TITLE.PM5

912 ENGINEERING THERMODYNAMICS

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32. Match List I (Gadgets undergoing a thermodynamic process) with List II (Property of the
    system that remains constant) and select the correct answer using the codes given below
    the Lists :
    List I List II
    A. Bomb calorimeter 1. Pressure
    B. Exhaust gas calorimeter 2. Enthalpy
    C. Junker gas calorimeter 3. Volume
    D. Throttling calorimeter 4. Specific heats
    Codes :
    (a) ABCD (b) ABCD
    3412 2413
    (c) ABCD (d) ABCD
    3142 4321


33. Consider the following statements :
    The maximum temperature produced by the combustion of an unit mass of fuel depends upon
    
    
    1. LCV 2. ash content 3. mass of air supplied 4. pressure in the furnace.
       Of these statements :
       (a) 1 alone is correct (b) 1 and 3 are correct
       (c) 2 and 4 are correct (d) 3 and 4 are correct.
    
    
    
    


34. The graph shown in the Fig. 15 represents
    the emission of a pollutant from an SI engine
    for different fuel/air ratios. The pollutant in
    question is
    (a) CO
    (b) CO 2
    (c) hydrocarbon
    (d) NOx.


35. Which of the following are the assumptions
    involved in the auto-ignition theory put forth for the onset of knock in SI engines?
    
    
    1. Flame velocity is normal before the onset of auto-ignition.
    
    
    2. A number of end-gas elements autoignite simultaneously.
    
    
    3. Preflame reactions are responsible for preparing the end-gas to ignite.
       Select the correct answer using the codes given below :
       (a) 1 and 2 (b) 1 and 3
       (c) 2 and 3 (d) 1, 2 and 3.
    
    
    
    


36. In a vapour compression refrigeration system, a throttle valve is used in place of an
    expander because
    (a) it considerably reduces the system weight
    (b) it improves the COP, as the condenser is small
    (c) the positive work in isentropic expansion of liquid is very small
    (d) it leads to significant cost reduction.

Fig. 15

Volume (per cent)

0.8 0.9 1.0 1.1 1.2

Equivalence ratio