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WATER DEFROST

The second most popular method of thawing industrial cooling coil, by spraying water on a reel, although the method is on the second place on popularity gas defrosting. Water is sprayed over the coil and a mixture of water and melted frost collected drain pan and passed outside the refrigerated space. There are some situations where water defrost profitable, and where its use is not recommended. Spraying water on the whole hog, when the purpose is to remove water from the surface may seem ridiculous, but the real purpose for the attack frost, which is on the outer surface of the heat exchanger, and the defrost water meets that goal.

A number of advantages defrost water compared hot gas defrost: (1) inexpensive source defrost environment, (2) the short time thawing, and (3) has a cleansing effect on the whole hog. Water defrosting may be appropriate if the refrigeration system is intended only for the coil(s) in question and the source of the refrigerant vapor is limited to gas defrosting. Water defrost finds application in a variety of objects, including a large low temperature in the premises, but one of the ideal application in a spiral freezer, working in production mode. In the application should be quick defrost, to return to production quickly. In addition, during the process of defrosting and cleaning interval of temperature in the chamber, as a rule, the temperature rises above freezing, so the presence of excess water is not a problem. In a refrigerated warehouse, on the other hand, the increase in temperature in the refrigerated space should be avoided.

Some design features and precautions surrounding water defrost22:

  • rate defrost water should be in the range from 1 to 1.36 L/s / m2 coil face area (11/2 to 2 l / h per ft2).
  • water temperature is about 16C (61F) an acceptable compromise. The higher the water temperature, the faster you will defrost, but high temperature of the water also leads to excessive sweating in the area of the coil. The evaporation rate of water in the fog is controlled by the pressure of water vapour, which in turn is a function of the temperature of the water. Furthermore, the pressure of water vapor is 31/2 times higher than 30C (86F), than 10C (50F).
  • the speed of water to be discharged in that melted frost plus defrost water, so the amount that drain pan and drain lines should handle will be much larger than the coil defrosted hot gas.
  • solenoid valve control defrost water should be warm environment, so that the water will not freeze. In addition, the position of the valves, pipelines should be sloped so minor that water is stored in a line between the valve and sprayheads on the coil.
  • in pumpout stage evacuation refrigerant coil for the first of the hot-gas defrost is equally important to defrost water.
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