Getting Started
The first class meeting includes discussion of a few problems in heat transfer, selected from the following.
- Suppose that a wall has a thickness L, a conductivity k, and an area A, with one side at T1 and the other side at T2. What is the heat flux through the wall?
- What is the difference between conduction and convection? Can you have conduction in a fluid?
- What is the purpose of cooling fins? Specifically, why bother to add fins?
- Do small diameter thermocouples have the same response time to sudden temperature changes in air flows as large diameter ones? Why?
- Does someone sitting close to the windows in the old MIT buildings feel as comfortable in winter as someone sitting far from the windows? What heat transfer mechanisms play at part in this?
- Why is the liquid fuel tank of the space shuttle insulated? How would you estimate the rate of frost formation on an uninsulated tank?
Data Useful in Heat and Mass Transfer
Whenever assigning property data in a heat transfer problem, bear in mind that many properties (especially liquid viscosity) are very sensitive to temperature changes. Pressure variations often have less impact on transport properties, although they can significantly alter thermodynamic properties such as the density of gases and liquid boiling points. Pressure is often important in phase change processes.
The thermal conductivity of solids can vary significantly with: alloying processing, density or compaction, and water content. For example, the conductivity of pure iron is 80W/m-K, of 1.0% carbon steel is 43 W/m-K, and of 304 stainless steel is 14 W/m-K, each at 293 K.
Study Materials is divided into a few sections:
- References for Physical Properties of Matter (see below)
- Selected Physical Constants (PDF)
- Selected Conversion Factors (PDF)
Some Sources for Physical Properties of Matter
Compilations of property data are published by many scientific and commercial organizations, including the International Union of Pure and Applied Chemistry (IUPAC), the American Society for Metals (ASM), the National Institute of Standards (NIST), and the International Association for the Properties of Water and Steam (IAPWS).
Purdue University Thermophysical Properties Research Center. Thermophysical Properties of Matter. New York, NY: IFI/Plenum, 1970-1979. ISBN: 9780306670206. Fourteen volumes.
Reid, R. C. The Properties of Gases and Liquids. 4th ed. New York, NY: McGraw-Hill, 1987. ISBN: 9780070517998.
Vargaftik, N. B. Handbook of Physical Properties of Liquids and Gases: Pure Substances and Mixtures. 3rd ed. Chem/Mats-Sci/E, 1996. ISBN: 9780891163565.
Bellows, James C., John S. Gallagher, Allan H. Harvey, and William T. Parry. ASME Steam Tables for Industrial Use. New York, NY: ASME Press, 2000. ISBN: 9780791801543.
Ho, C. Y. Thermal Conductivity of the Elements: A Comprehensive Review. Washington, DC: Published by the American Chemical Society and the American Institute of Physics for the National Bureau of Standards, 1974. ISBN: 9780883182161.
Poling, B. E., et al. The Properties of Gases and Liquids. 5th ed. New York, NY: McGraw-Hill, 2000. ISBN: 9780070116825.