etd 2mark with answer11

7/26/2019 Etd 2mark With Answer11

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UNIT-I

PART-A

SL.NO QUESTION AND ANSWERS1. State the law of conservation of energy.

The energy neither can be created nor destroyed but one form of energy can be convertedinto another form. The energies may cross the boundaries.

2. Define specific heat capacity and write their types with an example.

It is the amount of heat required to raise or lower the temperature of the body or substanceto through 1C.

3. State the zeroth law of thermodynamics.

Its stats that, when two systems are in thermal equilibrium with the third system separately,then they themselves are in thermal equilibrium

4. What do you understand from the thermodynamic system and boundaries, surrounding.

Thermodynamic system is defined as a definite space or area on which the study of energytransfer and energy conversion is made.The system and surroundings are separated by boundary. It may be affixed or movableand imaginary.Anything outside the boundary which affects the behavior of the system is calledsurroundings.

5. Classify the property and define them with example.

Thermodynamic property can be classified into two types.a. Intensive or Intrinsic andb. Extensive or Extrinsic property

The properties which are independent on the mass of the system is called intensiveproperties.

e.g., Pressure, Temperature, Specific Volume etc.

The properties which are dependent on the mass of the system is called extensiveproperties.

e.g., total energy, Total volume, weight etc,

6. What are the limitations of first law of thermodynamics?

(i) The first law of thermodynamics does not specify the direction of flow of heat and work.(ii) PMM-I is a machine which delivers work continuously without any input. Thus, it violates

the first law thermodynamics.

7. What is meant by PMM of first kind? Why it impossible?Perpetual motion machine of first kind is delivers the continuous work out put without anyinput so it violates the first law of thermodynamics so it is impossible.

8. State the concept of energy.

The energy neither can be created nor destroyed but one form of energy can be convertedinto another form. The energies may cross the boundaries. it can be stored and use whenwe required.

9. State the first law of thermodynamics.First of thermodynamics states that when system undergoes a cyclic process the net heattransfer is equal to work transfer

10. Write the Clausius statement with an example.

It is impossible to construct a device working on a cyclic process which produces no other

effect than the transfer of energy as heat from low temperature body to high temperaturebody.


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22. Define control volume and steady flow process.

Control volume

If a fluid passes through a specified area in steady flow process is called control volume.Steady flow processDuring the process the rate of flow of mass and energy across the boundary remainsconstant, is known as steady flow process.

23. What are the assumptions to be made for SFP?

i. The mass floe rate through the control volume is constantii. The state of fluid at any point remains constant at all times

24. Simplify the SFEE for steam generator.

Q= h2-h1 Kj

25. Derive the SFEE for steam nozzle. What is the function of nozzle?

Nozzle is used to increase the velocity of fluid by dropping the pressure of the fluid.SFEE of nozzle is C2= 2*Cp(T1T2) + C1

2

26. What are the applications of SFEE to various engineering system.

a. steam boiler

b. steam condenserc. nozzled. air compressorse. steam turbines

27. What is meant by adiabatic index?

It is ratio between the specific heat capacity at constant pressure to the specific heatcapacity at constant volume.

28. What is the reason for change in entropy is zero in reversible adiabatic process.

Adiabatic process is very rapid process, in this process there is no heat transfer sochange in entropy is zero.

29. Draw the p-v diagram for isothermal process.

30. Define ideal gas and real gas.

Ideal gasAn ideal gas is a imaginary substance that obeys the relation p V =C.Real gas

At high pressure, the gases start to deviate from ideal- gas behavior. So, that the deviationshould accounted.


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UNIT-II

PART-A

SL.NO QUESTION AND ANSWER

1. Write the two statement of second law of thermodynamics.

Its states that it is impossible to construct a heat engine working on cyclic process, whoseonly purpose is to convert all the heat energy given to it into an equal amount of work.

2. State Carnots theorem.

It states that, no heat engine operating in a cyclic process between two fixedtemperatures can be more efficient that a reversible engine operating between the sametemperature limits.

3. DefinePMM second kind.

PMM of second kind draws heat continuously from single reservoir and converts it intoequal amount of work. This it gives 100% efficiency.

4. What is the difference between heat pump and refrigerator?

Heat pumpis a machine which delivers the heat to the hot sources by extracting the heatfrom cold sink with the help of external work is called heat pump. It maintains only thetemperature of the source.Refrigerator is a machine which extracts the heat from cold sink and delivers to the

surrounding. it maintains only the temperature of the sink.

5. Define the term COP.

Co efficient of performance is defined as the ratio of heat extracted to the work input.

6. Define entropy.

Entropy is measure of disorder or index of unavailability of energy.

7. Sketch the p-v and T-s diagram for Carnot cycle.

8. What is meant by Clausius inequality?It is impossible for a self acting machine working in a cyclic process unaided by anexternal agency to convey heat from a body at lower temperature to body at highertemperature.

9. Define heat engine.

A heat engine is a device which is used to convert the thermal energy into mechanicalenergy

10. Write the formula for the COP of refrigerator.

Q=TL /( TH-TL)


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11. What is loss of availability? How it is related to the entropy of universe?

It is the difference between the maximum work and actual work obtained by the process is

called loss availability.

12.What is the principle increase of entropy?

For any infinitesimal process under gone by a system change in entropy dS dQ / T, forreversible process dQ = 0, so dS = 0. For irreversible dS>0 so, the entropy of an isolatedsystem would never decrease it will always increases and remains constant if thepressure is reversible is called as principle increase of entropy.

13. Why the second law is called a directional law of nature?

It gives the direction of flow of energy so it is called as directional law.

14. State the Second law of thermodynamics. Also write its physical significance.

It states that heat can flow from hot body to cold without any external aid but heat cannotflow from cold body to hot body without any external aid.

15. What is a process involved in a Carnot cycle, sketch the same in P-V and T-S diagram.

i. Isentropic compression

ii. Isothermal heat additioniii. Isentropic expansioniv. Isothermal heat rejection.

16. The coefficient of Performance of a heat pump is 5. Find the COP of refrigerator if both arereversible devices interacting between same source temperature and sink temperature.

COP ref=4

17. Why Carnot cycle is not practicable for a steam power plant?

(i)There are two processes to be carried out during compression and expansion. Forisothermal process the piston moves very slowly and for adiabatic process the piston moves

as fast as possible. This speed variation during the same stroke of the piston is not possible.

(ii) It is not possible to avoid friction moving parts completely.

18. What are the two major conclusions deduced from the Carnot principles?

(i) In all the reversible engine operating between the two given thermal reservoirs withfixed temperature, have the same efficiency.(ii) The efficiency of any reversible heat engine operating between two reservoirs isindependent of the nature of the working fluid and depends only on the temperature of thereservoirs.

19. What are the Corollaries of Carnot theorems?

(i) In the entire reversible engine operating between the two given thermal reservoirs withfixed temperature, have the same efficiency.(ii) The efficiency of any reversible heat engine operating between two reservoirs isindependent of the nature of the working fluid and depends only on the temperature of thereservoirs.

20. Why a heat engine cannot have 100% efficiency?

For all the heat engines there will be a heat loss between system and surroundings.Therefore we cant convert all the heat input into useful work.

21. When the Carnot cycle efficiency will be maximum?

Carnot cycle efficiency is maximum when the initial temperature is 0K.


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22. What is meant by reversible and irreversible process? Give two examples of reversible process.

Reversible processA process is said to be reversible, it should trace the same path in the reverse directionwhen the process is reversed. It is possible only when the system passes through acontinuous series of equilibrium state.Irreversible process

If a system does not pass through continuous equilibrium state, then the process is saidto be irreversible.

23. State the conditions to be satisfied for a process to be reversible.a. There is no heat loss by convection, conduction, radiation.

b. There is no friction between moving parts.

c. The process should passes through number of equilibrium stages.

24. What is the relation between COPHPand COP ref?COPHP= COPref+1

25. Define the term absolute entropy?The change of entropy of the system with respect to ambient conditions or any other standard

reference conditions is known as absolute entropy.


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UNIT-III

PART-A

1. What Is Pure Substance?Pure substance is a substance which has a fixed chemical composition throughout its

mass. Examples: water, nitrogen, carbon dioxide, and helium. A puresubstance does not have to be of a single chemical element or compound. A mixture ofvarious chemical elements or compounds is also called as pure substance as long as themixture is homogeneous.

2. What Is Saturation Temperature And Saturation Pressure?At a given pressure, the temperature at which a liquid boils is called saturation

temperature. At the given temperature the pressure at which the liquid boils is calledsaturation pressure .It is also called as vapour pressure.

3. Define Latent Heat Of Vaporization?The amount of heat added during heating of water from boiling point to dry saturated stage

is called as latent heat of vaporization or enthalpy of vaporization or enthalpy of vaporizationor latent heat of steam.

4. Find The Saturation Temp And Latent Heat Of Vaporization Of Steam At 1mpa.From steam table of 1 Mpa or 10 barsaturation temperature =179.880cLatent heat of vaporization =2013.6 KJ/Kg

5. Define The Terms 'Boiling Point' And 'Melting Point'.Boiling Point:It is the temperature at which the liquid starts to change its state from liquid to vapour.

Melting Point:It is the temp at which the solid starts to change its state from solid to liquid.

6. What Is Meant By Super Heated System? And Indicate Its UseIf the dry steam is further heated, then the process is called superheating and steam

obtained is known as super heated systemUSES:

1. Superheated steam has more heat energy and more work can be obtained using it.2. Thermal efficiency increases as the temp of superheated steam is high.

3.Heat losses be to condensation of steam an cylinder wall is reduced

7. Define: Sensible Heat Of Water.The amount of heat required to raise the temperature of unit mass of water from 0c to the

saturation temperature under a constant pressure. It is denoted by hs

8. Define The Term "Super Heat Enthalpy".The heat supplied to the dry steam at saturation temperature, to convert it into superheated

steam at the temperature T is called super heat enthalpy.

9. What Is Wet And Dry Steam?The steam which partially evaporated and having water particles in suspension is called

wet steam.The steam which fully in evaporated state and is not having any water particles is called dry

steam.

10. State phase rule of pure substances.The number of independent variables associated with multi compound, multiphase system

is given by the phase rule. It is also called as Gibbs phase rule. It is expressed by theequation as

n = C- # + 2where,

n = the number of independent variables,c = the number of components,# = the number of phases present in equilibrium.

11. Define dryness fraction of steam (or) what is quality of steam?

It is defined as the ratio of the masses of total steam actually present to the mass of thetotal system


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MASS OF DRY SYSTEM

DRYNESS FRACTION = ----------------------------------MASS OF TOTAL MIXTURE

12. Explain the terms: degree of super heat, degree of sub cooling?Degree of super heat:

It is the difference between superheated temperature and saturated temperature at thesame pressureDegree of sub cooling:

It is the amount by which the water is cooled beyond the saturated temperature at thesame pressure.

13. Define triple point and critical point for pure substance.TRIPLE POINT:

It is the state at where all three phases i.e. solid, liquid and vapour to exist in equilibrium.CRITICAL POINT:

It represents the highest pressure and temperature at which the liquid and vapour phasescoexist in equilibrium. At the critical point the liquid and vapour phases are indistinguishablei.e Liquid directly converted into vapour.

14. What are the merits and demerits of bleeding?MERITS:

It increases the thermodynamic efficiency as the heat of the bled steam is not lost in thecondenser but is utilized in feed heatingDEMERITS:

Cost of the plant increases and the work done per kg of steam is reduced which results inhigher boiler capacity for given output

15. What is the function of feed water heaters in the regenerative cycle with bleeding?The main function of feed water heater is to increase the temperature of feed water to the

saturation temperature corresponding to the boiler pressure before it enters into the boiler.

16. What are the merits and demerits of reheating?MERITS:

Marginal increase in thermal efficiency.Increase in work done per kg of stem which results in reduced size of the boilers and otherauxiliaries for the same output.we can prevent the turbine from erosionDEMERITS:

The cost of the plant increases due to the reheater and its long connections. It alsoincreases the condenser capacity due to increased dryness fraction.

17. Define triple point and critical pointTRIPLE POINT:

It is the state at where all three phases i.e solid, liquid and vapour to exist in equilibrium.CRITICAL POINT:

It represents the highest pressure and temperature at which the liquid and vapour phasescoexist in equilibrium. At the critical point the liquid and vapour phases are indistinguishable

i.e. Liquid directly converted into vapour

18. Define efficiency ratioThe ratio of actual cycle efficiency to that of ideal cycle efficiency is termed as efficiency ratio.

19. What are the advantages of bleeding?It increases the thermodynamic efficiency as the heat of the bled steam is not lost in the

condenser but is utilized in feed heating.By bleeding the volume floe at the low pressure end is considerably reduced, this reduces thedesign difficulties of blades, and also condenser size is reduced.

20. Why reheat cycle is not used for low boiler pressure.At low heat pressures the reheat cycle efficiency may be less than the Rankine cycle

efficiency. Since the average temperature during heating will then be low.

21. Define boiling point and melting pointBOILING POINT

It is the temperature at which the liquid starts to change its state from liquid to vapour.MELTING POINT

It is the temperature at which the solid starts to change its state from solid to liquid.


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22. Define latent heat of ice.

Total amount of heat added during conversion of ice of 0C into water of 0C.

23. What is meant by steam power cycles?Thermodynamic cycles which use steam as the working fluid is called steam power cycles.

24. Define specific steam consumption.It is defined as the mass flow of steam required per unit power output.

25. When will the efficiency of the Rankine cycle will be maximum?The temperature of the bled steam is approximately halfway between the extreme

temperatures of the primary flow cycle.


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UNIT-IVPART-A

1.

Determine the molecular volume of any perfect gas at 600N/m2 and 30oc.Universal gas constantmay be taken as 8314J/kg mole-K.

GIVEN DATA:p=600N/m2T= 300c= 30+273 = 303KR= 8314J/kg mole-K

SOLUTION:Ideal gas equation, pV = mRT

V = mRT/p= 1*8314*303/600= 4198.57m3/kg-mole

2.

State boyle's law.Boyle's law states, The volume of a given mass of a gas varies inversely as its absolute

pressure, When the temperature remains constantV = 1/p

3.

State charle's law.Charles law states, "The volume of a given mass of a gas varies directly as its absolute

temperature, When the pressure remains constant

V = T

4.State joule's law.

Joule's law states, "The internal energy of a given quantity of a gas depends only on thetemperature".

5.State Regnaults law.

Regnault's law states that Cp and Cv of a gas always remains constant

6.State Avogadros law.

Avogadros law states, "Equal volumes of different perfect gases at the same temperature andpressure, contain equal number of molecules".

7.

State Daltons law of partial pressure.Dalton's law of partial pressure states "The total pressure of a mixture of gases is equal to the

sum of the partial pressures exerted by individual gases if each one of them occupied separately inthe total volume of the mixture at mixture temperature"'

p = p1+p2+p3+........pk

8.

How does the vandar walls equation differ from the ideal gas equation of the state?Intermolecular attractive study is made.

Shape factor is considered.These assumptions are not made in ideal gas equations of state.

9.

What is meant by virtual expansion?Viral or virtual expansions are only applicable to gases of low and medium densities.

The equation state of a substance is given by

P = RT/v + a(T)/ v2 + b(T)/v3 + c(T)/v4 + ........The coefficient of a(T), b(T),c(T) ...... are viral coefficients. The viral coefficient will vanish

when the pressure becomes zero. Finally, the equation of state reduces to the ideal-gas equation.

10.

Distinguish between ideal and real gas.An ideal gas is one which strictly follows the gas laws under all conditions of temperature and

pressure.In actual practice, there is no real gas which strictly follows the gas laws over the entire range of

temperature and pressure. However hydrogen, oxygen, nitrogen and air behave as an ideal gasunder certain temperature and pressure limits.

11.Define joule-Thomson co-efficient.

Joule-Thomson co-efficient is defined as the change in temperature with change in pressure,keeping the enthalpy remains constant. It is denoted by the

u = (dv/dt)


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12.

Define co-efficient of volume expansion and isothermal compressibility.co-efficient of volume expansion:

Co-efficient of volume expansion is defined as the change in volume with change intemperature per unit volume keeping the pressure constant.Isothermal compressibility:

It is defined as the change in volume with change in pressure per unit volume by keeping thetemperature constant

13.

What is compressibility factor? What is its value for ideal gas at critical point?

We know that, the perfect gas equation is pv=RT. But for real gas, a correction factor has to beintroduced in the perfect gas equation to take into account the deviation of real gas from the

perfect gas equation. This factor is known as compressibility factor(Z) and is defined byZ = pv/RT

At, critical point ,the vanderwall's equationpcVc/RTc = 1 for ideal gases

14.

What is equation of state? write the same for an ideal gas?

An ideal gas is an substance which obeys the law of pv= RT or pV= RTwhere, p = pressure of the gas

v = specific volume of the gasV = Total volume of the gasR = Universal gas constant =8.314KJ/Kg mole KR = R/M for any gas

T = Absolute temperature in KIf we consider the mass of gas m, the equation of state becomes

pv= RT or pV = m RT

15.

What is the significance of compressibility factor?

1.Intermolecular active study is made2.Shape factor is considered

16.

State the Avogadros law and state its significance?Avogadros law states, "Equal volumes of different perfect gases at the same temperature

and pressure, contain equal number of molecules".

SIGNIFICANCE:

All gases whose mass is equal to its mole occupy the same volume with at normaltemperature and pressureAt NTP, Pressure p=1.013bar

Temperature=0ocMv = constant

where, M - Molecular weight of the gasv - specific volume of the gas

17.

Write down the vandar walls equation of state. How does it differ from the equation ideal gasequation of the state?

The equation of state is given by(p+a/V2)(V2-b)=RT

where, v =Molar volumeR =Universal gas constant = 8.314Nm/Kg mol K

18.

What is clapeyron equation?Clapeyron equation which involves relationship between the saturation pressure, saturation

temperature, the enthalpy of vaporization and the specific volume of two phases involveddp/dT = hfg/Tvfg

19.

State gibbs equation?Gibbs function is the property of a system and is given by

G = u-Ts+pv = h-TsWhere,

h-enthalpyT-temperature

s-entropy


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20.

State tds equationTds equations are

Tds= CpdT-T(dv/dT)pdp

Tds= CvdT+T(dv/dT)Tdv

21.

What is compressibility factor?We know that, the perfect gas equation is pv=RT. But for real gas, a correction factor has to be

introduced in the perfect gas equation to take into account the deviation of real gas from theperfect gas equation. This factor is known as compressibility factor(Z) and is defined by

Z = pv/RT


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UNIT-VPART-A

1 What is the difference between the air conditioning and refrigeration?refrigeration is the process of providing and maintaining the temperature in space belowatmospheric pressureAir conditioning is the process of supplying sufficient volume of clean air containing a specificvolume of water vapour and maintaining predetermined atmospheric condition with in a selected

enclosure.

2 What is psychrometry?The science which deals with the study of behavior of moist air is known as psychrometry.

3 Define dry bulb temperature (dbt).The temperature which is measured by an ordinary thermometer is known as dry bulbtemperature. It is denoted by td

4 Define wet bulb temperature.It is the temperature of the air measured by a thermometer when its bulb is covered with wet clothand exposed to a current rapidly moving air. It is denoted by tdp

5 Define dew point temperature.The temperature at which the water vapour present in air begins to condense when the air iscooled is known as dew point temperature.

6 Define relative humidity and specific humidity.RH is the ratio of mass of water vapour (mv) in a certain volume of moist air at a given temperatureto the mass of water vapour (mvs) in the same volume of saturated air at the same temperature.i.e., RH = mv/mvsSpecific humidity is the ratio of mass of water vapour (mv) to the mass of dry air in the givenvolume of mixture.i.e., w = mv/ma

7 Differentiate between absolute and relative humidity.Absolute humidity is defined as the ratio of mass of water vapour(mv)in a certain volume of moistair at a given temperature to the mass of water vapour(mvs)at atmospheric conditions.RH is the ratio of the mass of water vapour (mv) in a certain volume of moist air at a giventemperature to the mass of water vapour in the same volume of saturated air at the sametemperature.i.e,RH = mv/mvs

8 Define dpt and degree of saturation.dpt is the temperature to which moist air to be cooled before it starts condensing.Degree of saturation is the ratio of specific humidity of moist air to the specific humidity ofsaturated air temperature.

specific humidity of moist airu= --------------------------------

specific humidity of saturated air

9 What is dew point temperature? How is it related to dry bulb temperature at the saturetioncondition?It is the temperature at which the water vapour present in air begins to condense when the air isboiled.for saturated air, the dry bulb, wet bulb and dew point temperature are all same.

10 Define Daltonslaw of partial pressure.The total pressure exerted by air and water vapour mixture is equal to the barometric pressure.ph = pa+pvWhere, ph = barometric pressurepa = partial pressure of dry airpv = partial pressure of water vapour


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11 Define apparatus dew point of cooling oil.

For dehumidification, the cooling coil is to be kept at a mean temperature which is below the dewpoint temperature of the entering. The temperature of the coil is called adp temperature.

12 12. List down the psychometric process.Sensible heating processSensible cooling processHumidification processDehumidification processHeating and humidification processCooling and dehumidification processAdiabatic mixing airstreams process

evaporative cooling process

13 Define bypass factor of a coil.The ratio of amount of air which does not contact the cooling coil to the amount of supply air iscalled Bpf.i.e. amount of air bypassing the coilBpf = ------------------------------------

total amount of air passed

14 State the effects of very high and very low bypass factor.very high bypass factor:1. It requires more air. Larger fan and motor required.2. It requires less heat transfer area.

Very low bypass factor:1. Higher adp is employed.2. It requires less air. Fan and motor size reduced

15 What are the assumptions made while mixing two air streams?1.surrounding is small2.process is fully adiabatic3.there is no interactions4. Change in potential or kinetic energies are negligible.

16 What is evaporative cooling? Will it works in humid climates?in this type of cooling the air is passed through an insulated chamber. The insulating chamber hassprays in which water is maintained at a temperature of entering air but lower than its dry bulbtemperature.

it can be used in humid climates.

17 Define specific humidity how does it differ from relative humidity.Specific humidity is the ratio of mass of water vapour (mv) to the mass of dry air in the givenvolume of mixture.I.e., w = mv/maSpecific humidity has straight lines where relative humidity has curved lines.

18 What is adiabatic mixing and write the equation for that?It is a mixture of conditioned air with the fresh air before it is routed into the living space.m1/m2 = h3-h2/h1-h3

19 What is specific humidity and how do you calculate it?

Specific humidity is the ratio of mass of water vapour(mv)to the mass of dry air in the given volumeof mixture.i.e., w = mv/ma

20 What is meant by adiabatic saturation temperature?The equilibrium temperature is called adiabatic saturation temperature.


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etd 2mark with answer11

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