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A certain brand of freezer is advertised to use 880 kW*h of energy per year.
A) Assuming the freezer operates for 6 hours each day, how much power does it require while operating? P= ?
B) If the freezer keeps its interior at a temperature of -6.0?C in a 20.0 ?C room, what is its theoretical maximum performance coefficient? K= ?
C) What is the theoretical maximum amount of ice this freezer could make in an hour, starting with water at 20.0 ?C?

Sagot :

A certain brand of freezer is advertised to use 880 kW*h of energy per year, thus values are:

(A) P = 401.82 W

(B) K = 10.26

(C) m = 35.52 kg

What is maximum performance coefficient?

Both a thermal Carnot efficiency and a Carnot coefficient of performance exist. The temperatures of the system's hot and cold reservoirs affect its maximum coefficient of performance.

(A)

Use the relation between power and energy to calculate the require power to operate engine.

The required power for the freezer to operate is:

P = E/t

E = Energy and t = time

The freezer operates for 6 h each day, and then in 1 year, the freezer operates for a time period is:

t = (365 days) × (6 h /1 day)

or, t = 2190 h

Thus, P = E/t

or, P = (880 Kw.h/ 1 year) × (10³ W / 1 KW) × (1 year/2190 h)

or, P = 401.82 W

Therefore, the required power is: 401.82 W

(B)

The theoretical maximum performance co-efficient is:

K = T(C) / [T(H) - T(C)]

or, K = (-6°C +273)/[(20°C + 273) - (-6°C +273)]

or, K = 267 K / 293 K - 267 K

or, K = 10.26

Therefore, the theoretical maximum performance co-efficient is: 0.26

(C)

The heat needed to make 1 kg ice is:

Q = m×[c(water)]×ΔT +mL

Here, specific heat of water [c(water)], heat of fusion of water L.

Q = m×[c(water)]×ΔT +mL

or, Q = (1 kg) × (4190 J/kg.K) × (293K - 273K) +  (1 kg) × (334 × 10³ J/Kg)

or, Q = 417800 J

The heat of removal is,

Q(removal) = WK

or, Q(removal) = PtK

or, Q(removal) = (401.82 W) × (3600 sec) × (10.26)

or, Q(removal) = 14841623.52 K

Mass of the ice is,

m = Q(H) /Q

or, m = 14841623.52 Ws / 417800 J

or, m = 35.52 kg

Therefore, the mass of the ice is: 35.52 kg

To know more about energy per year refer to:

https://brainly.com/question/27438014

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