Test and Clean of chiller systems
Positive pressure experiment
The positive pressure test of the refrigeration system can use dry compressed air or nitrogen, or clean carbon dioxide. In order to facilitate leak detection, a small amount of Freon refrigerant can be charged into the refrigeration system to fully mix the refrigerant and nitrogen. Before charging, first close all valves leading to the atmosphere, open all connecting pipes, valves of the pressure gauge extraction and recovery device, etc., and then open the air compressor to inject nitrogen into the system. In the first step, when the pressure should be gradually increased to 10 of the specified pressure, and not more than 0.05MPa ~ 0.01MPa, keep it for 5min, and then conduct the initial leak detection on all welded joints and each connection part.
vacuum test
After filling a certain amount of lubricating oil into the refrigeration unit, use a vacuum pump to evacuate the unit into a vacuum state. The purpose of the vacuuming experiment is to remove the residual gas, moisture, etc. in the system, and to check the airtightness of the system in a vacuum state. Of course, the vacuuming experiment can also help to check the airtightness of the compressor itself. Prepare to inject refrigerant.
plumbing system flushing
The flushing of the pipeline system should be carried out after the pipeline pressure test is qualified and before the commissioning operation. Before flushing, the front and rear valves of the electric two-way valve in the system should be closed. After opening the bypass valve, the fan coil, two-way valve, etc., which should not be flushed with the pipeline, should be separated from the pipeline to be cleaned, and then the system will be chilled. rinse. When cleaning, it is necessary to pay attention to whether the water quality meets the requirements. Generally, it can be washed with clean tap water.
For the flushing of the chilled water system pipeline, the water source of the expansion tank located on the roof can be used to irrigate the system. After the irrigation is completed, the forced cleaning is performed, and the chilled water pump is started to pressurize to ensure a certain flow rate.
Water flushing should be carried out at the maximum flow rate that can be achieved in the pipe or at a flow rate of not less than 1.5m/s, and should be carried out continuously.
The cooling water system is poured into the cooling water system from the water receiving tray of the cooling tower. Before starting the water pump, open the water inlet valve and close the water outlet valve. After starting the water pump, slowly open the water outlet valve to achieve normal operation. In the process of flushing the chilled water and cooling water system, it is necessary to monitor the operating sound, temperature and vibration of each pressure gauge, ammeter, and water pump throughout the process to see if there is any abnormality.
Refrigeration unit refrigerant charging
There are three on-site refrigerant charging methods for the 30HXC165A unit, and these three methods are suitable for different stages. In large Freon refrigeration units, there is a special refrigerant charging valve (or charging port) on the liquid pipeline between the liquid receiver (some are filter driers) and the expansion valve (some are discharge valves).
After the system is evacuated, the refrigeration unit is charged with refrigerant for the first time. The most basic and accurate method is to completely remove the liquid and gaseous refrigerants in the unit according to the refrigerant quality indicated on the nameplate of the refrigeration unit. Recharge.
Refrigeration unit debugging
The single-unit commissioning of the chiller mainly includes the unit trial operation, the adjustment of chilled water pressure and flow, the adjustment of cooling capacity, and the adjustment of cooling water pressure and flow of the unit.
Before the test run of the unit, set the pressure value of the high and low pressure relays to be higher than the pressure value of the normal operation of the unit, set the low pressure value to be lower than the pressure value of the normal operation of the unit, and set the setting value of the differential pressure relay to 0.1MPa (gauge pressure), so that it can control the automatic shutdown when the difference between oil pressure and high pressure is lower than this value.
The liquid level of the refrigerating machine oil should be in accordance with the product manual, the oil pump should operate normally, the oil pressure should be maintained at 0.15MPa ~ 0.30MPa (gauge pressure), the pressure difference between the front and rear of the oil filter should not be greater than 0.1MPa, and the cooling water inlet temperature should not be higher than 32°C , the suction pressure of the unit shall not be lower than 0.05MPa (gauge pressure), and the exhaust pressure shall not be higher than 1.60MPa.
