Thermodynamics Mechanical Interview Questions and Answers pdf free download

131.    Thermal power plant works on
(a) Carnot cycle  
(b) Joule cycle
(d)    Rankine cycle
(d) Otto cycle
(e)    Brayton cycle.
Ans: c

132.    Which of the following is an irreversible cycle
(a) carnot  
(b) Stirling
(c) ericsson  
(d) all of the above
(e) none of the above.
Ans: e

133.    Otto cycle consists of following four processes
(a)    two isothermals and two isentropics
(b)    two isentropics and two constant volumes
(c)    two isentropics, one constant volume and one constant pressure
(d)    two isentropics and two constant pressures
(e)    none of the above.
Ans: b

134.    The efficiency of a Carnot engine depends on
(a)    working substance
(b)    design of engine
(c)    size of engine
(d)    type of fuel fired
(e)    temperatures of source and sink.
Ans: e

135.    For same compression ratio and for same heat added
(a)    Otto cycle is more efficient than Diesel cycle
(b)    Diesel cycle is more efficient than Otto cycle
(c)    efficiency depends on other factors
(d)    both Otto and Diesel cycles are equal¬ly efficient
(e)    none of the above.
Ans: a

136.    The efficiency of Carnot cycle is maximum for
(a)    gas engine
(b)    well lubricated engine
(c)    petrol engine
(d)    steam engine
(e)    reversible engine.
Ans: e

137.    Carnot cycle is
(a) a reversible cycle (ft) an irreversible cycle
(c)    a semi-reversible cycle
(d)    a quasi static cycle
(e) an adiabatic irreversible cycle.
Ans: a

138.    Diesel cycle consists of following four processes
(a)    two isothermals and two isentropics
(b)    two isentropics, and two constant volumes.
(c)    two isentropics, one constant volume and one constant pressure
(d)    two isentropics and two constant pressures
(e)    none of the above.
Ans: c

139.    If both Stirling and Carnot cycles operate within the same temperature limits, then efficiency of Stirling cycle

as compared to Carnot cycle
(a)     more  
(b)     less
(c)    equal
(d)    depends on other factors
(e)    none of the above.
Ans: c

140.    Stirling and Ericsson cycles are
(a)    reversible cycles
(b)    irreversible cycles
(c)    quasi-static cycles
(d)    semi-reversible cycles
(e)    adiabatic irreversible cycles.
Ans: a

141.    A cycle consisting of two adiabatic and two constant pressure processes is known as
(a) Otto cycle      
(b) Ericsson cycle
(c) Joule cycle     
(d) Stirling cycle
(e) Atkinson cycle.
Ans: c

142.    Reversed joule cycle is called
(a)    Carnot cycle
(b)    Rankine cycle
(c)    Brayton cycle
(d)    Bell Coleman cycle
(e)    Dual cycle.
Ans: c

143.    Brayton cycle consists of following four processes
(a)    two isothermals and two isentropics
(b)    two  isentropics  and two constant volumes
(c)    two isentropics, one constant volume and one constant pressure
(d)    two isentropics and two constant pressures
(e)    none of the above.
Ans: d

144.    Which of the following cycles is not a reversible cycle
(a) Carnot  
(b) Ericsson
(c) Stirling  
(d) Joule
(e) none of the above.
Ans: e

145.    The cycle in which heat is supplied at constant volume and rejected at constant pressure is known as
(a)    Dual combustion cycle
(b)    Diesel cycle
(c)    Atkinson cycle
(d)    Rankine cycle
(e)    Stirling cycle.
Ans: c

146.    The efficiency of Diesei cycle with decrease in cut off
(a) increases  
(b) decreases
(c) remains unaffected
(d) first increases and then decreases
(e) first decreases and then increases.
Ans: a

147.    Which of the following cycles has maximum efficiency
(a) Rankine  
(b) Stirling
(c) Carnot  
(d) Brayton
(e) Joule.
Ans: c

148.    The ideal efficiency of a Brayton cycle without regeneration with increase ni pressure ratio will
(a) increase  
(b) decrease
(c) remain unchanged
(d) increase/decrease depending  on application
(e) unpredictable.
Ans: a

149.    The ideal efficiency of a Brayton cycle with regeneration, with increase in pressure ratio will
(a) increase  
(b) decrease
(c)    remain unchanged
(d)    increase/decrease depending on application
(e)    unpredictable.   

Ans: b

150.    The following cycle is used for air craft refrigeration
(a)    Brayton cycle
(b)    Joule cycle
(c)    Carnot cycle
(d)    Bell-Coleman cycle
(e)    Reversed-Brayton cycle.
Ans: e

151.    Gas turbine cycle consists of
(a)    two isothermal and two isotropic
(b)    two isentropics and two constant volumes
(c)    two isentropics, one constant volume and one constant pressure
(d)    two isentropics and two constant pressures
(e)    none of the above.
Ans: d

152.    The thermodynamic difference between a Rankine cycle working with saturated steam and the Carnot cycle is that
(a)    carnot cycle can't work with saturated steam
(b)    heat is supplied to water at temperature below the maximum temperature of the cycle
(c)    a rankine cycle receives heat at two places
(d)    rankine cycle is hypothetical
(e)    none of the above.
Ans: b