KNOWN: Long, 30mm-diameter cylinder with embedded electrical heater; power required
to maintain a specified surface temperature for water and air flows.
FIND: Convection coefficients for the water and air flow convection processes, hw and ha,
respectively.
ASSUMPTIONS: Flow is cross-wise over cylinder which is very long in the direction
normal to flow.
The convection heat rate from the cylinder per unit length of the cylinder has
the form
q' = h*(pi*D)*(Ts-Tinf)
and solving for the heat transfer convection coefficient, find
Water
hw = q'/((pi*D)*(Ts-Tinf))
hw = (38*10^3 W/m) / ((pi*(0.030m))*(80-25)C)=
7330.77314 W/m^2K
Air
ha = (400W/m) / ((pi*(0.030m))*(80-25)C)=<span>
77.166033 </span> W/m^2K
COMMENTS: Note that the air velocity is 10 times that of the water flow, yet
hw ≈ 95 × ha.
These values for the convection coefficient are typical for forced convection heat transfer with
liquids and gases
Watter is a better convective heat transfer media than air
The mass number of a nucleus (except Hydrogen) is: number of protons + number of neutrons.
A=Z+N
A=mass number=protons + neutrons.
Z=atomic number=number of protons.
N=number of neutrons.
In the case of Hydrogen it depends of isotope of Hydrogen .
the hydrogen has three isotopes,
protium : A=Z, because N=0
deuterium: A=Z+N; N=1
tritium: A=Z+N; N=2
<h2>Emerging Technologies that will make Hydroelectric Energy Source Safer</h2>
The variation in technology to labor lower loads and higher peaks make the hydroelectric energy source safer, more usable, more efficient and cleaner. The plants can also adapt speed drives changing the capability to suffice various sorts of demands which includes great speed response. Such variation can alter the income rate by 85%. The spread of operating range of the plant can increase income rate by 61%.
Answer:
Stroke is the correct answer
