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Unit mass of certain fluid is contained in a
cylinder at an initial pressure of 20 bar. The fluid
is allowed to expand reversibly behind a piston
according to a law Pv2=constant until the volume
is doubled. The fluid is then cooled reversibly at
constant pressure until the piston regains its
original position; heat is then supplied reversibly
with the piston firmly locked in position until the
pressure rises to the original value of 20 bar.
Calculate the net work done by the fluid, for an
initial volume of 0.05m
Two streams of water are mixed to form the feed to a boiler. Process data are as follows:
Feed streams 1: 100 kg/min@30C
Feed streams 2: 195 kg/min@65C
Boiler pressure : 17 bar absolute
Calculate the required heat input to the boiler in kJ/min if the emerging steam is saturated at the boiler pressure. Neglect the kinetic energy, potential energy and work.
Your final answer must be in 1 decimal place with unit kJ/min.
Show that the energy level of an atom is decreasing according to
the number of electron shell. Draw the electron shell vs energy curve
including calculations.
Determine the energy (eV) of a photon having a wavelength of
x A0
. Where x is the summation. You
have to calculate your value of x=2+1+9+1+5+2+7+2=29. Find the
electron shell where the valence electrons are exist. What type of
material is it?
Calculate the temperature at which there is a .02 probability that
a state 1.2 eV above the valence band will not contain any positive
charge carriers. Assume that the Fermi level energy of a particular
material is 5 eV from valence band and the electron in this material
follow the Fermi-Dirac distribution. The band gap energy is 8 eV.
Draw the energy level diagram mentioning different energy level.
Derive the equation of hole concentration of extrinsic material in
terms of electron concentration of intrinsic material. Where the all
symbols have their usual meanings.
- A steam with a velocity of 600m/s enters an impulse turbine row of bladee at an angle of 25°C to the plane of rotation of the blades. The mean blade speed is 255m/s. The exit angle from the blades is 30°C. There is a 10% loss in-relative velocity due to friction in the blades. Determine:
(a) the entry angle of blades
(b) the work done /kg steam/s
(c) the diagram efficiency
(d) the end thrust/kg steam/ s
A long and rectangular metal blade is 4cm thick and has a surface temperature of 40°C. Both sides of the blade are in an environment of 20°C. the surface of the blade;
a) In case of vertical,
b) In case of inclination of 45°,
c) Find the temperature changes in case of horizontal.
2. Water enters a pipe at a temperature of 27°C and a flow rate of 450 kg/h. Heat flux is applied from outside the pipe, q'=ax (W/m). Here, a=20 W/m2 is a constant and x(m) is the length from the entrance.
a) Find the average temperature of the water flowing through the pipe as a function of the pipe length.
b) Find the outlet temperature of the water from a 30 m long pipe. (cp=4179 J/kgK)
1. A pipe with an inner diameter of 15 mm and a length of 2 m is heated with a constant heat flux. 8 kg of water flows through the pipe per hour and its temperature rises from 20 oC to 60 oC. According to this;
a. Find the pipe surface temperature and the average fluid temperature as a function of pipe length.
b. Find the constant heat flux.
