A Brief Explanation of Ice Machines

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This post was last edited by Zero Distance Contact on 2009-12-31 11:10. I. Explanation of the chiller cooling cycle system: The process flow is cooled to -20°C on the shell side of the evaporator, with heat being transferred to the tube side. R22 at low temperature (-25°C). This evaporation process takes place at a pressure of 1 bar (low pressure); the corresponding saturation temperature is -25°C, while the discharge pressure of the compressor is 14.5 bar. The corresponding saturation temperature is 40°C. Through this process, heat is released during the transfer between R22 and the cooling water, with the fluid in the heat exchanger remaining at 32–36°C. The condensation process is accomplished by evaporating R22 to compress it back into liquid R22. The liquid R22 undergoes isenthalpic expansion through TCV, PCV, and LCV to reach a pressure of 1 bar; the feed to the water evaporation vessel (inside the tube) is a mixture of liquid and gas R22, at a temperature of -25°C. The process proceeds as follows: after K-5231 evaporates the gas from E-5236, the resulting gas is compressed into a high-temperature, high-pressure gas. After passing through the VE-5215 gas-oil separator, this gas is cooled in E-5234 to become a high-pressure, low-temperature liquid, and its temperature can be further reduced to that of a supercooled liquid using an economizer. Through LCV or PCV, the TCV is adjusted to low pressure; the ultra-cold gas-liquid mixture is evaporated in E-5236 before proceeding to K-5231 to complete the cycle. 2. Ice II. The purpose, functions, and implementation methods of mechanical system interlocks; interlocks are mandatory mechanisms designed to protect equipment and ensure personal safety, based on the principle of shutting down operations to prevent equipment damage in unstable conditions. 1) Low suction pressure shutdown: This is a prerequisite for ensuring the stability of the chiller. Insufficient suction volume can cause vibration in the compressor, leading to abnormal wear of the equipment. The causes of this can be attributed to insufficient cooling capacity (damage to the LCV, PCV, or TCV). 2). Excessively high discharge pressure is caused by excessive feed to the evaporator, improper shutdown of the exhaust valve, and the presence of non-condensable liquids in the system. 3) Low oil pressure difference, low oil level, abnormal pump function, air in the oil, and clogged filter. 4). It prevents irregular power losses of the compressor during shutdown at low cooling water temperatures and startup at high temperatures, thereby providing a condition for stable system temperatures. III. Control principle of refrigeration units: The types I have come across include LCV, PCV, and a combination of TCV. The LCV system adjusts the amount of Freon gas drawn in by increasing or decreasing the compressor load; as a result, the liquid level evaporating at point E-5236 rises or falls. By controlling this liquid level stably, it is possible to compensate for or adjust the volume, thereby controlling the temperature of the fluid being exchanged. The PCV and TCV hybrid system adjusts the pressure of the fluorine compound entering E-5236 by increasing or decreasing the amount of fluorine compound drawn in at the compressor inlet. Since PCV maintains a constant inlet flow rate, it adjusts the amount of liquid entering E-5236 through pressure control; whereas TCV functions as a fine-tuning switch to ensure stability of pressure over a certain period of time. IV. Chiller equipment: screw compressors, coolers, LCV valves or PCV valves, TCV mixers, and economizers. V. Auxiliary pipelines in ice machines and their functions 1) The principle followed by ice machines is that the pipelines in the oil are used for exhaust. 2) The pipeline for the liquid portion of Freon is used to remove oil. The presence of oil in E-5236 will damage its evaporation surface, affecting its heat exchange efficiency. In this system, the pressure in E-5236 is similar to that at the inlet of the ice maker, so the oil cannot return to the inlet pipeline on its own. Therefore, an ejector pump is used; the high-pressure gas generated by VE-5715 serves as power to draw out the oil from the system using the siphon principle, thereby preserving the cooling surface area in E-5236 and improving efficiency. 6. The load adjustment of screw compressors is achieved by changing the suction area through the slide valve at the inlet, thereby increasing or decreasing the system load; the role of the lubricating oil in the system is also extremely important. During the lubrication process, an oil film is formed between the screws, as well as between the screws and the chamber; this oil film prevents high-pressure fluorocarbon from flowing back toward the low-pressure inlet. Thus, the oil also serves a sealing function within the system. 7. There are improvements that can be made to the system. Due to unreasonable design in Shandong Binglun’s self-priming oil filling process, the system is unable to fill itself with oil during operation; I intend to improve the structure as follows. The siphon theory is applied as the guiding principle; it is designed for self-priming, with the main material being throttled at the sleeve supporting the cylinder, thereby facilitating self-priming through the formation of a siphon at the throat. Due to limited time and knowledge, the theories and improvement methods presented may be incorrect; please feel free to offer your criticism and suggestions. Wang Yong