Can someone please help me this is urgent!?
2 answers:
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Answer:
e= 50 J/kg
Explanation:
Given that
Speed ,v= 10 m/s
Diameter of the turbine = 90 m
Density of the air ,ρ = 1.25 kg/m³
We know that mechanical energy given as
That is why mechanical energy per unit mass will be
Now by putting the values in the above equation we get
e= 50 J/kg
That why the mechanical energy unit mass will be 50 J/kg.
Answer:
Not possible.
Explanation:
According to second law of thermodynamics, the maximum efficiency any heat engine could achieve is Carnot Efficiency η defined by:
Where
and
are temperature (in Kelvin) of heat source and heatsink respectively
In our case (I will be using K = 273+°C) :
In percentage, this is 14.28% efficiency, which is the <em>maximum</em> theoretical efficiency <em>any</em> heat engine could have while working between -27 and 14 °C temperature. Any claim of more efficient heat engine between these 2 temperature are violates the second law of thermodynamics. Therefore, the claim must be false.
Answer:
the rate of heat loss by convection across the air space = 82.53 W
Explanation:
The film temperature
to kelvin = (5 + 273)K = 278 K
From the " thermophysical properties of gases at atmospheric pressure" table; At = 278 K ; by interpolation; we have the following
→ v 13.93 (10⁻⁶) m²/s
→ k = 0.0245 W/m.K
→ ∝ = 19.6(10⁻⁶)m²/s
→ Pr = 0.713
The Rayleigh number for vertical cavity
=
=
For the rectangular cavity enclosure , the Nusselt number empirical correlation:
h = 1.99 W/m².K
Finally; the rate of heat loss by convection across the air space;
q = hA(T₁ - T₂)
q = 1.99(1.4*0.96)(20-(-10))
q = 82.53 W