【Mechanical Equipment Technology Edition】Daily Question 20171220: Common Faults in Refrigeration Systems (2)
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This post was last edited by YORK Industrial Refrigeration on 2017-12-22 at 09:04. Starting from now, in order to enhance communication among users, a \"Question of the Day\" activity has been launched on the Mechanical Equipment Technology forum. We hope everyone will participate actively to progress and improve together! ! ! Rewards: 3 wealth points for active participation, 10-15 wealth points for correct answers. This question is valid for two days; no scoring will be given after that period. Leaks are an inevitable occurrence in refrigeration systems. So, what impact do leaks in the system have on the refrigeration system? There are two scenarios: First, if the leak is on the high-pressure side, the cooling efficiency will gradually decline, the temperature will not reach the set point, the suction and discharge pressures will be below normal levels, and the superheat of the exhaust gas will be too high. If the leak is in the condenser, when the pressure of the refrigerant is lower than that of water, water will enter the system; naturally, the system pressure will be very low, and these changes are easy to detect. II. The leakage occurs on the low-pressure side, and there are two scenarios: air ingress or water ingress. When the machine is running, low pressure leads to the entry of air, which results in excessive system pressure and poor cooling performance. When the machine is turned off, refrigerant leaks, and as a result, the suction and discharge pressures decrease over time; moreover, the refrigeration oil becomes contaminated, which affects the lubrication of the compressor. It’s easy to determine when water is entering the system: when the system pressure is higher than the water pressure, the suction pressure is low. If the expansion valve isn’t the problem, then it’s possible that the evaporator is leaking. Drain the oil and check whether it contains any water. psb (1).jpg (201.65 KB, Downloads: 0) Download attachment Save to album Uploaded yesterday at 10:34 =============================== High-quality promotions: Mechanical equipment——Summary of work by equipment managers for 2017 https://bbs.hcbbs.com/forum.php?mod=viewthread&tid=1881872 Mechanical equipment——Maintenance procedures for York screw compressors https://bbs.hcbbs.com/thread-1806833-1-1.html Mechanical equipment——Upgrade of York Quinton control centers https://bbs.hcbbs.com/thread-1804837-1-1.html Mechanical equipment——Major repairs of GEA Grasso screw compressors https://bbs.hcbbs.com/thread-1800467-1-1.html Mechanical equipment——Disassembly and maintenance of British HOWDEN screw compressors https://bbs.hcbbs.com/thread-1832529-1-1.html Mechanical equipment——Disassembly and maintenance of Japanese Maekawa MYCOM screw compressors https://bbs.hcbbs.com/forum.php?mod=viewthread&tid=
. Because these leaks are odorless, invisible, and difficult to detect, they result in a significant amount of refrigerant leakage without anyone realizing it. This not only results in huge waste of human and material resources, but it also leads to a shortage of refrigerant in the cooling system, thereby reducing its cooling efficiency; in severe cases, it can even cause the entire cooling system to lose its cooling function entirely. These leakages, which are imperceptible, invisible, and difficult to detect, often occur in the high-pressure areas of the refrigeration system or in areas where it comes into contact with water systems. They are extremely harmful, as they cause significant losses of refrigerant. Moreover, leaks of CFCs and HCFCs can damage the ozone layer, posing serious threats to global environmental protection. Especially those explosion points that are easy to overlook? They pose an even greater threat, not only causing huge economic losses but also readily leading to serious casualties. It deserves our utmost attention, and effective preventive measures should be taken.
1. Causes waste due to refrigerant leakage； 2. A leak in the refrigeration unit affects its cooling efficiency or even results in no cooling at all ； 3. Refrigerant leaks pollute the environment ； 4. Certain refrigerant leaks pose an explosion risk.
It causes a large leakage of refrigerant. This not only results in significant waste of human and material resources, but it also leads to a shortage of refrigerant in the cooling system, reducing its cooling efficiency; in severe cases, it can even cause the entire cooling system to lose its cooling function entirely. These leakages, which are imperceptible, invisible, and difficult to detect, often occur in the high-pressure areas of refrigeration systems or in areas in contact with water systems. They are extremely hazardous, leading to significant losses of refrigerant. Moreover, leaks of CFCs and HCFCs can damage the ozone layer, causing serious harm to global environmental protection. In particular, some explosion points that are prone to being overlooked are even more hazardous; they not only cause huge economic losses but also readily lead to serious casualties.
There will be a shortage of refrigerant, resulting in the following effects: 1. Both the suction pressure and exhaust pressure of the compressor will be lower than normal values. 2. When there is a shortage of refrigerant, the compressor operates without the rated load, resulting in the chiller running at a light load or even idling; in this case, the current is lower than the rated current. 3、Insufficient refrigerant charging can also reduce the amount of evaporation in the evaporator, which in turn leads to a decrease in cooling capacity and results in poor cooling performance of the unit, with slow temperature drops or no temperature reduction at all. 4. If it is observed that the thermal expansion valve of the chiller does not frost over or only minimally frosts over. In the case of no dew formation, very little or no condensate water, it could also be due to a insufficient amount of refrigerant. 5. If the evaporator of the chiller has little or no frost formation, or if there is no dew formation under operating conditions, with little or no condensate water, it is again due to insufficient refrigerant.
A decrease in refrigerant leads to a reduced cooling effect of the refrigerator
The main impacts of leaks on a refrigeration system are as follows: 1. Refrigerant leakage leads to a reduced cooling effect, lower system pressure, and increased energy consumption. 2. Oil leakage can cause abnormal operation of the refrigeration system and increased wear on the machinery.
Leaks often occur in the high-pressure areas of the refrigeration system or in those parts that come into contact with water systems; they are extremely harmful, causing significant loss of refrigerant. In addition, leaks of CFCs and HCFCs can damage the ozone layer, posing serious threats to global environmental protection. In particular, some explosion points that are prone to being overlooked are even more hazardous; they not only cause huge economic losses but also readily lead to serious casualties.
1. Leakage in the safety valve, resulting in refrigerant leakage； 2. Leaks in the condenser and in the screw oil cooler allow the refrigerant to mix with the cooling medium, resulting in contamination ； 3. Leaks in the brine evaporator and the cold water evaporator lead to contamination ； 4. Leakage in the piston machine’s cooling water system can cause the water accumulated there to freeze, leading to cracks. When the cooling water pressure is low, the refrigerant and refrigeration oil can flow out in large quantities along with the cooling water through the leakage points ； Conversely, when the cooling water pressure is high, it will mix into the entire refrigeration system through the leakage points, leading to poor lubrication of the components and damage to them. Both scenarios can severely impact or even disrupt the proper operation of the entire refrigeration system. 5. Moisture and heat insulation layers of refrigeration equipment can suffer from condensation, dripping water, corrosion, punctures, and leakage issues. If the design and construction quality are inadequate, or if proper daily maintenance is not carried out, severe condensation and dripping will occur after a short period of use, leading to the failure of the moisture and heat insulation layer; mold growth as well as freeze-thaw cycles can further damage this layer and cause it to peel off. The outer surfaces of the steel pipes inside also suffer from erosion by moisture, air, mold, and other factors, resulting in rapid corrosion and punctures. Since corrosion perforations occur within the moisture and heat insulation layer, they are generally difficult to detect. Over time, this leads to significant leakage of refrigerant, resulting not only in huge waste of energy as well as labor and resources, but also **shortens the service life of the pipes in refrigeration equipment, severely affecting normal production processes and even forcing a suspension of operations for repairs.