Test: Availability, Irreversibility, Thermodynamic Relations - 1 - Mechanical Engineering MCQ

A control mass gives out 10 kJ of energy in the form of heat transfer at 500°C. Find the change in availability of the control mass.

For a steady flow process from state 1 to 2, enthalpy changes from h1 = 400 kJ/kg to h₂ = 100 kJ/kg and entropy changes from s₁ = 1.1 kJ/kg-K to s₂ = 0.7 kJ/kg-K. Surrounding environmental temperature is 300 K. Neglect changes in kinetic and potential energy. The change in availability of the system is:

Consider the following statements:

Availability is the maximum theoretical work obtainable.

Clapeyron's equation for dry saturated steam is given by  

A gas can have any temperature at a given pressure unlike a vapour which has a fixed temperature at a given pressure.

Joule Thomson coefficient is expressed as    

Of these statements

Neglecting changes in kinetic energy and potential energy, for unit mass the availability in a non-flow process becomes  where ɸ is the availability function of the 

The irreversibility is defined as the difference of the maximum useful work and actual work: I = W_max,useful- W_actual. How can this be alternatively expressed?

Which of the following statement is incorrect?

An inventor claims that heat engine has the following specifications:

Power developed = 50 kW; Fuel burned per hour = 3 kg

Heating value of fuel =75,000 kJ per kg; Temperature limits = 627°C and 27°C

Cost of fuel = Rs. 30/kg; Value of power = Rs. 5/kWh

Increase in entropy of a system represents

Assertion (A): When a gas is forced steadily through an insulated pipe containing a porous plug, the enthalpy of gas is the same on both sides of the plug.

Reason (R): The gas undergoes an isentropic expansion through the porous plug.

Availability of a system at any given state is:

Consider the following two processes:

a. A heat source at 1200 K loses 2500 kJ of heat to sink at 800 K

b. A heat source at 800 K loses 2000 kJ of heat to sink at 500 K

Which of the following statements is TRUE?

What is the loss of available energy associated with the transfer of 1000 kJ of heat from a constant temperature system at 600 K to another at 400 K when the environmental temperature is 300 K?

Assertion (A): The change in availability of a system is equal to the change in the Gibbs function of the system at constant temperature and pressure.
Reason (R): The Gibbs function is useful when evaluating the availability of systems in which chemical reactions occur.

Availability function for a closed system is expressed as:

Consider the following statements:

1. Availability is generally conserved

2. Availability can either be negative or positive

3. Availability is the maximum theoretical work obtainable

4. Availability can be destroyed in irreversibility

Of these correct statements are: 

Assertion (A): All constant entropy processes are adiabatic, but all adiabatic processes are not isentropic.

Reason (R): An adiabatic process which resists the exchange of energy to the surroundings may have irreversibility due to friction and heat conduction.

What will be the loss of available energy associated with the transfer of 1000 kJ of heat from constant temperature system at 600 K to another at 400 K when the environment temperature is 300 K?