Basic Mechanical Engineering — Winter 2025

Give classification of Cochran boiler and Lancashire boiler.

Write a short note on CNG as a fuel.

(i) The absolute pressure in a compressed air tank is 200 kPa. What is the gauge pressure in the tank if atmospheric pressure is 1.01 bar? (ii) The temperature of a system rises by 130°Cduring a heating process. Express this rise in temperature in kelvins. (iii) A 4-kW resistance heater in a water heater runs for 3 hours to raise the water temperature to the desired level. Determine the amount of electric energy used in both kWh and kJ.

State the function of any three mountings in boilers.

Classify engineering materials.

0.4 kg of gas is expanded isentropically from 10 bar and 340oC to 1 bar. It is then heated at constant volume to 3 bar and 340 oC and then finally it is compressed isothermally until the initial pressure of 10 bar is attained. Draw the p-Vdiagram for these processes and find the value of the adiabatic index γ. Take C = 1.005 kJ/kgK. p

Agas expands from 450 kPa and 130 litres to 150 kPa and 260 litres. The decrease in enthalpy during the process is 55 kJ. Taking C = 718 J/kgK, determine (i) change in v internal energy, (ii) value of C , and (iii) value of R. p

What is a rigid coupling? What are its types?

Draw a schematic diagram of the vapor compression refrigeration system. Where is the condenser located in a split air-conditioner?

Arigid tank contains 10 kg of water at 90°C. If 8 kg of the water is in the liquid form and the rest is in the vapor form, determine (a) the pressure in the tank and (b) the volume of the tank.

What is a friction clutch? What are its types? Page 1 of

What is the difference between the working principle of vapor compression and vapor absorption refrigeration system?

Find the dryness fraction of steam supplied in a combined separating-and-throttling calorimeter from following data: initial pressure = 10 bar, final pressure = 1 bar, water separated = 1.5 kg, steam discharged from throttling calorimeter = 20 kg, temperature of steam after throttling = 120oC. Take specific heat of superheated steam as 2.1 kJ/kg K.

Find the incorrect statements from the following and correct them. -Rigid flange coupling is used when axes of shafts are parallel but not in alignment. -Pin type flexible coupling is used where angular misalignment is more. -Universal coupling requires proper alignment of shaft axes. -Oldham’s coupling is for small angular misalignment.

Describe main parts of a centrifugal pump in short.

A Diesel engine has a compression ratio of 15 and heat addition at constant pressure takes place 6% of the stroke. Find the air standard efficiency of the engine.

Draw a labeled diagram of a simple band brake.

Explain any one type of rotary pumps with figure.

In an air standard Otto cycle, the upper and lower limits of absolute temperatures are Tand Trespectively. Show that for maximum work, the ratio of compression31 should have the value .

Which mechanical drive will you suggest in each of the following different situations: -When there is less space available. -Where ‘slip’ is permitted. -When high velocity ratio is required.

What is isothermal efficiency, clearance ratio, and volumetric efficiency of a compressor?

Distinguish between petrol engine and diesel engine. Use the following points: cycle of operation, compression ratio, fuel ignition, governing, engine speed, thermal efficiency, engine weight.

State three disadvantages of using gear drives.

Give classification of air compressors.

The following data refer to a test on I.C. engine: Indicated power = 42 kW, frictional power = 7 kW, engine speed = 1800 rpm, specific fuel consumption per B.P. = 0.30 kg/kWh, calorific value of fuel used = 43000 kJ/kg. Calculate: (i) mechanical efficiency, (ii) brake thermal efficiency, and (iii) indicated thermal efficiency. Page 2 of