[Mechanical Equipment Technology Edition] Daily Question 201805026: Refrigeration Systems — Refrigeration Parameters (1)
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This post was last edited by YORK Industrial Refrigeration on 2018-5-28 09:06. This year’s 【Daily Question】 is divided into three categories: screw refrigeration compressors, refrigeration systems, and oil circuits, aiming to provide a comprehensive understanding of refrigeration technology. (If you encounter something you don’t know or can’t answer, please actively look up information; by doing so, your skills will improve!) ) All participants in the comments on this post will receive 1-3 wealth points; those who give complete answers will receive 10-15 points, with the validity period being two days. ============================== Refrigeration system — Refrigeration parameters (1): What is the suction superheat of a refrigeration unit? 1. Definition and purpose: Suction superheat is equal to the suction temperature minus the saturation temperature corresponding to the suction pressure. The presence of suction superheat ensures that no liquid refrigerant returns to the compressor, thereby preventing liquid slugging in the compressor. 2. Importance: From both theoretical and practical analyses, excessive or insufficient superheat has adverse effects. Firstly, during the initial operation of the system, high load (high evaporation temperature, which in turn represents a high load on the evaporator) causes excessive suction superheat in the compressor, which may lead to the activation of the compressor coil temperature protection switch and resulting shutdown. Secondly, insufficient suction superheat can cause the compressor to compress liquid, damaging the rotor and leading to oil loss. Or the lubricating oil is diluted by an excessive amount of liquid refrigerant, thereby affecting the lubrication of the rotor and the functioning of the bearings. 3. Regulation components: The throttling mechanism serves to control the superheat of the refrigerant at the evaporator outlet, thereby ensuring full utilization of the evaporator’s heat transfer area while preventing accidents caused by liquid in the suction gas that could damage the compressor. ============================== High-quality promotions: Mechanical equipment——Videos on the repair and adjustment of York compressors https://bbs.hcbbs.com/forum.php?mod=viewthread&tid=1806833 Mechanical equipment——Maintenance procedures for York screw compressors https://bbs.hcbbs.com/forum.php?mod=viewthread&tid=1806833 Mechanical equipment——Upgrading of York Quinton control centers https://bbs.hcbbs.com/thread-1804837-1-1.html Mechanical equipment——Major repairs of GEA Grasox 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=
Suction superheat is equal to the suction temperature minus the saturation temperature corresponding to the suction pressure; the presence of suction superheat ensures that no liquid refrigerant returns to the compressor, thereby preventing liquid slugging in the compressor.
To answer this question, one first needs to understand what the principle of cooling by freezing is The refrigerant absorbs heat as it evaporates in the evaporator; this process is accompanied by changes in temperature and pressure, meaning that different evaporation temperatures correspond to different evaporation pressures. Clarify this mindset before thinking about what superheat is. Since the compressor cannot draw in liquid, it is necessary to ensure that the refrigerant fully vaporizes in the evaporator in order to achieve this. Then it is necessary to set the superheat. It is usually 4K higher than the standard evaporation temperature, and is adjusted via an expansion valve. The corresponding condenser requires a subcooling value to ensure that the refrigerant fully condenses
The superheat of a refrigeration machine is generally divided into two types: exhaust superheat and suction superheat； The exhaust superheat is equal to the exhaust temperature minus the saturation temperature corresponding to the exhaust pressure; this superheat ensures that the compressor exhaust in the high-pressure chamber does not liquefy there, thereby preventing the refrigeration oil from being diluted ； Suction superheat is equal to the suction temperature minus the saturation temperature corresponding to the suction pressure; the presence of suction superheat ensures that no liquid refrigerant returns to the compressor, thereby preventing liquid slugging in the compressor.
The suction temperature minus the saturation temperature corresponding to the suction pressure gives the suction superheat; this superheat ensures that no liquid refrigerant returns to the compressor, thereby preventing liquid slugging in the compressor.
Suction superheat is equal to the suction temperature minus the saturation temperature corresponding to the suction pressure; the presence of suction superheat ensures that no liquid refrigerant returns to the compressor, thereby preventing liquid slugging in the compressor.
I’ll join in too; there are two refrigerators in the factory
It refers to the temperature measured at the location where a thermal bulb is placed on the intake pipe; it is the difference between the temperature at that thermal bulb and the evaporation pressure/evaporation temperature
Suction superheat is equal to the suction temperature minus the saturation temperature corresponding to the suction pressure; the presence of suction superheat ensures that no liquid refrigerant returns to the compressor, thereby preventing liquid slugging in the compressor.
The value by which the suction temperature exceeds the saturation temperature is called suction superheat, and it can prevent liquid slugging
Suction superheat: It is the difference between the superheated temperature and the saturated temperature of the refrigerant at the same evaporation pressure in a refrigeration cycle. During the initial operation of the system, high load (high evaporator water temperature, which corresponds to a high load on the evaporator) causes excessive suction superheat in the compressor, which may lead to the activation of the compressor coil temperature protection switch and subsequent shutdown. Insufficient suction superheat can cause the compressor to compress liquid, damaging the rotor and leading to oil loss. Or the lubricating oil is diluted by an excessive amount of liquid refrigerant, thereby affecting the lubrication of the rotor and the functioning of the bearings. Superheat plays a crucial role in the proper operation of an expansion valve. If the intake air has no superheat at all, it is possible for liquid to be carried back with the exhaust gas, which can even lead to wet-stroke liquid hammer and damage to the compressor. To avoid this phenomenon, a certain suction superheat is required to ensure that only dry steam enters the compressor (given the properties of the refrigerant, the presence of superheat indicates complete evaporation of the liquid refrigerant). However, too high a superheat also has its disadvantages; a high level of superheat causes the compressor’s exhaust temperature (exhaust superheat) to rise, which deteriorates the operating conditions of the compressor and reduces its lifespan. Therefore, the suction superheat should be kept within a certain range.