Measuring ventilation rate through naturally ventilated air openings by introducing heat flux

Abstract

Existing ventilation rate measuring techniques for natural ventilation do not provide an online quantification of ventilation rate through the building envelope. Therefore, a need for a practical, robust, and cheap direct measuring technique is obvious. This study investigates the possibility of using a heat source to trace ventilation rate through an air inlet/outlet. A rectangular heat source was introduced in the middle of the air inlet with a known ventilation rate, and afterwards, the 2D temperature field in the flow direction was recorded using an infrared camera. 2D temperature data obtained at different ventilation rates were used to design a sensor composed of 10 thermocouples attached to a circle or ellipse frame around a heat source. Maximum and average temperatures from these sensors were used to estimate the ventilation rate. If adequate heat was applied, it was possible to estimate the ventilation rate with 15% inaccuracy using temperature information from the arc.