ENROLLMENT NO.
EXAMINATION APRIL 2024
M.E. II Sem. (Grading) [Mechanical Engg.] {Heat Power Engg.)
Refrigeration Systems
Subject Code: ME116A
Paper Code: MAB2204
Time: Three Hours
No. of Pages: 02
Min. Mxriw
Instructions:
01. Attempt any five questions.
02. All questions carry equal marks.
03. Assume data suitably if necessary.
Q.1(a) Discuss the physical and
thermodynamics properties of the following rsirigerants;
R-11, R-12, R-22, R-410a, and R-134a. Also discuss the leak
detection in each case.
(b) What are binary mixtures? How analysis is made
to find parameters ike mole fracions, mass
fractions etc. for liquid and vapour mixture?
Q.2 A domestic refrigerator with 150W
-25°C evaporator and +55°C condenser refrigeration capacity operates on simple saturation cycle with
temperature for R - 12 and R. 134a. Calculate and
compare the specific volunme of suction vapour, refrigerating effect, mass flow rate, discharge
temperature, piston, displacement, power consumption and C.O.P. Also compare their pressure
dropsacross capillary.
Q.3 (a)What are the advantages of nultistage vapour
compression system over a single stage system?
sLt) Explain the cascade refrigeration system with the help of neat
of system. diagram. Write expression for C.0.P.
Q.4 A cascade refrigeration system is required to produce 20 TR at evaporator temperature of - 70°C
with R-13 in the low temperature cascade compressor. Heat is rejected in the cascade condenser at
20°C. The cascade condenser is cooled by high
temperature
overlap of cascade condenser is 10°C. Heat is rejected in thecascade using R- 22. Temperature
water cooled condenser at 40°C.
Assume simple saturated cycle for both low temperature and high temperature
cascade circuit.
Determine:
(i) Compression ratio for both cascades
(ii) Mass flow rate for both cascade
(iii) Piston displacement and power required to run the compressors
Q.5 (a) What are the advantages and disadvantages of centrifugal compressor over
compressor? reciprocating
(b) Compare the performance of reciprocating and centrifugal compressors,
Q.6 (a) Explain the working principle of thermostatic expansion valve with the help of neat diagram. Also
discuss heat pump in detail.
(0) What do you mean by solar powered absorption system? Explain in detail with the help of a neat
sketch.
Arefrigcration installation using R-134 consists of one compressor, one condenser and three,
Q.7 evaporators of 35 kW, S2 kW and 70 kW capacities. The temperature to be maintained in the
evaporators is correspondingto the pressures off4 bar(10°C); 2bar ( -10°C) and 1bar
Calculate:
respectively. There is no sub-cooling. (-30°C)
(i) The mass flow rate in each evaporator
(ii) Compressor power
(iii)COP
Assume that the vapour leaving each evaporator is in dry and saturated state and condenser
pressure is 10 bars.
Q.8 Write short note on any two of the following:
(i) Solar powered refrigeration system.
(ii) Automatic expansion valve; and
(iii) Multipressure System with Flash Chamber.
MAB2204,5w22
14a24
ENROLLMENT NO.
EXAMINATION APRIL 2024
M.E. II Sem. (Mechanical Engg.] {Heat Power Engg.}
Control Theory & Systems
Subject Code: MEl14
Paper Code: MAB2202
Time: Three Hours
Maximm Mar%s: 70
No. of Pages: 02 isnum Marks: 28
Instructions:
01. Attempt any five questions. All questions carry equal mar ks.
02. Assume suitable data if necessary.
03. Make suitable assumptions if required.
04. Draw neat sketches to support your answers.
05. Give suitable examples to support your answers.
06. Notations & symbols have their usual meaning.
Q.1 What do you understand by "Continuous data contrul systems and "Discrete
data-data control
systems'"? Explain the difference between these two with examples.
Q.2 Find the closed loop transfer function of the system shown below:
System"? Explain "Integral
Q.3 What do you understand by Performance Indices" and Adaptive Control
Square Error".
characteristic equation is:
Q4 Sketch the Root Locus" diagram for a feedback control system,whose
1+LssGl=0 example.
between time and frequency response with neat diagram &an
Q.5 Discuss the correlation Also
Parallel compensation" with neat diagrams.
and
Q.6 Differentiate between "Series compensation"
discuss the advantages ofDigital Control Systems". characteristics with a
describe the flapper valve
Q.7 Explain the working of pneumatic flapper nozzle &
suitable diagram. Cont...
Q.8 Write short notes (any two):
controllc.s
() Servo mechanisms, Regulators and process
(11) Steady state error and error constants
(iii) Concept of state variable and state model
(iv) Proportional + rate controller
MAB2202p5sie
1k24
ENROLLMENT NO.
EXAMINATION APRIL 2024
M.E. II Sem. [Mechanical Engg.]{Heat Power Engg.}
Design of Heat Exchanger Equipments
Subject Code: ME115
Paper Code: MAB2203
Time: Three Hours
No. of Pages: 02 Maximnum Marks: 7h
Instructions:
01. Attempt any five questions.
02. Allquestions carry equal marks.
03. Draw neat sketch and assume suitable data wherever you
required.
Q.1 (a) Explain various fouling mechanism that may occur on the liquid side of a heai
cxchunger.
| ) What is corrosion? What are its effects on heat exchanger? Discuss the remedial measures to be
used toavoid it in a heat exchanger.
What is Fouling resistant? Describe Fouling resistances in plate heat exchangers.
(b) Based on constructional features classifies heat exchangers.
Q.3 (a) Explain heat pipe heat exchanger for gas to gas application with the help of neat diagram.
b ) What is compact heat exchanger? Enlist their characteristics as compared to conventional shelland
tube exchangers.
Q.4 (a)When a correction factor will become unity.
(b) 20 kg/s of benzene [c = 1,650 J/(kg. K)] must be cooled down from 35 to 30°C. It is intended to
use 4 kg/s of cooling water, available at 20°C. What would be the reduction in the heat exchanger
area if the water flow rate were doubled?
Q.5 (a) What is number of transfer unit (NTU)? What does it indicates? Derive the relationship
between
effectiveness andNTUfor a counter flow single pass heat exchanger.
(by What do you understand by thermal analysis of a heat exchanger? What are the
advantages of
using computer software for designing a heat exchanger?
Q.6 (a) Under what condition, the effectiveness NTU method is preferred over LMTD method as a method
of analysis of Heat exchanger.
(b) A double-pipe heat exchanger is used to condense steam at a rate of 113.7 kgh at 50°C. Cooling
water (brackish water) enters through the tubes at a rate of 0.9 kg/s at 10°C. The specific enthalpy
of phase change h'g of water is 2382.7 kJ/kg and the specific heat of water is 4.18 kJkg K. The
tube (25.4 mm OD and 22.1 mm ID) is made of mild steel (k-45 W/m²K). The heat transfer
Coefficient on the steam side is 10,000 W/m2. Kand that on the cooling water side 8000 W/m».K.
Inside and outside fouling resistances Rei and Reo are 0.176 and 0.088 mKkW, respectively.
Determine the outside surface area reguirement for the nlain tube for clean and fouled exchangers.
Cont...
water at
acetorie at a pressure of 120 kPa using cooling
Q.7 It is desired to condense 8,000 kg/h of
of acetone is 61°C. A cooling water fow rate
35°C. At this pressure, the condensation temperature
following design was proposed:
of 100 mh will be used. After some preliminary trials, the
N= number oftubes: 192
L= tube length: 4 m
Tube diameters: Do: 19.05 mm, Di: 14.4 mm; triangular array,
30 degrees; tube pitch: 23.81 mm
Ds= shell diameter = 438 mm
N= number of tube passes: 2
B=baffles spacing: 450 mm
Physicalproperties are as follows:
Vapour Liquid
Density, kg/m³ 2.54 738
Viscosity, cP 0.0072 0.215
Thermal conductivity, W/(m.k) 0.0147 0.142
Specific heat, J/(kg.k) 1,381 2,255
Heat of condensation, kJ/kg 497.5
Verify whether this unit is suitable to be installed in horizontal and vertical positions and
calculate
the pressure drops for acetone and the cooling water. Use a total fouling factor of
0.0005
(m². k)/W.
Q.8 A triple effect evaporator is concentrating a liquid that has no
appreciable elevation in boiling
point. The temperature of the steam to the Ieffect is, the boiling point of the solution in
the last
effect is 52. The overall heat transfer coefficient in arc 2500 in Ieffect, 2000 in II
effect and 1000
in II effect. At what temperature will the liquid boil in the Iand II
effects.
MAB2203/5m20
14024
ter at
ate ROLLMENT NO.
M.E. II Sem. EXAMINATION
(Grading) APRIL
Numerical Methods[Mechanical
2024
Engg.] {Heat
in Fluid Flow & Het Power ngg}
Subject Code: ME113 Transfer
ine: Three Hours Paper Code: MAB2201
No. ofPages: 01
astructions: Max. Marks: 70
Min. Marks: 28
01. Attempt any5 questions.
02. All questions carry equal marks.
03. Use of heat transfer
data book is permitted.
0.1 (a) What do you
understand by PDEs and ODE? State their
, Lb List 5 classification.
numerical mnethods and discuss advantages of using
transfer over other methods. numerical methods for fluid flow and heat
0.2 (a) Explain basics of Finite
Difference Methods (FDMs) used in heat conduction. State
Discretization and Consistency. about their
(b) Explain OS algorithm applied in
solving fluid flow and heat transfer problems.
Q.3 (a) What do you mean by the term
Matrix Inversion? Discuss its techniques.
b) Compare Explicit and Implicit schemes.
Q.4 (a) Write and discuss
(b) Compare
fundamental/governing equations used in fluid flow and heat transfer.
() Steady and Transient heat conduction
(i)) Free and force convection.
5 (a) Define boundary layer
formation? Compare laminar and turbulent flow.
(b) Write and discuss Nevior Stroke
Equation. State its applications and limitations
Q.6 (a) Explain Conservative and
transportive properties of fluid flow.
6) Discuss Treatment of
non-linearity.
What are the various waysto represent
computational data? Discuss few important techniques.
(b) Explain the GS iterative
Q.8
technique.
Write a short technical note on
following (any tvro):
() Pre and post processing of heat
transfer problems
(iü) Continuity Equation in fluid
flow
(iii) ADI Method
(iv) Turbulent Viscosity
BAK2201/05w16
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