Measurements of heat transfer coefficients within convection ovens Original Research Article

Measurements of apparent heat transfer coefficients within a typical domestic fan oven and a commercial batch oven were performed using four different methods: back-calculation from transient temperature data; using heat flux sensors; from the mass-loss rate; a psychrometric method. The majority of the measured data ranged between 15 and 40 W m−2 K−1, and were approximately twice as high as predicted by a Nusselt number correlation for laminar flow over flat-plates, which was partially attributable to radiation. Of all the methods, the heat flux sensor was the simplest to use and was the only method which revealed the time-variation in the heat transfer coefficient. However, although it was the least practical to implement, the mass-loss-rate method incorporated the effect of evaporation, and since the data measured by this method were more reliable than the data from the psychrometric method, they would be most useful for modelling cooking processes.