Javier Ojeda, P.Eng MBA PMP CEM REP CRE

ABSTRACT
A common situation on industrial refrigeration is the formation of frost on the evaporators. This is, generally, an inevitable phenomenon that has his explanation: When the evaporator’s coil temperature drops below the dew point temperature, dew will begin to collect on the evaporator’s cool surface. If the temperature of the evaporator coil continues to drop below the freezing point of water, the moisture on the evaporator’s coil will begin to freeze into a thin layer of ice. This… Show more

ABSTRACT
A common situation on industrial refrigeration is the formation of frost on the evaporators. This is, generally, an inevitable phenomenon that has his explanation: When the evaporator’s coil temperature drops below the dew point temperature, dew will begin to collect on the evaporator’s cool surface. If the temperature of the evaporator coil continues to drop below the freezing point of water, the moisture on the evaporator’s coil will begin to freeze into a thin layer of ice. This is the frost. On industries like food processing and food conservation, when it’s common to use freezing tunnels and freezing rooms with temperatures below -4 ˚F, no matter how efficient could be our evaporator, the formation of frost is inevitable. That’s why the evaporator has systems to melt the frost. There are 2 very common systems for defrost: the use of hot gas from the refrigeration circuit, and the use of an electrical resistance. Both of them are valid, and has his advantages and disadvantages, and we can find both of them in a single facility. The problem is that in some cases, the defrost process is too frequent, adding unnecessary thermal load to the system. Researchers like Cole, Hoffenbecker, and Fricke in various research works, have demonstrated that there are conditions that can be achieved to reduce the amount of energy used for defrost, related particularly to the time and the thickness of the frost layer. The idea in this presentation is to show in an easy way with the help of an example, the calculations of the thermal loads and the amount of energy and money that can be saved, if those conditions are met and controlled by automatic systems so the attendants can make estimations on retrofits projects or new installations on industrial refrigeration systems, show them to their clients or organizations as an interesting Energy Saving Opportunity, and have a better understand of the process of defrost and how the systems that control it work Show less