The thermal efficiency of a power cycle operating in a reversible manner is found to be 50%. Assuming that the same 2 thermal reservoirs are now used to power a reversible refrigeration system and then a reversible heat pump, determine the Coefficient of Performance of these two systems.

Respuesta :

Answer:

Explanation:

The thermal efficiency of a Power cycle [tex]\eta = \dfrac{Q_H -Q_c}{Q_H}[/tex]

where;

[tex]\eta = 50\% = 0.5[/tex]

[tex]Q_H = Heat \ flow \ from \ higher \ temperature[/tex]

[tex]Q_c = Heat \ flow \ from \ lower \ temperature[/tex]

[tex]0.5 = \dfrac{Q_H -Q_c}{Q_H}[/tex]

[tex]0.5 Q_H = Q_H - Q_c[/tex] --- (1)

[tex]Q_c = 0.5 Q_H[/tex]         ---- (2)

The coefficient of performance is:

[tex]COP_R = \dfrac{Q_c}{Q_H -Q_c}[/tex]

let replace the value of [tex]Q_c = 0.5 Q_H[/tex]   in the above equation then;

[tex]COP_R = \dfrac{0.5Q_H}{Q_H -0.5 Q_H}[/tex]

[tex]COP_R = \dfrac{0.5Q_H}{0.5 Q_H}[/tex]

[tex]COP_R = 1[/tex]

The

On the other hand,  the heat pump

[tex]COP_{HP} = \dfrac{Q_H}{Q_H -Q_c}[/tex]

By replacing equation (1) into the above equation; we have:

[tex]COP_{HP} = \dfrac{Q_H}{0.5Q_{H}}[/tex]

[tex]COP_{HP} = \dfrac{1}{0.5}[/tex]

[tex]COP_{HP} =2[/tex]

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