
	Trending ▼ ICSE CBSE 10th ISC CBSE 12th CTET GATE UGC NET Vestibulares ResFinder

2003 Course Refrigeration & Air Conditioning

6 pages, 40 questions, 0 questions with responses, 0 total responses,

	pune_eng	+Fave Message
	Profile Timeline Uploads Q & A

Home > pune_eng >

Instantly get Model Answers to questions on this ResPaper. Try now!
NEW ResPaper Exclusive!

Formatting page ...

Total No. of Questions : 12] P1042 [Total No. of Pages : 6 [3864]-153 B.E. (Mech.) S/W REFRIGERATION AND AIR CONDITIONING (2003 Course) Time : 3 Hours] [Max. Marks : 100 Instructions to the candidates: 1) Answer any three questions from each section. 2) Answers to the two sections should be written in separate books. 3) Use of logarithmic tables, slide rule, Mollier charts, electronic pocket calculator and steam tables is allowed. 4) Assume suitable data, if necessary. SECTION - I Q1) a) Discuss the advantages of air as a refrigerant in air- craft. [4] b) Explain necessity of air-craft refrigeration. [4] c) Explain the analysis of simple air -refrigeration system with the help of p-h diagram. [8] OR Q2) a) b) An aircraft is cruising with a speed of 900km/h at an altitude of 11000 m, where the ambient conditions are 0.3 bar and -30o C. Assuming the compression ratio 5, cabin pressure 0.8 bar and air leaving the cabin at 27o C, obtain the power for pressurization and refrigeration and COP. The flow rate through the system is 1 kg/s. [12] Explain the term Ram Efficiency . [4] Q3) a) Differentiate between dry compression and wet compression. Why expansion device is used in VCC instead of expander. Discuss with the help of P-V and T-S diagram. [8] b) An ice production machine produces 20 tons of ice in 24 hours when water is supplied at 0o C. The temperature range of the machine is - 15o C to 25o C. The vapour leaves the compressor in dry and saturated conditions and there is no under-cooling in the condenser. If the actual C.O.P., is 75% of theoretical, find the power required of a compressor. P.T.O. The properties of NH3 used in machine as refrigerant are Given below:[8] Temperatureo C hf (kJ/kg) sf (kJ/kg-K) hg (kJ/kg) 25 100.4 0.349 1324 -15 -54.77 -0.214 1310 OR Q4) a) Discuss briefly the factors affecting the choice of refrigerants commonly used in refrigerating plants. [8] b) Explain the losses occurred in actual vapour compression cycle with the help of p-h and T-s diagram. [8] Q5) a) What is necessity of multi staging? Explain the analysis of two stage compression system with flash gas chamber as a flash intercooler. [8] b) A two-stage refrigeration system works between the pressures limits 40o C and - 15o C. Obtain the COP and capacity for a flow rate of 0.2 kg/s through the evaporator. The intermediate pressure is 4.238 bar. Compare the COP and capacity of the two stage system with a corresponding single stage operating between the above pressure limits. The refrigerant used is R-12. [10] OR Q6) a) In a vapour absorption refrigeration system,. the refrigeration -15o C. The generator is operated by solar heat where the temperature reached is 110o C, the temperature of heat sink is 55o C. What is the maximum possible COP of the system? [6] b) Explain with neat sketch lithium bromide refrigeration system. [6] c) Explain with neat sketch Cascade refrigeration system. Why CO2 is a suitable refrigerant for this system. [6] SECTION - II Q7) a) b) Sketch comfort chart and show on it the comfort zone . The values obtained from a sling psychrometer are DBT 30 C and WBT 20 C. The barometric reading is 740 mm of Hg. Calculate : [10] i) DPT and RH. ii) [3864]-153 [6] degree of saturation. 2 iii) specific humidity. iv) specific volume and v) specific enthalpy. OR Q8) a) Use of adsorbent for air conditioning system for hot and humid climate.[4] b) What is the effective temperature? What are the factors that influence the optimum effective temperature? [4] c) A room is to be cooled using a desert cooler having humidification efficiency of 70% in desert area where the environmental condition is 45o C DBT and 15% RH. The room size is 10m 5m 4m high. Electrical appliances and occupancy heat load amounts 3 kW, overall HTCs, Uwall = 0.95 W/m2 o C and that of the ceiling as 2.5 W/m2 o C. The air leaves the room at 3o C above the cooler exit temperature. Determine i) volume flow rate of air to be humidified, ii) water evaporated per 8 hour of operation, iii) area of desert cooler if the velocity of air across the desert cooler is 0.75 m/s. [8] Q9) The following data refer to a 200 capacity theater. Room condition: DBT 26o C, RH 50%, room dimension 15m 10m 10m high with 15m side as EW oriented. Outside condition: DBT 42o C, w = 0.02 kg/kg of d.a.U w a l l =4 kJ/m 2-h-K (S and W), U wall=2.4 kJ/m 2-h-K (E & W), Ucelling = 3 kJ/m2-h-K, Udoor = 3 kJ/m2 -h-K. Door size 2 m 1 m on the north side. Solar radiation amounts of 19.5% of the structure heat load. No smoking and ventilation air equal to the make-up air. Air enters the theater at 17o C. Sensible energy release from persons is 60% of the total energy release and rest as latent heat. The make up air is mixed before the coil. Electric appliances inside the room equivalent to 3 kW. Duct and blower heat gains are equivalent to 8000 kJ/h and 4 kW respectively. Determine a) RSHF. b) Amount of ventilation air. c) Inlet conditions of air entering theatre. d) Amount of air supply to theatre. e) TR of coil. f) GSHF and ADP. [16] [3864]-153 3 OR Q10)a) List the various equipments used in an air conditioning system. Explain the function of each. [6] b) Explain the working of thermostatic expansion valve. [6] c) Explain the procedure of charging of refrigerant in the system. [4] Explain pressure losses in duct. [6] Q11)a) b) Why the ducts are used in an air-conditioning system. Classify ducts.[4] c) Derive an expression for the equivalent diameter of circular duct corresponding to a rectangular duct of sides a and b for the same pressure loss per unit length when i) the quantity of air passing through both the ducts is same, and ii) the velocity of air flowing through both the ducts is same. [8] OR Q12)a) b) [3864]-153 What is Cryogenics? Discuss its applications. [8] Explain construction and working of Linde system liquefaction of gas.[10] 4 [3864]-153 5 ccc [3864]-153 6

Formatting page ...

Tags : Pune, Engineering, University of Pune, Engineering question papers, Pune University, previous year question papers, question papers, india, model question paper, pune university paper pattern, pune university syllabus, old question papers

pune_eng chat

Horizontal lines at:
Guest Horizontal lines at:
AutoRM Data:
Box geometries: