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3 years ago

How can a heat pump warm a house by causing a refrigerant to evaporate and condense

1 answer:

4 0

The hot discharge gas from the refrigerant compressor is normally cooled and condensed at high pressure. This is then passed through an 'Expansion' valve which decreases the pressure to a low level causing expansion of the refrigerant liquid.
The liquid partially vapourises causing a 'Joule's/Thompson' refrigeration effect' which decreases temperature of the refrigerant which then passes to an evaporator coil in the air circulation system of the building. 
In the evaporator coil, the heat exchange between the cold refrigerant and the warm air of the building, vaporises and heats the refrigerant which returns to the compressor. 
The cycle is repeated until the air temperature reaches the thermostat set-point and switches off the system. 

As a Heat pump, the hot refrigerant gas is not evaporating and condensing. 
From the compressor discharge, the hot gas is by-passing the cooler/condenser unit and the expansion valve and passes directly to the 'evaporator' coils but now, as the heating medium for the air circulation system where it's cooled by the heat exchange between the hot gas and the cooler air in the building and returns to the compressor in a continuous cycle. 

A Thermostat in the system starts and stops the compressor motor according to the heat or cool temperature settings.

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Attached here is the question:

ICE Princess25 [194]

Answer:

t = 6 [s]

Explanation:

In order to solve this problem we must first use this equation of kinematics.

$v_{f}^{2}=v_{o}^{2} +2*a*x$

where:

Vf = final velocity = 0 (the car comes to rest)

Vo = initial velocity = 72 [km/h]

a = acceleration [m/s²]

x = distance = 60 [m]

First we must convert the velocity from kilometers per hour to meters per second.

$72 [\frac{km}{h}]*\frac{1000m}{1km} *\frac{1h}{3600s} =20 [m/s]$

$0=(20)^{2} -2*a*60\\400 = 120*a\\a=3.33[m/s^{2} ]$

Now using this other equation of kinematics.

$v_{f}=v_{o}-a*t$

0 = 20-3.33*t

t = 6[s]

5 0

4 years ago

Which phrase describes an irregular galaxy?

viktelen [127]

Answer:b

Explanation:

Just did the test

7 0

3 years ago

A car traveling at 40 ft/sec decelerates at a constant 5 feet per second per second. how many feet does the car travel before co

Tema [17]

This problem is solved by the equation of motion: x = x0 + v0*t + 1/2*a*t^2, Here x0 = 0, v0 = 40ft/sec and a = -5 ft/s^2, we need to solve for t: v = v0 + a*t, solve how long does it take to stop: 0 = v0 + a*t --> a*t = -v0 --> t = -v0/a -- > 40/5 = 8 seconds to stop. In this time, the car travels x = 0 + 40*8 + 0.5*-5*8^2 ft ~ 160 ft. Answer: The car travels 160 ft.

3 0

3 years ago

A roller coaster car is going over the top of a 18-mm-radius circular rise. At the top of the hill, the passengers "feel light,"

Andre45 [30]

Answer:

0.29713 m/s

Explanation:

m = Mass of person

g = Acceleration due to gravity = 9.81 m/s²

v = Velocity

r = Radius = 18 mm

By balancing the forces in the system we have

$mg-N=\dfrac{mv^2}{r}\\\Rightarrow mg-\dfrac{mg}{2}=\dfrac{mv^2}{r}\\\Rightarrow v=\sqrt{r(g-\dfrac{g}{2})}\\\Rightarrow v=\sqrt{0.018\times (9.81-\dfrac{9.81}{2})}\\\Rightarrow v=0.29713\ m/s$

The velocity of the coaster is 0.29713 m/s

7 0

3 years ago

Describe measurement in our daily life

Murljashka [212]

We’re all pretty active and do a lot

8 0

3 years ago