Name: heat transfer calculations with conduction, convection
Uploaded: 2023-09-18T17:11:17.000Z
Duration: 1 min 20 s
Channel: JoVE

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NC K-12 Science Standard Course of Study

9-12

Physical Science

Energy

PS.PSc.7.1

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Conduction, Convection and Radiation: Problem Solving

A 13 cm thick wall with a 100 m2 area and 1.5 W/mK thermal conductivity separates a room from the outer atmosphere, which is at 3 degrees Celsius.
The outside surface of the wall is at 10 degrees Celsius, and its emissivity is 0.8. If the convective heat transfer coefficient is 15 W/m2K , find the total heat loss rate to the surrounding. Also, calculate the temperature of the inner surface of the wall.
Here, all three mechanisms of heat transfer are involved. Heat is transferred from the inner to the outer surface of the wall through conduction, while heat loss to the surroundings occurs due to convection and radiation.
The rate of heat loss through convection depends on the temperature gradient, surface area, and heat transfer coefficient.
So, total heat loss to the surrounding due to convection and radiation can be calculated as 13.27 x 103 W.
Employing the conservation of energy and substituting the terms in the heat equation, the temperature of the inner surface of the wall can be calculated.

conduction, convection and radiation: problem solving

There are three methods by which heat transfer can take place: conduction, convection, and radiation. Each method has unique and interesting characteristics, but all three have two things in common: they transfer heat solely because of a temperature difference; and the greater the temperature difference, the faster the heat transfer.
In order to solve a problem related to heat transfer, first of all, the situation needs to be examined to determine the type of heat transfer involved. This could be conduction, convection, radiation, or all three of them. The second step is to identify and write down the unknown quantities in the problem. A list can be prepared of what is given or what can be inferred from the problem as stated, i.e., the known quantities, followed by solving the appropriate equation for the quantity to be determined.
For heat transfer through conduction, the following equation should be used.
<img alt="Heat conduction formula, P=kA(Th-Tc)/d, equation; thermal energy transfer concept." src="/files/ftp_upload/14166/14166_Equation_1.svg" style="text-align: center; height: 46px;" data-altupdatedat="1761830439000" data-alt="Equation1">
For convection, the rate of heat loss depends on the temperature gradient, surface area, and heat transfer coefficient.
<img alt="Convection heat transfer formula, P_convection=hAΔT, illustrating thermal dynamics concepts." src="/files/ftp_upload/14166/14166_Equation_2.svg" style="text-align: center; height: 18px;" data-altupdatedat="1761830439000" data-alt="Equation2">
The following equation gives the net heat transfer rate for radiation.
<img alt="Radiative heat transfer equation: P_radiation = σAe(T₂⁴-T₁⁴), formula for thermal energy analysis." src="/files/ftp_upload/14166/14166_Equation_3.svg" style="text-align: center; height: 25px;" data-altupdatedat="1761830439000" data-alt="Equation3">
Substituting the known quantities along with their units into the appropriate equation and solving it numerically gives the correct solution.

There are three methods by which heat transfer can take place: conduction, convection, and radiation. Each method has unique and interesting ...

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Temperature and Heat

KEY TERMS AND CONCEPTS

heat transfer calculations with conduction, convection

Heat transfer calculations with conduction and convection use the temperature difference to find the rate of heat flow. Radiation can also be part of the process. The main idea is that heat moves only because one area is hotter than another, and a larger temperature difference leads to faster transfer.

To solve a heat transfer problem, first identify the type of transfer involved. It may be conduction, convection, radiation, or a combination of all three. Next, write down the unknown quantities and sort the given information from the problem statement.

After the known values are listed, choose the correct equation for the type of heat transfer. Use the conduction equation for heat flow through materials. For convection, the rate of heat loss depends on the temperature gradient, the surface area, and the heat transfer coefficient. For radiation, use the equation for net heat transfer rate.

Finally, substitute the known quantities and their units into the selected equation. Solve the equation numerically to find the answer. This method helps students work through heat transfer problems in a clear, step-by-step way.

Heat Transfer Calculations with Conduction, Convection

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Heat transfer calculations with conduction and convection use the temperature difference to find the rate of heat flow. Radiation can also be part of the process. The main idea is that heat moves only because one area is hotter than another, and a larger temperature difference leads to faster transfer. To solve a heat transfer problem, first identify the type of transfer involved. It may be conduction, convection, radiation, or a combination of all three. Next, write down the unknown...

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key terms and concepts

Learn how to solve heat transfer problems by identifying conduction, convection, or radiation, choosing the right equation, and calculating the unknowns.

Heat Transfer Calculations with Conduction, Convection | JoVE K12

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PS.PSc.7.3

Power

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PS.PSc.7.4

Analyze energy transfers and transformations within a mechanical system.

Heat Transfer Calculations with Conduction, Convection

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