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a) Air enters the compressor of a gas turbine at 100 kPa and 25°C. For a pressure ratio of 5 and a maximum temperature of 850°C determine the back work ratio and the thermal efficiency using the Brayton cycle.
A flat belt is required to transmit 22 kW from a 250 mm diameter pulley running at 1450 rpm to a 355 mm diameter pulley. The proposed belt is 3.5 mm thick. The other system specifications are as follows: Coefficient of friction 0.7, Density of the belt is 1100 kg/m3, Maximum permissible stress is 7 MPa. The distance between the shafts is 1.8 m.
Calculate the width required.
A 20° full depth spur pinion is required to transmit 1.8 kW at a speed of 1540 rpm. If the pinion has 21 teeth and is manufactured from a heavy duty 817M40 steel; Select a suitable gear from the limited choice given in Tables 6.7 -6.10, specify the:
1.1 module and face width based on the Lewis formula. (9)
1.2 the gear module and the face width if the power transmitted is doubled (3)
1.3 the gear module and the face width if the speed is doubled and the power is still 1.8 kW? (3)
Hint: In all the above, show all your calculation steps (Start with m =1) in all cases.
A flat belt is required to transmit 22 kW from a 250 mm diameter pulley running at 1450
rpm to a 355 mm diameter pulley. The proposed belt is 3.5 mm thick.
The other system specifications are as follows:
Coefficient of friction 0.7,
Density of the belt is 1100 kg/m3
Maximum permissible stress is 7 MPa.
The distance between the shafts is 1.8 m.
2.1 Calculate the width required. [15]
A 20
The inductance of moving iron ammeter in micro henry is given by expression: L=20+5θ-2θ2 Where θ is deflection in radians from the zero position. Determine the angular in radians for a current of 10A if the for a current of 5A is 300.Also determine the spring constant
A wire of diameter D= 2 mm and uniform temperature T has an electrical
resistance of 0.01Ω /m and a current flow of 20 A.
a) What is the rate at which heat is dissipated per unit length of wire? What is
the heat dissipation per unit volume within the wire?
b) If the wire is not insulated and is in ambient air and large surroundings for
which T∞= Tsur= 20oC, what is the temperature T of the wire? The wire
has an emissivity of 0.3, and the coefficient associated with heat transfer
by natural convection may be approximated by an expression of the form,
h= C[(T- T∞)/D]1/4, where C= 1.25 W/m7/4 K
5/4
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