Out of the following refrigeration cycles, which one has the minimum COP (Co-efficient of performance)?
Air cycle
Carnot cycle
Ordinary vapour compression cycle
Vapour compression with a reversible expansion engine
Correct Answer :
A. Air cycle
Related Questions
Henry's law is closely obeyed by a gas, when its __________ is extremely high.
Pressure
Solubility
Temperature
None of these
The partial molar enthalpy of a component in an ideal binary gas mixture of composition Z, at a temperature T and pressure P, is a function only of
T
T and P
T, P and Z
T and Z
In an ideal gas mixture, fugacity of a species is equal to its
Vapor pressure
Partial pressure
Chemical potential
None of these
Heat of formation of an element in its standard state is
0
< 0
> 0
A function of pressure
Heating of water under atmospheric pressure is an __________ process.
Isochoric
Isobaric
Adiabatic
Isothermal
Which of the following processes cannot be made reversible even under ideal condition of operation?
Free expansion of a gas
Compression of air in a compressor
Expansion of steam in a turbine
All (A), (B) & (C)
4 kg moles of an ideal gas expands in vacuum spontaneously. The work done is
4 J
∞
0
8 J
The partial pressure of each constituent present in an alloy is __________ the total vapor pressure exerted by the alloy.
Less than
Equal to
More than
Either (B) or (C); depends on the type of alloy
COP of a refrigerator drawing 1 kW of power per ton of refrigeration is about
0.5
3.5
4.5
8.5
Claude's liquefaction process employs the cooling of gases by
Expansion in an engine
Following a constant pressure cycle
Throttling
None of these
The expression, nRT ln(P1/P2), is for the __________of an ideal gas.
Compressibility
Work done under adiabatic condition
Work done under isothermal condition
Co-efficient of thermal expansion
Which of the following exemplifies an adiabatic process?
Melting of ice
Condensation of alcohol vapor
Sudden bursting of a cycle tube
Evaporation of water
Specific/molar Gibbs free energy for a pure substance does not change during
Sublimation
Vaporisation
Melting
Either (A), (B) or (C)
The internal energy of an ideal gas is a function of its __________ only.
Molecular size
Volume
Pressure
Temperature
Out of the following refrigeration cycles, which one has the minimum COP (Co-efficient of performance)?
Air cycle
Carnot cycle
Ordinary vapour compression cycle
Vapour compression with a reversible expansion engine
An irreversible process
Is the analog of linear frictionless motion in machines
Is an idealised visualisation of behaviour of a system
Yields the maximum amount of work
Yields an amount of work less than that of a reversible process
All gases above its inversion temperature, in a throttling process will show
A heating effect
No change in temperature
A cooling effect
Either (A) or (C)
In Joule-Thomson porous plug experiment, the
Enthalpy does not remain constant
Entire apparatus is exposed to surroundings
Temperature remains constant
None of these
The unity of Planck's constant 'h' in the equation, E = hv is
J/s
J.S
J/kmol
kmol/J
Critical temperature is defined as the temperature above which a gas will
Not liquify (barring exceptions)
Immediately liquify
Never liquify however high the pressure may be
None of these
The expression for the work done for a reversible polytropic process can be used to obtain the expression for work done for all processes, except reversible __________ process.
Isobaric
Isothermal
Adiabatic
None of these
The effect of changing the evaporator temperature on COP as compared to that of changing the condenser temperature (in vapour compression refrigeration system) is
Less pronounced
More pronounced
Equal
Data insufficient, can't be predicted
The number of degrees of freedom at the triple point of water is
0
1
2
3
Rotary lime kiln is an example of a/an __________ system.
Closed
Open
Isolated
Non-thermodynamic
The reaction A (l) → R(g) is allowed to reach equilibrium conditions in an autoclave. At equilibrium, there are two phases, one a pure liquid phase of A and the other a vapor phase of A, R and S. Initially A alone is present. The numbers of degrees of freedom are:
1
2
3
0
Consider the reaction, C + O2 CO2; ΔH = - 94 kcal. What will be the value of ΔH for the reaction CO2 → C + O2?
-94 kcal
+94 kcal
> 94 kcal
< -94 kcal
For the reversible exothermic reaction, N2 + 3H2 2NH3, increase of pressure would
Shift the equilibrium towards right
Give higher yield of NH3
Both (B) and (C)
Neither (A) nor (B)
If the heat of solution of an ideal gas in a liquid is negative, then its solubility at a given partial pressure varies with the temperature as
Solubility increases as temperature increases
Solubility increases as temperature decreases
Solubility is independent of temperature
Solubility increases or decreases with temperature depending on the Gibbs free energy change of solution
Pick out the undesirable property for a good refrigerant.
High thermal conductivity
Low freezing point
Large latent heat of vaporisation
High viscosity
The theoretical minimum work required to separate one mole of a liquid mixture at 1 atm, containing 50 mole % each of n- heptane and noctane into pure compounds each at 1 atm is
-2 RT ln 0.5
-RT ln 0.5
0.5 RT
2 RT