Requirements for adding refrigerant to industrial chiller systems
After the industrial chiller system passes the vacuum test, the vacuum state in the system can be used to charge the refrigerant.
First, the charging of refrigerant
For newly installed systems, refrigerant can be added from the high-pressure end as follows:
1) Turn on the cooling water system for the condenser, and the valve in the system is kept in the state at the time of vacuum test.
2) Connect the cylinder with refrigerant with a west 14mm ×2mm seamless steel pipe (copper tube when filling with Freon). The bottle mouth is tilted downward, the cylinder is at an angle of 30° to the ground, or the tail of the cylinder is raised by about 200~300mm.
3) Open the charging valve. When a certain pressure is reached in the system (ammonia system is 0.1~0.2 MPa; Freon system is 0.2~0.3 MPa), suspend the refrigerant charging, and then check the sealing of the system at each connection and welding, if there is no leakage, you can continue to charge the refrigerant.
4) Close the outlet valve on the reservoir, continue to fill the refrigerant, when the cylinder pressure and the pressure in the reservoir reach a balance, the outlet valve on the reservoir should be opened.
5) Start the freezer to bring the refrigeration device into operation while continuing to charge the refrigerant. When white frost appears in the lower part of the cylinder, it means that the liquid refrigerant in the bottle is close to being filled, at this time, the cylinder valve and the filling valve can be closed, and the bottle can be changed to continue to fill.
6) Unless the outside temperature is very low, it is generally not necessary to use hot water on the cylinder to increase the pressure in the cylinder when filling the refrigerant, because it is not safe to do so. If you need to speed up the filling speed, the hot water temperature should not exceed 50 °C and strictly prohibit other methods to heat the cylinder.
7) When filling with freon, a filter drier must be set on a special pipe to reduce the possibility of moisture entering the system. When using high-pressure section charging, the compressor must not be started, and pay attention to the exhaust valve must not leak, otherwise liquid hammer will be generated.
8) When the refrigerant reaches 90% of the charging dose, the charging work can be temporarily stopped and the trial operation of the system can be carried out to check whether the system dose has met the requirements of operation and avoid unnecessary trouble caused by excessive charging. For old refrigeration systems, when refrigerant needs to be replenished, it should be charged from the low-pressure end.
Second, leak detection after filling
(1) The test strip leak detection method generally uses phenolphthalein test paper to detect leakage at the weld, flange, threaded interface, etc. of the system. Wet the test strip and approach the test site, if it turns red, it indicates ammonia leakage (pay attention to avoid the illusion caused by contact between the test strip and the soapy water on the pipe). Litmus test strips that turn blue in ammonia can also be used.
(2) Halogen blowtorch leak detection method Halogen blowtorch is a common tool for leak detection of Freon refrigeration system, domestic halogen blowtorch is shown in the figure below, the use method is as follows:
1. Add alcohol: first unscrew the base 1, add anhydrous alcohol with a purity of not less than 99.5% to the inside of the cylinder, but the injection amount should not be too much, just fill 1/2~3/4 of the volume of the lamp tube, and then screw the base tightly.
2. Start a fire: turn the handwheel 2 to the right, close the valve core, and then fill the wine glass with the glass, and then ignite, so that the lamp tube and the upper part of the blowtorch are heated, wait for a little heating, and check whether the blowtorch is leaking.
3. Ignition: When the alcohol in the beaker is close to burning, turn the handwheel 2 to the left, and ignite the alcohol volatile gas in the nozzle in the flame circle 4, at which time the suction hose 6 of the halogen lamp emits a sound of gas inhalation, and you can start to detect leaks with the lamp.
4. Use: the suction hose 6 nozzle close to the inspected place during detection, and slowly move, if there is Freon gas leakage, decomposition in case of flame, at this time the orange-red flame will turn green, the flame color change with the amount of Freon leakage is different, the darker the color indicates that the more serious the Freon leakage.
The working principle of a refrigerator
In the circulation system of the refrigerator, the compressor inhales low-temperature and low-pressure refrigerant steam from the evaporator, which is adiabatically compressed by the compressor into high-temperature and high-pressure superheated steam, and then pressed into the condenser for constant pressure cooling, and heat is released to the cooling medium, and then cooled into a supercooled liquid refrigerant.