ABSTRACT
The optimum thickness is determined by the minimum of the total variable costs. The optimum thickness of insulation to be used in a particular application can be determined by a cost calculation for a number of standard thicknesses. As one would suppose, as the thickness of the insulation is increased, the cost of heat loss decreases, but the fixed charges on the insulation increase. Despite the fact that shell-and-tube heat exchangers generally provide greater surface area for heat transfer with a more compact design, greater ease of cleaning, and less possibility of leakage, the double pipe heat exchanger still finds use in practice. The maximum heat loss from a pipe occurs when the critical radius equals the ratio of the thermal conductivity of the insulation to the surface coefficient of heat transfer. The term phase for a pure substance refers to a state of matter that is gas, liquid, or solid. Latent enthalpy effects are associated with phase changes.
