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S.No Question Option A Option B Option C Option D Answer Solution Comments Status Action
1 As per the steady flow energy equation, work is done in rotary compressors due to___. increase in viscosity increase in the adiabatic index increase in entropy increase in enthalpy d Steady flow energy equation (S.F.E.E.);
\((h_{1}+\frac{v12}{2}+gz_{1})+q=(h_{2}+\frac{v22}{2}+gz_{2}) +w\)
when potential and kinetic energy changes are zero or negligible
\(h_{1}+q=h_{2}+w\)
Given reversible adiabatic process so, (q = 0)
\(w=h_{1}-h_{2}=∆h\)
∴ In a steady flow reversible adiabatic process, work done is equal to change in enthalpy.		 Comments Active
2 Based on the two statements given below, selectthe correct option.
Statements:		 Both Statement A and Statement B are correct but are not related. Statement A is incorrect, but Statement B is correct. Statement A is correct but Statement B is incorrect Both Statement A and Statement B are correct and are related to each other. d Both Statement A and Statement B are correct and are related to each other.
Statement (A)–The first law of thermodynamics is also known as the conservation of energy principle because the energy can be neither created nor destroyed during a process; it can only change forms.
Statement (B)–For all the adiabatic processes between two specified states of a closed system, the net work done is the same, regardless of the nature of the closed system and the details of the process. This statement, which is largely based on the experiments of joule.		 Comments Active
3 A gaseous system having internal energy of 50J is being added by 100 J of heat. Calculate the amount of external work done. 20 J 50 J 2 J 150 J b Given that,
Internal energy (dU) = 50J
Heat added \( (∂Q)=100 J\)
External work \((∂w)=?\)
From first law of thermodynamics
+ \(∂Q=\) \(dU\) \(∂w\)
\(100=50 +∂w\)
\(∂w=50J\)		 Comments Active
4 Regarding the pressure distribution of a fluid in an open rectangular tank, which of the below-mentioned statements is FALSE? Pressure is uniform on the bottom The pressure is maximum at the middle of the side wall of the tank. The gauge pressure at the water surface on the side wall is zero The resultant force acts through the centroid of the area of the bottom of the tank. b Pressure distribution of a fluid in an open rectangular tank: Pressure is uniform on the bottom.
• The gauge pressure at the water surface on the side wall is zero.
• The pressure is not maximum at the middle of the side wall of the tank because pressure at bottom is uniform.
• The magnitude of the resultant force can be found by summing these differential forces over the entire surface. In equation form,
\(F_{R}=γhdAA\)
• The resultant force acts through the centroid of the area of the bottom of the tank.		 Comments Active
5 Based on the following two statements related to the manometer, select the correct option. Statement A is incorrect, but Statement B is correct. Both Statement A and Statement B are incorrect. Both Statement A and Statement B arecorrect. Statement A is correct, but Statement B isincorrect. b Piezometer–
• It is suitable for small and positive pressure.
• It cannot measure the pressure in a container that islesser than the atmospheric pressure or vacuum pressure or negative pressure.
• It is not used for measuring the high pressure.
• Gas pressure is not measured by piezometer.
U-tube manometer
• It is used for measure the moderate and high pressure.
• Positive as well as negative pressure of the fluid is measured by U-tube manometer.
• Gas pressure is also measured by U-tube manometer.
• If preferred lighter gauge fluid then it's measured lowpressure and if preferred heavier gauge fluid then it's measured high pressure.		 Comments Active
6 Which of the following statements expresses the main function of a steam generator? In transfer the heat produced by the combustion of fuel to water and, ultimately, produces steam. It transfer the water directly to the feed pump and develops electric power. It transfer the heat to the atmospheric air and thereby, causes condensation of the steam. It reduces the water energy storage capacity and diminishes the steam generation. a The main functions of steam generator–
A steam generator or boiler is a thermal devices used to generate steam at a desired pressure and temperature by transferring heat energy produced by burning coal (fuel), to water to ultimately, produce steam.		 Comments Active
7 The sum of datum head and pressure head from Bernoulli's equation is known as____. piezometric head atmospheric head manometric head datum head a Bernoulli's equation– (Assumptions)
• Fluid is ideal.
• Fluid is steady
• Flow is continuous
• Fluid is incompressible
• Flow is non-viscous
• Flow is irrotational
• Applicable along a stream line.
This equation is obtained by integrating Euler's equation.
\(\frac{P}{w}+Z+\frac{v^{2}}{2g}=C\)
Here,
= Pressure head + gravitational head \((\frac{P}{W}+z)\)
= Piezometric head \((\frac{P}{W}+z)\)
• Bernoulli's equation is applicable across the streamlines, if flow is irrotational.		 Comments Active
8 The Darcy friction factor (f) for fully developed laminar flow in a circular pipe with the Reynolds number of 1600 is given as: 0.01 0.005 0.02 0.04 d Given that,
Reynolds number (Re) = 1600
For laminar flow;
Darcy friction factor (f) = \(\frac{64}{Re}\) \((Re<2000)\)
\( =\frac{64}{1600}=0.04\)		 Comments Active
9 Match column A wit column B.
Column A
Column B
A. Newtonian fluid
1. Fluid having viscosity
B. Ideal fluid
2. Fluid obeying Newton's law of viscosity
C. Real fluid
3. Fluid is incompressible and non-viscous		 A-3; B-1; C-2 A-1; B-3; C-2 A-2; B-3; C-1 A-2; B-1; C-3 c Column A
Column B
Newtonian fluid
Fluid obeying Newton's law of viscosity
Ideal fluid
Fluid is incompressible and non-viscous
Real fluid
Fluid having viscosity
Noted points–
• Ideal fluid are imaginary and do not exist in nature. It has no surface tension. Its bulk modulus is infinite.
• Real fluid have viscosity, finite compressibility and surface tension.		 Comments Active
10 Calculate the kinetic head (in meter) for a system wherein water flowing through a pipe of 4 cm diameter under pressure of 20 N/cm2 and mean velocity of 2 m/s. Take g = 10 m/s2. 0.35 0.5 0.2 0.1 c Given that–
Pressure (P) = 20 N/cm2
= 20 × 10–4 N/m2
Velocity (v) = 2 m/s
g = 10 m/s2
Kinetic head = \(\frac{v^{2}}{2g}\)
\(=\frac{(2)^{2}}{2×10}\)
= 0.2m		 Comments Active
11 Based on the following two statements related to the Curtis stage turbine, select the correct option.
Statements:		 Statement A is correct, but Statement B is incorrect Both Statement A and Statement B are correct Both Statement A and Statement B are incorrect Statement A is incorrect, but Statement B is correct b Curtis stage turbine–It is known as velocity compounded impulse turbine.
• It is composed of one stage of nozzles as the single stage turbine, followed by two rows of moving blades instead of one.
• In the curtis stage, the total enthalpy drop and hence pressure drop occur in the nozzles so that the pressure remains constant in all three rows of blades.
• In fixed (static) blade passage both pressure and velocity remain constant.
 Comments Active
12 Calculate the total head of water at the cross section of 5 m above the datum line. The pipe has diameter of 5 cm, and the water is flowing with a pressure of and mean velocity of 2m/s Take g = 10 m/. \(100×_{} N/^{}\) \(m^{2}\) 19.2 10.2 14.1 15.2 d Given that,
Datum head (z) = 5 m
Pipe diameter (d) = 5 cm = 5 × 10–2 m
Pressure (P) = 100 × 103 N/m2
Velocity (V) = 2 m/s
Density (ρ) = 1000 kg/m3
Total head = \(\frac{P}{pg}+Z+\frac{V^{2}}{2g}\)
\(=\frac{100×10^{3}}{1000×10}+5+\frac{(2)^{2}}{2×10}\)
\(=10+5+0.2=15.2\)		 Comments Active
13 Calculate the magnitude of resultant of two like parallel forces of 20N separated by a distance of 20 cm. 20 N 0 N 40 N 60 N c
Given that– Like parallel forces = F1 = F2 = 20 N
Resultant force (R) = \(F12+F22+2F_{1}F_{2}cosθ\)
\(R= F12+F22+2F_{1}F_{2}\)
\(R= (20)^{2}+ (20)^{2}+2×20×20\)
\(R=40N\)		 Comments Active
14 In case of frictionless flow with no work or heat transfer, the height of the energy grade line (EGL) is _____ and is equal to the ___. variable; elevation and pressure head constant; total Bernoulli head variable; total Bernoulli head constant; elevation and pressure head b Total energy line (T.E.L.)–In case of frictionless flow with no work or heat transfer, the height of the energy grade line (EGL) is equal to the sum of the elevation head (datum head), pressure head and velocity head. This is because the total energy of the fluid remains constant in a frictionless flow.
\(T.E.L. =\frac{P}{ρg} +Z+\frac{v^{2}}{2g}\)
• T.E.L. is also known as Bernoulli head.
• For a pipe of uniform cross-section the slope of H.G.L. is equal to the slope of T.E.L.
Hydraulic gradient line (H.G.L.)–It is a lined drawn
joining the piezometric head at various points. \((\frac{P}{pg}+Z)\)		 Comments Active
15 Which of the following statements is INCORRECT regarding a thermodynamic system? The surface separating the system and its surroundings is known as boundary. The system boundary may be movable or fixed Everything including the system is known as surroundings An isolated system is a closed system that does not interact in any way with its surroundings. c System and surrounding–
• A system is a matter or region on which analysis is done. System is separated from the surrounding by boundary.
• Everything external to the system is called surroundings.
• System and surrounding together is called a universe.
Boundary–
• It separate system and surroundings.
• It can be fixed or movable.
• Fixed boundary e.g. rigid box containing gas.
• Movable boundary e.g. cylinder with piston.
• An isolated system is a closed system that does not interact in any way with its surroundings.		 Comments Active
16 Based on the two statements given below, select the correct option. Statements: Statement A is incorrect, but Statement B is correct. Statement A is correct, but Statement B is incorrect. Both Statement A and Statement B are incorrect Both Statement A and Statement B are correct. a Simple compressible substance (system)–It is completely specified by any two independent intensive thermodynamic properties like as a P (pressure), υ (specific volume), T (temperature), ρ (density), h (specific enthalpy), e (specific internal energy), s (specific entropy) and x (quality).
• It is that permits only expansion work
\(dw_{x}=P.dv\)
• In this system, the effects of the following are negligible: motion, fluid shear, surface tension, gravity and magnetic and electrical fields.		 Comments Active
17 A fluid cannot cross a streamline. The reason is that, at all the points, the velocity perpendicular to the streamline is ____. zero unity infinity non-zero a Stream line–A streamline is an imaginary line drawn in a flow field such that a tangent drawn at any point on this line represents the direction of velocity vector at that point.
• A fluid cannot cross a streamline because all points of fluid has zero velocity at perpendicular to the streamline.
• There is no velocity component normal to streamlines.
• In steady flow streakline, pathline and stream line are identical.		 Comments Active
18 The basic function of an expansion valve in a refrigerator is to____ the ________ refrigerant from the ___ pressure to the _____ pressure. condense; gaseous; condenser: evaporator expand; liquid; evaporator; condenser condense; gaseous; evaporator; condenser expand; liquid; condenser; evaporator d The basic function of an expansion valve in a refrigerator is to expand the liquid refrigerant from the condenser pressure to the evaporator pressure. Comments Active
19 The ratio of the sensible heat transfer to the heat transfer in air conditioning systems is known as_______ sensible heat factor bypass factor cooling factor humidity factor a Sensible heat factor or sensible heat ratio It is the ratio of the sensible heat transfer to the total heat transfer in air-conditioning system.
\(SHF=\frac{Sensible heat}{Total heat}\)
\(SHF=\frac{SH}{LH+SH}=\frac{h_{3}-h_{2}}{h_{1}-h_{2}}\)
• SHF = 1 (for sensible heating or cooling)
• SHF = 0 (for humidification or dehumidification)		 Comments Active
20 In the P-V diagram for a pure substance, the point at which the saturated liquid line and the saturated vapour line meet is called____. triple point saturation point normal point critical point d Critical point–In this point, the saturated liquid line and the saturated vapour line are meat each other for a pure substance in P-V diagram.
•The temperature, pressure and specific volume corresponding to the critical point are termed as critical properties.
• At critical point,
Pressure (Pc) = 221.2 bar
Temperature (tc) = 374.15C \(°\)
Volume (Vc) = 0.00317 m3/kg		 Comments Active
21 Select the correct option on the basis of the statements given below.
Statement A: Water tube boilers are lowpressure boilers.
Statement B: Fire tube boilers are high- pressure boilers.		 Both statements A and B are true. Both statements A and B are true Statement A is true, but Statement B is false Statement B is true, but Statement A is false b Fire tube steam boilers–In this boilers, the flames and not gases produced by combustion of fuel, pass through the tubes (called multi-tubes) which are surrounded by water.
Examples–Simple vertical boiler, cochran boiler, lancashire boiler, cornish boiler, scoth marine boiler, locomotive boiler and velcon boiler.
• It's boiler basically low pressure boiler. Water tube steam boilers–In this boilers water is contained inside the tubes (called water tubes) which are surrounded by flames and hot gases from outside.
Examples–Babcock and Wilcox boiler, Stirling boiler, La-mont boiler, Benson boiler, Yarrow boiler and Loeffler boiler.
• It's boiler basically high pressure boiler.		 Comments Active
22 The Rankine cycle comprises: two isentropic processes and two isothermal processes two isentropic processes and two constantvolume processes two isentropic processes and two constantpressure processes two isothermal processes and two constantvolume processes c Rankine cycle–It has two isentropic and two constant pressure (isobaric) processes.

• Steam power plant is based on Rankine cycle.		 Comments Active
23 Which of the following is NOT a natural circulation boiler? Babcock & Wilcox boiler LaMont boiler Lancashire boiler Locomotive boiler b Natural circulation steam boilers–In this type of boilers the circulation of water is by natural convection currents which are set up during the heating of water.
• In most of the steam boilers, there is a natural circulation of water.
Examples–Lancashire boiler, locomotive boiler, cochran boiler, cornish boiler, babcock and wilcox boiler etc.
Forced circulation steam boilers–There is a forced circulation of water by a centrifugal pump driven by some external power.
• Used of force circulation is made in high pressure boilers such as La-mont boiler, Benson boiler, Loeffler boiler and Velcon boiler.		 Comments Active
24 In the gas welding process, a neutral flame contains___ and ______ in equal proportions. oxygen; propane oxygen; natural gas oxygen; propylene oxygen; acetylene d Neutral flame–It is obtained by supplying equal volumes of oxygen and acetylene. It has the following two sharply defined zones:
1. An inner luminous cone (3200ºC) and
2. An outer cone or envelope of bluish colour (1250ºC)
• In gas welding, a neutral flame contains oxygen and acetylene in equal proportions.
• It is used for welding of steel, cast iron, copper and aluminium.		 Comments Active
25 The operation of enlarging an already drilled hole is known as____ coining boring Punching shearing b The operation of enlarging an already drilled hole is known as boring process.
• Boring is an operation to enlarging of an existing hole, which may have been made by a drill or may be the result of a core in a casting.
 Comments Active
26 Which of the following is NOT a boiler accessory? Economiser Steam stop valve Air preheater Steam trap b Accessories– Components used to increase efficiency of boiler.
• Air preheater
• Water preheater (Economizer)
• Super heater
• Feed water equipment
• Steam separator
• Steam trap
• Draught equipments
Mountings– Its main purpose is safety of boiler and proper control of process of steam generation.
• Safety valve
• Water level indicator
• Pressure gauge
• Fusible plug
• Blow off cock
• Feed check valve
• Steam stop valve and junction valve
• Man/mud/inspection hole.		 Comments Active
27 Centrifugal pumps dealing with mud, slurry and sewage have______. closed impeller isolated impeller semi-closed impeller open impeller d Centrifugal pumps dealing with mud, slurry and sewage have open impeller.
Types of impeller–
Impeller
Uses
Shrouded/closed/ enclosed impeller
For pumping chemicals, pure liquids
Semi closed/Non clag impeller
For paper pulp, sugar molasses and sewage water
Open impeller
For abrasive liquids, slurry, sand water		 Comments Active
28 Considering a grinding wheel and a regulating wheel in regard to the centreless grinding machine working principle, the _____ is of greater diameter and has a high rotational speed, whereas the ______ is of smaller diameter and has a low speed. grinding wheel; regulating wheel regulating wheel; work rest blade regulating wheel; grinding wheel grinding wheel; work rest blade a Considering a grinding wheel and a regulating wheel in regard to the centreless grinding machine working principle, the grinding wheel is of greater diameter and has a high rotational speed, whereas the regulating wheel is of smaller diameter and has a low speed. Comments Active
29 Identify the cycle on the basis of the T-S diagram shown below.
 Diesel cycle Sterling cycle Otto cycle Carnot cycle c
Processes–
(0-1) : Suction at constant atmospheric pressure.
(1-2) : Reversible adiabatic or isentropic compression of air.
(2-3) : Reversible heat addition at constant volume.
(3-4) : Reversible adiabatic expansion of air.
(4-1) : Reversible heat rejection at constant volume.
(1-0) : Exhaust at constant atmospheric pressure.
Thermal efficiency–
\(n=1-\frac{1}{(r_{c})^{γ-1}}\)
• Heat addition and heat rejection are at constant volume.
• In Otto cycle compression ratio equal to expansion ratio.
• Petrol engine role model on Otto cycle.
• Compression ratio 6 to 12.		 Comments Active
30 Which of the following is NOT a type of oil pump used in IC engine. Row type oil pump Gear type oil pump Plunger type oil pump Vane type oil pump a Oil pump–
• The oil pump is used to pump oil from the oil sump to the oil galleries at a certain pressure.
• It is located in the crankcase and is driven by the camshaft.
Four types of oil pumps are used–
• Gear-type oil pump
• Rotor-type oil pump
• Vane-type oil pump
• Plunger-type oil pump		 Comments Active
31 The absolute pressure is equal to: gauge pressure + atmospheric pressure gauge pressure + atmospheric pressure + vacuum pressure gauge pressure - atmospheric pressure vacuum pressure + gauge pressure a Absolute pressure– Absolute pressure measured with reference to absolute zero. Absolute pressure cannot be negative.
• Absolute pressure = gauge pressure + atmospheric pressure.
• Pabsolute = Patm + Pgauge
Gauge pressure–When pressure in a fluid is measured with respect to the atmospheric pressure, then it is called gauge pressure. Gauge pressure can be positive, negative or zero.
Vacuum pressure–It is defined as the pressure below the atmospheric pressure.
Pvacuum = Patm – Pabsolute		 Comments Active
32 Select the correct option based on the assertion (A) and reason (R) listed below.
Assertion (A): Two surfaces are polished and brought in contact with each other to reduce friction.
Reason (R): Rough surfaces have less friction between them.		 Both A and R are false A is false but R is true Both A and R are true A is true but R is false d • Two surfaces are polished and brought in contact with each other to reduce friction or roughness.
• The friction force between two surfaces is due to the roughness of the contact surface.
• Rough surfaces have more friction when two surfaces contact.		 Comments Active
33 The main purpose of using the evaporator in a refrigeration system is to_______. absorb heat from the surrounding air expand the refrigerant liquid compress the refrigerant gas condense the refrigerant gas a Evaporator–It is the part where cooling takes place. The heat is absorbed in the evaporator from the surrounding air. The liquid refrigerant is converted into vapour refrigerant in the evaporator. Comments Active
34 Match the thermodynamic systems with their correct examples.
Thermodynamic System
Example
A. Open
I. The gas sealed within the cylinder of a spark-ignition engine
B. Closed
II. Liquid nitrogen stored in a sealed and insulated container
C. Isolated
III. A car radiator		 A-II, B-III, C-I A-III, B-I, C-II A-I, B-III, C-II A-I, B-II, C-III b Thermodynamic System
Example
Open
A car radiator
Closed
The gas sealed within the cylinder of a spark-ignition engine
Isolated
Liquid nitrogen stored in a sealed and insulated container		 Comments Active
35 Based on the following two statements related to the actual vapour power cycle and the ideal Rankine cycle, select the correct option.
Statements:		 Both Statement A and Statement B are correct. Both Statement A and Statement B are incorrect. Statement A is correct, but Statement B is incorrect. Statement A is incorrect, but Statement B is correct. a As a result of irreversibilities in various components such as fluid friction and heat loss to the surroundings, the actual cycle derivates from the ideal Rankine cycle. The deviations of actual pumps and turbines from the isentropic ones can be accounted for by utilizing isentropic efficiencies defined as–

\(η_{P }= \frac{W_{s}}{W_{a}}=\frac{h_{2s}-h_{1}}{h_{2a}-h_{1}}\)
\(η_{T}=\frac{W_{a}-h_{3}-h_{4a}}{W_{s}-h_{3}-h_{4s}}\)		 Comments Active
36 As per the valve timing diagram of the fourstroke cycle diesel engine. Typically, the fuel valve closes____. The inlet valve opens at 10°-20° before TDC and closes at 25°-40° after BDC. The fuel value opens at 10°-15° before TDC and closes at 15°-20° after TDC. The compression starts at 25°-40° after BDC and ends at 10°-15° before TDC. The expansion starts at 10°-15° after TDC and ends at 30°-50° before BDC.
(e) The exhaust valve opens at 30°-50° before BDC and closes at 10°-15° after TDC.
 d Valve timing diagram for a four stroke cycle diesel engine– Comments Active
37 A draft tube has the inlet diameter of 1 m and the outlet diameter of 2m. The absolute pressure at the inlet of the draft tube is 0.4 bar. The outlet of the draft tube is exposed to atmosphere. The flow rate of water through the draft tube is 1600 liters per second. Then, the vertical distance between the inlet and the outlet is approximately. 0.6 m 6 m 60 m 0.06 m b Given, d1 = 1 m
P2 = 0.4 bar = 40 kPa
d2 = 2 m
P2 = 101.32 kPa

Discharge (Q) = 1600 litres/sec
= 1600 × 10–3 m3/s
Q = \(A_{1}V_{1}\)
\(1600 × 10^{-3}= \frac{π}{4} ×(1)^{2} ×V_{1}\)
\(V_{1}=2m/s\)
\(Q= A_{2}V_{2}\)
\(1600 × 10^{-3}= \frac{π}{4} ×(2)^{2} ×V_{2}\)
\(V_{2}=0.5m/s\)
Applying Bernoulli's equation–
\(\frac{P_{1}}{Pg}+\frac{V12}{2g}+Z_{1}=\frac{P_{2}}{pg}+\frac{V22}{2g}+Z_{2}\)
\(\frac{40×10^{3}}{10^{3}×9.81}+\frac{(2)^{2}}{2×9.81}+Z_{1}=\frac{101.32×10^{3}}{10^{3}×9.81}+\frac{(0.5)^{2}}{2×9.81}+Z_{2}\)
\(Z_{1}-Z_{2}=10.33-4.27\)
Z= 6m		 Comments Active
38 Which of the following is a boiler accessory? Fusible plug Economiser Steam stop valve Pressure gauge b Boiler Mountings
Boiler Accessories
Water level indicator
Super heater
Pressure gauge
Economizer
Safety valve
Air preheater
Steam stop valve
Feed water heater
Blow off cock
Boiler feed pump
Fusible plug
Steam separator
Feed check valve
Steam trap
Man/mud hole
Draught equipment’s		 Comments Active
39 The flywheel of a steam engine has radius of gyration 1 m and mass of 3000 kg. The starting torque of the engine is 3000 N.m. The kinetic energy of such a flywheel after to sec from rest position will be______ 15 kN-m 1500 kN-m 150 kN-m 1.5 kN-m c Given,
Radius of gyration (K) = 1 m
Mass (m) = 3000 kg
Torque (T) = 3000 N-m
t = 10 sec, = 0 \(ω_{0}\)
\((M.O.I.)I =mK^{2}\)
\(I=3000 × (I)^{2}=3000 kg-m^{2}\)
\(T=Iα\)
\(3000=3000α\)
\(α=1rad/s\)
Kinetic energy of flywheel \(=\frac{1}{2}Iw^{2}\)
\(=\frac{1}{2}×3000×(10)^{2}\)
N-m = 150 kN-m \(=150×10^{3}\)		 Comments Active
40 About which of the following aspects of a thermodynamic process does the first law of thermodynamics NOT provide information? Total energy change in a system Heat transfer into or out of a system Work done by a system Direction of a spontaneous process d "First law of thermodynamics is nothing but law of conservation of energy, with respect to heat and work".
Heat Work \( ⇌\)
Heat and work are mutually convertible. The limitation of the first law of thermodynamics is that it does not say anything about the direction of flow of heat.		 Comments Active
41 A mass of 2.4 kg of air at 150 kPa and 12°C is contained n a gas-tight frictionless piston cylinder device. The air is then compressed to a final pressure of 600 kPa. During tis process, heat is transferred from the air in such a way that the temperature inside the cylinder remains constant. Calculate the work input during the process. 272 kJ -272 kJ -11kJ 11 kJ b Given, m = 2.4 kg
P1 = 150 kPa, T1 = 12ºC = 285 K
P2 = 600 kPa
\(W_{isothermal}= P_{1}V_{1}(\frac{P_{1}}{P_{2}})\)
\(=mRT_{1}In(\frac{P_{1}}{P_{2}})\)
\(=2.4 ×0.287×285×In(\frac{150}{600})\)
\(=196.308×In(0.25)\)
\(= -272 kJ\)		 Comments Active
42 What is the primary purpose of using an economizer in a boiler system? To increase the pressure within the boiler To reduce the emission of greenhouse gases To heat the feed water by utilising heat from the exhaust flue gases To cool down the exhaust flue gases c Economizer– It is a device which increases temperature of feed water using heat of flue gases leaving boiler through chimney. It has been estimated that every 1% of fuel cost can be saved for every 6 degree centigrade (6C) rise in temperature of boiler feed water. \(°\)
Air preheater– It is device which increases the temperature of air before it supply to the furnace us heat from flue gases passing through chimney. An increase of 20 degree centigrade (20C) in the air temperature increases the boiler efficiency by 1%. \(°\)
Super heater– The heat of combustion gases from furnace is utilized for removal of moisture from steam and to super heat the steam.		 Comments Active
43 Darcy's friction factor for a fully developed flow through a closed duct is given by ______. (Consider that Dh is hydraulic diameter, is wall shear stress. * p ∆ is piezometric pressure drop over a length of L, ρ is density and V is average flow velocity.) \(τ_{w}\) \(\frac{D_{h}∆ρ^{*}}{2LρV^{2}}\) \(\frac{D_{h}∆ρ^{*}}{L(\frac{1}{2})ρV^{2}}\) \(\frac{ρV^{2}}{τ_{ω}}\) \(\frac{(\frac{1}{2})ρV^{2}}{τ_{ω}}\) b \(h_{f}=\frac{∆p^{*}}{pg}=\frac{fLV^{2}}{2gD_{h}}\)
\(\frac{∆p^{*}}{p}=\frac{fLV^{2}}{2D_{h}}\)
\(f=\frac{D_{h}∆p*}{\frac{1}{2}LpV^{2}}\)
Where,
Dh = Hydraulic diameter
∆p* = Piezometric pressure
L = Length of duct
ρ = Density
V = Average flow velocity
f = Darcy friction factor		 Comments Active
44 Which of the following statements is true? Impulse turbine occupies more space than reaction turbines for same power output. Impulse turbine occupies more space than reaction turbines for same power output. Impulse turbine occupies double the space than reaction turbine for the same power output Impulse turbine occupies less space than reaction turbine for the same power output d Impulse turbine
Reaction turbine
All the available energy of the fluid is converted into kinetic energy by an efficient nozzle that forms a free jet
Only a portion of the fluid energy is transformed into kinetic energy before the fluid enters the turbine runner
The jet is unconfined and at atmospheric pressure throughout the action of water on the runner and during its subsequent flow to the tail race
Water enters the runner with an excess pressure and then both the velocity and pressure change as water passes through the runner
Blades are only in action when they are in front of the nozzle
Blades are in action all the time
These occupy less space for the same power output
These occupy large space for the same power output
Less efficiency and less power output
Higher efficiency and large power output		 Comments Active
45 In the winter air conditioning for comfort, moisture is added without changing its dry bulb temperature and the air is made to warm up. Identify the type of process. Heating and dehumidification Cooling and dehumidification Heating and humidification Cooling and humidification c In the winter air conditioning for comfort, moisture is added without changing its dry bulb temperature and the air is made to warm up. This type of process is known as heating and humidification.

OA = Humidification
OB = Sensible heating
OC = Dehumidification
OD = Sensible cooling
OE = Heating and humidification
OF = Cooling and dehumidification
w = Specific humidity
t = Temperature (inC) \(°\)		 Comments Active
46 Match column A with column B.
Column A
Column B
A. Velocity compounded impulse turbine
1. Parson turbine
B. Simple impulse turbine
2. Curtis turbine
C. 50% reaction turbine
3. De-Laval turbine		 A-2; B-1; C-3 A-3; B-1; C-2 A-2; B-3; C-1 A-1; B-3; C-2 c Column A
Column B
Velocity compounded impulse turbine
Curtis turbine
Simple impulse turbine
De-Laval turbine
50% reaction turbine
Parson turbine		 Comments Active
47 A steel with the area of cross-section 500 mm2 is acted upon by the forces shown in the figure below. What is the total elongation in the bar if the value of Young's modulus is 200 GPa?
 0.61 mm 0.09 mm 1.21 mm 0.51 mm c Given,
Area of cross-section (A) = 500 mm2
Young's modulus (E) = 200 GPa = 200 × 103 N/mm2
Total elongation () = ? \(δl\)
\(δl=\frac{P_{1}l_{1}}{AE}+\frac{P_{2}l_{2}}{AE}+\frac{P_{3}l_{3}}{AE}\)
\(=\frac{50×10^{3}×600}{500×200×10^{3}}+\frac{35×10^{3}×1000}{500×200×10^{3}}+\frac{45×10^{3 }×1250}{500 ×200×10^{3}}\)
\(=1.21mm\)		 Comments Active
48 What is the maximum coefficient of performance (COP) for an absorption type refrigerator where in heating, cooling and refrigeration occur at temperatures of 1000 C, 200 C and -50 C, respectively? 1.15 4.6 6.9 2.3 d Given,
Evaporator Temperature (Te) = –5C = 268 K \(°\)
Condenser Temperature (Tc) = 20C = 293 K \(°\)
Generator Temperature (TG) = 100C = 373 K \(°\)
\((COP)=\frac{T_{e}(T_{G}-T_{a})}{T_{G}(T_{c}-T_{e})}\)
\(= \frac{268(373-298)}{373(293-268)}\)
= 2.299 = 2.3		 Comments Active
49 Which of the following statements is INCORRECT regarding heat and work? Systems possess heat and work, but not energy. Heat and work are boundary phenomena Heat and work are associated with a process; not with a state. Heat and work are path functions. a • Heat and work both are path function.
• Heat and work both are boundary phenomena, they represent energy in transition.
• Heat and work are not characteristic of the system (Not property of the system).
• Heat and work are associated with process, not with storage (stored energy).
• Heat and work both are in-exact differential.
• Heat is low grade energy.
• Work is high grade energy.
• Heat is energy interaction due to temperature difference only.
• Work is energy transfer by reasons other than temperature difference.		 Comments Active
50 What is the coefficient of performance (COP) of a vapour compression refrigeration system if the enthalpies at the start of compression, at the end of compression and at the end of condensation are 195 kJ/kg, 220 kJ/kg and 95 kJ/kg. respectively? 1 4 0.25 2 b Given,
Enthalpy of inlet of compression (h1) = 195 kJ/kg
Enthalpy of outlet of compression (h2) = 220 kJ/kg
Enthalpy of outlet of condenser (h3) = 95 kJ/kg
= \((COP)_{VCRS }\) \(\frac{h_{1}-h_{4}}{h_{2}-h_{1}}\)
= \((COP)_{VCRS }\) \(\frac{195-95}{220-195}=4\)
= 4 \((COP)_{VCRS }\)		 Comments Active
51 What will be the brake power (BP) of the engine if it is tested with a rope brake dynamometer?
Given, W=Dead load (in Newton), S = Spring balance reading (in Newton), D= Diameter of the wheel (in meters), d = Diameter of the rope (in meters) and N = Speed of the engine shaft (in RPM)s		 BP = \(\frac{(W+S)π(D-d)N}{60}Watts\) BP = \(\frac{(W-S)π(D+d)N}{60}Watts\) BP = \(\frac{(W-S)π(D-d)N}{60}Watts\) BP = \(\frac{(W+S)π(D+d)N}{60}Watts\) b The brake power (BP) of the engine is given by–
BP = \(\frac{(W-S)Ï€(D+d)N}{60}Watts\)
Where, W = Dead load (N)
S = Spring balance reading (N)
D = Diameter of the wheel (m)
d = Diameter of the rope (m)
N = Speed of the engine shaft (rpm)		 Comments Active
52 According to laws of thermodynamics, which of the following statements is INCORRECT? The first law of thermodynamics is the same as the law of conservation of energy. Heat energy can be fully converted into work energy. Fraction of heat energy can be converted into work energy. Work energy can be fully converted into heat energy. b Law of thermodynamics–
• First law of thermodynamics is the same as the law of conservation of energy. It states that energy can be converted from one form to another, but cannot be created or destroyed.
\(∂Q=∂U+∂W\)
• Second law of thermodynamics is not possible to create a cyclical heat engine that draws heat from a reservoir without wasting some heat energy.
• Third law of thermodynamics states that the entropy of the system approaches a constant value as the temperature approaches absolute zero.		 Comments Active
53 Which of the following diagrams is that of a lobe compressor? a Lobe type or roots blower rotary air compressor, in its simplest form, consists of two rotor lobes rotating in an air tight casing which has inlet and outlet ports. There are many designs of wheels, but it generally has two or three lobes.
 Comments Active
54 Which of the following is NOT a type of centrifugal pump? Mixed flow pump Axial flow pump Linear flow pump Radial flow pump c Centrifugal pump can be defined as a mechanical device used to transfer liquid of various types. Centrifugal pumps are used to transport fluids by the conversion of rotational kinetic energy to the hydrodynamic energy of the fluid flow. Comments Active
55 Which of the following options represents the correct order of flow of water in the power conversion of the Pelton wheel turbine? Nozzle, penstock, runner buckets, tail race Penstock, runner buckets, nozzle, tail race Runner buckets, nozzle, penstock, tail race Penstock, nozzle, runner buckets, tail race d Pelton wheel turbine is a tangential flow impulse turbine in which the pressure energy of water is converted into kinetic energy to form a high speed water jet and this strikes the wheel tangentially to make it rotate. Pelton wheel turbine is high head and low discharge turbine.
 Comments Active
56 A cylindrical pipe of diameter 1.5m and thickness 1.5 cm is subjected to internal fluid pressure of 1.2 N/mm2 Determine the longitudinal stress developed in the pipe. 30 N /mm2 15 N/mm2 45 N/mm2 60 N/mm2 a Given, Dia. (d) = 1.5 m = 1500 mm
Thickness (t) = 1.5 cm = 15 mm
Internal fluid pressure (P) = 1.2 N/mm2
Longitudinal stress developed in pipe–
= = = 30N/mm2 \(σ_{ι}\) \(\frac{Pd}{4t}\) \(\frac{1.2×1500}{4×15} \)		 Comments Active
57 In a steady-flow air compressor, air enters at a speed of 5 m/s with a pressure of 1 bar and leaves at a speed of 7.5 m/s with a pressure of 7 bar. If the inlet specific volume is 0.5 m3/kg and the outlet specific volume is 0.15 m3 /kg. what is the ratio of the inlet pipe diameter to the outlet pipe diameter ? 2.236:1 1:2.236 1:1.118 1.118:1 a Given, Inlet air velocity (C1) = 5 m/s
Inlet air pressure (P1) = 1 bar
Inlet specific volume (Ï…1) = 0.5 m3/kg
Outlet air velocity (C2) = 7.5 m/s
Outlet air pressure (P2) = 7 bar
Outlet specific volume (Ï…2) = 0.15 m3/kg
d1/d2 = ?
Conservation of mass
\(\frac{A_{1}C_{1}}{Ï…_{1}}=\frac{A_{2}C_{2}}{Ï…_{2}}\)
\(\frac{(\frac{π}{4}×d12)×5}{0.15}= \frac{(\frac{π}{4}×d22)×7.5}{0.15}\)
\(10d12=50d22\)
= \(\frac{d_{1}}{d_{1}}\) \(5\)
=2.236:1		 Comments Active
58 Which of the following is an INCORRECT statement? Lancashire boiler is a natural circulation boiler. Locomotive boiler is natural circulation boiler. Cochran boiler is a forced circulation boiler. Babcock-Wilcox boiler is a natural circulation boiler. c In natural circulation type of boiler water in boilers takes place due to natural convection currents. In forced circulation, circulation of water is done by a pump. Comments Active
59 The ratio of the power produced by the power supplied by water at the turbine inlet is defined as _____. Mechanical efficiency Overall efficiency monometric efficiency hydraulic efficiency d Hydraulic efficiency is defined as the ratio of power produced by the turbine runner to the power supplied by water at the turbine inlet.
\(n_{hydroulic= \frac{Runner Power (R.P.)}{Water Power (W.P.)}}\)

\(n_{σ}= n_{hydrolic}× n_{mechenical}\)		 Comments Active
60 Based on the following two statements related to the pressure in a static fluid, select the correct option.
Statements:
A) Absolute pressure are always positive, but gauge pressure can be either positive or negative .
B) A gauge pressure of zero corresponds to a pressure that is below the local atmospheric pressure.		 Statement A is incorrect, but Statement B is correct. Statement A is correct, but Statement B is incorrect. Both Statement A and Statement B are incorrect. Both Statement A and Statement B are correct. b Absolute pressure measured with reference to absolute zero. Absolute pressure cannot be negative.

If pressure is measured above atmospheric pressure it is called positive gauge.
If pressure is measure below atmospheric pressure is called negative gauge pressure.
Gauge pressure can be positive, negative or zero.		 Comments Active
61 _______ pressure is measured at any point in a fluid which is non-moving. Differential Hydrostatic Manometric Atmospheric b Hydrostatic pressure refers to the fluid pressure at rest and it is caused due to gravity. Hydrostatic pressure and its measurements are complicated as hydrostatic pressure is easily affected by gravity, open lid tanks, atmospheric pressure, etc.
\(P=ρgh\)
Where, P = Hydrostatic pressure (N/m2)
ρ = Density of liquid (kg/m3)
g = Gravity (9.81 m/s2)
h = Height of the fluid column (m)		 Comments Active
62 The Rankine efficiency of a steam power plant: improves in winter as compared to that in summer worst in winter as compared to that in summer is unaffected by climatic conditions improves in summer as compared to that in winter a In the winter the cooling water temperature is low compared to summer.
η= \(1-\frac{T_{L}}{T_{H}}\)
\(T_{L}↓=h↑\)
Mean temperature of heat rejection is decreases than Rankine efficiency will improve.		 Comments Active
63 Among the following impeller arrangements, which impeller of the centrifugal pump offers the maximum efficiency? Backward-curved blade Radial blade Forward-curved Straight blade a A centrifugal pump is a mechanical device that uses centrifugal force to transport fluids by converting mechanical energy into hydraulic energy. It works on principle of forced vortex motion. The blades of centrifugal pumps are curved backward to prevent overloading of the impeller motor. Comments Active
64 Base on the following two statements related to boilers, select the correct option. Statements:
A) The major drawback in a Lamont boiler is formation and sticking of bubbles in the inner surface of heating tubes.
B) If the boiler pressure is raised to critical pressure, the steam and the water will have the same density and thereby. the risk of bubble formation can be eliminated.		 Statement A is incorrect, but Statement B is correct. Both Statement A and Statement B are correct. but B is not the correct solutions to the problem presented in A. Statement A is correct, but Statement B is incorrect. Both Statement A and Statement B are correct and B is the solution to the problem presented in A. b Lamont boiler is a high pressure (above 170 bar) water tube boiler with internally fixed furnace and the circulation is of forced type. An external agency (pump) is used to circulate the water throughout the tubes of the boiler. If the boiler pressure is raised to critical pressure the steam and the water will have the same density and thereby, the risk of bubble formation can be eliminated. The major drawback in a lamont boiler is formation and sticking of bubbles in the inner surface of heating tubes. Comments Active
65 Match column A with column B.
Column A
Column B
A. Mechanical efficiency
1. Ratio of brake power to indicated power
B. Indicated thermal efficiency
2. Ratio of actual volume to swept volume
C. Volumetric efficiency
3. Ratio of indicated power to fuel power		 A-2; B-3; C-1 A-2; B-1; C-3 A-1; B-3; C-2 A-3; B-1; C-2 c Column A
Column B
Mechanical efficiency
Ratio of brake power to indicated power
Indicated thermal efficiency
Ratio of indicated power to fuel power
Volumetric efficiency
Ratio of actual volume to swept volume		 Comments Active
66 In a fluid flow, if the inertia forces are very large as compared to the viscous force, then the type of flow of fluid is called ______. laminar flow turbulent flow transition flow either laminar flow or turbulent flow b Reynold's Number (Rc) = \(\frac{Inertia force(F_{1})}{Viscous force(F_{v})}\)
According to the question \(F_{1}>R_{e}\)
\(↑F_{1}=R_{e}↑=Flow is turbulent\)
Turbulent flow, fluid particle moves in a zig-zag or in random order. It generally occurs at high velocity.		 Comments Active
67 The velocity profile of a turbulent flow along a wall consists of four regions, characterized by the distance from the wall. The correct sequence of these regions from the wall is: Viscous sub-layer, buffer layer. Transition layer, turbulent layer Viscous sub-layer, transition layer, buffer layer, turbulent layer Buffer layer, viscous sub-layer, transition layer, turbulent layer Buffer layer, transition layer, viscous sublayer, turbulent layer a
• The laminar sub-layer, also called the viscous sublayer is the region of a mainly turbulent flow that is near a no slip boundary and in which viscous shear stresses are important. As such, it is a type of boundary layer.
• The buffer layer is fairly thin but thicker than the viscous sub-layer. The broad region outside the buffer layer and extending all the way to the free surface is called the outer layer.
• Transition is caused by external perturbations, like free-stream turbulence or incident wakes, it is said to bypass orderly route.
• A turbulent boundary layer on the hand is marked by mixing across several layers of it.		 Comments Active
68 What is the pressure increase inside a soap bubble (∆p), , which has two interfaces with air, an inner and outer surface of nearly the same radius 'R' ? (Consider that 'γ' is the coefficient of surface tension.) \(∆ρ=\frac{2γ}{R}\) \(∆ρ=\frac{4γ}{R}\) \( ∆ρ=\frac{γ}{2R}\) \(∆ρ=\frac{γ}{R}\) b Excess pressure inside soap bubble
\((∆ρ)=\frac{8γ}{D}=\frac{8γ}{2R}\)
= \(∆ρ\) \(\frac{4γ}{R}\)		 Comments Active
69 Free air of volumetric flow rate 30m3/min is compressed from 101.3 kPa to 2.23 bar in a Roots blower. Determine the indicated power required. 44.83 kW 36.51 kW 65.72 kW 60.85 kW d Given,
Volumetric flow rate of air (Q) = 30 m3/min
=30/60 m3/sec
P1 = 101.3 kPa
P2 = 2.23 bar =223 kPa
Indicated power of root blower = (223 101.3) \(× \frac{30}{60}\)
= 121.7 × 0.5 = 60.85 kW		 Comments Active
70 Which of following is a defect the would never occur is shielded metal arc welding? Crack Slag inclusion Tungsten inclusion Porosity c Shielded metal arc welding (SMAW) also known as flux shielded arc welding or manual metal arc welding. In shielded metal arc welding, the electrode is consumable. The filler metal is deposited by the arc which is completely surrounded by an inert gas.
There is no tungsten electrode therefore no tungsten inclusion.		 Comments Active
71 Identify the correct options based on the assertion and reason listed below.
Assertion (A): Compounding is done in the turbine.
Reason (R): Compounding is done to prevent over speeding of turbine.		 A is true but R is false A is false but R is true Both A and R are true Both A and R are false c • The compounding of turbine helps to design the turbine of proper size.
• Compounding reduces the speed of the rotor. If the same energy extracted by the single stage the speed of rotor will too high to practical use.
• Minimize the vibration and noises.
• The turbine compounded for high efficiency with reasonable speed, dimensions.
• Reduce the wastage of steam and energy loss due to carry over loss (by the high exit velocity of fluid).
Types of compounding of turbine–
1. Velocity compounding
2. Pressure compounding
3. Pressure-velocity compounding		 Comments Active
72 The specific gravity of a fluid is 0.8.What is its specific weight at 40 C? 7848 N/m3 14000 N/m3 9800 N/m3 12,250 N/m3 a Given, Sp. gravity of a fluid (S.G.) = 0.8
g = 9.81 m/s2
S.G. = \(\frac{ρ_{fluid}}{ρ_{standard fluid}}\)
0.8 = \(\frac{ρ_{fluid}}{1000}\)
800 kg/m3 \(ρ_{fluid}=\)
Sp. weight () = × g \(γ\) \(ρ_{fluid}\)
= 80 × 9.81 = 7848 N/m3		 Comments Active
73 Identify the correct option based on the assertion (A) and reason (R) listed below. Assertion (A): Dam walls are made thicker at the bottom than top. Reason (R): Pressure due to water is highest at the bottom. A is true but R is false Both A and R are false A is false but R is true Both A and R are true d Liquid pressure increases with increasing depth. To withstand the greater pressure at the bottom of a water reservoir, dams are thicker at the bottom than at the top.
\(\frac{∂P}{∂Z}=ρg \)
 Comments Active
74 The basic difference between reversed Carnot cycle and the ideal vapour-compression refrigeration cycle is that a/an__ in the reversed Carnot cycle is replaced with a/an___ in the ideal vapour-compression refrigeration cycle. turbine; expansion valve nozzle; expansion valve turbine; nozzle expansion valve; turbine a The basic difference between reverse Carnot cycle and the ideal vapour-compression refrigeration cycle is that a turbine in the reversed Carnot cycle is replaced with an expansion valve in the ideal vapour compression refrigeration cycle.

Processes (1 - 2): Isentropic compression
(2 - 3): Isothermal compression
(3 - 4): Isentropic expansion
(4 - 1): Isothermal expansion

Processes (1 - 2): Isentropic compression
(2 - 3): Isobaric heat rejection
(3 - 4): Isenthalpic expansion
(4 - 1): Isobaric heat extraction.		 Comments Active
75 Identify the correct statement from the following. In an SI engine, the carburetor supplies grease to the cylinder. In an SI engine, the carburetor supplies only fuel to the cylinder. In an SI engine, the carburetor supplies both air and fuel mixture to the cylinder. In an SI engine, the carburetor supplies both air and grease mixture to the cylinder. c Carburettor is a device which atomises, vapourises, the fuel (petrol) and prepare a homogeneous mixture of fuel vapour and air supply. It according to varying operating conditions of the engine.
This process is known as carburetion.
Carburetion process is affected by–
1. Temperature of incoming air
2. Time available for mixture preparation
 Comments Active
76 Which of the following is NOT a method of steam turbine governing? By-pass governing Throttle governing Nozzle governing Excel governing d The function of a governor in a steam turbine is to maintain its speed constant irrespective of the load. It is done by controlling the supply of steam to the turbine.
Steam turbines are governed by the following methods–
1. Throttle governing
2. Nozzle governing
3. By-pass governing		 Comments Active
77 Identify the odd one on the basis of the number of tubes. Cochran boiler Lancashire boiler Cornish boiler Locomotive boiler c Out of the given options except for cornish boiler rest three are multi-tubular boiler. Hence cornish boiler is the odd one out. Lancashire boiler–It is a horizontal drum axis, natural circulation, natural draught, two tube, low pressure, solid fuel fired tube boiler with internally located furnace.
\(d=\frac{2}{5}D\)
d = dia of fire tube
D = dia of shell
Cornish boiler–It is similar to lancashire boiler in all respects, except there is only one flue tube.
\(d=\frac{3}{5}D\)		 Comments Active
78 A diesel engine has a compression ratio of 15 and heat addition at a constant pressure takes place at 6% of stroke. Find the air standard efficiency of the diesel engine.
(Take γ for air = 1.4.)		 η diesel = 59.5% η diesel = 59.5% η diesel = 41.2% η diesel = 61.2% d
Given, Compression ratio (r) = \(\frac{V_{1}}{V_{2}}=15\)
\(γ=1.4\)
\(V_{3}-V_{2}= \frac{6}{100}V_{s}\)
where, Vs = stroke volume V1 = V2
V3 – V2 = 0.06 (V1 – V2)
V3 – V2 = 0.06 (15V2 – V2)
V3 = 1.84 V2
Cut-off ratio \((ρ)= \frac{V_{3}}{V_{2}}= \frac{1.84V_{2}}{V_{2}}=1.84\)
Air standard efficiency of diesel cycle is given by–
\(n_{diesel}=1- \frac{1}{γ(r)^{γ-1}}(\frac{ρ^{γ}-1}{ρ-1})\)
\(1- \frac{1}{1.4(1.5)^{1.4-1}}(\frac{(1.84)^{1.4}-1}{1.84-1})\)
= 0.6118 ≃ 61.2%		 Comments Active
79 A Carnot cycle runs between ______ adiabatic and ______ isothermal processes. 1,3 2,2 0,4 3,1 b Carnot cycle consists of two isothermal and two isentropic process. Heat is supplied at constant temperature and rejected at constant temperature.

Processes (1 - 2): Isentropic compression
(2 - 3): Isothermal expansion
(3 - 4): Isentropic expansion
(4 - 1): Isothermal compression		 Comments Active
80 What is the effect of increase in the evaporator temperature on the COP of a vapour compression refrigeration cycle?
Statement 1: The coefficient of performance (COP) of a vapour compression refrigeration cycle is directly proportional to the evaporator temperature an inversely proportional to the condenser temperature.
Statement 2: A vapour compression refrigeration cycle with a higher COP is more energy efficient. Considering the above-mentioned question and statements, select the correct option.		 Both Statement 1 and Statement 2 are required to answer the question. Neither Statement 1 nor Statement 2 is required to answer the question. Statement 1 alone is required to answer the question. Statement 2 alone is required to answer the question c
COP = \(\frac{Refrigerating effect}{Work done by compressor}= \frac{RE}{W_{c}}\)
\(COP= \frac{T_{e}}{T_{c}-T_{e}}\)
(COP) \(↑=T_{c}↑\)		 Comments Active
81 Surface tension can also be expressed as___ . force acting per unit length area per unit length torsion acting per unit length velocity per unit length a Surface tension is the tension of the surface film of a liquid caused by the attraction of the particles in the surface layer by the bulk of the liquid, which tends to minimize surface area.
Surface tension N/m J/m2 \(T=\frac{F}{L}\) \(T= \frac{Work done}{Area}\)
Examples of surface tension–
• Insects walking on water.
• Floating a needle on the surface of the water.
• Cleaning of clothes by soaps and detergents which lowers the surface tension of the water.		 Comments Active
82 The law of thermodynamics that hints at the fact that no heat engine can have efficiency equal to 100% is the ______. zeroth law first law second law third law c It is impossible for heat engines to achieve 100% thermal efficiency (η = 1) according to the second law of thermodynamics. This is impossible because some waste heat is always produced in a heat engine, shown in figure

Thermal efficiency, \(n=\frac{w}{Q_{H}}\)		 Comments Active
83 What will be the maximum coefficient of performance (COP) for the vapour absorption cycle if Tg is generator temperature, Tc is environment temperature and Te is refrigerated space temperature? \(\frac{T_{c}(T_{g}-T_{e})}{T_{g}(T_{c}-T_{e})}\) \( \frac{T_{g}(T_{c}-T_{e})}{T_{c}(T_{g}-T_{e})}\) \( \frac{T_{e}(T_{g}-T_{c})}{T_{g}(T_{c}-T_{e})}\) \(∆ρ=\frac{2γ}{R}\) c
COP= \((\frac{T_{G}-T_{A}}{T_{G}})×(\frac{T_{E}}{T_{C}-T_{E}})\)
(COP)max = \(\frac{T_{E}(T_{G}-T_{A})}{T_{G}(T_{C}-T_{E})}\)
TA = TC
(COP)max = \(\frac{T_{e}(T_{g}-T_{c})}{T_{g}(T_{c}-T_{e})}\)		 Comments Active
84 The shear stress at the outer surface of a solid shaft diameter D and torque T is _______. \(\frac{16D^{3}}{πT}\) \(\frac{ 16T}{πD^{3}}\) \(\frac{πD^{3}}{16T}\) \(\frac{T_{c}(T_{g}-T_{c})}{T_{g}(T_{c}-T_{e})}\) b \(\frac{T}{J}= \frac{τ}{R}=\frac{Gθ}{L}\)
\(τ=\frac{T}{J}×R\)

Where,
T = Twisting moment
R = Radius of the shaft
J = Polar moment of inertia
Polar M.O.I. of solid shaft – J= \(\frac{π}{32}d^{4}\)
\(τ=\frac{T}{\frac{π}{32}D^{4}}×\frac{D}{2}\)
\(Ï„=\frac{16T}{Ï€D^{3}}\)		 Comments Active
85 A single-stage, reciprocating air compressor takes in 1.4 kg of air per minute at 1 bar and
170C and delivers it at 6 bar. Assuming that the compression process follows the law pV1.35=constaant, = calculate the indicated power input to the compressor.		 0.26 kW 1.57 kW 3.42 kW 4.43 kW d Given, m = 1.4 kg/min = 0.023 kg/sec
P1 = 1 bar, P2 = 6 bar, T1 = 17ºC = 290 K
PV1.35 = constant
W= \(\frac{n}{n-1}P_{1 V_{1}}\) \(\frac{P_{2}^{ }}{P_{1}^{\frac{n-1}{n}}}\) \(-1\)
W = \(\frac{n}{n-1} mRT_{1}\) \(\frac{P_{2}^{ }}{P_{1}^{\frac{n-1}{n}}}\) \(-1\)
= \(\frac{1.35}{1.35-1}×0.023×287×290×((\frac{6}{1})^{\frac{1.35-1}{1.35}}-1)\)
= 4.43 kW		 Comments Active
86 Calculate the discharge through a convergent mouthpiece of diameter 50mm that is discharge water under a constant head of 20 meters in litre/second. (Consider g = 10 m/s2) 41.25 39.25 37.25 38.25 b Given,
Convergent mouthpiece of diameter (d)=50mm= 0.05m
Head (h) = 20 m, g = 10 m/s2
Discharge (Q) = ?
Q = A× \(2gh\)
= \(\frac{π}{4}d^{2}×2gh\)
= \(\frac{π}{4}×(0.05)^{2}×2×10×20\)
=0.03925 m3/sec
=39.25 litre/sec		 Comments Active
87 High carbon steels have carbon percentage in the range of: 6-8% 11-15% 8-10% 0.6-2% d Types of steel
% of carbon
Dead mild steel
upto 0.15%
Low carbon steel or mild steel
0.15% - 0.3%
Medium carbon steel
0.3% - 0.8%
High carbon steel
0.8% - 1.5%		 Comments Active
88 Which of the following options is NOT considered as an assumption when deriving Bernoulli's equation for a fluid flow? Streamline flow Incompressible flow Unsteady flow Ideal fluid c Assumptions in Bernoulli's equation–
• Fluid is ideal
• Flow is steady
• Flow is non-viscous
• Fluid is incompressible
• Flow is irrotational
• Applicable along a steamline		 Comments Active
89 An efficient lubrication system ensures that...... the engine runs without noise the engine runs roughly the engine runs with greater friction the engine runs with greater noise a The lubrication of engines has the following advantages–
1. The engine runs without noise
2. It reduces wear and tear of the moving parts
3. It damps down the vibrations of the engine
4. It dissipates the heat generated from the moving parts due to friction
5. It cleans the moving parts
6. It makes the piston gas-tight.		 Comments Active
90 As per the boiler regulations, every boiler must be fitted with at least............safety valves. four two five three b These are attached to the steam chest for preventing explosions due to excessive internal pressure of steam. A steam boiler is, usually, provided with two safety valves. Comments Active
91 Match the properties of fluids mentioned in Column (A) with the related parameters mentioned in Column (B).
A. Properties of Fluids
B. Related Parameters
A. Density
1. Reciprocal of Bulk modulus of elasticity
B. Coefficient of compressibility
2. Centistoke
C. Kinematic viscosity
3. J/m2
D. Surface tension
4. Reciprocal of specific volume		 A-1, B-2, C-3, D-4 A-4, B-3, C-2, D-1 A-4, B-1, C-2, D-3 A-2, B-1, C-4, D-3 c Density
Reciprocal of specific volume
Coefficient of compressibility
Reciprocal of bulk modulus of elasticity
Kinematic viscosity
Centistoke
Surface tension
J/m2		 Comments Active
92 A single-stage, reciprocating air compressor is required to compress 1 kg of air from 1 bar to 4 bar. The initial temperature is 270C. Select the correct option.
(Given, W = Work required for isothermal compression, Wpoly = Work required for polytrophic compression (pv1.2 = constant) and Wisen = Work required for isentropic compression)		 W W < Wpoly W > Wisen > Wpoly W > Wpoly > Wisen b
Where, P1 = Initial pressure of air
P2 = Final pressure of air
V1 = Initial volume of air
V2 = Final volume of air
W< Wpoly 		Comments Active
93 Which of the following pressure measurement gauges is gravity based? Pirani gauge McLeod gauge Bourdon tube Manometer d The pressure of a liquid may be measured by the manometers. These are the devices used for measuring the pressure at a point in a liquid by balancing the column of the liquid by the same or another column of liquid. The manometers are classified as follows–
1. Simple manometers such as piezometer and U-tube manometer.
2. Differential manometer.		 Comments Active
94 Which of the following is/are the correct pair(s) of reaction turbines?
1. Francis turbine – Mixed-flow turbine
2. Kaplan turbine – Radial flow turbine
3. Propeller turbine – Axial flow turbine		 Only 1 and 3 Only 2 and 3 Only 1 and 2 Only 1 a Turbine
Turbine type
Flow type
Pelton
Impulse
Tangential flow
Francis
Reaction
Mixed flow (radial in & axial out)
Kaplan
Reaction
Axial flow
Propeller
Reaction
Axial flow		 Comments Active
95 Calculate the head due to friction using Darcy for formula when water flow through a pipe of 100 mm in diameter and 50 m long with velocity of 2 m/s. Assume f = 0.005 and g = 10m/s2. 2.2 1 2.9 2 d Given,
Diameter of pipe (d) = 100 mm
= 0.1 m
Length of pipe (L) = 50 m
Velocity (V) = 2 m/s
Coefficient of friction (f) = 0.005
g = 10 m/s2
Using Darcy's formula
hL = = \(\frac{4fLV^{2}}{2gd}\) \(\frac{4×0.005×(2)^{2}}{2×10×(0.1)}\)
= = 2 \(\frac{4×5×50×4×10}{2×1000×10×1}\)		 Comments Active
96 Which of the following points correctly pairs boiler mountings with primary functions of boilers?
1. Manhole - Melts and releases steam if the water lever in the boiler drops too down.
2. Feed check valve - Prevents backflow of water into the feed pump.
3. Safety valve - Releases excess steam from the boiler to prevent over pressure.
4. Fusible plug - Allows the boiler to be drained for inspection and maintenance.		 1 4 3 2 d Feed check valve - Prevents backflow of water into the feed pump.
Safety valve - Prevents explosions due to excessive internal pressure of steam.
Fusible plug - To protect the boiler from damage due to overheating of boiler tubes by low water level.
Manhole - Which allow access to the water side of the boiler for inspection, cleaning or repairs.		 Comments Active
97 In an engine cooling system, the ........spreads the hot water over a large area. coolant chamber piston rings air valves radiator d In an engine cooling system, the radiator spread the hot water over a large area. Convection is process in which heat transfers takes place between liquid and surrounding air. So radiator there is liquid present which gets heated and emits that heat into atmosphere. So cooling system in motor car works on the principle of convection as a made of heat transfer. Comments Active
98 Match column A with column B.
Column A
Column B

1. Radial vanes

2. Backward curved vanes

3. Forward curved vanes		 A-2, B-1, C-3 A-3, B-1, C-2 A-1, B-3, C-2 A-2, B-3, C-1 b Column A Column B
A Forward curved vanes
B Radial vanes
C Backward curved vanes		 Comments Active
99 Isochoric process means: constant-entropy process constant-pressure process constant-volume process constant-temperature process c A thermodynamic process taking place at constant volume is known as the isochoric process. It is also called an isometric process. In such a process, the work done is zero. The volume of the gas remains constant. Comments Active
100 .........is the pressure that a fluid attains when it is brought to rest isentropically. Stagnation pressure Static pressure Thermodynamic pressure Dynamic pressure a When a fluid particle is brought to rest isentropically at a point then that point is called stagnation point and pressure at this point is called stagnation pressure. Stagnation pressure-Static pressure + Dynamic pressure. When static and stagnation pressures are measured at a specified location, the fluid velocity at that location can be calculated from Comments Active