PROPERTIES OF SOLIDS: Introduction
In contrast to the sections on the properties of fluids, this section deals mainly with the materials from which the heat exchangers themselves could be fabricated and only selectively with solid materials that could also be handled in heat exchangers, e.g., pebble heaters. This narrows considerably the range of materials to be treated.
For the more common materials such as metals and alloys, graphite and silicon carbide, refractories and glasses as well as organic polymers, most of the required values are tabulated in the suppliers’ catalogs and in the literature. Where such knowledge is lacking (e.g., where the tables do not cover the materials or the temperature range of interest), the problems of predicting physical properties begin.
The solid state is a state of much higher regularity than that of gases and liquids. Therefore even the prediction of simple properties such as density or thermal conductivity requires the knowledge of other properties — the availability of which is far less probable (e.g., lattice constants of the crystal) than that of the property in questions itself.
Methods of predicting physical properties on such a basis are very interesting from a scientific point of view, but they are obviously of no use for the engineer who is in the course of designing heat exchanger equipment. The objective of this section is therefore to provide general rules of material behavior rather than predicting exact values.