A home air conditioner operating on a reversible Carnot cyck the inside, absolute temperature T2, and the outside, absolute ture T1 > T2, consumes P joules/sec from the power lines when continuously.

Elements Of Electromagnetics
7th Edition
ISBN:9780190698614
Author:Sadiku, Matthew N. O.
Publisher:Sadiku, Matthew N. O.
ChapterMA: Math Assessment
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An air conditioner is a device used to cool the inside of a home. It is, in
essence, a refrigerator in which mechanical work is done and heat removed
from the (cooler) inside and rejected to the (warmer) outside.
A home air conditioner operating on a reversible Carnot cycle between
the inside, absolute temperature T2, and the outside, absolute tempera-
ture T1 > T2, consumes P joules/sec from the power lines when operating
continuously.
(a) In one second, the air conditioner absorbs Q2 joules from the house
and rejects Q1 joules outdoors. Develop a formula for the efficiency ratio
Q2/P in terms of T1 and T2.
(b) Heat leakage into the house follows Newton's law Q = A(T, – T2).
Develop a formula for T, in terms of T1, P, and A for continuous operation
of the air conditioner under constant outside temperature T and uniform
(in space) inside temperature T2.
(c) The air conditioner is controlled by the usual on-off thermostat
and it is observed that when the thermostat set at 20°C and an outside
temperature at 30°, it operates 30% of the time. Find the higtest outside
temperature,
absolute zero).
in °C, for which it can maintain 20°C inside (use -273°C for
(d) In the winter, the cycle is reversed and the device becomes a heat
pump which absorbs heat from outside and rejects heat into the house.
Find the lowest outside temperature in °C for which it can maintain 20°C
inside.
Transcribed Image Text:An air conditioner is a device used to cool the inside of a home. It is, in essence, a refrigerator in which mechanical work is done and heat removed from the (cooler) inside and rejected to the (warmer) outside. A home air conditioner operating on a reversible Carnot cycle between the inside, absolute temperature T2, and the outside, absolute tempera- ture T1 > T2, consumes P joules/sec from the power lines when operating continuously. (a) In one second, the air conditioner absorbs Q2 joules from the house and rejects Q1 joules outdoors. Develop a formula for the efficiency ratio Q2/P in terms of T1 and T2. (b) Heat leakage into the house follows Newton's law Q = A(T, – T2). Develop a formula for T, in terms of T1, P, and A for continuous operation of the air conditioner under constant outside temperature T and uniform (in space) inside temperature T2. (c) The air conditioner is controlled by the usual on-off thermostat and it is observed that when the thermostat set at 20°C and an outside temperature at 30°, it operates 30% of the time. Find the higtest outside temperature, absolute zero). in °C, for which it can maintain 20°C inside (use -273°C for (d) In the winter, the cycle is reversed and the device becomes a heat pump which absorbs heat from outside and rejects heat into the house. Find the lowest outside temperature in °C for which it can maintain 20°C inside.
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