Duct Heat Transfer (New Features - VentSim 5.0)

[Martin Griffith]

VentSim DESIGN Heat simulations now feature heat exchange between airways and ventilation ducts.

In particular mine conditions, where a temperature difference exists between the temperatures of the air inside and outside of the duct, significant heat loss can occur through the ducting material. The effect is most noticeable when a heat source is located in a blind heading ventilated by an auxiliary duct (such as in the image shown), where the temperature of the fresh air in the duct increases as the duct is heated by the surrounding airway, leading to hotter air at the duct exit. 

A setting is available to toggle the effect in Heat Settings-> Duct-Airway Heat Transfer.

Different ducting material properties (eg. duct wall thickness, thermal conductivity, additional insulation) can be added as part of the VentSim DESIGN Presets. 

In existing VentSim models with ducts, the heat exchange will not occur automatically. To enable it, the user needs to select a Duct Heat Transfer option on the Duct Construction Form when adding new ducts, or modifying existing ducts. The calculations for the heat exchange between a duct and the airway rely on the connections that VentSim establishes to simulate duct leakage. Therefore when building a duct, a leakage porosity must be selected, as well as a short enough leakage interval.