notes/uni/mmme/2047_thermodynamics_and_fluid_dynamics/heat_transfer.md

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Akbar Rahman \today MMME2047 // Heat Transfer
heat_transfer
d3ba66c2-e486-464a-a4df-f23f2155ee6d
./lecture_slides/6ConvHeatTransfer-without-written-comments.pptx
./lecture_notes/ConvectHeatTrans2022-2023.pdf
./exercise_sheets/ExamplesConvectionHeatTransfer.pdf

Convection

  • conduction and radiation heat transfer can be estimated by calculations and properties
  • convection is dependent on fluid properties, flow type, and flow characteristics

The rate of convective heat transfer, \dot Q, is given by

\begin{equation} \dot Q = hA(T_f-T_w) \label{eqn:convectionheattransfer} \end{equation}

where T_w is the wall temperature, T_f is the fluid temperature, A is the area of heat flow, and h is the heat transfer coefficient.

Thermal Resistance

Equation \ref{eqn:convectionheattransfer} can also be expressed in terms of thermal resistance, R_\text{thermal}:

\dot Q = \frac{T_f-T_w}{\sum R_\text{thermal}}

where R_\text{thermal} = \frac{1}{hA}.

In a way this analogous to Ohm's law, specifically with resistors in series (I = \frac{\Deta V}{\sum R_\text{electrical}}).