Differences between measured pipe wall surface temperatures and internal fluid temperatures

This report sets forth a case study to clarify the accuracy of a measurement technique commonly used in industry to estimate the temperature of a flowing fluid. That technique utilizes a temperature measurement on the outside surface of the pipe in which the fluid is flowing and assumes that that value is the temperature of the fluid. The goal of the work reported here is to quantify the possible differences between the measured pipe wall temperature and the temperature of the flowing fluid. Numerical simulation was the method employed to determine this information. The end result of this work is a simple algebraic formula that enables the difference between the temperatures of the pipe fluid and at the measurement point to be evaluated. A worked-out example was included to demonstrate how the algebraic formula is to be used.