1. No category

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Roll No.
I I I I I I I I I
Total No. of Questions:
Total No. of Pages:
03
09
B.Tech (ME) (Sem.-6th)
REFRIGERATION
AND AIR-CONDITIONING
Subject Code: ME-304
Paper 10 : [A0820]
Time:
3 Hrs.
INSTRUCTIONS
1.
2.
3.
Max. Marks : 60
TO CANDIDATES
SECTION·A Is COMPULSORY
consisting of TEN questions carrying
TWO marks each.
SECTION·B contains FIVE questions carrying FIVE marks each and
students have to attempt any FOUR questions.
SECTION·C contains THREE questions carrying TEN marks each and
students have to attempt any TWO questions.
SECTION-A
I. Answer briefly:
a) What is difference between boiling and evaporation?
b) Draw vapour
compression
refrigeration
cycle on T-S diagram
for
which super heat horn is zero.
c) Can there happen any rise in temperature
during throttling
process,
how?
d) What are advantages
of S02 as refrigerant?
e) What is difference between flash intercooler and water intercooler?
f)
What is the working principle of thermoelectric
refrigeration?
g) What is significance of wet bulb depression?
h) What is alignment circle?
i)
In sensible cooling of air what is the minimum temperature to which it
can be cooled and why?
j)
List any three applications
[N- 2-68
of cryogenic system.
SECTION-C
SECTION-B
2. An air refrigerator
working on the principle
air enter into the compressor
of Bell-Coleman
cycle. The
is at 1 atm at _lOoC. It is compressed
to
10 atm and cooled to 40°C at the same pressure. It is then expanded to
1 atm and discharged to take cooling load. The air circulation is 1 kg/so
The isentropic efficiency of the compressor
7. A compound
load purposes.
cooling
saturated.
and
refrigeration
system (as shown in figure) is used for multi
Freon-12
suction
is used as a refrigerant.
vapour
to compressor
Using p-h chart determine;
There is no under
C-I is also
dry
&
power required to run the system
& COP of the combined system.
= 80%
The isentropic efficiency of the expander = 90%
Find the following:
i.
Refrigeration
capacity of the system
ii. C.O.P. of the system
Take
r=
1.4,
c, =
1.00 kJ/kgOC
EV2
3. Derive an expression for volumetric efficiency for a reciprocating refrigerant
compressor.
possible
Using P-V diagram
suction pressure
establish
the condition
for a fixed discharge
factor and hence derive an expression
pressure
and clearance
for the minimum possible suction
pressure.
the prescribed
method
of refrigerant
designation
to assign
designation for following refrigerants:
i.
8. a) With the help of a neat sketch explain the working of thermostatic
expansion valve.
4. Explain the need and working of three stage Cascade system of refrigeration.
5. Describe
b) What is By-pass factor of cooling coil? Explain with neat diagram.
Also give its significance.
9. Explain the following psychrometric processes :
Dichlorodifluoromethane
a) Cooling and Dehumidification
ii. Ammonia
b) Heating and Humidification.
iii Butane
iv. Ethylene
6.
39.6 m3/min of a mixture of re-circulated
a cooling coil at 31°C DBT and 18.5
temperature of the coil is 4.4°C. The
as would give 12.5 kW of refrigeration
Using psychometric chart determine the
room air and outdoor air enters
"C WBT. The effective surface
surface area of the coil is such
with the given entering air state.
dry and wet bulb temperatures of
the air leaving the coil and the coil by-pass factor.
[N- 2-68
EVI
for minimum
[N- 2-68