water system and fresh air system.

　　6. ​​The fan-coil unit consists of a fan, a surface heat exchanger and a filter.

　　7. Commonly used air treatment processes include filtration, heating, cooling, humidification and dehumidification.

　　 8. Air filters are equipment used to evolve air with higher dust content in air conditioning engineering. According to the filtration efficiency, it can be classified into four types: primary efficiency filter, medium efficiency filter, and sub-high efficiency filter.

　　 9. Currently, the widely used air heating equipment includes two types: surface air heater and electric heater.

　　10. There are water-cooled surface cooler cooling methods, direct evaporative surface cooler cooling, and water spray chamber cooling.

　　11. Commonly used dehumidification methods include heating dehumidification, cooling dehumidification, absorption or adsorption dehumidification.

　　12. There are two aspects of noise reduction measures: one is to reduce the generation of noise; the other is to install a muffler in the system.

　　13. There are two types of refrigerants used in air conditioning engineering: vapor compression and absorption.

　　14. The compression refrigerator is composed of four main components: a refrigeration compressor, a condenser, an expansion valve and an evaporator, which are connected by pipes to form a closed cycle system.

　　 15. 95~70℃ hot water should be used as the heat medium in the centralized heating system of civil buildings.

　　 16. Compared with steam heating, small room temperature fluctuation is the obvious advantage of hot water heating system.

　　17. According to the medium that bears the heat and cold load of the air-conditioned room, the air-conditioning system is divided into: all-air system, all-water system, air-water system, and refrigerant system.

　　18. Central heating system is mainly composed of three parts: heat source, transmission pipe network and heat dissipation equipment.

　　19. According to the different heat dissipation methods of the heating system, it can be divided into convection heating and radiant heating.

　　20. Heating with convection heat exchange as the main method is called convection heating.

　　 21. Radiant heating is a heating method based on radiant heat transfer.

　　22. A heating system that uses hot air as a heat medium to supply heat to the room is called a hot air heating system.

　　23. The main difference between the mechanical circulation hot water heating system and the natural circulation hot water heating system is that a circulating water pump is installed in the system, and the mechanical energy of the pump is mainly used to force water to circulate in the system.

　　24. The steam heating system can be divided into top-fed, middle-fed and bottom-fed steam heating systems according to the different arrangements of the main pipes.

　　25. Steam heating systems can be divided into single-tube and double-tube steam heating systems according to the characteristics of the riser layout.

　　26. Steam heating system can be divided into two forms of gravity backwater and mechanical backwater steam heating system according to the different backwater power.

　　27. The central heating system is composed of three parts: heat source, heat supply pipe network and heat user.

　　28. Generally, there are two kinds of heat load estimation algorithms: heat index method per unit area and heat index method per unit volume.

　　29. According to the power of the ventilation system, it can be divided into natural ventilation and mechanical ventilation.

　　 30. Commonly used forms of air organization in a ventilated room are: upper and lower rows, lower and upper rows, middle and upper and lower rows, etc.

　　31. The local exhaust system is composed of exhaust hoods, ducts, purification equipment and fans.

　　32. There are combustion method, condensation method, absorption method and adsorption method to purify harmful gas.

　　33. Natural ventilation can be divided into organized natural ventilation, ducted natural ventilation, infiltration ventilation and other forms.

　　34. The heat pumps that are often used at present usually have two categories: air source heat pumps and water source heat pumps.

　　35. There are many methods for calculating the cooling load of the envelope structure. At present, the harmonic response method and the cooling load coefficient method are mostly used in China.

　　36. According to the source of the air used, air conditioning systems can be divided into closed systems, direct current systems, and hybrid systems.

　　37. According to the structure of the air conditioning unit, there are three types of air conditioning units: integral, split and combined.

　　38. The common airflow organization forms of air conditioning systems include the top-sending and bottom-returning methods, the top-sending and the top-returning methods, the middle air-supplying method, and the lowering air-supplying method.