What are the common reasons for high pressure failure of chiller units?

In the after-sales maintenance or commissioning of refrigeration systems, high condensation pressure or high pressure protection is particularly common. At the same time, the close temperature of the condenser (i.e. the difference between the condensation temperature and the cooling water outlet temperature) or the large temperature difference at the condensation end is also frequent. These abnormal conditions will not only affect the normal operation of the refrigeration system, but may also lead to increased energy consumption of equipment, shortened life, and even cause safety accidents. So, what exactly causes these phenomena to occur?

The condenser is too dirty: the most common "culprit"

Too dirty condensers are the most common cause of the above problems. The condenser plays a crucial role in the refrigeration system, which is responsible for cooling and condensed into liquid state, high temperature and high pressure gaseous refrigerant discharged from the compressor. Since the working temperature of the condenser is relatively high, taking common working conditions in the industry as an example, the inlet and outlet water temperature is usually 32/37 degrees Celsius.

For chiller units, the cooling water generally adopts an open system, and the spray water of the cooling tower can easily absorb various dust in the air during the circulation. At the same time, the warm and humid environment also provides a breeding ground for the breeding of algae. As the cooling water enters the condenser, these impurities will gradually deposit on the tube wall of the condenser to form scale. The thermal conductivity of scale is extremely poor. Its existence will seriously hinder the transfer of heat, causing the heat exchange performance of the unit condenser to deteriorate sharply. As the scale continues to accumulate, the close temperature of the condenser will gradually increase.

Too much charge for the snow group: a counterproductive operation

Snow species, namely refrigerant, are the key substances in the refrigeration system to realize the refrigeration cycle. During the installation or maintenance of the refrigeration system, if too much snow is filled, the liquid level of the refrigerant in the condenser will be too high, thereby reducing the effective area of ​​the condenser participating in condensation and heat exchange.

At this time, the technician can judge whether the snow seed is overfilled by observing the condenser liquid lens. The liquid viewing mirror can visually display the state and liquid level of the refrigerant in the system. In addition, it can also be judged in combination with the supercooling degree of the condenser. Generally speaking, when there is too much snow type filling, the cooler outlet of the condenser will be relatively high. This is because too much refrigerant cannot be fully condensed in the condenser, resulting in the refrigerant at the outlet still having a certain degree of supercooling.

Water chamber separator peeling or aging: hidden dangers of water-cooled chiller

For shell and tube condensers that use 2 or multiple processes in water-cooled chiller units, there is also a situation where the water chamber separator falls off or aging causes the water chamber to sprinkle water. The function of the water chamber partition is to separate the cooling water into different processes so that the cooling water can flow in a predetermined path, thereby improving the heat exchange efficiency.

When the water chamber partition tendons fall off or age, the cooling water will short-circuit flow in the water chamber, causing some cooling water to be unable to fully participate in the heat exchange, thereby affecting the overall heat exchange performance of the condenser. This situation can be judged by measuring the condenser water resistance and comparing it with the nominal water resistance. If the measured water resistance is obviously small, there is a possibility that the water chamber separator may fall off or age, and it needs to be repaired or replaced in time.

Shanghai KUB Refrigeration Equipment Co., Ltd.

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