Abstract
A combined radiation and convection furnace has heaters radiating directly to a charge and, in addition, a fan to circulate the air inside it. The circulating air transfers by convection a part of the heat that the heaters would otherwise radiate to the charge. Although the heating rate of the charge is undoubtedly improved, the air flow is so indefinite that the calculation of the heat transfer is still not possible.
For the purpose of visualizing and measuring the air flow inside the furnace, author makes a simple model analogous to the furnace for the air flow inside it and measures the air flow inside the model by a hot-wire smoke stream method.
From the measurements, he visualizes the air flow inside the furnace and obtains the velocity distribution of the air inside it. He obtains the heat transfer coefficients between the air and each part (that is, the heaters, inner furnace-wall and charge) inside the furnace.
He ascertains a degree of accuracy of the heat transfer coefficients according to the measurements made for an experimental furnace and the calculated results of its heat transfer.
