vv Y _ DO NOT OPEN THIS TEST BOOKLET UNTIL YOU ARE ASKED: TO DO SO

T.B.C. : R-FTF-M-NFA Test Booklet Series

Serial No.

TEST BOOKLET

MECHANICAL ENGINEERING ( OBJECTIVE-TYPE )

PAPER-I

T_ime lAllowed : Two Hours Maximum Marks : 200

INSTRUCTIONS

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DOV NOT OPEN THIS TES?` BOOKLET UNTIL YOU ARE ASKED TO DO SO

(b)

(C)

(d)

(a)

(b)

(d)

(a)

(b)

(C)

(d)

1. In highly rareñed gases, the concept

of this loses validi-ty

(a) ‘Thermodynamic equilibrium

Continuum

Stability

Macroscopic viewpoint

2. The constant volume gas thermometer Works on the principle that

at low pressure, the temperature of the gas is independent of its pressure at constant volume

at high pressure, the temperature of the gas is independent of its pressure at constant volume

.atl low pressure, the temperature of the gas is proportional to its pressure at constant volume

at high pressure, the temperature of the gas is proportional to its pressure at constant volume

3. There is no work transfer involved in

this process

Adìabatic expansion

Isothermal expansion

Polytropic expansion

Free expansion

4.. ThisV` process is one in which there is only work interaction between the system and the surroundings

(a)

" (b)

(C)

(d)

Diabatìc process

Adiabatic process

Isothermal process

Quasi-static process

5. In which of the following processes, the heat is fully converted into work?

(a)

(b)

(C)

(d)

6. An

Reversible adiabatic process

Reversible isobaric process

Reversible isometric process

Reversible isothermal process

inventor states that his new

conceptual engine, while operating

between

temperature limits of

377 “C and 27 °C, will reject 50% of heat absorbed from the source. What type of cycle will this engine have?

(a)

(b)

(C)

(d)

Carnot cycle

Stirling cycle

Impossible cycle

Possible cycle

I 7. The continual motion of a movable

9. A heat engine

device in absence of friction

(a) violates the first law of

thermodynamics

(ß) violates the second law of

thermodynamics

second kind

(d) is the perpetual motion of the

third kind

8. For a given temperature T1, as the

difference between T1 and T2 increases, the COP of a Carnot heat

Pump

(a) increases

(b) decreases

(d) ñrst decreases, then increases

11.

is supplied with 2512 kJ/min of heat at 650 °C. Heat rejection with 900 kJ/rnin takes place at 100 °C. This type of heat engine is

(a) ideal

(b) irreversible

(d) practical

10.

Consider the following statements for

a throttling process :

1. It is an adiabatic process.

2. There is no work transfer in the

process.

3. Entropy increases in throttling

process.

Which of these statements are

correct?

(a) 1, 2 ands

(b) 1 and i2 only

(d) l and 3 only

If the work done on a closed system is 20 kJ/kg, and 40 kJ/kg heat

is rejected from the system, its internal energy“ decreases by

. A Carnot heat pump is used'to heat a house.-The outside temperature is -3 rJC and the indoor temperature is 27 °C. If the heat loss from the houseis 40 kW, the power required to operate theheat pump is

. The enthalpy drop for flow through convergent horizontal nozzles is 100 kJ/kg. If the velocity 0f approach at inlet to the nozzle is negligible, the Vexit velocity of the fluid is

(a) 20 m/s

(b) 400

(d) 520'8

. By integrating Euler equation between two sections 1 and 2 for

flow of an incompressible inviscid fluid through a pipe, we get

(a) steady flow energy equation

(b) Bernoulli equation

(d) variable flow equation

15. For steady flow through an insulated

horizontal constant diameter pipe, this property remains constant

(a) Enthalpy

(b) Internal energy

(d) Volume

16. 100 kJ of energy is transferred from

a heat reservoir at 1000 K to a heat

reservoir at 500 K. The ambient

temperature is 300 'K1 The loss of available energy due to heat transfer process is

17. When a system reaches the state of

equilibrium, `the following property assumes its maximum value

(a) Availability

(b) Entropy

{c} Gibbs function

(d) Helmholtz function

18. The difference between constagt pressure speciñc heat Cp and constant volume speciñc heat Cv for pure substance

(a) approaches zero at triple point

{b} approaches zero as the abso

lute teraperature approaches

zero

constant R

(d) approaches zero at critical

point

19. Joule-Thomson coefficient is the

slope of

(a) constant enthalpy lines on T-s

diagram

(b) constant enthalpy lines on T-p

diagram

(d) inversion curve on T-p diagram

20. Which gas shows a heating effect

in the Joule-Thomson experiment, while undergoing throttling process through a porous plug of cotton wool?

(a) Carbon dioxide

(b) Hydrogen

(d) Nitrogen

21. The following remarks pertain to _the

properties of gases and vapours :

1. The equation of state is not by itself sufficient for the calculation of pï'operties such as u, h and s.

"2. Throttling process is an

adiabatic steady flow process.

3. Increase in entropy in wet region is directly proportional to the increase in enthalpy.

Which of these remarks are correct?

(a) 1, 2 and 3

(b) 1 and 2 only

(d) 2 and 3 only

22. An ideal gas at 27 “C is heated at

constant pressure till the volume becomes three times. The temperature of the gas will then be

23. A gas turbine operating on Brayton

cycle has the maximum temperature of 1200 K and the minimum temperature of 300 K. The cycle efficiency for the maximum work capacity will be

(a) 75%

(b) 60%

(d) 25%

.24. No substance can exist in the liquid

phase in stable equilibrium

(a) at temperature below the triple

point temperature

(b) at pressure the triple

point pressure

point pressuŕe

(all)l at temperature above the triple

point temperature

25. The COP of a refrigerator working

on a reversed Carnot cycle is The ratio of the highest absolute temperature to the lowest absolute temperature would be

26. This reversible cycle consists of

Constant volume heat addition, reversible adiabatic expansion and constant pressure heat rejection

(a) Otto cycle

(b) Lenoir cycle

(d) Brayton cycle

27.

28.

‘l Ya) Increasing p1

An ideal vapour compression refrigerator operates between a condenser Vpressure pl and an evaporator pressure p2. Which of the following changes would increase its COP?

by Ap and keeping p2 constant

(b) Decreasing p2 by Ap and

keeping p1 constant

(d) Subcooling the refrigerant

An absorption refrigeration system is supplied with energy Q1 in the form of heat at temperature T1, while it extracts energy 03 as heat from a cold space at temperature T3. The ambient temperature is T2. Then the COP of the refrigerator is (ignoring the small amount of energy supplied in the pump)

29. For a 2-stage air compressor for the maximum ei'ñciency of compressor, consider the following statements :

P2 = JP1 'P3

Intercooling between the stages

is complete.

Work is equally shared by the two stages.

Which of these _statements are

correct?

(a)

(b)

(C)

(d)

land 4 only

1, 3 and4

2,3 and4

2 and 3 only

30. An IC engine has a bore and stroke each equal to 2 units. The total area to calculate heat loss from the

engine can be taken as

(a)

(b)

(C)

(d)

31. In a petrol engine, the tendency for

detonation increases with

(a)

(b)

(C)

(d)

retardec-Í» spark timing

running the engine at high speed

supercharging

increasing the cooling rate

32. Consider the following statements:

Diesel are compared using an ‘ignition delay criterion.

Cetane number is equal to the percentage of cetane plus 15% of the percentage of heptamethyl nonane in the

Cetane number of alphamethyl naphthalene is assigned the value of 15.

Which of these statements are

correct?

(b)

(C)

(d)

1,2ands

1 and 2 only

2 and 3 only

1 and 3 only

33. When a hydrocarbon fuel burns in insufñcìent air, the Orsat apparatus for flue gas analysis will show which of the following sets of gases?

(a)

(b)

(C)

(d)

34. A satellite floats

with very high velocity.

in deep space It will

continuously lose heat by

(a)

(b)

(C)

(d)

convection

conduction and convection

radiation

radiation and convection

35. A furnace has a 2O cm thick wall with thermal conductivity W/rn-K. For the same heat loss from the furnace, what will be the thickness of the wall if the thermal

çonductivity of the material is

36. Which of the following expressions gives the thermal resistance for heat conduction through a hollow sphere of radii r1 and r2?

41rkr1 r2

(a)

(C)

(d)

where k is thermal conductivity of the material.

37. A furnace wall is 10 cm thick and

has a thermal conductivity of kW/rn-K. Inner temperature is maintained at 525 °C, while the surrounding _temperature outside the furnace is 25 °C. If the surface area of the furnace is 20 m2, the heat flux through the wall is

(a) 50 kw/m2

(b) 500 kw/m2

(d) 10000 kw/m2

38. In unsteady-state heat conduction for bodies with negligible temperature gradients, the timetemperature variation curve is

(a) linear

(b) parabolic

(d) exponential

39. The fouling factor in heat exchanger

is deñned as

40. For quick response of a thermocoupqle to observe varying temperatures of Huids

1 (a) wire diameter must be large

(b) wire material density must be

large

{c} wire material specific heat

must be large

(d) wire surface heat transfer coefñcients must be large

'41. A will be necessary and effective

only when

(a) k'is small and h is large

(b) k is large and h is also large

(d) k is large and h is small

where k =thermal conductivity of fm material, h=convective heat transfer coefficient between the

surface and environment

temperature.

42. Which one of the following

statements is correct?

(a) Fins should be attached on the side Where heat transfer

.coefficients are high

(b) Effectiveness of depends

on thermal conductivity only

(d) In boiling heat transfer appliances, ñns will be very eíïective

43. In a heat exchanger, the hot gases enterwith a temperature of 150 °C and leave at 75 °C. The cold fluid

enters at 25°C and leaves at

125 "C. The capacity ratio of the exchanger is

44. What .does NTU indicate?

(a) Effectiveness of'heat exchanger

(b) Efñciency of heat exchanger

._ (c) Size of heat exchanger

(d) Temperature drop in heat

exchanger

45. When is a transient heat transfer

problem considered as a lump capacity problçm?

(a) The internal resistance of the

object is negative

(b) The internal resigtançe of the

object is zero

object is infinite

(d) The internal resistance of the

object is negligible

46. The correct sequence for different

types of rheat exchangers in the decreasing order of effectiveness is

(a) parallel-flow, .counterñow, shell

öl» tube and cross-flow

(b) cross-flow, counterflow“, shell 81.

tube and parallel-flow

cross-flow and parallelëilow

(d) counterflow, cross-How, shell 8:

tube and parallel-flow

47. In laminar flow over a flatplate, the 50. The laminar boundary layer occurs convective heat transfer coefficient when a cold fluid flows over a hot is proportional to (x is the distance plate. In which of the following from the leading edge) positions, the temperature gradient

l assumes zero value2 (a) r2

_l (b.) x 2 ifa) At bottom of boundary layer

„l Y (d) x E (c) At top of boundary layer

48. In a double-pipe counterñow heat (d) At the junction OfIamînaI" and exchanger, 1000 kg/h of oil having turbulent boundary layer

a specific heat 20 J /kg-K is cooled from 150 °C to A 125 ‘C by 1250 kg/h of fluid of speciíìc heat 5]" The

Reynolds-Colburn analog, 16 J / kg-K. The iluid leaves the heat

which is used to determine heat exchanger at 75 In Such Case» transfer coefficient from the

the temperature at which the measurement of frictional drag, is cooling fluid- is entering the heat applicable to

exchanger and LMTD will be

(a) 25 °C and 50 °C (a) circumferential ñns

(b) 50 c'C and 50 ‘C

(b) flat plates

{d} 75 @C and 50 .C (c) rectangular fins

. _ (d) triangular ñns 49. Whlch of the followmg properties ,f

of air increase with rise in temperature?

52. An oxygen and nitrogen mixture has transmissivity for heat radiations

2. Specific heat that is practically equal to

3. Thermal conductivity

1. Speciñc gravity

4. Kinematic viscosity (a) 1

(a) 1, 2, 3 and 4 (b) 0.5 (b) 1, 2 and 3l only

(d) 1 and .4 only {d} O