FROST PROTECTION / TARGETED ICING
Unwanted freezing of air humidity at the exhaust heat exchanger is prevented by means of a frost protection bypass . Targeted icing with an automated de-icing process can result in significantly better utilization of the energy contained in the exhaust air.
IMPORTANCE OF FOST PROTECTION
Konvekta high performance heat exchangers allow for very high transfer rates with very low approach temperatures. This means that when the outside air temperature is, for example, 5°F, the water/glycol mixture is cooled to about 8.6°F. When such a cold water/glycol mixture enters the exhaust air heat exchanger, the exhaust air cools to about 12.2°F. This causes moisture contained in the exhaust air to condense in the heat exchanger. Without intervention, this leads to ice formation on the fins and to reduced air permeability of the heat exchanger, and possibly, even to failure of the ventilation system.
DEW POINT CONTROL
To prevent this, when the return fluid is very cold, the bypass is opened to increase the water/glycol temperature to about 28.4°F. To be able to recover as much energy as possible, the bypass is opened by means of the dew point control, only when needed and only as far as needed, to heat the water/glycol to 28.4°F.
TARGETED ICING
With dew point control and the bypass circuit, the heat exchangers are protected against icing. At the same time, heat recovery is deliberately reduced to below its potential. To recover heat in this situation, Konvekta has developed the unique application of targeted icing with periodic defrosting. Here, the heat exchangers are operated below the dew point and the onset of icing is monitored by the Konvekta Controller. When icing occurs, the Konvekta Controller starts an automated de-icing process. This ensures maximum energy recovery even in icing conditions.
The advantage of targeted icing is the significantly greater utilization of the energy contained in the exhaust air at low outside temperatures.
