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1.
Consider a steam power plant using a reheat cycle as shown. Steam leaves the boiler and enters the turbine at 4 MPa, 350°C (h3 = 3095 kJ/kg). After expansion in the turbine to 400 kPa (h4 = 2609 kJ/kg), the steam is reheated to 350°C (h5 = 3170 kJ/kg), and then expanded in a low pressure turbine to 10 kPa (h6 = 2165 kJ/kg). The specific volume of liquid handled by the pump can be assumed to be
[1] The thermal efficiency of the plant neglecting pump work is [2 marks]
(a) 15.8%
(b) 41.1%
(c) 48.5%
(d) 58.6%[2] The enthalpy at the pump discharge (h2) is [2 marks]
(a) 0.33 kJ/kg
(b) 3.33 kJ/kg
(c) 4.0 kJ/kg
(d) 33.3 kJ/kgasked in Mechanical Engineering, 2004
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2.
A compacting machine shown in the figure below is used to create a desired thrust force by using a rack and pinion arrangement. The input gear is mounted on the motor shaft. The gears have involutes teeth of 2 mm module.
[1] If the drive efficiency is 80%, the torque required on the input shaft to create 1000 N output thrust is [2 marks]
(a) 20 Nm
(b) 25 Nm
(c) 32 Nm
(d) 50 Nm[2] If the pressure angle of the rack is 20°, the force acting along the line of action between the rack and the gear teeth is [2 marks]
(a) 250 N
(b) 342 N
(c) 532 N
(d) 600 Nasked in Mechanical Engineering, 2004
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3.
A steel beam of breadth 120 mm and height 750 mm is loaded as shown in the figure. Assume Esteel =200GPa.
[1] The beam is subjected to a maximum bending moment of [2 marks]
(a) 3375 kNm
(b) 4750 kNm
(c) 6750 kNm
(d) 8750 kNm[2] The value of maximum deflection of the beam is [2 marks]
(a) 93.75 mm
(b) 83.75 mm
(c) 73.75 mm
(d) 63.75 mmasked in Mechanical Engineering, 2004
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4.
From the lists given below, choose the most appropriate set of heat treatment process and the corresponding process chracteristics
Process Characteristics P. Tempering 1. Austenite is converted into bainite Q. Austempering 2. Austenite is converted into martensite R. Martempering 3. Cementite is converted into globular structure 4. Both hardness and brittleness are reduced 5. Carbon is absorbed into the metal
(a) P-3, Q-1, R-5
(b) P-4, Q-3, R-2
(c) P-4, Q-1, R-2
(d) P-1, Q-5, R-4
asked in Mechanical Engineering, 2004
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5.
Typical machining operations are to be performed on hand-to-machine materials by using the processes listed below. Choose the best set of Operation-process combinations
Operation Process P. Deburring (internal surface) 1. Plasma Arc Machining Q. Die sinking 2. Abrasive Flow Machining R. Fine hole drilling in thin sheets 3. Electric Discharge Machining S. Tool sharpening 4. Ultrasonic Machining 5. Laser beam Machining 6. Electrochemical Grinding
(a) P-1, Q-5, R-3, S-4
(b) P-1, Q-4, R-1, S-2
(c) P-5, Q-1, R-2, S-6
(d) P-2, Q-3, R-5, S-6
asked in Mechanical Engineering, 2004
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6.
Match the following
Product Process P. Molded luggage 1. Injection molding Q. Packaging containers for liquid 2. Hot rolling R. Long structural shapes 3. Impact extrusion S. Collapsible tubes 4. Transfer molding 5. Blow molding 6. Coining
(a) P-1, Q-4, R-6, S-3
(b) P-4, Q-5, R-2, S-3
(c) P-1, Q-5, R-3, S-2
(d) P-5, Q-1, R-2, S-2
asked in Mechanical Engineering, 2004
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