## Sample Film Coefficient

INSTED®/Database contains ballpark values of the heat transfer (or film) coefficients for the following:

- forced convection
- free convection
- boiling water
- condensation of water vapor at one atmosphere
- Shell and Tube heat exchanger systems (over all U-values)
- Concentric Tubes heat exchanger systems (over all U-values)

For forced and free convection, knowing the heat transfer coefficient, calculate the heat transfer rate using the following formula:

*Q = hA(T _{s} - T_{f})*

Where *Q* is the heat transfer rate in Watts (W), *h* is the heat transfer coefficient in (W/m^{2}K), *A* is the surface area (m^{2}), *T _{s}* is the temperature of the surface in (K) and

*T*is the “free stream” temperature in (K).

_{f}The overall heat transfer coefficient for various duties and configurations for Shell and Tube heat exchanger systems is also available in INSTED/Database. The heat load, *Q*, is defined as:

*Q = UA**D**T*,

where *U* is the overall heat transfer coefficient, *A* is the heat transfer area, and *D**T* is the mean temperature difference (single-phase) or some suitable average value (multi-phase).

It is often desirable to obtain a quick estimate of the size of the Shell and Tube system required for a particular duty and configuration. If the value of the overall heat transfer coefficient is known, the equation given above for the heat load may be used to calculate this size.