Railways Technical Ability Automobile Engineering Question Bank Automobile Engineering

  • question_answer Upto the critical radius of insulation:

    A) Added insulation increases heat loss.

    B) Added insulation decreases heat loss.

    C) Convection heat loss is less than conduction heat loss.

    D) Heat flux decreases.

    Correct Answer: C

    Solution :

    \[Q=\frac{2\pi L({{t}_{1}}-{{t}_{0}})}{\left[ \frac{In\,\left( \frac{{{r}_{2}}}{{{r}_{1}}} \right)}{k}+\frac{1}{{{h}_{0}}{{r}_{2}}} \right]}\] Conductive thermal resistance increases with increasing \[{{r}_{2}}\] and convective thermal resistance decreases with increasing\[{{r}_{2}}\]. \[Thus\,\,{{Q}_{convective}}<{{Q}_{conductive}}\]


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