1. Compressor

A. Function: compress the gaseous refrigerant at low temperature and low pressure into superheated refrigerant steam at high temperature and high pressure;

B. Main classification: piston type, scroll type, scraper type, screw type, centrifugal type;

C. Usage:

The power of the cold dryer is 1~2 horsepower, heat pump, scraper type (for reference only);

The power of the cold dryer is 3~12 hp, scroll type;

The power of the cold dryer is: 12~20 hp, (full) piston type;

The power of the cold dryer is 25~65 horsepower, (half) piston type;

The power of the cold dryer is more than 65 horsepower, screw type.

2. Condenser

A. Function: After cooling and condensation, the superheated refrigerant steam at high temperature and high pressure becomes liquid refrigerant at high temperature and high pressure;

B. Condensers are divided into air-cooled and water-cooled. Determined according to the actual situation of users

3. Expansion valve

A. Function: make liquid refrigerant at high temperature and high pressure become liquid refrigerant at low temperature and low pressure;

B. Expansion valve is divided into internal balance type and external balance type. Attachment: Schematic diagram

Operating principle of internal balance expansion valve:

When the internal balance expansion valve is in operation, its temperature sensing bulb is installed at the evaporator outlet to sense the return steam superheat of Freon and conduct automatic adjustment. After throttling through the valve hole, the refrigerant enters the evaporator at point A. The refrigerant absorbs heat and evaporates to point B. All the refrigerant is vaporized into dry saturated steam. [Ignore the internal resistance of the evaporator] The temperature of the evaporator remains unchanged before point B. The refrigerant is superheated steam from point B. The temperature at point C is the temperature felt by the temperature sensor. The pressure Ps in the temperature sensor is equal to the saturation pressure of the filling agent (R22, R12) corresponding to this temperature.

When the valve is in the balance position: PS=P+Pf

Refrigerant R22

Therefore, when the temperature sensing bulb breaks, the diaphragm pressure Ps=1 bar (standard atmospheric pressure)

Ps ＜ P ＋ Pf expansion valve is closed, the refrigeration system is open, and the high voltage trip.

4. Evaporator

A. Function: the refrigerant exchanges heat with the air, the low temperature and low pressure liquid Freon absorbs the heat in the air, and becomes the low temperature and low pressure gas refrigerant and returns to the compressor;

B. Evaporators are divided into shell-tube type and plate-fin type.

Source: Heating and Ventilation South Society