Skip to content
InsemOct 20222019 patternBE Mech

Heating, Ventilation, Air Conditioning & Refrigeration (HVACR) SPPU Insem Question Paper Oct 2022

All 4 questions from this SPPU insem paper, as printed. Read them here or open the PDF.

Open the PDFMost repeated HVACR questions
Pattern
2019 pattern
Exam
Insem
Session
Oct 2022
Max. marks
30
Time
1 Hour
Semester
VII
Paper code
Oct-22/BE/Insem-54

Printed for: B.E. (Mechanical)

Instructions to the candidates

  1. Answer Q1 or Q2, Q3 or Q4.
  2. Neat diagrams must be drawn wherever necessary.
  3. Figures to the right indicate full marks.
  4. Use of Steam Tables, Mollier charts and electronic pocket calculator is allowed.
  5. Assume suitable data if necessary.

Questions

  1. Q1

    1. a)

      Explain the concept of DART in air refrigeration cycles and compare various air refrigeration cycles using DART.

      Also asked:Aug 2025

      [5]
    2. b)

      Explain the following properties of refrigerants : i) Latent heat of vaporization ii) Boiling point iii) Miscibility. iv) Specific heat of vapour refrigerant v) Critical point

      Also asked:Aug 2025

      [10]

  2. Q2

    1. a)

      Write note on: (i) ODP (ii) Secondary Refrigerants iii) LCCP

      [6]
    2. b)

      The following data refers to a bootstrap air cycle evaporative refrigeration cycle used for an evaporator to take 20 tonnes of refrigeration load : Ambient air temperature = 15°C Ambient air pressure = 0.8 bar Mach number of flight = 1.2 Ram efficiency = 90% Oct-22/BE/Insem-54 2 Pressure of air after main compressor = 4 bar Pressure of air after secondary compressor = 5 bar Isentropic efficiency of main compressor = 90% Isentropic efficiency of secondary compressor = 80% Isentropic efficiency of cooling turbine = 80% Temperature of air leaving the first heat exchanger = 170 °C Temperature of air leaving the second heat exchanger = 155 °C Cabin pressure = 1 bar : Cabin temperature = 25 °C Find : i) Draw neat temperature entropy plot of given system ii) Temperature of air at the entry of main compressor iii) Actual pressure of air at the entry of main compressor iv) Actual temperature of air at the exit of main compressor Actual temperature of air at the exit of secondary compressor.

      Also asked:Aug 2025

      [9]

  3. Q3

    1. a)

      Explain with schematic and p-h diagram CO 2 -NH 3 cascade refrigeration system.

      [6]
    2. b)

      A R134a refrigeration system works with two evaporators, individual expansion valves, individual compressors and with single condenser find, i) Mass of refrigerant circulated in each evaporator, ii) Compressor power for each compressor and total power iii) COP of the system. Assume that the refrigerant leaving each evaporator is dry and saturated and the liquid refrigerant leaving the condenser is saturated liquid. Compression is isentropic in each compressor. Oct-22/BE/Insem-54 3 Draw process on Ph chart provided and attach as supplement Tempt (°C) Pressure (Bar) hf (kJ/kg) hg(kj/kg) cooling load –20 1.350 172 387 4 TR 0 2.90 199 398 2 TR 40 11.00 258 418 - USe P-h chart to find ‘h’ at exit of compressor

      [9]

  4. Q4

    1. a)

      Explain a two-stage vapour compression cycle with flash chamber for gas removal and intercooling with schematic and P-h diagram. Also write formula to calculate COP.

      [6]
    2. b)

      A typical multi-pressure system is shown in below figure with R134a as refrigerant in the cycle. Refrigerant is subcooled by 10 °C at the condenser exit. Consider the exit of each evaporator to be saturated vapour. Find i) Draw neat Log P Vs h plot on the R 134a chart provided and attach as supplement ii) Mass flow rate through each evaporator iii) Cooling load on condenser iv) C.O.P of system Oct-22/BE/Insem-54 4 Oct-22/BE/Insem-54 5 

      [9]