1, Undercooling/undercooling degree
Supercooling refers to further cooling the refrigerant that has already condensed into a saturated liquid, so that its temperature is lower than the saturation state temperature at that pressure. This process can be seen as a further cooling step beyond the conventional condensation temperature.
The degree of supercooling is an indicator of the degree of supercooling, specifically defined as the difference between the actual temperature of the liquid after supercooling and the saturation temperature of the liquid at the same pressure. In other words, if the temperature of a liquid is lower than the temperature at which it should theoretically begin to solidify (or remain in a saturated liquid state) at the current pressure, then this additional low temperature difference is called undercooling.
Why do we need undercooling
Improving efficiency: Subcooling can significantly reduce the flash gas (i.e., some liquid evaporates into gas) generated by sudden pressure drops during refrigerant throttling processes (such as through expansion valves or capillaries). These flashing gases occupy more volume but cannot effectively contribute to the cooling capacity, thereby reducing the efficiency of the refrigeration system. Undercooling can reduce the proportion of flash gases, allowing a unit mass of refrigerant to provide more cooling capacity.
Optimizing system stability: By controlling the degree of supercooling, the operation of the refrigeration system can be stabilized, temperature fluctuations can be reduced, and overall reliability and control accuracy can be improved.
The significance of undercooling
Improve refrigeration efficiency: By reducing unnecessary phase change losses, the system can achieve the same refrigeration effect with lower energy consumption.
Extend equipment lifespan: Avoid compressor damage due to liquid impact, reduce maintenance frequency, and extend the service life of the entire system.
Enhance system responsiveness: Stable subcooling helps the system quickly respond to load changes, especially in situations where rapid cooling is required.
Energy conservation and emission reduction: Reducing energy consumption while meeting the same cooling needs, in line with modern energy conservation and environmental protection requirements.
2, Overheating/overheating degree
Overheating refers to the temperature of refrigerant vapor exceeding the temperature of saturated vapor at a certain pressure condition. At this time, the refrigerant vapor is called superheated vapor, and the phenomenon of overheating is common in the exhaust stage of the compressor in the refrigeration system.
Overheating degree is an indicator 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. That is to say, superheat is the temperature value at which the actual temperature of superheated steam is higher than its saturation temperature.
Why do we need overheating
Avoiding liquid hammer: In the refrigeration system, an appropriate amount of superheat can ensure that the steam sucked in by the compressor is dry, avoiding the entry of wet steam or liquid refrigerant into the compressor, thereby preventing liquid hammer phenomenon. Liquid hammer may cause damage to the compressor, reduce system efficiency, and even damage equipment.
Adjustment control: In refrigeration systems using expansion valves, superheat is used as an important feedback signal to adjust the opening degree of the thermal expansion valve. By controlling the degree of superheat, the flow rate of refrigerant can be more accurately adjusted, thereby controlling the cooling effect of the evaporator and maintaining the stable operation of the system.
Improving system efficiency: Appropriate overheating can help reduce the situation where refrigerant is not completely evaporated at the end of the evaporator and is sucked into the compressor, which can increase the refrigeration capacity per unit mass of refrigerant and thus improve the overall refrigeration efficiency of the system.
The significance of overheating
Ensuring compressor safety: By avoiding liquid impact and overheating, the compressor is protected from damage and the equipment life is extended.
Improving system stability: Through precise control, the degree of superheat helps maintain the stability and reliability of the system operation, ensuring the continuity and consistency of the refrigeration effect.
Optimizing energy efficiency: Reasonable control of superheat can ensure refrigeration efficiency while avoiding unnecessary energy waste and improving system energy efficiency.
Easy to diagnose and maintain: Monitoring superheat is also an important parameter for determining whether the refrigeration system is operating normally
