Answer:
Yes
Explanation:
Yes it is true that COP of heat pump always greater than 1.But the COP of refrigeration can be greater or less than 1.
We know that
COP of heat pump= 1 + COP of refrigeration
It is clear that COP can not be negative .So from the above expression we can say that COP of heat pump is always greater than one.
Answer:
Amount of air left in the cylinder=m
=0.357 Kg
The amount of heat transfer=Q=0
Explanation:
Given
Initial pressure=P1=300 KPa
Initial volume=V1=0.2
Initial temperature=T
=20 C
Final Volume=
=0.1
Using gas equation
m1==(300*0.2)/(.287*293)
m1=0.714 Kg
Similarly
m2=(P2*V2)/R*T2
m2=(300*0.1)/(0.287*293)
m2=0.357 Kg
Now calculate mass of air left,where me is the mass of air left.
me=m2-m1
me=0.715-0.357
mass of air left=me=0.357 Kg
To find heat transfer we need to apply energy balance equation.
Where me=m1-m2
And as the temperature remains constant,hence the enthalpy also remains constant.
h1=h2=he=h
Q=(me-(m1-m2))*h
me=m1-me
Thus heat transfer=Q=0
Answer:
ΔQ = 1.06 KJ
Explanation:
The amount of heat transfer between the piston-cylinder system and the surrounding can easily be found by using the First Law of Thermodynamics. The first law of thermodynamics can be written as follows:
ΔQ = ΔU + W
ΔQ = mΔu + PΔV
where,
ΔQ = Heat transfer between system and surrounding = ?
Δu = specific change in internal energy of the system = - 175 KJ/kg
m = mass of air = 20 g = 0.02 kg
P = Constant Pressure = 101.3 KPa
ΔV = Change in Volume = 0.05 m³ - 0.005 m³ = 0.045 m³
Therefore,
ΔQ = (0.02 kg)(-175 KJ/kg) + (101.3 KPa)(0.045 m³)
ΔQ = -3.5 KJ + 4.56 KJ
<u>ΔQ = 1.06 KJ</u>
Answer:
option C
option A
Explanation:
Enthalpy gained by air= 1023-290
= 733 kJ/kg
Rate of energy gain= mass flow rate × Enthalpy gained by air
= 0.1 × 733
= 73.3 kJ/s
rate of heat transfer between compressor and air= 77kW
Heat loss by air to surroundings= 77-73.3
=3.7kW
Enthalpy lost by steam in turbine= 1407.6-1236.4
= 171.2 Btu/lb
Rate of energy transfer to turbine= Enthalpy lost by steam× mass flow rate
= 171.2×5
= 856 Btu/s
Net rate of energy transfer to turbine=rate of Energy transfer to turbine- rate of heat transfer to turbine
= 856-40
= 816 Btu/s
Answer and explanation:
Deformation means change in position plastic deformation mainly cause due to motion of dislocation
THERE ARE MAINLY TWO MECHANISM BY WHICH PLASTIC DEFORMATION TAKES PLACE
- SLIP
- TWINNING
SLIP : slip is a process of sliding of blocks over one another along the planes these planes are called slip planes slip takes place when the shear stress exceeds than the critical value of stress distance between the slip planes are called slip lines the resistance for slip plane is very less as compared to any other planes the slip plane is the plane has very high density
