Roll No. ......................

Total No. of Questions : 09]. UV/"'I---

[rotal No. of Pages: 03

B.Tech. (Sem. - 6th)

REFRIGERATIONAND AIR CONDITIONINGSUBJECT CODE : ME -304

Paper ID : [A0820]

[Note: Please fiU subject code and ,Japer ID on OMR]

Maximum Marks: 60Time: 03 Hours

Instruction to Candidates:

Q1)

"

1)

2)

3)

Section -A is Compulsory.

Attemptany Four questionsfromSection- B.. .

Attempt any Two questions from Section -C.

Section -A

(10 X 2 =20)

a) Name the main components of a refrigeration system.

b) Which type of aircraft refrigeration system is preferred for very highspeed of planes & why?

c) What is the purpose of boot strap compressor?

d) What are the desirable properties of an absorption system refrigerant?

e) What do you understand by steamjet refrigeration?

f)

g)

Define bypass factor.

What are cooling towers?

h) Differentiate sensible and latent heat load.

i) . What do you understand by dry bulb and wet bulb temperatures?

j) Compare field of application of various refrigerants.

,M-729 {1859J P.T.o.

Section - B """

(4 X 5 =20)

Q2) Explain in detail by taking suitable example, how expansion of air causesrefrigerationeffect? .

Q3) Compare Linde and Claude system for liquefaction of air. .

Q4) Discuss the advantages and disadvantages along with working and principleof domestic Electrolux refrigerator. .

Q5) 40 m3of air at 35° C DBT and 50% RR is cooled 25° C DBT maintaining itsspecific humidity as constant. Calculate the

(a) Relative humidity (RR) of cooled air.

(b) Heat removed from air.

Q6) Discuss in detail the role"ofducts, dampers and air filters in air conditioningsystem.

Section -C

(2 xlO =20)

Q7) Discuss and plot simple vapour compression cycle on temperature entropychart in following conditions . .

(a) When vapou:r:.is dry and saturated at the end of compression.

(b) When.yapour is super heated after compression.

(c) When vapour is wet after compression.

Q8) (a) Discuss the compound compression with water intercooler and singleexpansion valve with neat sketches.

(b) 28 tonnes of ice'from and at 0° C is produced per day ip an ammoniarefrigerator. The temperature range in the compressor is from 25° C.to-15°C. The vapour is dry and saturated at the end of compression and anexpansion valve is used. Assuming the COP of 62% of the theoreticalcalculate the power required for driving the compressor.

M-729

Take latent heat of ice = 335 kJ/kg.

2

Temp °C Enthalpy(kJ/kg) Entropy of liquid Entropy of

Liquid Vapour kJ/kg K VapourkJ/kgK25 100.04 1319.22 0,3473 4.4852

-15 -54.56 1304.99 -2.1338, 5.0585

Q9) The following data relates to~acold storage for storing 450 tonnes of vegetables.

If tl)e air conditioning is achieved by first c'oolingand dehumidifyingand thenheating and the,temperature of air entering the room is not to exceed 16° Cdetenhine

(a) Amount of recirculated air, if the recirculated air is mixed with fresh airbefore entering the cooling coil. ' , '

(b) Capacity of the cooling coil in tonnes of refrigeration and its by pas~factor if the dew point temperature of the coil is 6° C and

(c) Capacity of heating coil inkW.

~~~.....- - - ~

'.,

M-729 J

Inside design conditions 19° CDBT60% RH

Outside design conditions 36° C DBT 28° C WBT

Infiltrated air 180 m3/ min

Fresh air supply 4500 m3/ min"

No. of prs(jns working in cold store 20

Sensible heat gain.through glass, 16.3 kW .walls, ceiling etc. .

I

Water content of vegetables 74%.-.Loss of water content . 0.01 (0 per hour

Heat from equiplnent and reaction 3.1 kW

heat of vegetables