Heat Loss Through Enclosure Walls Equations and Calculations

Heat Transfer Engineering | Thermodynamics

Determine required wall thickness of an enclosure for temperature control and insulation requirements.

Known Design Data: Size (thickness) of insulated encluosure walls and inside and external surface temperatures

Find: Thickness of walls (insulation material) required to maintain heat load.

Assumptions:

• Perfectly insulated bottom
• Constant material properties
• One-dimensional conduction through 5 walls of area (A)

Note: The wall intersection or corners will cause local departures from one-dimensional conduction and a larger heat loss.

Data within boxes variables and can be modified.

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ΔT = T2 - T1

q' = k ΔT / L

L = Atotal ΔT / q = Fouriers Equation

Atotal = 2w1h + 2w2 h + 2w1w2

w1 & w2 = Wall height and width

h = depth of enclosure

Reference: Incropera Fundamentals of Heat and Mass Transfer, Frank P. Incropera and David P. DeWitt