Punjab University 2006 B.Tech REFRIGERATION AND AIR CONDITIONING - Question Paper

REFRIGERATION AND AIR CONDITIONING

Note: part A is compulsory. Attempt any 4 ques. every carrying five marks from part B and any 2 every carrying 10 marks from part C.

part A (10 x two = 20)

I

1. Write any 5 applications of refrigeration.
2. Differentiate ranging from Heat engine and Heat pump.
3. Compare open cycle and closed cycle refrigeration systems.
4. What is the effect of subcooling and superheating on refrigeration work in VCR systems?
5. Draw a sketch of Electolux refrigeration system.
6. Write applications of steam jet refrigeration and mention its limitations.
7. describe RSHF and Bypass factor.
8. Differentiate ranging from Ventilation load and Infiltration load.
9. Differentiate ranging from split A/C system and window A/C system.
10. Write the advantages of cooling towers used in refrigeration industry.

part B (4 x five = 20)

II A Bell-Coleman cycle works ranging from one bar and six bar pressure limits. The compression and expansion indices are 1.25 and 1.3 respectively. find COP and tonnage of the unit for an air flow rate of 0.5 kg/sec. Neglect clearance quantity and take temperatures at the beginning of compression and expansion to be seven oC and 37 oC respectively.

III A five ton Freon-12 refrigeration plant has saturated suction temperature of -5 oC. The condensation takes place at 30 oC and there is no undercooling of refrigerant liquid. Assuming isentropic compression obtain (i) COP (ii) Mass flow rate of refrigerant (iii) power needed to drive the compressor in kW. Take the subsequent properties of Freon-12 and Cpv= 0.615 kJ/kgK.
P T hf hg sg
(bar) (oC) (kJ/kgK) (kJ/kgK) (kJ/kg)
8 30 130 265 1.55
3 -5 -- 250 1.57

IV Draw a neat sketch of Linde and Claude cycles and compare both cycles in their construction.

V discuss with a neat sketch the working of thermostatic expansion valve.

VI elaborate the different leak detection systems used in refrigeration industry and discuss any one.

part C (2 x 10 = 20)

VII
(a) Compare VAR system with VCR system.
(b) discuss with a neat sketch the working of NH3-H2O VAR system. Write its applications.

VIII Write the Detailed procedure foe estimating the cooling load of a computer centre with 100 capacity.

IX
(a) discuss the importance o comfort chart.
(b) Distinguish ranging from water inter cooling and Flash inter cooling of a compound compression system.

Earning:   Approval pending.