The amount of heat absorbed or lost by a substance that causes a change in the temperature of the substance is sensible heat. It is called sensible heat because it can be measured by the change in temperature it causes. For example, as heat is added to a piece of steel the temperature of that steel increases and can be measured. The general equation for calculating sensible heat is:
The specific heat of hydrocarbon vapors and liquids is given by Figures 2-13 and 2-14. It was assumed that C = 0.5 Btu/lb-0F for crude oil. It can be seen from Figure 2-13 that this is true for the range of treating temperatures and crude gravities normally encountered in oil treating.