In a refrigerator, the low temperature coil of evaporator is at -23℃ and the compressed gas in the condenser has a temperature of 77℃ . The amount of electrical energy spent in freezing 1 kg of water at 0℃ is

Question

In a refrigerator, the low temperature coil of evaporator is at -23℃ and the compressed gas in the condenser has a temperature of 77℃ . The amount of electrical energy spent in freezing 1 kg of water at 0℃ is (A) 134400 J (B) 1344 J (C) 80000 J (D) 3200 J

Tardigrade Admin · Accepted Answer

COP =(T2/T1 - T2)=(273 - 23/(273 + 77) - (273 - 23))=(250/100)=2.5 As COP =(Q2/W) ∴ 2.5=(1000 × 80 × 4.2/W) or W=(1000 × 80 × 4.2/2.5)=134400 J

Q. In a refrigerator, the low temperature coil of evaporator is at $- 23℃$ and the compressed gas in the condenser has a temperature of $77℃$ . The amount of electrical energy spent in freezing 1 kg of water at $0℃ i s$

134400 J

1344 J

80000 J

3200 J

COP $= \frac{T _{2}}{T _{1} - T _{2}} = \frac{273 - 23}{( 273 + 77 ) - ( 273 - 23 )} = \frac{250}{100} = 2.5$
As COP $= \frac{Q _{2}}{W}$
$∴ 2.5 = \frac{1000 \times 80 \times 4.2}{W}$
or $W = \frac{1000 \times 80 \times 4.2}{2.5} = 134400 J$

Q. In a refrigerator, the low temperature coil of evaporator is at −23℃ and the compressed gas in the condenser has a temperature of 77℃ . The amount of electrical energy spent in freezing 1 kg of water at 0℃is