Thermodynamics

Air is compressed adiabatically in a steady flow process with negligible change in potential and kinetic energy. The work done in the process is given by

Which one of the following is the extensive property of a thermodynamic system?

The time constant of a thermocouple is the time taken to attain

For the expression $ \int pdv $ to represent the work, which of the following conditions should apply?

For a closed system, the difference between the heat added to the system and the work done by the system is equal to the change in

Change in internal energy in a reversible process occurring in a closed system is equal to the heat transferred, if the process occurs at constant

A reversible engine operates between temperatures 900 K and $ T_2 $ ($ T_2 < 900 \text{ K} $), and another reversible engine between $ T_2 $ and 400 K ($ T_2> 400 \text{ K} $) in series. What is the value of $ T_2 $ if work outputs of both the engines are equal?

A Carnot engine operates between $ 327^\circ\text{C} $ and $ 27^\circ\text{C} $. If the engine produces 300 kJ of work, what is the entropy change during heat addition?

In which one of the following situations the entropy change will be negative?

Neglecting changes in kinetic energy and potential energy, for unit mass the availability in a non-flow process becomes $ a = \phi - \phi_0 $, where $ \phi $ is the availability function of the

Define thermodynamic equilibrium. With the help of practical example, explain the phenomenon of achieving a thermodynamic equilibrium of system.

0.1 $ \text{m}^3 $ of an ideal gas at 300 K and 1 bar is compressed adiabatically to 8 bars. It is then cooled at constant volume and expanded isothermally so as to reach the condition from where it started. Calculate (i) pressure at the end of constant volume cooling, (ii) change in internal energy during constant volume process and (iii) net work done and heat transferred during the cycle.

What is SFEE? Derive the SFEE equation of an open system.

Air at a temperature of $ 20^\circ\text{C} $ passes through a heat exchanger at a velocity of 40 m/s where its temperature is raised to $ 820^\circ\text{C} $. It then enters a turbine with same velocity of 40 m/s and expands till the temperature falls to $ 620^\circ\text{C} $. On leaving the turbine, the air is taken at a velocity of 55 m/s to a nozzle where it expands until the temperature has fallen to $ 510^\circ\text{C} $. If the air flow rate is 2.5 kg/s calculate (i) rate of heat transfer to the air in the heat exchanger, (ii) the power output from the turbine assuming no heat loss, (iii) the velocity at exit from the nozzle, assuming no heat loss. Take the enthalpy of air as $ h = C_pt $, where $ C_p $ is the specific heat equal to 1.005 kJ/kg$^\circ\text{C}$ and $ t $ be the temperature.

Draw a neat sketch of throttling calorimeter and explain how dryness fraction of steam is determined. Clearly explain its limitations.

A quantity of steam at 13 bars and 0.8 dryness occupies 0.1 $ \text{m}^3 $. Determine the heat supplied to raise the temperature of the steam to $ 250^\circ\text{C} $ at constant pressure and percentage of this heat which appears as external work. Take specific heat for superheated steam as 2.2 kJ/kgK.

Prove the equivalence of Clausius statement to the Kelvin-Planck statement with schematic diagram.

A reversible heat pump is used to maintain a temperature of $ 0^\circ\text{C} $ in a refrigerator when it rejects the heat to the surroundings at $ 25^\circ\text{C} $. (i) If the heat removal rate from the refrigerator is 1440 kJ/min, determine the COP of the machine and work input required. (ii) If the required input to run the pump is developed by a reversible engine which receives heat at $ 380^\circ\text{C} $ and rejects heat to atmosphere, then determine the overall COP of the system.

Derive expressions for entropy changes for a closed system in the cases- (i) general case for change of entropy of a gas, (ii) heating a gas at constant volume and (iii) heating a gas at constant pressure.

1.2 $ \text{m}^3 $ of air is heated reversibly at constant pressure from 300 K to 600 K, and is then cooled reversibly at constant volume back to initial temperature. If the initial pressure is 1 bar, calculate (i) the net heat flow, (ii) the overall change in entropy. Represent the processes on T-S plot.

Deduce an expression for decrease in available energy when heat is transferred through a finite temperature difference.

8 kg of air at 650 K and 5.5 bars pressure is enclosed in a closed system. If the atmospheric temperature and pressure are 300 K and 1 bar respectively, determine (i) the availability if the system goes through the ideal work producing process, (ii) the availability and effectiveness if the air is cooled at constant pressure to atmospheric temperature without bringing it to complete dead state. Take $ C_v = 0.718 \text{ kJ/kgK} $; $ C_p = 1.005 \text{ kJ/kgK} $.

A mass of air initially at $ 260^\circ\text{C} $ and a pressure of 6.86 bars has a volume of 0.03 $ \text{m}^3 $. The air is expanded at constant pressure to 0.09 $ \text{m}^3 $ a polytropic process with $ n = 1.5 $ is then carried out, followed by a constant temperature process which completes the cycle. All processes are reversible. Find (i) the heat received and rejected in the cycle, (ii) the efficiency of the cycle. Show the cycle on p-v and T-s planes.

A steel flask of 0.04 $ \text{m}^3 $ capacity is to be used to store nitrogen at 120 bars, $ 20^\circ\text{C} $. The flask is to be protected against excessive pressure by a fusible plug which will melt and allow the gas to escape if the temperature rises too high. (i) How many kg of nitrogen will the flask hold at the designed conditions? (ii) At what temperature must the fusible plug melt in order to limit the pressure of a full flask to a maximum of 150 bars?

Define the following: (i) Dew-point temperature (ii) Relative humidity (iii) Degree of saturation

On a particular day, the atmospheric air was found to have a dry bulb temperature of $ 30^\circ\text{C} $ and a wet bulb temperature of $ 18^\circ\text{C} $. The barometric pressure was observed to be 756 mm of Hg. Using the tables of psychrometric properties of air, determine the relative humidity, the specific humidity, the dew-point temperature, the enthalpy of air per kg of dry air and the volume of mixture per kg of dry air.

Air is compressed adiabatically in a steady flow process with negligible change in potential and kinetic energy. The work done in the process is given by

Which one of the following is the extensive property of a thermodynamic system?

The time constant of a thermocouple is the time taken to attain

For the expression $ \int pdv $ to represent the work, which of the following conditions should apply?

For a closed system, the difference between the heat added to the system and the work done by the system is equal to the change in

Change in internal energy in a reversible process occurring in a closed system is equal to the heat transferred, if the process occurs at constant

A reversible engine operates between temperatures 900 K and $ T_2 $ ($ T_2 < 900 \text{ K} $), and another reversible engine between $ T_2 $ and 400 K ($ T_2> 400 \text{ K} $) in series. What is the value of $ T_2 $ if work outputs of both the engines are equal?

A Carnot engine operates between $ 327^\circ\text{C} $ and $ 27^\circ\text{C} $. If the engine produces 300 kJ of work, what is the entropy change during heat addition?

In which one of the following situations the entropy change will be negative?

Neglecting changes in kinetic energy and potential energy, for unit mass the availability in a non-flow process becomes $ a = \phi - \phi_0 $, where $ \phi $ is the availability function of the

Define thermodynamic equilibrium. With the help of practical example, explain the phenomenon of achieving a thermodynamic equilibrium of system.

0.1 $ \text{m}^3 $ of an ideal gas at 300 K and 1 bar is compressed adiabatically to 8 bars. It is then cooled at constant volume and expanded isothermally so as to reach the condition from where it started. Calculate (i) pressure at the end of constant volume cooling, (ii) change in internal energy during constant volume process and (iii) net work done and heat transferred during the cycle.

What is SFEE? Derive the SFEE equation of an open system.

Air at a temperature of $ 20^\circ\text{C} $ passes through a heat exchanger at a velocity of 40 m/s where its temperature is raised to $ 820^\circ\text{C} $. It then enters a turbine with same velocity of 40 m/s and expands till the temperature falls to $ 620^\circ\text{C} $. On leaving the turbine, the air is taken at a velocity of 55 m/s to a nozzle where it expands until the temperature has fallen to $ 510^\circ\text{C} $. If the air flow rate is 2.5 kg/s calculate (i) rate of heat transfer to the air in the heat exchanger, (ii) the power output from the turbine assuming no heat loss, (iii) the velocity at exit from the nozzle, assuming no heat loss. Take the enthalpy of air as $ h = C_pt $, where $ C_p $ is the specific heat equal to 1.005 kJ/kg$^\circ\text{C}$ and $ t $ be the temperature.

Draw a neat sketch of throttling calorimeter and explain how dryness fraction of steam is determined. Clearly explain its limitations.

A quantity of steam at 13 bars and 0.8 dryness occupies 0.1 $ \text{m}^3 $. Determine the heat supplied to raise the temperature of the steam to $ 250^\circ\text{C} $ at constant pressure and percentage of this heat which appears as external work. Take specific heat for superheated steam as 2.2 kJ/kgK.

Prove the equivalence of Clausius statement to the Kelvin-Planck statement with schematic diagram.

A reversible heat pump is used to maintain a temperature of $ 0^\circ\text{C} $ in a refrigerator when it rejects the heat to the surroundings at $ 25^\circ\text{C} $. (i) If the heat removal rate from the refrigerator is 1440 kJ/min, determine the COP of the machine and work input required. (ii) If the required input to run the pump is developed by a reversible engine which receives heat at $ 380^\circ\text{C} $ and rejects heat to atmosphere, then determine the overall COP of the system.

Derive expressions for entropy changes for a closed system in the cases- (i) general case for change of entropy of a gas, (ii) heating a gas at constant volume and (iii) heating a gas at constant pressure.

1.2 $ \text{m}^3 $ of air is heated reversibly at constant pressure from 300 K to 600 K, and is then cooled reversibly at constant volume back to initial temperature. If the initial pressure is 1 bar, calculate (i) the net heat flow, (ii) the overall change in entropy. Represent the processes on T-S plot.

Deduce an expression for decrease in available energy when heat is transferred through a finite temperature difference.

8 kg of air at 650 K and 5.5 bars pressure is enclosed in a closed system. If the atmospheric temperature and pressure are 300 K and 1 bar respectively, determine (i) the availability if the system goes through the ideal work producing process, (ii) the availability and effectiveness if the air is cooled at constant pressure to atmospheric temperature without bringing it to complete dead state. Take $ C_v = 0.718 \text{ kJ/kgK} $; $ C_p = 1.005 \text{ kJ/kgK} $.

A mass of air initially at $ 260^\circ\text{C} $ and a pressure of 6.86 bars has a volume of 0.03 $ \text{m}^3 $. The air is expanded at constant pressure to 0.09 $ \text{m}^3 $ a polytropic process with $ n = 1.5 $ is then carried out, followed by a constant temperature process which completes the cycle. All processes are reversible. Find (i) the heat received and rejected in the cycle, (ii) the efficiency of the cycle. Show the cycle on p-v and T-s planes.

A steel flask of 0.04 $ \text{m}^3 $ capacity is to be used to store nitrogen at 120 bars, $ 20^\circ\text{C} $. The flask is to be protected against excessive pressure by a fusible plug which will melt and allow the gas to escape if the temperature rises too high. (i) How many kg of nitrogen will the flask hold at the designed conditions? (ii) At what temperature must the fusible plug melt in order to limit the pressure of a full flask to a maximum of 150 bars?

Define the following: (i) Dew-point temperature (ii) Relative humidity (iii) Degree of saturation

On a particular day, the atmospheric air was found to have a dry bulb temperature of $ 30^\circ\text{C} $ and a wet bulb temperature of $ 18^\circ\text{C} $. The barometric pressure was observed to be 756 mm of Hg. Using the tables of psychrometric properties of air, determine the relative humidity, the specific humidity, the dew-point temperature, the enthalpy of air per kg of dry air and the volume of mixture per kg of dry air.

For reversible adiabatic compression in a steady flow process, the work transfer per unit mass is

Ice kept in a well insulated thermoflask is an example of which system?

Pressure reaches a value of absolute zero

Work done in a free expansion process is

Two blocks which are at different states are brought into contact with each other and allowed to reach a final state of thermal equilibrium. The final temperature attained is specified by the

A gas is compressed in a cylinder by a movable piston to a volume one-half of its original volume. During the process, 300 kJ heat left the gas and the internal energy remained same. What is the work done on the gas?

A series combination of two Carnot's engines operates between the temperatures of $ 180^\circ\text{C} $ and $ 20^\circ\text{C} $. If the engines produce equal amount of work, then what is the intermediate temperature?

If a closed system is undergoing an irreversible process, the entropy of the system

The entropy of a mixture of ideal gases is the sum of the entropies of constituents evaluated at

Increase in entropy of a system represents

Define a thermodynamic system. Differentiate between open system, closed system and an isolated system with examples.

1 kg of a fluid is compressed reversibly according to a law $ pv = 0.25 $ where p is in bar and v is in $ \text{m}^3/\text{kg} $. The final volume is $ \frac{1}{4} $ of the initial volume. Calculate the work done on the fluid and sketch the process on a p-v diagram.

0.15 $ \text{m}^3 $ of an ideal gas at a pressure of 15 bar and 550 K is expanded isothermally to 4 times the initial volume. It is then cooled to 290 K at constant volume and then compressed back polytropically to its initial state. Calculate net work done and heat transferred during the cycle.

0.2 $ \text{m}^3 $ of air at 4 bar and $ 130^\circ\text{C} $ is contained in a system. A reversible adiabatic expansion takes place till the pressure falls to 1.02 bar. The gas is then heated at constant pressure till enthalpy increases by 72.5 kJ. Calculate (i) the work done and (ii) the index of expansion, if the above processes are replaced by a single reversible polytropic process giving the same work between the same.

With the help of p-v, T-s and p-T diagram, explain the nature of common salt (NaCl).

A spherical vessel of 0.9 $ \text{m}^3 $ capacity contains steam at 8 bar and 0.9 dryness fraction. Steam is blown off until the pressure drops to 4 bar. The valve is then closed and the steam is allowed to cool until the pressure falls to 3 bar. Assuming that the enthalpy of steam in the vessel remains constant during blowing-off periods, determine (i) the mass of steam blown-off; (ii) the dryness fraction of steam in the vessel after cooling and (iii) the heat lost by steam per kg during cooling.

Give the following statements of second law of thermodynamics: (i) Clausius statement (ii) Kelvin-Planck statement

A reversible heat engine operates between two reservoirs at temperatures $ 700^\circ\text{C} $ and $ 50^\circ\text{C} $. The engine drives a reversible refrigerator which operates between reservoirs at temperatures of $ 50^\circ\text{C} $ and $ -25^\circ\text{C} $. The heat transfer to the engine is 2500 kJ and the net work output of the combined engine refrigerator plant is 400 kJ. (i) Determine the heat transfer to the refrigerant and the net heat transfer to the reservoir at $ 50^\circ\text{C} $; (ii) Reconsider (i) above given that the efficiency of the heat engine and the COP of the refrigerator are each 45 per cent of their maximum possible values.

What do you mean by Clausius inequality? Explain with a practical example.

1 kg of air initially at 8 bar pressure and 380 K expands polytropically ($ pv^{1.2} = \text{constant} $) until the pressure is reduced to one-fifth value. Calculate (i) final specific volume and temperature; (ii) change of internal energy, work done and heat interaction and (iii) change in entropy. Take $ R = 0.287 \text{ kJ/kg K} $ and $ \gamma = 1.4 $.

Explain the concept of available and unavailable energy. When does the system become dead?

Calculate the decrease in available energy when 20 kg of water at $ 90^\circ\text{C} $ mixes with 30 kg of water at $ 30^\circ\text{C} $, the pressure being taken as constant and the temperature of the surroundings being $ 10^\circ\text{C} $. Take $ C_p $ of water as 4.18 kJ/kg K.

Differentiate between ideal and real gas with the help of equation of state.

(i) 1 kg of air at a pressure of 8 bar and a temperature of $ 100^\circ\text{C} $ undergoes a reversible polytropic process following the law $ pv^{1.2} = \text{constant} $. If the final pressure is 1.8 bar, determine- (1) the final specific volume, temperature and increase in entropy; (2) the work done and the heat transfer. Assume $ R = 0.287 \text{ kJ/kg K} $ and $ \gamma = 1.4 $. (ii) Repeat (a) assuming the process to be irreversible and adiabatic between end states.

The readings from a sling psychrometer are as follows: Dry-bulb temperature = $ 30^\circ\text{C} $, Barometer reading = 740 mm of Hg. Using steam tables, determine (i) dew point temperature; (ii) relative humidity; (iii) specific humidity; (iv) degree of saturation; (v) vapour density and (vi) enthalpy of mixture per kg of dry air.

39.6 $ \text{m}^3/\text{min} $ of a mixture of recirculated room air and outdoor air enters cooling coil at $ 31^\circ\text{C} $ dry-bulb temperature and $ 18.5^\circ\text{C} $ wet-bulb temperature. The effective surface temperature of the coil is $ 4.4^\circ\text{C} $. The surface area of the coil is such as would give 12.5 kW of refrigeration with the given entering air state. Determine the dry- and wet-bulb temperatures of the air leaving the coil and the by-pass factor.

For reversible adiabatic compression in a steady flow process, the work transfer per unit mass is

Ice kept in a well insulated thermoflask is an example of which system?

Pressure reaches a value of absolute zero

Work done in a free expansion process is

Two blocks which are at different states are brought into contact with each other and allowed to reach a final state of thermal equilibrium. The final temperature attained is specified by the

A gas is compressed in a cylinder by a movable piston to a volume one-half of its original volume. During the process, 300 kJ heat left the gas and the internal energy remained same. What is the work done on the gas?

A series combination of two Carnot's engines operates between the temperatures of $ 180^\circ\text{C} $ and $ 20^\circ\text{C} $. If the engines produce equal amount of work, then what is the intermediate temperature?

If a closed system is undergoing an irreversible process, the entropy of the system

The entropy of a mixture of ideal gases is the sum of the entropies of constituents evaluated at

Increase in entropy of a system represents

Define a thermodynamic system. Differentiate between open system, closed system and an isolated system with examples.

1 kg of a fluid is compressed reversibly according to a law $ pv = 0.25 $ where p is in bar and v is in $ \text{m}^3/\text{kg} $. The final volume is $ \frac{1}{4} $ of the initial volume. Calculate the work done on the fluid and sketch the process on a p-v diagram.

0.15 $ \text{m}^3 $ of an ideal gas at a pressure of 15 bar and 550 K is expanded isothermally to 4 times the initial volume. It is then cooled to 290 K at constant volume and then compressed back polytropically to its initial state. Calculate net work done and heat transferred during the cycle.

0.2 $ \text{m}^3 $ of air at 4 bar and $ 130^\circ\text{C} $ is contained in a system. A reversible adiabatic expansion takes place till the pressure falls to 1.02 bar. The gas is then heated at constant pressure till enthalpy increases by 72.5 kJ. Calculate (i) the work done and (ii) the index of expansion, if the above processes are replaced by a single reversible polytropic process giving the same work between the same.

With the help of p-v, T-s and p-T diagram, explain the nature of common salt (NaCl).

A spherical vessel of 0.9 $ \text{m}^3 $ capacity contains steam at 8 bar and 0.9 dryness fraction. Steam is blown off until the pressure drops to 4 bar. The valve is then closed and the steam is allowed to cool until the pressure falls to 3 bar. Assuming that the enthalpy of steam in the vessel remains constant during blowing-off periods, determine (i) the mass of steam blown-off; (ii) the dryness fraction of steam in the vessel after cooling and (iii) the heat lost by steam per kg during cooling.

Give the following statements of second law of thermodynamics: (i) Clausius statement (ii) Kelvin-Planck statement

A reversible heat engine operates between two reservoirs at temperatures $ 700^\circ\text{C} $ and $ 50^\circ\text{C} $. The engine drives a reversible refrigerator which operates between reservoirs at temperatures of $ 50^\circ\text{C} $ and $ -25^\circ\text{C} $. The heat transfer to the engine is 2500 kJ and the net work output of the combined engine refrigerator plant is 400 kJ. (i) Determine the heat transfer to the refrigerant and the net heat transfer to the reservoir at $ 50^\circ\text{C} $; (ii) Reconsider (i) above given that the efficiency of the heat engine and the COP of the refrigerator are each 45 per cent of their maximum possible values.

What do you mean by Clausius inequality? Explain with a practical example.

1 kg of air initially at 8 bar pressure and 380 K expands polytropically ($ pv^{1.2} = \text{constant} $) until the pressure is reduced to one-fifth value. Calculate (i) final specific volume and temperature; (ii) change of internal energy, work done and heat interaction and (iii) change in entropy. Take $ R = 0.287 \text{ kJ/kg K} $ and $ \gamma = 1.4 $.

Explain the concept of available and unavailable energy. When does the system become dead?

Calculate the decrease in available energy when 20 kg of water at $ 90^\circ\text{C} $ mixes with 30 kg of water at $ 30^\circ\text{C} $, the pressure being taken as constant and the temperature of the surroundings being $ 10^\circ\text{C} $. Take $ C_p $ of water as 4.18 kJ/kg K.

Differentiate between ideal and real gas with the help of equation of state.

(i) 1 kg of air at a pressure of 8 bar and a temperature of $ 100^\circ\text{C} $ undergoes a reversible polytropic process following the law $ pv^{1.2} = \text{constant} $. If the final pressure is 1.8 bar, determine- (1) the final specific volume, temperature and increase in entropy; (2) the work done and the heat transfer. Assume $ R = 0.287 \text{ kJ/kg K} $ and $ \gamma = 1.4 $. (ii) Repeat (a) assuming the process to be irreversible and adiabatic between end states.

The readings from a sling psychrometer are as follows: Dry-bulb temperature = $ 30^\circ\text{C} $, Barometer reading = 740 mm of Hg. Using steam tables, determine (i) dew point temperature; (ii) relative humidity; (iii) specific humidity; (iv) degree of saturation; (v) vapour density and (vi) enthalpy of mixture per kg of dry air.

39.6 $ \text{m}^3/\text{min} $ of a mixture of recirculated room air and outdoor air enters cooling coil at $ 31^\circ\text{C} $ dry-bulb temperature and $ 18.5^\circ\text{C} $ wet-bulb temperature. The effective surface temperature of the coil is $ 4.4^\circ\text{C} $. The surface area of the coil is such as would give 12.5 kW of refrigeration with the given entering air state. Determine the dry- and wet-bulb temperatures of the air leaving the coil and the by-pass factor.

In a cycle

Zeroth law of thermodynamics forms the basis of

The cyclic integral of which of the following is zero?

Which one of the following parameters remains constant in a throttling process?

An isentropic process is always

A cyclic heat engine operates between a source temperature of $ 927^\circ\text{C} $ and a sink temperature of $ 27^\circ\text{C} $. What will be the maximum efficiency of the heat engine?

Which of the following expressions is true for Tds?

With increase in saturation pressure of water vapour

Availability function of a closed system is expressed as

At a pressure of 4 MPa, the temperature at which liquid water boils is

Explain what you understand by thermodynamic equilibrium.

Distinguish between the terms 'change of state', 'path' and 'process'.

One mol of air at 0.45 MPa and 450 K initially undergoes the processes- (i) heating at constant pressure till the volume gets doubled and (ii) expansion at constant temperature till the volume is five times of initial volume sequentially. Determine the work done by air.

Show that energy is a property of a system.

Write the steady flow energy equation for a single stream entering and a single stream leaving a control volume.

In a gas turbine the gas enters at the rate of 5 kg/s with a velocity of 50 m/s and enthalpy of 900 kJ/kg and leaves the turbine with a velocity of 150 m/s and enthalpy of 400 kJ/kg. The loss of heat from the gases to the surroundings is 25 kJ/kg. Assume for gas $ R = 0.285 \text{ kJ/kgK} $ and $ c_p = 1.004 \text{ kJ/kg-K} $ and the inlet conditions to be at 100 kPa and $ 27^\circ\text{C} $. Determine the power output of the turbine and the diameter of the inlet pipe.

Establish the equivalence of Kelvin-Planck and Clausius statement.

An engine has a heat input of 500 kJ at $ 437^\circ\text{C} $. It rejects 200 kJ at $ 82^\circ\text{C} $. The engine develops 250 kJ of work. Check whether such an engine is possible or not.

"Two reversible adiabatic paths cannot intersect each other." Write True or False. Justify with proper explanation.

A reversible engine operates between temperatures $ T_1 $ and $ T $, where $ T_1 > T $. The energy rejected from this engine is received by a second reversible engine at the same temperature $ T $. The second engine rejects energy at temperature $ T_2 $, where $ T_2 < T_1 $. Show that the temperature $ T $ is the arithmetic mean of temperatures $ T_1 $ and $ T_2 $ if the engines produce the same amount of work output.

Establish the inequality of Clausius.

Steam flows in a pipeline at 1.5 MPa. After expanding to 0.1 MPa in a throttling calorimeter, the temperature is found to be $ 120^\circ\text{C} $. Find the quality of steam in the pipeline. What is the maximum moisture at 1.5 MPa that can be determined with this set-up if at least $ 5^\circ\text{C} $ of degree of superheat is required after throttling for accurate readings?

What is meant by availability?

Air expands through a turbine from 500 kPa, $ 520^\circ\text{C} $ to 100 kPa, $ 300^\circ\text{C} $. During expansion 10 kJ/kg of heat is lost to the surroundings which is at 98 kPa, $ 20^\circ\text{C} $. Neglecting the KE and PE changes, determine per kg of air (i) the decrease in availability, (ii) the maximum work and (iii) the irreversibility. For air, take $ c_p = 1.005 \text{ kJ/kg-K} $, $ h = c_pT $ where $ c_p $ is constant.

Define the terms 'unsaturated air' and 'relative humidity'.

With the help of a suitable diagram, explain the psychrometric chart.

With the help of a suitable diagram, explain the process of cooling and dehumidification.

In a cycle

Zeroth law of thermodynamics forms the basis of

The cyclic integral of which of the following is zero?

Which one of the following parameters remains constant in a throttling process?

An isentropic process is always

A cyclic heat engine operates between a source temperature of $ 927^\circ\text{C} $ and a sink temperature of $ 27^\circ\text{C} $. What will be the maximum efficiency of the heat engine?

Which of the following expressions is true for Tds?

With increase in saturation pressure of water vapour

Availability function of a closed system is expressed as

At a pressure of 4 MPa, the temperature at which liquid water boils is

Explain what you understand by thermodynamic equilibrium.

Distinguish between the terms 'change of state', 'path' and 'process'.

One mol of air at 0.45 MPa and 450 K initially undergoes the processes- (i) heating at constant pressure till the volume gets doubled and (ii) expansion at constant temperature till the volume is five times of initial volume sequentially. Determine the work done by air.

Show that energy is a property of a system.

Write the steady flow energy equation for a single stream entering and a single stream leaving a control volume.

In a gas turbine the gas enters at the rate of 5 kg/s with a velocity of 50 m/s and enthalpy of 900 kJ/kg and leaves the turbine with a velocity of 150 m/s and enthalpy of 400 kJ/kg. The loss of heat from the gases to the surroundings is 25 kJ/kg. Assume for gas $ R = 0.285 \text{ kJ/kgK} $ and $ c_p = 1.004 \text{ kJ/kg-K} $ and the inlet conditions to be at 100 kPa and $ 27^\circ\text{C} $. Determine the power output of the turbine and the diameter of the inlet pipe.

Establish the equivalence of Kelvin-Planck and Clausius statement.

An engine has a heat input of 500 kJ at $ 437^\circ\text{C} $. It rejects 200 kJ at $ 82^\circ\text{C} $. The engine develops 250 kJ of work. Check whether such an engine is possible or not.

"Two reversible adiabatic paths cannot intersect each other." Write True or False. Justify with proper explanation.

A reversible engine operates between temperatures $ T_1 $ and $ T $, where $ T_1 > T $. The energy rejected from this engine is received by a second reversible engine at the same temperature $ T $. The second engine rejects energy at temperature $ T_2 $, where $ T_2 < T_1 $. Show that the temperature $ T $ is the arithmetic mean of temperatures $ T_1 $ and $ T_2 $ if the engines produce the same amount of work output.

Establish the inequality of Clausius.

Steam flows in a pipeline at 1.5 MPa. After expanding to 0.1 MPa in a throttling calorimeter, the temperature is found to be $ 120^\circ\text{C} $. Find the quality of steam in the pipeline. What is the maximum moisture at 1.5 MPa that can be determined with this set-up if at least $ 5^\circ\text{C} $ of degree of superheat is required after throttling for accurate readings?

What is meant by availability?

Air expands through a turbine from 500 kPa, $ 520^\circ\text{C} $ to 100 kPa, $ 300^\circ\text{C} $. During expansion 10 kJ/kg of heat is lost to the surroundings which is at 98 kPa, $ 20^\circ\text{C} $. Neglecting the KE and PE changes, determine per kg of air (i) the decrease in availability, (ii) the maximum work and (iii) the irreversibility. For air, take $ c_p = 1.005 \text{ kJ/kg-K} $, $ h = c_pT $ where $ c_p $ is constant.

Define the terms 'unsaturated air' and 'relative humidity'.

With the help of a suitable diagram, explain the psychrometric chart.

With the help of a suitable diagram, explain the process of cooling and dehumidification.

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Ice kept in a wall-insulated thermoflask is an example of which system?

Which one of the following is the extensive property of a thermodynamic system?

In a general compression process, 1 kJ of mechanical work is supplied to 2 kg of fluid and 400 J of heat is rejected to the cooling jacket. The change in specific internal energy would be

First law of thermodynamics defines

Under what conditions, the change in the enthalpy of a system equals the heat supplied?

In a Carnot cycle, the rejection of heat is

A Carnot cycle is having an efficiency of 0.75. If the temperature of the high temperature reservoir is $ 727^\circ\text{C} $, what is the temperature of the low temperature reservoir?

Second law of thermodynamics defines

For a thermodynamic cycle to be irreversible, it is necessary that

Which of the following parameters remains constant during superheating of steam?

State the first law of thermodynamics. What is PMM1?

Define quasi-static process.

The internal energy of a certain substance is given by the equation $ u = 3.56pv + 84 $, where u is given in kJ/kg, p is in kPa and v is in $ \text{m}^3/\text{kg} $. A system composed of 3 kg of this substance expands from an initial pressure of 500 kPa and a volume of 0.22 $ \text{m}^3 $ to a final pressure 100 kPa in a process in which pressure and volume are related by $ pv^{1.2} = \text{constant} $. If the expansion is quasi-static, find Q, $ \Delta U $, and W for this process.

Derive an expression for conservation of energy for a steady flow process.

Consider a nozzle which is used to increase the velocity of a steady flowing stream. At the inlet to the nozzle, the enthalpy of fluid is 3000 kJ/kg and the velocity is 50 m/s. At the exit of the nozzle, the enthalpy is 2700 kJ/kg. The nozzle is kept horizontal and is well-insulated. (i) Find the velocity at the exit of the nozzle and the mass flow rate. (ii) If the inlet area is 0.12 $ \text{m}^2 $ and the sp. volume of the fluid at the inlet is 0.19 $ \text{m}^3/\text{kg} $, find the exit area of the nozzle, if the specific volume of the fluid at the exit is 0.5 $ \text{m}^3/\text{kg} $.

State the Carnot theorem and explain with the help of suitable example.

Two reversible heat engines A and B are arranged in series, engine A rejecting heat directly to engine B. Engine A receives 180 kJ at a temperature of $ 422^\circ\text{C} $ from a hot source, while engine B is in communication with a cold sink at a temperature of $ 5.5^\circ\text{C} $. If the work output of A is twice that of B, find (i) the intermediate temperature between A and B, (ii) the efficiency of each engine and (iii) heat rejected to the cold sink.

State and prove Clausius theorem.

Show that there is a decrease in available energy, when heat is transferred through a finite temperature difference.

Show that the adiabatic mixing of two fluids is irreversible.

"An adiabatic process need not be isentropic, but if the process is adiabatic and reversible, it must be isentropic." Is it true or false? Explain with proper justification.

A reversible power cycle operates with temperature limits 800 K and 300 K. If it takes 480 kJ of heat, then what would be the unavailable work?

What are various forms of energy?

Consider a system of cylinder and piston arrangement containing gas. Initially, the gas is at 500 kPa and occupies a volume of 0.2 $ \text{m}^3 $. The force exerted by the spring is proportional to the displacement from its equilibrium position. Take ambient pressure as 100 kPa. The gas is heated until the volume becomes 0.4 $ \text{m}^3 $ and the pressure attained as 1 MPa. Determine the work done by the gas. Draw the schematic and p-V diagram.

What is the critical state? Draw the phase equilibrium diagram for a pure substance on h-s plot with relevant constant property lines.

Why do the isobars on Mollier diagram diverge from one another?

What is quality of steam? What are the different methods of measurement of quality of steam?

Steam initially at 1.5 MPa, $ 300^\circ\text{C} $ expands reversibly and adiabatically in a steam turbine to $ 40^\circ\text{C} $. Determine the ideal work output of the turbine per kg of steam.

With the help of suitable diagram, explain heating and humidification.

Ice kept in a wall-insulated thermoflask is an example of which system?

Which one of the following is the extensive property of a thermodynamic system?

In a general compression process, 1 kJ of mechanical work is supplied to 2 kg of fluid and 400 J of heat is rejected to the cooling jacket. The change in specific internal energy would be

First law of thermodynamics defines

Under what conditions, the change in the enthalpy of a system equals the heat supplied?

In a Carnot cycle, the rejection of heat is

A Carnot cycle is having an efficiency of 0.75. If the temperature of the high temperature reservoir is $ 727^\circ\text{C} $, what is the temperature of the low temperature reservoir?

Second law of thermodynamics defines

For a thermodynamic cycle to be irreversible, it is necessary that

Which of the following parameters remains constant during superheating of steam?

State the first law of thermodynamics. What is PMM1?

Define quasi-static process.

The internal energy of a certain substance is given by the equation $ u = 3.56pv + 84 $, where u is given in kJ/kg, p is in kPa and v is in $ \text{m}^3/\text{kg} $. A system composed of 3 kg of this substance expands from an initial pressure of 500 kPa and a volume of 0.22 $ \text{m}^3 $ to a final pressure 100 kPa in a process in which pressure and volume are related by $ pv^{1.2} = \text{constant} $. If the expansion is quasi-static, find Q, $ \Delta U $, and W for this process.

Derive an expression for conservation of energy for a steady flow process.

Consider a nozzle which is used to increase the velocity of a steady flowing stream. At the inlet to the nozzle, the enthalpy of fluid is 3000 kJ/kg and the velocity is 50 m/s. At the exit of the nozzle, the enthalpy is 2700 kJ/kg. The nozzle is kept horizontal and is well-insulated. (i) Find the velocity at the exit of the nozzle and the mass flow rate. (ii) If the inlet area is 0.12 $ \text{m}^2 $ and the sp. volume of the fluid at the inlet is 0.19 $ \text{m}^3/\text{kg} $, find the exit area of the nozzle, if the specific volume of the fluid at the exit is 0.5 $ \text{m}^3/\text{kg} $.

State the Carnot theorem and explain with the help of suitable example.

Two reversible heat engines A and B are arranged in series, engine A rejecting heat directly to engine B. Engine A receives 180 kJ at a temperature of $ 422^\circ\text{C} $ from a hot source, while engine B is in communication with a cold sink at a temperature of $ 5.5^\circ\text{C} $. If the work output of A is twice that of B, find (i) the intermediate temperature between A and B, (ii) the efficiency of each engine and (iii) heat rejected to the cold sink.

State and prove Clausius theorem.

Show that there is a decrease in available energy, when heat is transferred through a finite temperature difference.

Show that the adiabatic mixing of two fluids is irreversible.

"An adiabatic process need not be isentropic, but if the process is adiabatic and reversible, it must be isentropic." Is it true or false? Explain with proper justification.

A reversible power cycle operates with temperature limits 800 K and 300 K. If it takes 480 kJ of heat, then what would be the unavailable work?

What are various forms of energy?

Consider a system of cylinder and piston arrangement containing gas. Initially, the gas is at 500 kPa and occupies a volume of 0.2 $ \text{m}^3 $. The force exerted by the spring is proportional to the displacement from its equilibrium position. Take ambient pressure as 100 kPa. The gas is heated until the volume becomes 0.4 $ \text{m}^3 $ and the pressure attained as 1 MPa. Determine the work done by the gas. Draw the schematic and p-V diagram.

What is the critical state? Draw the phase equilibrium diagram for a pure substance on h-s plot with relevant constant property lines.

Why do the isobars on Mollier diagram diverge from one another?

What is quality of steam? What are the different methods of measurement of quality of steam?

Steam initially at 1.5 MPa, $ 300^\circ\text{C} $ expands reversibly and adiabatically in a steam turbine to $ 40^\circ\text{C} $. Determine the ideal work output of the turbine per kg of steam.

With the help of suitable diagram, explain heating and humidification.

Choose the correct answer from the following (any seven):

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Which of the following are intensive properties?
1. Kinetic energy
2. Specific enthalpy
3. Pressure
4. Entropy
Select the correct option using the code given below:

Ice kept in a well-insulated thermo-flask is an example of which system?

A gas contained in a cylinder is compressed, the work required for compression being 5000 kJ. During the process, heat interaction of 2000 kJ causes the surroundings to be heated. The change in internal energy of the gas during the process is

A reversible heat engine operating between hot and cold reservoirs delivers a work output of 54 kJ while it rejects a heat of 66 kJ. The efficiency of this engine is

A reversible engine operates between temperatures 900 K and $ T_2 $ ($ T_2 < 900 \text{ K} $), and another reversible engine between $ T_2 $ and 400 K ($ T_2> 400 \text{ K} $) in series. What is the value of $ T_2 $ if work outputs of both the engines are equal?

In a cyclic heat engine operating between a source temperature of $ 600^\circ\text{C} $ and a sink temperature of $ 20^\circ\text{C} $, the least rate of heat rejection per kW net output of the engine is

If a closed system is undergoing an irreversible process, the entropy of the system

A Carnot engine operates between $ 327^\circ\text{C} $ and $ 27^\circ\text{C} $. If the engine produces 300 kJ of work, what is the entropy change during heat addition?

A gas having a negative Joule-Thompson coefficient ($ \mu < 0 $), when throttled, will

Which one of the following represents the condensation of a mixture of saturated liquid and saturated vapour on the enthalpy-entropy diagram?

Convert the following readings of pressure to kPa, assuming that the barometer reads 760 mmHg: (i) 90 cmHg gauge (ii) 40 cm Hg vacuum (iii) 1.2 m $ \text{H}_2\text{O} $ gauge (iv) 3.1 bar

The resistance of a platinum wire is found to be 11,000 ohms at the ice point, 15.247 ohms at the steam point, and 28.887 ohms at the sulphur point. Find the constants A and B in the equation $ R = R_0(1 + At + Bt^2) $ And plot R against t in the range 0 to $ 660^\circ\text{C} $.

Show that heat and work are path functions and not a property. A single-cylinder, double-acting, reciprocating water pump has an indicator diagram which is a rectangle 0.075 m long and 0.05 m high. The indicator spring constant is 147 MPa per m. The pump runs at 50 r.p.m. The pump cylinder diameter is 0.15 m and the piston stroke is 0.20 m. Find the rate in kW at which the piston does work on the water.

State the first law of thermodynamics for a closed system undergoing a change of state. A gas of mass 1.5 kg undergoes a quasi-static expansion which follows a relationship $ p = a + bV $ where a and b are constants. The initial and final pressures are 1000 kPa and 200 kPa respectively and the corresponding volumes are 0.20 $ \text{m}^3 $ and 1.20 $ \text{m}^3 $. The specific internal energy of the gas is given by the relation $ u = 1.5pv - 85 \text{ kJ/kg} $, where p is the kPa and v is in $ \text{m}^3/\text{kg} $. Calculate the net heat transfer and the maximum internal energy of the gas attained during expansion.

Derive the steady flow energy equation (SFEE). Under what conditions the SFEE does reduce to Euler's equation?

A turbo compressor delivers 2.33 $ \text{m}^3/\text{s} $ at 0.276 MPa, $ 43^\circ\text{C} $ which is heated at this pressure to $ 430^\circ\text{C} $ and finally expanded in a turbine which delivers 1860 kW. During the expansion, there is a heat transfer of 0.09 MJ/s to the surroundings. Calculate the turbine exhaust temperature if changes in kinetic and potential energy are negligible.

A heat pump working on the Carnot cycle takes in heat from a reservoir at $ 5^\circ\text{C} $ and delivers heat to a reservoir at $ 60^\circ\text{C} $. The heat pump is driven by a reversible heat engine which takes in heat from a reservoir at $ 840^\circ\text{C} $ and rejects heat to a reservoir at $ 60^\circ\text{C} $. The reversible heat engine also drives a machine that absorbs 30 kW. If the heat pump extracts 17 kJ/s from the $ 5^\circ\text{C} $ reservoir, determine- (i) the rate of heat supply from the $ 840^\circ\text{C} $ source; (ii) the rate of heat rejection to the $ 60^\circ\text{C} $ sink.

What do you understand by exergy and energy? In a steam generator, water is evaporated at $ 260^\circ\text{C} $, while the combustion gas ($ C_p = 1.08 \text{ kJ/kg K} $) is cooled from $ 1300^\circ\text{C} $ to $ 320^\circ\text{C} $. The surroundings are at $ 30^\circ\text{C} $. Determine the loss in available energy due to the above heat transfer per kg of water evaporated (Latent heat of vaporization of water at $ 260^\circ\text{C} = 1662.5 \text{ kJ/kg} $).

Give the criteria of reversibility, irreversibility and impossibility of a thermodynamic cycle. Two vessels, A and B, each of volume 3 $ \text{m}^3 $ may be connected by a tube of negligible volume. Vessel A contains air at 0.7 MPa, $ 95^\circ\text{C} $, while vessel B contains air at 0.35 MPa, $ 205^\circ\text{C} $. Find the change of entropy when A is connected to B by working from the first principles and assuming the mixing to be complete and adiabatic. Take $ C_p = 1.005 $ and $ C_v = 0.718 \text{ kJ/kg-K} $ and assume the specific heats to be constant. Also assume for air $ pv = 0.287 T $ where p is the pressure in kPa, v is the specific volume in $ \text{m}^3/\text{kg} $ and T is the temperature in K.

Show that the adiabatic mixing of two fluids is irreversible. Each of three identical bodies satisfies the equation $ U = CT $, where C is the heat capacity of each of the bodies. Their initial temperatures are 200 K, 250 K, and 540 K. If $ C = 8.4 \text{ kJ/K} $, what is the maximum amount of work that can be extracted in a process in which these bodies are brought to a final common temperature?

Explain why the specific heat of a saturated vapour may be negative.

Explain, with suitable example, what is a pure substance? Draw the labelled phase equilibrium diagram for table salt on p-v, T-s and h-s coordinates. A large insulated vessel is divided into two chambers, one containing 5 kg of dry saturated steam at 0.2 MPa and the other 10 kg of steam, 0.8 quality at 0.5 MPa. If the partition between the chambers is removed and the steam is mixed thoroughly and allowed to settle, find the final pressure, steam quality and entropy change in the process.

With the help of neat sketch, differentiate between the working of Otto and Diesel cycle.

A geothermal power plant utilizes steam produced by natural means underground. Steam wells are drilled to tap this steam supply which is available at 4.5 bar and $ 175^\circ\text{C} $. The steam leaves the turbine at 100 mmHg absolute pressure. The turbine isentropic efficiency is 0.75. Calculate the efficiency of the plant. If the unit produces 12.5 MW, what is the steam flow rate?

What is the difference between specific and relative humidity? When does they become maximum?

Atmospheric air at dry bulb temperature of $ 15^\circ\text{C} $ enters a heating coil whose surface temperature is maintained at $ 40^\circ\text{C} $. The air leaves the heating coil at $ 25^\circ\text{C} $. What will be the by-pass factor of the heating coil?

For chemical reaction
$ \text{CO}_2 + \text{H}_2\text{O} \rightleftharpoons \text{CO} + \text{H}_2\text{O} $
The equilibrium value of the degree of reaction at 1200 K is 0.56. Determine the equilibrium constant and the Gibbs function change.

Which of the following are intensive properties?
1. Kinetic energy
2. Specific enthalpy
3. Pressure
4. Entropy
Select the correct option using the code given below:

Ice kept in a well-insulated thermo-flask is an example of which system?

A gas contained in a cylinder is compressed, the work required for compression being 5000 kJ. During the process, heat interaction of 2000 kJ causes the surroundings to be heated. The change in internal energy of the gas during the process is

A reversible heat engine operating between hot and cold reservoirs delivers a work output of 54 kJ while it rejects a heat of 66 kJ. The efficiency of this engine is

A reversible engine operates between temperatures 900 K and $ T_2 $ ($ T_2 < 900 \text{ K} $), and another reversible engine between $ T_2 $ and 400 K ($ T_2> 400 \text{ K} $) in series. What is the value of $ T_2 $ if work outputs of both the engines are equal?

In a cyclic heat engine operating between a source temperature of $ 600^\circ\text{C} $ and a sink temperature of $ 20^\circ\text{C} $, the least rate of heat rejection per kW net output of the engine is

If a closed system is undergoing an irreversible process, the entropy of the system

A Carnot engine operates between $ 327^\circ\text{C} $ and $ 27^\circ\text{C} $. If the engine produces 300 kJ of work, what is the entropy change during heat addition?

A gas having a negative Joule-Thompson coefficient ($ \mu < 0 $), when throttled, will

Which one of the following represents the condensation of a mixture of saturated liquid and saturated vapour on the enthalpy-entropy diagram?

Convert the following readings of pressure to kPa, assuming that the barometer reads 760 mmHg: (i) 90 cmHg gauge (ii) 40 cm Hg vacuum (iii) 1.2 m $ \text{H}_2\text{O} $ gauge (iv) 3.1 bar

The resistance of a platinum wire is found to be 11,000 ohms at the ice point, 15.247 ohms at the steam point, and 28.887 ohms at the sulphur point. Find the constants A and B in the equation $ R = R_0(1 + At + Bt^2) $ And plot R against t in the range 0 to $ 660^\circ\text{C} $.

Show that heat and work are path functions and not a property. A single-cylinder, double-acting, reciprocating water pump has an indicator diagram which is a rectangle 0.075 m long and 0.05 m high. The indicator spring constant is 147 MPa per m. The pump runs at 50 r.p.m. The pump cylinder diameter is 0.15 m and the piston stroke is 0.20 m. Find the rate in kW at which the piston does work on the water.

State the first law of thermodynamics for a closed system undergoing a change of state. A gas of mass 1.5 kg undergoes a quasi-static expansion which follows a relationship $ p = a + bV $ where a and b are constants. The initial and final pressures are 1000 kPa and 200 kPa respectively and the corresponding volumes are 0.20 $ \text{m}^3 $ and 1.20 $ \text{m}^3 $. The specific internal energy of the gas is given by the relation $ u = 1.5pv - 85 \text{ kJ/kg} $, where p is the kPa and v is in $ \text{m}^3/\text{kg} $. Calculate the net heat transfer and the maximum internal energy of the gas attained during expansion.

Derive the steady flow energy equation (SFEE). Under what conditions the SFEE does reduce to Euler's equation?

A turbo compressor delivers 2.33 $ \text{m}^3/\text{s} $ at 0.276 MPa, $ 43^\circ\text{C} $ which is heated at this pressure to $ 430^\circ\text{C} $ and finally expanded in a turbine which delivers 1860 kW. During the expansion, there is a heat transfer of 0.09 MJ/s to the surroundings. Calculate the turbine exhaust temperature if changes in kinetic and potential energy are negligible.

A heat pump working on the Carnot cycle takes in heat from a reservoir at $ 5^\circ\text{C} $ and delivers heat to a reservoir at $ 60^\circ\text{C} $. The heat pump is driven by a reversible heat engine which takes in heat from a reservoir at $ 840^\circ\text{C} $ and rejects heat to a reservoir at $ 60^\circ\text{C} $. The reversible heat engine also drives a machine that absorbs 30 kW. If the heat pump extracts 17 kJ/s from the $ 5^\circ\text{C} $ reservoir, determine- (i) the rate of heat supply from the $ 840^\circ\text{C} $ source; (ii) the rate of heat rejection to the $ 60^\circ\text{C} $ sink.

What do you understand by exergy and energy? In a steam generator, water is evaporated at $ 260^\circ\text{C} $, while the combustion gas ($ C_p = 1.08 \text{ kJ/kg K} $) is cooled from $ 1300^\circ\text{C} $ to $ 320^\circ\text{C} $. The surroundings are at $ 30^\circ\text{C} $. Determine the loss in available energy due to the above heat transfer per kg of water evaporated (Latent heat of vaporization of water at $ 260^\circ\text{C} = 1662.5 \text{ kJ/kg} $).

Give the criteria of reversibility, irreversibility and impossibility of a thermodynamic cycle. Two vessels, A and B, each of volume 3 $ \text{m}^3 $ may be connected by a tube of negligible volume. Vessel A contains air at 0.7 MPa, $ 95^\circ\text{C} $, while vessel B contains air at 0.35 MPa, $ 205^\circ\text{C} $. Find the change of entropy when A is connected to B by working from the first principles and assuming the mixing to be complete and adiabatic. Take $ C_p = 1.005 $ and $ C_v = 0.718 \text{ kJ/kg-K} $ and assume the specific heats to be constant. Also assume for air $ pv = 0.287 T $ where p is the pressure in kPa, v is the specific volume in $ \text{m}^3/\text{kg} $ and T is the temperature in K.

Show that the adiabatic mixing of two fluids is irreversible. Each of three identical bodies satisfies the equation $ U = CT $, where C is the heat capacity of each of the bodies. Their initial temperatures are 200 K, 250 K, and 540 K. If $ C = 8.4 \text{ kJ/K} $, what is the maximum amount of work that can be extracted in a process in which these bodies are brought to a final common temperature?

Explain why the specific heat of a saturated vapour may be negative.

Explain, with suitable example, what is a pure substance? Draw the labelled phase equilibrium diagram for table salt on p-v, T-s and h-s coordinates. A large insulated vessel is divided into two chambers, one containing 5 kg of dry saturated steam at 0.2 MPa and the other 10 kg of steam, 0.8 quality at 0.5 MPa. If the partition between the chambers is removed and the steam is mixed thoroughly and allowed to settle, find the final pressure, steam quality and entropy change in the process.

With the help of neat sketch, differentiate between the working of Otto and Diesel cycle.

A geothermal power plant utilizes steam produced by natural means underground. Steam wells are drilled to tap this steam supply which is available at 4.5 bar and $ 175^\circ\text{C} $. The steam leaves the turbine at 100 mmHg absolute pressure. The turbine isentropic efficiency is 0.75. Calculate the efficiency of the plant. If the unit produces 12.5 MW, what is the steam flow rate?

What is the difference between specific and relative humidity? When does they become maximum?

Atmospheric air at dry bulb temperature of $ 15^\circ\text{C} $ enters a heating coil whose surface temperature is maintained at $ 40^\circ\text{C} $. The air leaves the heating coil at $ 25^\circ\text{C} $. What will be the by-pass factor of the heating coil?

For chemical reaction
$ \text{CO}_2 + \text{H}_2\text{O} \rightleftharpoons \text{CO} + \text{H}_2\text{O} $
The equilibrium value of the degree of reaction at 1200 K is 0.56. Determine the equilibrium constant and the Gibbs function change.

Answer the following:

Answer the following:

Answer the following: