Question

Imagine an ideal Carnot freezer that operates between the house at a temperature of TH = 47oC and the inside of the freezer at a temperature of TL. This refrigerator is rated to do work at 300W. If the ideal COP for the freezer is 4. (for parts a, b, c use COP as 4)

a) Calculate TL?

b) How much heat will be taken from the freezer per second?

c) How much heat will be going outside the freezer (QH) per second?

d) When the freezer is working at a non-ideal COP, it takes 5 minutes to freeze 800 g of water at 0oC. Calculate the non-ideal COP of the freezer. Heat of fusion for water 3.33x105 J/kg

Answer #1

A heat pump is used to keep a house warm at 22C.
∘C
A. How much work is required of the pump to deliver 2500 J of
heat into the house if the outdoor temperature is 0∘C . Assume a
COP of 3.0
B.How much work is required of the pump to deliver 2500 J of
heat into the house if the outdoor temperature is -15∘C ? Assume a
COP of 3.0
C. How much work is required of the...

A heat pump is used to keep a house warm at 22∘C.
How much work is required of the pump to deliver 3000 J of heat
into the house if the outdoor temperature is 0∘C. Assume a COP of
3.0
How much work is required of the pump to deliver 3000 J of heat
into the house if the outdoor temperature is -15∘C? Assume a COP of
3.0
How much work is required of the pump to deliver 3000 J...

500g of water at temperature of 15°C is placed in a
freezer. The freezer has a power rating of 100W and is 80%
efficient.
1- Calculate the energy required to convert the water
into ice at a temperature of -20°C.
2- How much energy is removed every second from the air
in the freezer?
3- How long will it take the water to reach a
temperature of -20°C?
4- Explain the process that cools the air in the
freezer.
5-...

10)When a metal bar is temporarily connected between a hot
reservoir at Th and a cold reservoir at
Tc, the energy transferred by heat from the hot
reservoir to the cold reservoir is Qh. In this
irreversible process, find expressions for the change in entropy of
the following. (Use any variable or symbol stated above as
necessary.)
(a) the hot reservoir
ΔSh =
(b) the cold reservoir
ΔSc =
(c) the Universe
ΔSU =
12)A Carnot engine operates...

2) A heat engine operates between two fixed temperature
reservoirs, TH = 127 0C, TC = 7 0C. In each cycle 5 J are extracted
from the hot reservoir and 4 J are deposited into the cold
reservoir. [ 0 0C = 273 K] (a) How much work is performed by the
engine per cycle ? (4) (b) What is the efficiency of the engine ?
(4) (c) What is the entropy change of the hot reservoir during one
cycle...

1) A nozzle is a device for increasing the velocity of a
steadily flowing stream of fluid. At the inlet to a certain nozzle
the enthalpy of the fluid is 3025 kJ/kg and the velocity is 60 m/s.
At the exit from the nozzle the enthalpy is 2790 kJ/kg. The nozzle
is horizontal and there is negligible heat loss from
it.
(i) Find the velocity at the nozzle exit.
(ii) If the inlet area is 0.1 m2 and specific volume...

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