Mechanical Engineering Answers

At15°c and 105bar occupies a volume of 0.02m³.The air is heated at constant volume until the pressure is 4.2bar and then cooled at constant pressure back to original temperature. Calculate the net heat follow to and from the air and net enthropy change

Compare the percentage increase in the bending moment that can be carried to produce
the same maximum bending stress when a rectangular beam section is
1) Doubled in breadth, and 2) Doubled in depth.

c) Design a bushed pin type flexible coupling to connect a motor shaft to a pump shaft transmitting 20kW power at 1440 rpm. The allowable shear and crushing stress for steel shafts,keys and pins are 40 MPa and 80 MPa respectively. The allowable shear iron flange is 10 MPa and the allowable bearing pressure for rubber bush is 0.5 Mpa.

.19.Power in a dc circuit is calculated as the product of current and voltage if the value of current and voltage are given by 6.3A and 110.2V and the uncertainities involved in their measurement being 0.06A and 0.1V .Calculate the power dissipated by the loads and the uncertainity involved in measurement.

Q5 A mixture of air and water vapour at 1.013 bar and 16 degree C has a dew
point of 5degree C. Calculate the relative and specific humidity’s?

Q2 In an air compressor the pressures at inlet and outlet are 1bar and 5bar
respectively. The temperature of the air at inlet is 15 degree C and the
volume at the beginning of compression is three times that at the end of
compression. Calculate the temperature of the air at outlet and the increase
of internal energy per kg of air.

Q5 A mixture of air and water vapour at 1.013 bar and 16 degree C has a dew
point of 5degree C. Calculate the relative and specific humidity’s?

Q4 Air is compresses in a two-stage vane-type compressor from 1.013 bar to.
8.75 bar Using the data below, and assuming equal pressure ratios in each
stage, that compression is complete in each stage that the machine
operates in an ideal manner and is uncooled apart from the intercooler,
calculate:
(i) the power required.
(ii) The volume flow rate measured at the delivery pressure.

Q2 In an air compressor the pressures at inlet and outlet are 1bar and 5bar
respectively. The temperature of the air at inlet is 15 degree C and the
volume at the beginning of compression is three times that at the end of
compression. Calculate the temperature of the air at outlet and the increase
of internal energy per kg of air?

Q6 A double pipe heat exchanger has an effectiveness of 0.5 when the flow is
counter- current and the thermal capacity of one fluid is twice that of the
other fluid. Calculate the effectiveness of the heat exchanger if the direction
of flow of one of the fluids is reversed with the same mass flow rates as
before?