EXPERIMENTS ON HEAT TRANSFER CONDUCTED IN DUNBAR LABORATORY

Conducting research in heat transfer, Mr. F. Downie-Smith is working in Dunbar Laboratory of the Engineering School with a specially constructed apparatus for determining thermal conductivity. This work is the direct result of a demand made by the oil refining industry for reliable information concerning rates of heat transfer.

In this industry there is constant need for heating and cooling oil at both high and low temperatures--up to perhaps 1200 degrees Fahrenheit and down to 90 degrees below zero. In order that apparatus may be intelligently designed to do this work it is essential that the engineer have dependable information, so that he is often forced to substitute guesses for accurate knowledge.

Fellowships Established

In an effort to supply some of this needed information the National Research Council has established several fellowships for the study of heat transfer, one of them being held by Mr. Smith. For the purpose of this study, Mr. Smith has designed and built an elaborate apparatus specially suited to the work. It is fitted with means for measuring differences with an accuracy of about one-hundredth of a degree, together with pressure manometers and orifices whereby the rate of flow of oil and water, and the corresponding pressure drops, are determined to a high degree of accuracy.

Study Influences

It is well known that the rate of heat transfer between a fluid and a metal tube through which it is flowing varies widely, depending upon the temperature of the tube, the size of the tube, the nature of the fluid, and the velocity of flow. All of those influences are to be studied in this research, and it is hoped that ultimately it will be possible to predict rates of heat transfer from values of simple properties of the fluid which can be measured with ordinary laboratory apparatus, such as density, viscosity, thermal conductivity, and the like.

The desire for correlating the experimentally determined heat transfer rates with these various properties of the fluid makes it necessary that these properties be determined for the fluids used in the test apparatus. Mr. Smith has therefore set up an apparatus originally designed by Professor Bridgman for determining thermal conductivity. An apparatus for measuring specific heats was set up last year by another graduate student. The laboratories already had apparatus for viscosity, specific gravity, and the like.