Air conditioning system

Air conditioning system

1. Cold and heat source units

a. Electric-driven compression chiller

Electric-driven compression chiller mainly use Freon and ammonia as refrigerants, and most civilian refrigerators use Freon as refrigerants. According to the type of cooling medium, it can be divided into two types: air cooling and water cooling. According to the type of compressor, it can be divided into three types: piston type, screw type and centrifugal type. According to the provided cold or heat source, it can be divided into water chilling units and heat pump units.

b. Piston water chilling unit

Piston water chilling unit are composed of piston refrigeration compressors, air-cooled or water-cooled condensers, thermal expansion valves and evaporators, and are equipped with automatic or manual energy adjustment and automatic safety protection devices. Commonly used water-cooled piston chillers, the temperature of the inlet and outlet water of the condenser is set to 32°C and 37°C, the temperature of the chilled water at the outlet of the evaporator is set to 7°C, and the cooling capacity range is generally 35-580kW.

c. Screw water chilling unit 

The screw water chilling unit is a complete refrigeration system consisting of a screw refrigeration compressor, condenser, evaporator, thermal expansion valve, oil separator, automatic control components and instruments. Commonly used water-cooled screw chiller condenser inlet and outlet water temperature is set to 32 ℃, 37 ℃ respectively, the evaporator outlet chilled water temperature is set to 7 degrees, the cooling capacity range is 580 ~1163kW.

d. Centrifugalwater chilling unit 

The centrifugal water chilling unit is an integral unit composed of a centrifugal refrigeration compressor, condenser, evaporator, throttling mechanism and adjustment mechanism, and various control components. The cooling capacity of centrifugal chillers is relatively large. The inlet and outlet water temperatures of the commonly used water-cooled centrifugal chillers are set to 32°C and 37°C respectively, and the chilled water temperature at the evaporator outlet is set to 7°C. The single unit capacity is usually above 1163kW. So, centrifugal chillers are generally used in large central air conditioning systems

e. Heat pump unit

The circulation process of the heat pump unit has several forms, but no matter what, in addition to the four major components in the refrigeration system, the system must also be equipped with a four-way reversing solenoid valve, a one-way valve, etc., to make the refrigerant flow’s direction can be controlled in the cooling or heating state. Heat pump units can be divided into air-cooled heat pump units, water source heat pump units and soil heat pumps according to the cooling method.

2. Cleanroom AHU

The cleanroom AHU realizes the functions of refrigeration, heating, dehumidifying, heating, humidification, purification and sterilization through a variety of heat and humidity treatment schemes and air purification treatment, so as to achieve precise control of the indoor environment temperature, humidity, and cleanliness.

The air volume of the combined AHU ranges from 3500m³/h to 200,000m³/h for users to choose and combine freely. It is mainly suitable for the air purification system of various clean workshops. Such as industrial electronics factory, precision machinery manufacturing factory, textile workshop, automobile spraying workshop, GMP pharmaceutical factory, cosmetics, food factory, pure water workshop, hospital operation department, ICU and other occasions.

According to the structure type, it can be divided into horizontal, vertical and ceiling type; according to the characteristics of use, it can be divided into general unit, fresh air unit, purification unit and special unit (such as roof unit, subway unit and computer room special unit, etc. ); it can also be classified according to specifications, the basic specifications of the unit can be expressed by the rated air volume.

The basic principle of setting the functional section of the purification unit is determined according to the production process or cleanroom requirements; the combination and selection of the functional section of the purification unit should be closely integrated with the design of the air-conditioning room, and the microbial contamination points in the purification unit must be controlled. Because the structure, temperature and humidity are more suitable for the growth of bacteria and other microorganisms, the cabinet, filter, muffler, humidifier, etc. of the purification unit have become potential microbial contamination place, which must be controlled. If the unit box is free from damage and corrosion, disinfection resistance, heat preservation and sealing performance, we can use antibacterial materials that have been widely used in refrigerators; filter performance indicators meet the requirements; mufflers, humidifiers, etc., do not retain materials. The functional segments of the air conditioning unit are as follows:

• New return air mixing section; the new return air opening position can be set at the end, top or left and right sides according to the design requirements, and specific opening positions should be provided for special requirements. A regulating valve can be installed on the new air return port. The actuator has three types of manual, electric and pneumatic, which can be selected by the user.
• The filter section has two kinds of primary and medium-efficiency filtration. It is equipped with a diamond bag type, a four-peak bag type, and an automatic winding type. The filter material is made of high-quality polyester non-woven fabric, and the filter is quickly assembled and disassembled, gland display and alarm device
• The new exhaust section (also known as the flat air-distribution mixing section) is equipped with a primary air return valve in the box. The top of the box before and after the valve is equipped with an exhaust outlet and a new air outlet, and is equipped with a regulating valve. Its function is: When there is a return fan, supply the air conditioner to discharge part of the return air, so that the fresh air and the primary return air are mixed according to the required ratio; when the direct current system is adopted in the transition season, the primary return air valve should be closed, and the exhaust valve and fresh air valve should be fully opened.
• The energy recovery section is used for cross-air mixing and exhaust air energy recovery in the dual fan system. This section of the box is equipped with a primary air return valve, and the top is an energy recovery device. It uses the cold (heat) of the exhaust air to indirectly cool (heat) the fresh air. The fresh air passes through the plate energy recovery device to recover about 60% of the sensible heat energy of the exhaust air. At the same time, the exhaust air and the fresh air are not direct contact, which is especially suitable for energy recovery of the DC air-conditioning system that eliminates harmful indoor gases. When used as a DC system, the return air valve should be closed once. Places with highly toxic gases should have a separate exhaust system.
• Intermediate section (maintenance section) This section is used for the connection of the transition section and the internal maintenance lighting of the unit. Before the filtering section, there must be an intermediate section before and after the surface cooling section, heating section, and muffler section.
• The middle section of the second air return pipe of the secondary air return section, the top can be equipped with an adjustable valve, and it is equipped with manual, electric or pneumatic adjustment mechanisms, which can be selected by the user. This section can also be combined in the blower section.
• The surface cooler of the surface cold section adopts the structure of copper pipes and aluminum foil. The aluminum foil is in the form of flanging and corrugated edges. The large elbow heat exchanger reduces the welding elbow by 60%, which increases the heat exchange power. The advanced mechanical expansion tube form ensures the contact performance of the heat exchanger. The heat exchanger is divided into two types: fixed type and rotary type. Users can choose one according to their needs. The heat medium is steam or hot water.