## Solution for Engineering Heat Transfer 2nd Edition Chapter 4, Problem 1

by William S. Janna
196 Solutions 12 Chapters 15998 Studied ISBN: 9780849321269 5 (1)

# Chapter 4, Problem Example 1 : FIGURE 4.3 A spherical thermocouple junction in a...

FIGURE 4.3 A spherical thermocouple junction in a fluid Stream.

A thermocouple is used to measure the temperature of a gas stream. The thermocouple junction is shown schematically in Figure 4.3. Take the junction to be spherical and to have the following properties:

K = 12BTU/(hr.ft.oR)

c =0.1 BTU/(lbm.oR)

D=0.025 IN

PS=525lbm/ft3

The initial temperature of the sphere is 65oF. The fluid temperature is 140oF, and the velocity is such that the convection coefficient is 80 BTU/(hr.ft2 oR). Determine the response time of the junction.

Solution

The thermocouple junction is a metal having a relatively high thermal conductivity and a small diameter. When the sphere is immersed in a high-velocity stream of different temperature,. heat is transferred at the upstream side at a different rate than at the downstream side.

## Step-By-Step Solution

Example 4.1

Solution

The thermocouple junction is a metal having a relatively high thermal conductivity and a small diameter. When the sphere is immersed in a high-velocity stream of different temperature,. heat is transferred at the upstream side at a different rate than at the downstream side.