Ideal refrigeration cycle is
Same as Carnot cycle
Same as reverse Carnot cycle
Dependent on the refrigerant's properties
The least efficient of all refrigeration processes
Correct Answer :
B. Same as reverse Carnot cycle
Related Questions
Degree of freedom of the system ice-watervapour will be
0
1
2
3
In case of an __________ process, the temperature of the system increases.
Isothermal compression
Isothermal expansion
Adiabatic expansion
Adiabatic compression
dW and dq are not the exact differential, because q and W are
State functions
Path functions
Intensive properties
Extensive properties
Sound waves propagation in air exemplifies an __________ process.
Adiabatic
Isothermal
Isometric
None of these
Which of the following is Clausius-Clapeyron Equation for vaporisation of an ideal gas under the condition that the molar volume of liquid is negligible compared to that of the vapor?
d ln p/dt = Hvap/RT2
d ln p/dt = RT2/Hvap
dp/dt = RT2/Hvap
dp/dt = Hvap/RT2
Any substance above its critical temperature exists as
Saturated vapour
Solid
Gas
Liquid
Which of the following is not a common refrigerant?
Freon-12
Ethylene
Ammonia
Carbon dioxide
When a system is in equilibrium for all possible processes, the differential or finite change of entropy is
< 0
> 0
= 0
None of these
In a turbine, the fluid expands almost
Isothermally
Isobarically
Adiabatically
None of these
Enthalpy changes over a constant pressure path are always zero for __________ gas.
Any
A perfect
An easily liquefiable
A real
Out of the following refrigeration cycles, which one has maximum COP?
Air cycle
Carnot cycle
Ordinary vapor compression cycle
Vapor compression with a reversible expansion engine
The expression for entropy change, ΔS = n Cp . ln (T2/T1), is valid for the __________ of a substance.
Simultaneous pressure & temperature change
Heating
Cooling
Both (B) and (C)
Joule-Thomson co-efficient which is defined as, η = (∂T/∂P)H = 1/Cp (∂H/∂T)P, changes sign at a temperature known as inversion temperature. The value of Joule-Thomson co-efficient at inversion temperature is
0
∞
+ve
-ve
Pick out the wrong statement.
Cp of monatomic gases such as metallic vapor is about 5 kcal/kg.atom
The heat capacity of solid inorganic substance is exactly equal to the heat capacity of the substance in the molten state
There is an increase in entropy, when a spontaneous change occurs in an isolated system
At absolute zero temperature, the heat capacity for many pure crystalline substances is zero
Entropy of an ideal gas depends upon its
Pressure
Temperature
Both (A) & (B)
Neither (A) nor (B)
Melting of ice exemplifies a/an
Adiabatic process
Endothermic reaction
Exothermic reaction
Process involving a chemical reaction
In an irreversible process
Tds = dE - dW = 0
dE - dW - Tds = 0
Tds - dE + dW < 0
Tds - dT + dW < 0
Gibbs-Helmholtz equation is
ΔF = ΔH + T [∂(ΔF)/∂T]P
ΔF = ΔH - TΔT
d(E - TS) T, V < 0
dP/dT = ΔHvap/T.ΔVvap
Internal energy of an ideal gas
Increases with increase in pressure
Decreases with increase in temperature
Is independent of temperature
None of these
A gas can be liquefied by pressure alone only, when its temperature is __________ its critical temperature.
Less than
More than
Equal to or higher than
Less than or equal to
With increase in pressure (above atmospheric pressure), the Cp of a gas
Increases
Decreases
Remains unchanged
First decreases and then increases
Clapeyron Equation deals with the
Rate of change of vapour pressure with temperature
Effect of an inert gas on vapour pressure
Calculation of ΔF for spontaneous phase change
Temperature dependence of heat of phase transition
During a reversible isothermal expansion of an ideal gas, the entropy change is
+ve
0
-ve
∞
What is the degree of freedom for two miscible (non-reacting) substances in vapor-liquid equilibrium forming an azeotrope?
0
1
2
3
When a gas is expanded from high pressure region to low pressure region; temperature change occurs. This phenomenon is related to the
Gibbs-Duhem equation
Gibbs-Helmholtz equation
Third law of thermodynamics
Joule-Thomson effect
Which of the following has the minimum value of COP for a given refrigeration effect?
Reverse Carnot cycle
Ordinary vapour-compression cycle
Vapour-compression process with a reversible expansion engine
Air refrigeration cycle
The minimum number of phases that can exist in a system is
0
1
2
3
Specific volume of an ideal gas is
Equal to its density
The reciprocal of its density
Proportional to pressure
None of these
Pick out the wrong statement.
Enthalpies of all elements in their standard states are assumed to be zero
Combustion reactions are never endothermic in nature
Heat of reaction at constant volume is equal to the change in internal energy
Clausius-Clapeyron equation is not applicable to melting process
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