If you want to know the reason for the high degree of supercooling, you should first know what is the degree of supercooling?
The liquid temperature reaches the theoretical crystallization temperature and can not be crystallized.
But must be below its temperature at a certain temperature (called the actual start crystallization temperature) before crystallization begins.
In the actual crystallization process, the actual crystallization temperature is always lower than the theoretical crystallization temperature.
This phenomenon becomes the phenomenon of supercooling, the temperature difference between the two is called the degree of supercooling.
Reasons for Excessive Subcooling Degree.
√ Because the average steam pressure on the outer surface of the cooling water pipe is lower than the average steam pressure between the pipe bundles.
So that the condensation temperature of the steam is lower than the temperature of the mixed steam flow between the tube bundles, resulting in subcooling.
√ due to the existence of steam resistance in the condenser, steam from the discharge port to the lower flow when encountering resistance.
This causes the lower steam pressure to be lower than the upper pressure and the lower condensate temperature to be lower than the upper, resulting in subcooling.
√ When steam is cooled into droplets, it flows between the condenser cooling water pipes and is cooled by the circulating water inside the pipes.
Because of the temperature of liquid droplets than the cooling water pipe wall temperature, condensate cooling is thus lower than its saturation temperature, resulting in subcooling.
√ Due to the condenser side of the accumulation of air, the average pressure of air increases, the average pressure of steam is relatively lower, steam still condenses under its own pressure.
so that the temperature of condensate is lower than the temperature of the discharge steam, resulting in subcooling.
√ Defects in the structure of the condenser, cooling water bundle arrangement is unreasonable, so that the condensate outside the cooling water pipe to form a layer of the water film.
When the water film thickens and sags into water droplets.
The temperature of the water droplets, that is, the average temperature of the inner and outer layers of the water film is lower than the saturation temperature of the outer surface of the water film, resulting in overcooling.
√ condenser leak into the air more or work abnormally, the air can not be pumped out in time, the air pressure increases, so that the subcooling degree increases.
√ Circulating water temperature is too low and the amount of circulating water is too large so that the condensate is over-cooled and the degree of subcooling increases.
√ condenser copper pipe rupture, circulating water leakage into the condensate, so that the condensate temperature decreases, the degree of subcooling increases.
Know More: What Happens to High Side Pressure & Subcooling?
The condensate subcooling degree is an important index to measure the economics of condenser operation.
A small subcooling degree means that the circulating water takes away less heat and the unit has good economics.
On the contrary, if the subcooling degree is large, the circulating water will take away more heat, and the economy of the unit will be poor.
Research shows that for every 1℃ increase in subcooling degree, the heat consumption rate of the unit will rise by 0.02%.
Read more: Define degree of superheat