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Register Number:                                                                     3201
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                    DIPLOMA EXAMINATION - 2010
                 (REFRIGERATION AND AIR CONDITIONING)
                                        (PAPER – I)
                         110. THERMAL ENGINEERING
May.)                                                                        (Time: 3 Hours
                                 Maximum: 100 Marks
                           Answer any FIVE questions                         (5×20=100)
            Steam table, Heat and Mass Transfer data books permitted

  1. A fluid system undergoes a non flow frictionless following the pressure volume relation
     as p = 4.5/v +2 where p is in bar and v is in m3. During the process, the volume changes
     from 0.12 m3 to 0.04m3 and the system rejected 40kj of heat. Determine the change in
     internal energy and enthalpy.
  2. In a steady flow system, the working fluid flowing at 5kg/sc enters the system at 6 bar
     with a velocity of 300m/s. Its internal energy is 150kj/kg and specific volume is 0.4
     m3/kg. the pressure, velocity, internal energy and specific volume values at exit are
     1.5bar, 150m/s, 100J/Kg and 1.26m3/kg respectively. The substance loses 5kj/kg heat as
     it passes through the system. Determine the power of the system.
  3. State and derive the expression of clauses theorem.
  4. Draw a neat diagram of vapour compression refrigeration system and explain its working.
  5. A large window glass 0.5 cm thick (k=0.78 W/ m K) is exposed to warm air at 25º C,
     over its inner surface, with convection coefficient of 15 W/m2 K. The outside air is at =
     15º C, with convection coefficient of 50 W/m2 K. Determine the heat transfer rate and
     temperature at inner and outer surface of the glass.
  6. Air at 10º C and at a pressure of 100 kPa is flowing over a plate at a velocity of 3m/s. if
     the plate is 30cm wide and at temperature of 60º C. Calculate the following quantities at
     x = 0.3m
       Boundary layer thickness
         Local friction coefficient
         Heat transfer from the plate
  7. Derive an expression for Nusselt number for laminar film condensation on a vertical
     surface.
  8. A heat exchanger is required to cool 55000 kg/h alcohol from 66º C to 40º C using
     40000kg/h of water entering at 5º C. Calculate exit temperature of water, area and heat
     transfer rate in parallel flow arrangement
        Take U = 580 W/m2 K
        Cp (alcohol) = 3760J/kg.K
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