CONDUCTIVITY

1. Impairment of heat flow caused by the imperfect contact between two materials at an interface. 2. Quantitatively, the temperature difference across the interface divided by the heat flux through it.

1. To heat to a high temperature without fusing, as to heat unformed ceramic materials in a kiln, or to heat ores, precipitates, concentrates, or residues so that hydrates, carbonates, or other compounds are decomposed and the volatile material is expelled. 2. To heat under oxidizing conditions.

All warm bodies emit light (electromagnetic radiation, mostly infrared). When this radiation is absorbed or emitted by a body, heat is transferred and termed 'heat transfer by radiation'. Such heat transfer requires a line of sight (view factor) and is proportional to the fourth power of the absolute temperature difference between bodies and the emissivity of the bodies.

In heat exchange calculations, a pseudo average temperature difference between the warmer and colder fluids at inlet and outlet conditions.

The proposition that the rate of heat loss from a body by free convection is proportional to the fivefourths power of the difference between the temperature of the body and that of its surroundings.

A material of low thermal conductivity used to reduce heat loss.

For a fluid confined in a vessel, the rate of flow of heat out of the fluid, per unit area of vessel wall divided by the difference between the temperature in the interior of the fluid and the temperature at the surface of the wall. Also known as convection coefficient.

Heat will flow only from material at higher temperature to material at lower temperature.

A calorimeter in which the heat to be measured is absorbed by water flowing through a tube at a constant rate, and the quantity of heat is determined by the rate of flow and the temperature difference between water at ends of the tube.

The amount of heat which passes through a unit area of a medium or system in a unit time when the temperature difference between the boundaries of the system is 1 degree.