Thermal Transmittance and Thermal Resistance

Thermal transmittance U and thermal resistance R

Thermal transmittance related to thermal resistance can be expressed as

U = 1 / R                                  (1)

where

U = overall thermal transmittance (W/m2 oC)

R = overall thermal resistance (m2oC/W)

Thermal resistance can be expressed by transforming (1) to

R = 1 / U                                 (1b)

The overall thermal transmittance from a layered construction with individual thermal resistances - like a wall with insulation and outside and inside cladding - can be expressed as

U = 1 / Σ Ri                                (2)

Example - Thermal Transmittance in Heat Exchanger

The thermal transmittance in an heat exchanger can be calculated as

U = 1 / (Rair film + Rcondensate film + Rmetal wall + Rproduct film)

Related Topics

Related Documents

Tag Search

Search the Engineering ToolBox

- "the most efficient way to navigate!"

Engineering ToolBox - SketchUp Extension - Online 3D modeling!

3D Engineering ToolBox Extension to SketchUp - add parametric components to your SketchUp model

Add standard and customized parametric components - like flange beams, lumbers, piping, stairs and more - to your SketchUp model with the Engineering ToolBox - SketchUp Extension/Plugin - enabled for use with the amazing, fun and free SketchUp Make and SketchUp Pro . Add the Engineering ToolBox extension to your SketchUp from the Sketchup Extension Warehouse!

Translate the Engineering ToolBox!
About the Engineering ToolBox!

close