EUROCLIMA SDF – Sectional defrosting for ZHK Nano
The energy saving solution for the plate heat exchanger in defrost operation
If the outside temperature is cold, the plate exchanger can freeze on the exhaust air side. De-icing normally takes place by opening the bypass damper, which means that heat is no longer recovered. The required supply air temperature is then only achieved with increased heating power or by reducing the supply air volume flow.
The Euroclima SDF unit (Sectonal De-Frosting) consists of 4 dampers and solves this problem. In addition, the SDF unit means that the devices have a significantly lower energy requirement that in most cases there is no need for an energy-intensive preheater coil. Depending on the outside air conditions, the necessary defrosting of the plate heat exchanger can take place in 3 phases.
Mild winter climate
The air flow from the outside air is partially guided through the modulating opening bypass damper. This leads to a higher temperature on the exhaust air side and prevents freezing. Depending on the actual temperature and humidity of the air, the opening degree of the bypass damper can vary.
Cold winter climate
Frost formation is prevented by the flow in sections of the coil via 3 sectoral dampers and the bypass damper. During the defrosting period, one damper closes depending on the outside temperature – in extreme cases, two dampers can be closed. The bypass damper is closed during this process. Since only part of the coil is deactivated, the supply air volume flow decreases in the defrosting period. This depends on the fan output due to the additional pressure loss. If defrosting in sections is not sufficient, the bypass damper is also activated.
Extremely cold winter climate
At temperatures below – 20 ° C it is not possible to guarantee continuous defrosting. Therefore, a heating coil for preheating the outside air is installed in the fresh air volume flow. This heating coil can be either an electric heating coil or a water heating coil.
Image 1: ZHK Nano with mounted SDF-element
Image 2: 4 dampers of the SDF-element