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Refrigeration and Air Conditioning 4-1 Set-4 (K).doc (Size: 346 KB / Downloads: 8)
Explain the working of Bell Colemann cycle with a neat sketch. [9] (Unit-I, Topic No. 1.3)
Explain how does the body attempt to compensate for a cool environment which tends to lower the internal
temperature. [6] (Unit-VII, Topic No. 7.1)
Explain the methods that are to be employed to improve the C.O.P of a vapour compression refrigeration
system. [8] (Unit-II, Topic No. 2.1)
Distinguish between dry and wet compression. What are the advantages of one over the other? [7]
(Unit-II, Topic No. 2.1)
With a neat sketch explain the working of automatic expansion valve. [8] (Unit-III, Topic No. 3.4)
Explain how Ozone is depleted by CFCs. [7] (Unit-III, Topic No. 3.5)
With a neat sketch explain the working of simple vapour absorption system. [7] (Unit-IV, Topic No. 4.1)
In an absorption type refrigerator, the heat is supplied to NH3 generator by condensing steam at 2 bar and 90%
dry. The temperature to be maintained in the refrigerator is – 5° C. The temperature of the atomosphere is 30° C.
Find the maximum possible COP of the refrigerator. If the refrigeration load is 20 tons and actual COP is 70% of
maximum COP. Find the mass of steam required per hour. [8] (Unit-IV, Topic No. 4.2)
In a steam jet refrigeration installation, the steam is available at 6.5 bar dry and saturated and chilled water flash
chamber is kept at 5 cm of Hg. The mixture of steam and flashed water at the entry of the diffuser has a quality
of 0.90. Assuming nozzle efficiency 0.90, mixing efficiency 0.67 and diffuser efficiency 0.78 and make up water
at 28° C. Determine,
(i)
Mass of motive steam per kg of flashed vapour
(ii) Mass of motive steam per ton of refrigeration effect
(iii) COP
(iv) COP as compared to an ideal cycle. [10] (Unit-V, Topic No. 5.1)
Explain with a neat diagram, the working of vortex tube. [5] (Unit-V, Topic No. 5.3)
Draw and explain the comfort chart and zone of comfort for year-round air conditioning. [7]
(Unit-VII, Topic No. 7.1)
A sling psychrometric reads 44° C DBT and 30° C WBT. Calculate the following,
(i)
Specific humidity
(ii) Relative humidity
(iii) Dew point temperature
(iv) Enthalpy of mixture assume pressure of atmospheric air to be 1.013 bar. [8] (Unit-VI, Topic No. 6.1)