Question 442: Thermodynamics & KTG

Question

A Carnot freezer takes heat from water at 0
o
C inside it and rejects it to the room at a temperature of 27
o
C. The latent heat of ice is 336×10
3
J kg
−1
. If 5 kg of water at 0
o
C is converted into ice at 0
o
C by the freezer, then the energy consumed by the freezer is close to :

Accepted Answer

Total heat required to freeze 5 kg water,
=   5 $$ 	imes $$ 336  $$ 	imes $$ 10
3
J
=   1680  $$ 	imes $$  10
3
Joule
=   1680 kJ
For carnot cycle,
$${{{Q_2}} \over {{Q_1}}}$$ = $${{{T_2}} \over {{T_1}}}$$
$$ \Rightarrow $$   $${{{Q_2}} \over {1680}}$$ = $${{300} \over {273}}$$
$$ \Rightarrow $$   Q
2
= 1680 $$ 	imes $$  $${{300} \over {273}}$$ kJ
$$ 	herefore $$   W = Q
2
$$-$$ Q
1
=   1680$$\left( {{{300} \over {273}} - 1} ight)$$
=   1680 $$ 	imes $$ $${{27} \over {273}}$$
=   166.15 kJ
=   166.15 $$ 	imes $$ 10
3
J
=   1.66 $$ 	imes $$ 10
5
J

Answer

1.67 $$ 	imes $$ 10
5
J

Answer

1.68 $$ 	imes $$ 10
6
J

Answer

1.51 $$ 	imes $$ 10
5
J

Answer

1.71 $$ 	imes $$ 10
7
J

Thermodynamics & KTG

A Carnot freezer takes heat from water at 0 o C inside it and rejects it to the room at a temperature of 27 o C. The latent heat of ice is 336×10 3 J kg −1 . If 5 kg of water at 0 o C is converted into ice at 0 o C by the freezer, then the energy consumed by the freezer is close to :

Choose the correct answer: