Fisicaexe - Solved Problems in Physics

Heat Transfer

A metal rod of constant cross-section and length L has its ends maintained at constant temperatures t₁ and t₂. Determine the temperature at the midpoint of the rod when heat flows through it at a steady state. The side surfaces of the bar are thermally insulated.

Solution

An aluminum rod, thermal conductivity 0,5 cal/s.cm.°C, is in contact at one end with melting ice and the other with boiling water vapor under normal pressure. Its length is 25 cm and the cross section area 5 cm². The bar being isolated laterally and given the latent heat of ice melting 80 cal/g and latent heat of water vaporization 540 cal/g, determine:
a) The mass of ice melting in half an hour;
b) The mass of vapor that condenses at the same time.

Solution

A wall consists of two overlapping sheets made of different materials. The heat transfer coefficients and the sheet thicknesses are equal to k₁, d₁ and k₂, d₂, respectively. The temperatures of the external surfaces of the walls are equal to T₁ and T₂ (T₁ > T₂) and remain constant. Determine:
a) The temperature at the interface between the two plates;
b) If the thicknesses of the two sheets are the same, what is the heat transfer coefficient of the wall.

Solution

A wall consists of alternating sheets made of thickness d of two different materials. The heat transfer coefficients of the sheets are equal to k₁ and k₂. The cross-section areas of the sheets are the same, and the number of sheets of each material is the same, the temperatures of the external surfaces of the walls are equal to T₁ and T₂ (T₁ > T₂) and remain constant. Determine the heat transfer coefficient of the wall.

Solution

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