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Question

Difficulty: MediumHeat Transfer: Conduction

An engineer is designing a solid metal support bracket to connect a high-temperature engine block to a heat-sensitive electronic sensor. The primary goal is to minimize the rate of heat transfer through conduction from the engine block to the sensor. Which design modification will best achieve this goal?

  1. Increasing the length of the metal bracket between the engine and the sensorAnswer
  2. B
    Increasing the cross-sectional thickness of the metal bracket
  3. C
    Allowing heated engine fluids to circulate directly around the sensor housing
  4. D
    Selecting a metal for the bracket that contracts instead of expands when heated

Answer

Increasing the length of the metal bracket between the engine and the sensor
Increasing the length of the material increases the physical distance over which the temperature drops. Because the rate of heat conduction is inversely proportional to the length of the conductive path, a longer bracket slows down the direct transfer of thermal energy to the sensor.

Step-by-Step Solution

1
Identify the mode of heat transfer being targeted in the scenario.
The scenario requires minimizing heat transfer via conduction through a solid metal bracket.
Different modes of heat transfer (conduction, convection, radiation) require different physical mitigation strategies.
2
Analyze the physical factors that affect the rate of thermal conduction.
The rate of conduction depends on the material's thermal conductivity, its cross-sectional area, and its length (distance).
Fourier's law of heat conduction dictates these physical relationships.
3
Evaluate how dimensional changes impact the conduction rate.
Increasing length decreases the rate of conduction, whereas increasing cross-sectional area increases the rate of conduction.
A greater length reduces the temperature gradient across the material, slowing the transfer of thermal energy.

Key Concept

Factors Affecting Thermal Conduction
Estimated Time:1m 0s
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Topics

Heat Transfer: Conduction

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