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Darya [45]
3 years ago
15

Refrigerant-134a enters the condenser of a residential heat pump at 800 kPA and 35oC at a rate of 0.018 kg/s and leaves at 800 k

Pa as a saturated liquid. If the compressor consumes 1.2 kW of power, determine
(a) the COP of the heat pump

(b) the rate of heat absorbtion from the outside air.
Physics
1 answer:
Assoli18 [71]3 years ago
5 0

Answer:

(A) COP = 2.64

(B) rate of heat absorption= 1.9637 kW

Explanation:

mass flow rate (m) = 0.018 kg/s

work input (Win) = 1.2kW

inlet pressure (P1) = 800kPa

inlet temperature (T1) = 35 degree Celsius

h1 = 271.24 KJ/Kg

outlet pressure (P2) = 800 kPa

outlet temperature (T2) = ?

entalphy (h2) = 95.48 KJ/Kg

The entalphies are gotten from tables for refrigerant 134a at the temperatures and pressures above

(A) COP = Qh ÷ Win

     where Qh  = m(h1 -h2) from the energy balance equation

     Qh = 0.018 ( 271.24 - 95.48 ) = 3.1637 kW

     COP = 3.1637 ÷ 1.2 = 2.64

(B) rate of heat absorption = Qh - Win

    = 3.1637 - 1.2 = 1.9637 kW

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A 2137 kg car moving east at 12.91 m/s collides with a 3264 kg car moving north. The cars stick together and move as a unit afte
IRINA_888 [86]

Answer:

The speed of the 3264 kg car before collision is 6.32 m/s

Explanation:

Let first car, mass m₁, moving east be moving with velocity, v₁ and second car, mass m₂, moving north be moving with velocity, v₂. Let the velocity of the two cars after collision be v₃

In a Collison (whether elastic or inelastic), momentum is always conserved.

Momentum before collision = momentum after collision.

Momentum before collision = m₁v₁ + m₂v₂

v₁ = (12.91î) m/s in vector form, m₁ = 2137 kg

v₂ = ?, v₂ = (v₂j) m/s in vector form, m₂ = 3264 kg

Momentum before collision = (2137)(12.91î) + (3264)(v₂j) = (27590î + 3264v₂j) kgm/s

Momentum after collision = (total mass of the cars after collision) × (velocity of the stuck-together cars after collision)

Total mass of the cars after collision = m₁ + m₂ = 2137 + 3264 = 5401 kg

Velocity after collision, v₃ = 6.38 m/s In the N36.8°E direction, put in vector form,

v₃ = (6.38 cos 36.8°î + 6.38 sin 36.8°j)

v₃ = (5.11î + 3.82j) m/s

Momentum after collision = 5401 (5.11î + 3.82j) = (27590î + 20641.4j) kgm/s

Momentum before collision = momentum after collision.

(27590î + 3264v₂j) = (27590î + 20641.4j)

Comparing components

3264v₂ = 20641.4j

v₂ = 6.32 m/s

Hope this Helps!!!

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3 years ago
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Answer:

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When a liquid is cooled, the kinetic energy of the particles . The force of attraction between the particles , the space between
anzhelika [568]

Answer:

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Explanation:

For the first blank, the answer is decreases. For the second blank, the answer is increases. And finally for the third blank, the answer is decreases.

When a liquid is cooled, the kinetic energy of the particles decreases. The force of attraction between the particles increases, the space between the particles decreases, and the matter changes its state to solid.

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First runner:  KE = (1/2) (45kg) (49 m/s)  =  1,102.5 Joules  

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