8–21 Heat in the amount of 100 kJ is transferred directly from a hot reservoir at 1200 K to a cold reservoir at 600 K. Calculate the entropy change of the two reservoirs and determine if the increase of entropy principle is satisfied

Respuesta :

Entropy change of hot and cold reservoir are -0.08333 kJ/k and 0.16666 kJ/k respectively.

Explanation:

Given:

Temperature at hot reservoir,[tex]T_{H}=1200 \mathrm{K}[/tex]

Temperature at cold reservoir,[tex]T_{L}=600 \mathrm{K}[/tex]

Amount oh heat transferred,[tex]Q=100 \mathrm{kJ}[/tex]

Entropy change at hot reservoir,[tex]\Delta S_{H}=\frac{Q_{H}}{T_{H}}[/tex]

[tex]\Delta S_{H}=\frac{-100}{1200}[/tex]

[tex]\Delta S_{H}=-0.083333 \frac{\mathrm{kJ}}{\mathrm{k}}[/tex]

Entropy change at cold reservoir,[tex]\Delta S_{L}=\frac{Q_{L}}{T_{L}}[/tex]

[tex]\\\Delta S_{L}=\frac{100}{600}\\[/tex]

[tex]\Delta S_{L}=0.166666 \frac{\mathrm{kJ}}{\mathrm{k}}[/tex]

Total entropy change,

[tex]\Delta S=\Delta S_{n}+\Delta S_{L}[/tex]

[tex]\Delta S=-0.083333+0.166666[/tex]

[tex]\Delta S=0.083333 \frac{\mathrm{kJ}}{\mathrm{k}}[/tex]

[tex]\Delta S[/tex] is not less than zero.Hence,it fulfills increase of entropy principle.