How to solve the problem of low cooling capacity and high power consumption of the unit

The cooling capacity of the unit is not as good as before, and the unit consumes a lot of electricity. Do you have such troubles? Have you ruled out this item?

After long-term use, the condenser is prone to scale formation in the pipes. If it is not handled in time, these scales will affect the heat exchange effect, causing the condensation temperature of the unit to increase, which in turn leads to a decrease in cooling capacity and an increase in unit power consumption. Therefore, the condenser should be descaled frequently.

1. Calculation of condenser temperature difference

The focus of condenser cleaning is to pay attention to: chilled water inlet and outlet water temperature, cooling water inlet and outlet water temperature, condensation pressure, and evaporation pressure. We can calculate the end temperature difference and convert the condensation pressure and evaporation pressure into the corresponding condensation saturation temperature and evaporation saturation temperature. If the condensation temperature and evaporation temperature can be queried on the touch screen, the value is the corresponding condensation saturation temperature and evaporation saturation temperature. As shown below:

If the calculated end temperature difference is greater than 5℃, it can be preliminarily judged that the heat exchanger has been scaled. When the end temperature difference is greater than 7℃, it is severely scaled.

For example: the temperature difference at the condensing end = 36℃-32.3℃=3.7℃, the temperature difference at the evaporating end = 12.1℃-9.7℃=2.4℃. It can be seen that the temperature difference at the condensing end and the temperature difference at the evaporating end are both small, the shell and tube heat exchange effect is good, and there is basically no scaling.

In addition, you can also look at the color of the copper tube of the condenser. If you can't see the original color of the copper tube, the scaling is already very serious and needs to be cleaned in time.

2. The main methods and operations of condenser cleaning

There are three main methods for removing scale from the condenser:

1. Mechanical descaling method

2. Chemical pickling descaling method

3. Electronic magnetic water descaling method

Here we introduce these three cleaning and descaling methods.

1. Mechanical descaling:

Mechanical descaling is to use a soft shaft pipe washer (commonly known as a gun machine) to descale the condenser of the cooling tube, which is suitable for vertical shell and tube condensers.

Principle and method of flexible shaft pipe cleaner:

The umbrella gear-shaped scraper connected to the flexible shaft pipe cleaner rotates and scrapes from top to bottom in the vertical pipe of the condenser to remove scale, and uses circulating cooling water to cool the heat generated by the friction between the scraper and the pipe wall, and at the same time washes the removed scale, rust and other dirt into the pool.

During the descaling process, it is necessary to determine the appropriate diameter of the roller according to the scale thickness of the condenser, the degree of rust on the pipe wall, and the length of time it has been used. The diameter of the roller selected for the first descaling should be slightly smaller than the inner diameter of the cooling pipe to prevent damage to the pipe wall, and then a roller close to the inner diameter of the cooling pipe is selected for the second descaling.

2. Chemical pickling and descaling:

The chemical pickling and descaling method is suitable for vertical and horizontal shell and tube condensers (steel pipes). The normal operation of the condenser must be stopped during the descaling process to ensure safety.

Principle and method of chemical pickling and descaling:

The condenser is cleaned with a prepared weak acid descaling agent to remove scale.

Close the air inlet valve, liquid outlet valve, balance pipe valve, mixed gas valve, oil drain valve and other valves on the condenser, and stop the cooling water pump of the condenser.

Prepare the descaling solution in the pickling tank, start the pickling pump, and let the descaling solution circulate in the condensing tube of the condenser for 24 hours. Check the scale shedding and decide whether to continue cleaning. Generally, the scale is basically removed after 24 hours. After stopping the pickling pump, repeatedly clean the descaling solution remaining in the tube with clean water until it is completely clean.

3. Electronic magnetic water descaling method:

The electronic magnetic water descaling method is suitable for various condensers, and it can descale and prevent scaling without affecting the normal operation of the refrigeration system. Moreover, this method can not only effectively prevent the formation of new scale, but also remove the original scale.

Working principle of electronic magnetic water device:

Calcium, magnesium and other salts in the cooling water flowing through the condenser are dissolved in water in the state of positive and negative ions at room temperature. When the cooling water flows through the transverse magnetic field of the magnetic water device at a certain speed, the dissolved calcium, magnesium and other ions obtain induced electrical energy, causing their charge state to change, and the electrostatic attraction between ions is disturbed and destroyed, making the structure of the crystal loose, becoming loose mud and discharged with the flow of cooling water.

Among the above three cleaning and descaling methods, the descaling method of the electronic magnetic water device is simple and easy, with low labor intensity, not easy to damage the tube wall in the condenser, and can be carried out at any time. Pickling and mechanical descaling require the normal operation of the refrigeration system to be stopped, and should be arranged in the off-season.

Note: After the mechanical descaling method and the chemical pickling descaling method are cleaned, the condenser must be tested for air tightness (air pressure 1.8Mpa) to check whether the condenser tube has leakage caused by damage to the tube wall during the descaling process. After the inspection is completed and it is confirmed that the condenser is normal, the air in the condenser can be extracted (vacuumed) to put it into normal operation.

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