Degree of undercooling/undercooling

Supercooling refers to the further cooling of the refrigerant that has been condensed into a saturated liquid, so that its temperature is lower than the temperature of the saturated state at that pressure. This process can be seen as a further cooling step beyond the conventional condensing temperature.

The degree of supercooling is an index to measure the degree of supercooling, which is specifically defined as the difference between the actual temperature of the liquid after supercooling and the saturation temperature of the liquid under the same pressure. In other words, if a liquid is cooler than the temperature at which it should theoretically start solidifying (or remain a saturated liquid) at its current pressure, then this additional low temperature difference is the degree of supercooling.

Why the need for supercooling

Increased efficiency: Supercooling can significantly reduce the amount of flash gas (that is, partial liquid evaporation into gas) generated by a sudden drop in pressure during a throttling process, such as through an expansion valve or capillary. These flash gases occupy more volume, but do not contribute effectively to the cooling capacity, thus reducing the efficiency of the refrigeration system. Supercooling can reduce the proportion of flash gas, so that the unit mass of refrigerant to provide more cooling capacity.

Optimize system stability: By controlling the supercooling degree, the operation of the refrigeration system can be stabilized, the temperature fluctuations can be reduced, and the overall reliability and control accuracy can be improved.

The significance of the degree of supercooling

Improved cooling efficiency: By reducing unnecessary phase change losses, the system can achieve the same cooling effect with lower energy consumption.

Prolong equipment life: Avoid compressor damage due to liquid strike, reduce maintenance frequency, extend the service life of the entire system.

Increased system responsiveness: Stable undercooling helps the system respond quickly to load changes, especially where rapid cooling is required.

Energy saving and emission reduction: reduce energy consumption while meeting the same refrigeration needs, in line with the requirements of modern energy saving and environmental protection.

2. Overheat/overheat

Overheating means that under a certain pressure condition, the temperature of the refrigerant steam exceeds the temperature of the saturated steam under the pressure. At this time, the refrigerant steam is called superheated steam, and the overheating phenomenon is common in the exhaust stage of the compressor in the refrigeration system.

Superheat is a measure of the degree of overheating, specifically defined as the difference between the temperature of superheated steam and the temperature of saturated steam at the same pressure. In other words, the superheat is the temperature of the superheated steam above its saturation temperature.

Why do you need superheat

Avoid liquid shock: In the refrigeration system, the right amount of superheat can ensure that the steam inhaled by the compressor is dry, avoid wet steam or liquid refrigerant into the compressor, thereby preventing liquid shock phenomenon. Hydraulic strikes may damage the compressor, reduce system efficiency, and even damage the device.

Regulating control: In refrigeration systems that use expansion valves, superheat is used as an important feedback signal to regulate the opening of the thermal expansion valve. By controlling the superheat, the flow of refrigerant can be adjusted more accurately, and then the cooling effect of the evaporator can be controlled, and the stable operation of the system can be maintained.

Improve the efficiency of the system: The appropriate superheat helps to reduce the refrigerant at the end of the evaporator is not completely evaporated and is inhaled by the compressor, which can improve the cooling capacity of the refrigerant per unit mass, thereby improving the overall refrigeration efficiency of the system.

The meaning of superheat

Ensure compressor safety: By avoiding liquid shock, the superheat protects the compressor from damage and extends the life of the equipment.

Improve system stability: Through precise control, the superheat helps maintain the stability and reliability of the system operation, ensuring the continuity and consistency of the cooling effect.

Optimize energy efficiency: Reasonable control of superheat can ensure the cooling effect, avoid unnecessary energy waste, and improve the system energy efficiency ratio.

Easy to diagnose and maintain: The monitoring of superheat is also an important parameter to determine whether the refrigeration system is operating normally, and the abnormal superheat may be an indication of system failure, which helps to find problems and maintain them in time.

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