13/09/2025
084154 - Experimental Methods
Heat transfer - PreLab
Section 1:
Heat is transferred in nature via 3 different mechanisms:
1. Conduction: Heat transfer through a body (between different points in the
body) or between two bodies in contact.
2. Convection: Heat transfer between a body and a moving fluid which surrounds
the body.
3. Radiation: Heat transfer via electro-magnetic radiation from a body that emits
the radiation to a body that absorbs the radiation.
Section 2:
𝑄̇𝑐𝑜𝑛𝑑 = −𝑘𝐴𝑐
𝑑𝑇
𝑑𝑥
𝑤
Where 𝑄̇𝑐𝑜𝑛𝑑 [𝑤] is the heat transfer rate, 𝑘 [𝑚∙𝑘] is the thermal conductivity of the
𝑑𝑇 𝑘
material, 𝐴𝑐 [𝑚2 ] is the contact area and 𝑑𝑥 [𝑚] is the 1-dimensional temperature
gradient.
Section 3:
𝑄̇𝑐𝑜𝑛𝑣 = ℎ𝐴𝑠 (𝑇𝑠 − 𝑇∞ )
𝑤
Where 𝑄̇𝑐𝑜𝑛𝑣 [𝑤] is the heat transfer rate, ℎ [𝑚2∙𝑘 ] is the heat transfer coefficient,
𝐴𝑠 [𝑚2 ] is the body’s surface area, 𝑇𝑠 [𝑘] is the body’s surface temperature and 𝑇∞ [𝑘]
is the surroundings temperature.
Section 4:
Black body is a body that absorbs all the radiation that hits it.
Emissivity 𝜀 is a non-dimensional measure of how much radiation a body absorbs from
the total radiation that hits it. 𝜀 ∈ [0,1], 𝜀 = 1 for a black body.
084154 Heat Transfer PreLab
Assif Goren 206816225
𝑄̇𝑟𝑎𝑑 = 𝜀𝜎𝐴𝑠 (𝑇𝑠4 − 𝑇∞4 )
Where 𝑄̇𝑟𝑎𝑑 [𝑤] is the heat transfer rate, 𝜀 is the body’s surface’s emissivity, 𝐴𝑠 [𝑚2 ] is the
𝑤
body’s surface’s area, 𝜎 = 5.67 ∙ 10−8 [𝑚2 ∙𝑘4 ] is Stefan–Boltzmann constant, 𝑇𝑠4 [𝑘] is the
body’s surface’s temperature and 𝑇∞ [𝑘] is the surroundings temperature.
Section 5:
Thermal camera absorbs the infra-red radiation emitted by objects and converts it into
visible thermal image. The camara determines the object’s temperature based on the
infra-red radiation intensity and displays the temperature data as a color-coded image.
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