Example 8.2-1. Effect of Pressure on Thermal Conductivity

By: Hoalong Lee and Hoason Lee

Estimate the thermal conductivity (k) of ethane at 153 F and 191.9 atm from the atmospheric value ko=.0159 Btu/hr/ft/F at the given temperature.

> restart;

Enter the given data

> T:=153*F; P:=191.9*atm; ko:=.0159*Btu/hr/ft/F;

[Maple Math]

[Maple Math]

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Use the table of critical temperatures and pressures to find ethane's Tc and Pc so that reduced temperatures and pressures can be calculated.

For ethane Tc=305.3 K, Pc=48.08 atm

> Tc:=549.54*R; Pc:=48.08*atm;

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[Maple Math]

Convert all temperatures and pressures to Kelvin and Atmospheres, respectively

> T:=T*R/F+459.67*R;

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> R:=K/1.8; Tc; T;

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Calculate reduced temperature and pressure

> Tr:=T/Tc; Pr:=P/Pc;

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Look at the chart below to find the k# using Tr and Pr.

For Tr=1.11, Pr=3.99, the chart value of k# is approximately 4.7

k#=k/ko

> knum:=4.7;

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Solve for k

> k:=knum*ko;

[Maple Math]