### STP718: Optimum Economic Thickness of Pipe Insulation Accounting for Variable Heat-Transfer Parameters

Simmons, LD

*Associate professor, Engineering, and research assistant, University of Portland, Portland, Ore.*

Beckman, JW

*Associate professor, Engineering, and research assistant, University of Portland, Portland, Ore.*

Pages: 13 Published: Jan 1980

**Abstract**

During recent years guides have been published to allow industries to choose pipe insulation that accounts optimally for rapid expected rises in fuel costs relative to insulation costs. The analysis in these guides is based on three simplifying assumptions: thermal conductivity of the insulation is assumed constant, the surface resistance is assumed constant, and thermal radiation is neglected (or included in the constant surface resistance). These assumptions can have the effect of introducing error in the insulation thickness chosen, possibly leading to choosing too little insulation.

A study was conducted to rederive the optimization equations accounting for variable heat-transfer parameters and to apply them to selected examples to determine the consequences of the simplifying assumptions. The major conclusions from the study were: 1. The errors introduced by assuming convection and radiation surface loss parameters constant are negligible. 2. The errors introduced by assuming constant insulation conductivity could be made negligible if the conductivity values were made to more closely represent correct values for the temperature range of the particular installation being analyzed.

**Keywords:**

pipe insulation, optimization, heat transfer, thermal insulation

**Paper ID:** STP29293S

**Committee/Subcommittee:** C16.97

**DOI:** 10.1520/STP29293S

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