b.tech. [sem iii (me)] quiz test-1 - being...

EME-303/Ms. Dolly Singh Date: 23/08 /2011

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SHRI RAMSWAROOP MEMORIAL COLLEGE OF ENGG. & MANAGEMENT

B.Tech. [SEM III (ME)] QUIZ TEST-1

(Session: 2010-11)

THERMODYNAMICS (EME-303)

Roll No.

(To be filled by the Student) Note: All questions are compulsory.

Part – A (Questions from Tutorial Sheet) [10 Marks]

Q.1) Two thermometers, one Centigrade and other Fahrenheit, are immersed in a fluid. After the

thermometers reach equilibrium with the fluid, it is noted that the both thermometers indicate the same numerical value. Find the identical numerical value shown by the thermometers. What would be the corresponding temperature of the fluid expressed in degrees Kelvin and degrees Rankine? {Q. No.1} (2.5+2.5)

Q.2) Air initially at 60kPa pressure, 800K temperature and occupying a volume of 0.1 m3 is compressed isothermally until the volume is halved and subsequently it goes further compression at constant pressure till the volume is halved again. Sketch the process on p-V plot and make calculations for the total work done and total heat interaction for the two processes. Assume ideal gas behavior for air and take Cp= 1.005kJ/kg K. {Q.No.5} (1+2+2) Part – B [20 Marks] Q.1) What is Free Expansion Process? Why does free expansion have zero work transfer? (3+3) Q.2) A vessel of 2 m3 volume contains hydrogen at atmospheric pressure and 27°C temperature. An evacuating pump is connected to vessel and the evacuation process is continued till its pressure becomes 70 cm of Hg vacuum. Estimate the mass of the hydrogen pumped out. Also determine the final pressure in vessel if cooling is carried up to 10°C. Take atmospheric pressure as 76 cm of Hg and universal gas constant as 8.314kJ/kg K. (3+3) Q.3) The piston of an oil engine, of area 0.0045m2, moves downwards 75mm drawing in 0.00028m3 of fresh air from the atmosphere. The pressure in the cylinder is uniform during the process at 80kPa,while the atmospheric pressure is 101.325kPa. Estimate the displacement work done by the air finally in the cylinder. (8) _________X__________

Academic/26 Refer/WI/ACAD/18

Time: 1 Hour Max. Marks: 30


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(Session: 2010-11)


Roll No.



Q.1) Given that the ice point is 0°C and 32°F and that the steam point is 100°C and 212°F set up a correlation between the Celsius and Fahrenheit scales. Determine the temperature at which the Celsius and Fahrenheit scales have the same numerical value. Is there any temperature at which the Kelvin and Rankine scales have the same numerical value? { Q. No 2} (2.5+2.5) Q.2) 2 kg of an ideal gas is compressed adiabatically from pressure 100kPa and temperature 220K to a final pressure of 400kPa. Make calculation for [1]initial volume, [2] final volume and temperature, [3] work performed ,[4] heat interaction to or from the system, and [5] change in internal energy. It may be presumed that for the given ideal gas Cp=1kJ/kg K and Cv=0.707kJ/kg K. {Q. No. 6} (1+1+1+1+1) Part – B [20 Marks]

Q.1) What is Free Expansion Process? Why does free expansion have zero work transfer? (3+3) Q.2) A vessel of 2 m3 volume contains hydrogen at atmospheric pressure and 27°C temperature. An evacuating pump is connected to vessel and the evacuation process is continued till its pressure becomes 70 cm of Hg vacuum. Estimate the mass of the hydrogen pumped out. Also determine the final pressure in vessel if cooling is carried up to 10°C. Take atmospheric pressure as 76 cm of Hg and universal gas constant as 8.314kJ/kg K. (3+3) Q.3) The piston of an oil engine, of area 0.0045m2, moves downwards 75mm drawing in 0.00028m3 of fresh air from the atmosphere. The pressure in the cylinder is uniform during the process at 80kPa,while the atmospheric pressure is 101.325kPa. Estimate the displacement work done by the air finally in the cylinder. (8) __________x___________




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(Session: 2010-11)


Roll No.



Q.1) A vertical piston cylinder assembly that initially has a volume of 0.1m3 is filled with 0.1 kg of nitrogen gas. This is weighted so that the pressure of nitrogen is always maintained at 1.15 bar. Heat transfer is allowed to take place until the volume is reduced to 75% of initial volume. Determine: [1] initial and final temperatures of nitrogen ,[2] magnitude and direction of heat transfer. Assume the process to be quasi static and take Cv=0.745kJ/kg K for nitrogen. {Q. No. 4} (2.5+2.5)

Q.2)A vessel of 5m3 capacity contains air at 100kPa and temperature of 300 K. Some air is removed from vessel so as to reduce pressure and temperature to 50kPa and 7°Crespectively. Find the amount of the air removed and volume of this mass of air at initial states of air. Take R= 287 J/kg K for air.{Q. No. 9} (2.5+2.5)

Part – B [20 Marks]

Q.1) What is Free Expansion Process? Why does free expansion have zero work transfer? (3+3) Q.2) A vessel of 2 m3 volume contains hydrogen at atmospheric pressure and 27°C temperature. An evacuating pump is connected to vessel and the evacuation process is continued till its pressure becomes 70 cm of Hg vacuum. Estimate the mass of the hydrogen pumped out. Also determine the final pressure in vessel if cooling is carried up to 10°C. Take atmospheric pressure as 76 cm of Hg and universal gas constant as 8.314kJ/kg K. (3+3) Q.3) The piston of an oil engine, of area 0.0045m2, moves downwards 75mm drawing in 0.00028m3 of fresh air from the atmosphere. The pressure in the cylinder is uniform during the process at 80kPa,while the atmospheric pressure is 101.325kPa. Estimate the displacement work done by the air finally in the cylinder. (8) _________X__________




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(Session: 2010-11)


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Q.1) The work output and heat input involved by a system in a process A are 20kJ and 15 kJ respectively. Another process B between the same en conditions involves a heat input of 10kJ. Determine the change in internal energy involved and also the work done in process B. Show that if a cycle is formed using processes A and B, the given data is consistent with the first law. {Q. No.3} (1.5+1.5+2) Q.2) A temperature scale is being developed using the following relation t =a.ln(p)+(b/2) , where the p is thermometric property and a & b are constants. Determine Celsius temperature corresponding to thermometric property of 6.5. If ice point and steam point give thermometric property value of3& 8.{Q.No. 8} (5) Part – B [20 Marks]





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(Session: 2010-11)


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Q.1) 0.2m3 of an ideal gas at a pressure of 2MPa and 600 K is expanded isothermally tro 5 time the initial volume. It is then cooled to 300K at constant volume and then compressed back polytropically to its initial state. Determine the net work done and heat transfer during the cycle.(Take n=1.43). {Q. No. 7} (2.5+2.5) Q.2) 0.15m3 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 the net work done and heat transferred during the cycle. (take n=1.46). { Q. No. 11) (1+2.5+1.5)





EME-303 / Ms. Dolly Singh Date: 17 / 09 / 2011

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B.Tech. [SEM III (ME-31, 32, 33 & 34)] QUIZ TEST-2

(Session: 2011-12)


Roll No.



Q1). A steam turbine operates under steady flow conditions receiving steam at the following state pressure 15 bar, internal energy 2700 kJ/kg, specific volume 0.17 m3/kg and velocity 100m/s. The exhaust of steam from the turbine is at 0.1 bar with internal energy 2175 kJ/kg, specific volume 15 m3/kg and velocity 300m/s. The intake is 3 meters above the exhaust. The turbine develops 35 kW and heat loss over the surface of turbine is 20kJ/kg. Determine the steam flow rate through the turbine. {Q No. 8} [5] Q2). A inventor claims that his engine has the following specifications: Temperature limits

=750°C and 25°C , Power developed =75kW , Fuel burned per hr = 3.9kg and Heating value of the fuel =74500kJ/kg. State whether his claim is valid or not. { Q No.10} [5]

Part – B [20 Marks] Q1). Show that the efficiency of a reversible engine operating between two given constant temperature is the maximum. [6] Q2). A Carnot engine E1 operates between temperatures T1 and T2, rejects its waste heat at its sink temperature T2 to Carnot engine E2 which operates between the temperatures limits T2 and T3. Set up an expression relating the thermal efficiency of engines E1 and E2 to that of a Carnot engine E3 operating directly between temperatures T1 and T3. [3+4] Q3). A heat pump working on a reversed Carnot cycle takes in energy from a reservoir maintained at 3°C and delivers it to another reservoir where temperature is 77°C. The heat pump drives power fir its operation from a reversible engine operating within the higher and lower temperature limits of 1077°C and 77°C. For 100kJ/s of energy supplied to the reservoir at 77°C, estimate the energy taken from the reservoir at 1077°C. [7] __________X__________




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(Session: 2011-12)


Roll No.


Part – A

(Questions from Tutorial Sheet) [10 Marks]

Q1). A reversible heat engine receives heat from a high temperature reservoir at T1 K and rejects heat to a low temperature sink at 800 K. A second reversible engine receives the heat rejected by the first engine at 800 K and rejects to a cold reservoir at 280 K. Make calculation for temperature T1 : (i) for equal thermal efficiencies of the two engines, (ii) for the two engines to deliver the same amount of work. {Q No. 3} [2.5+2.5] Q2). A nozzle is device for increasing the velocity of a steadily flowing stream. At inlet to a

certain nozzle, the fluid parameters are: Enthalpy =2850kJ/kg, velocity =50m/s . Area =0.1m2 and specific volume = 0.18 m3/kg. At the discharge end the enthalpy is 2650kJ/kg and specific volume is 0.49m3/kg. Make calculations for the velocity of fluid at exit from the nozzle, mass flow rate of fluid, and the exit area of the nozzle. The nozzle is horizontal and there is negligible heat loss from it. { Q No.6} [2.5+2.5]

Part – B [20 Marks] Q1). Show that the efficiency of a reversible engine operating between two given constant temperature is the maximum. [6] Q2). A Carnot engine E1 operates between temperatures T1 and T2, rejects its waste heat at its sink temperature T2 to Carnot engine E2 which operates between the temperatures limits T2 and T3. Set up an expression relating the thermal efficiency of engines E1 and E2 to that of a Carnot engine E3 operating directly between temperatures T1 and T3. [3+4] Q3). A heat pump working on a reversed Carnot cycle takes in energy from a reservoir maintained at 3°C and delivers it to another reservoir where temperature is 77°C. The heat pump drives power fir its operation from a reversible engine operating within the higher and lower temperature limits of 1077°C and 77°C. For 100kJ/s of energy supplied to the reservoir at 77°C, estimate the energy taken from the reservoir at 1077°C. [7] __________X_________




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(Session: 2011-12)


Roll No.



Q1). In a winter season when outside temperature is -1˚C, the inside of house is to be

maintained at 25˚C. Estimate the minimum power required to run the heat pump for maintaining the temperature. Assume heating load as 125MJ/h. {Q No.1} [5]

Q2). A reversible engine is used foe only driving a reversible refrigerator. Engine is supplied 2000 kJ/s heat from a source at 1500 K and rejects some energy to low temperature sink. Refrigerator is desired to maintain the temperature of 15˚C while rejecting heat to the same low temperature sink. Determine the temperature of the sink if total 3000kJ/s heat is received by the sink. {Q No.2} [5] Part – B [20 Marks] Q1). Show that the efficiency of a reversible engine operating between two given constant temperature is the maximum. [6] Q2). A Carnot engine E1 operates between temperatures T1 and T2, rejects its waste heat at its sink temperature T2 to Carnot engine E2 which operates between the temperatures limits T2 and T3. Set up an expression relating the thermal efficiency of engines E1 and E2 to that of a Carnot engine E3 operating directly between temperatures T1 and T3. [3+4] Q3). A heat pump working on a reversed Carnot cycle takes in energy from a reservoir maintained at 3°C and delivers it to another reservoir where temperature is 77°C. The heat pump drives power fir its operation from a reversible engine operating within the higher and lower temperature limits of 1077°C and 77°C. For 100kJ/s of energy supplied to the reservoir at 77°C, estimate the energy taken from the reservoir at 1077°C. [7] __________X__________




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(Session: 2011-12)


Roll No.



Q1). A reversible heat engine receives heat from two thermal reservoirs maintained at constant temperature of 750K and 500K. The engine developes100 kW and rejects 3600kJ/min of heat to a heat sink at 250 K. Determine thermal efficiency of the engine and heat supplied by each thermal reservoir. . {Q No. 4} [5] Q2). A perfect gas flows through a nozzle where it expands in a reversible adiabatic manner. The inlet conditions are 22 bar, 500˚C, 38 m/s. At exit the pressure is 2 bar. Determine the exit velocity and exit area if the flow rate is 4kg/s. Take R= 190J/kg K and γ=1.35 { Q No.7} [2.5+2.5] Part – B [20 Marks] Q1). Show that the efficiency of a reversible engine operating between two given constant temperature is the maximum. [6] Q2). A Carnot engine E1 operates between temperatures T1 and T2, rejects its waste heat at its sink temperature T2 to Carnot engine E2 which operates between the temperatures limits T2 and T3. Set up an expression relating the thermal efficiency of engines E1 and E2 to that of a Carnot engine E3 operating directly between temperatures T1 and T3. [3+4] Q3). A heat pump working on a reversed Carnot cycle takes in energy from a reservoir maintained at 3°C and delivers it to another reservoir where temperature is 77°C. The heat pump drives power fir its operation from a reversible engine operating within the higher and lower temperature limits of 1077°C and 77°C. For 100kJ/s of energy supplied to the reservoir at 77°C, estimate the energy taken from the reservoir at 1077°C. [7] __________X__________




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(Session: 2011-12)


Roll No.



Q1). A refrigerator operating on the reversed Carnot cycle consumes 150 W power in summer when the ambient atmosphere is at 310 K. The heat leakage into the refrigerator through the doors is estimated to be at the continuous rate of 15 W per degree temperature difference between the ambient air and the cold space of the refrigerator. For continuous operation of the refrigerator, Determine the temperature at which the cold space is maintained. [5] {Q No. 5} Q2). Two Carnot engines work in series between the source and sink temperature of 550 K and.

if the both engine have equal power, Determine the intermediate temperature. [5] { Q No.11} Part – B [20 Marks] Q1). Show that the efficiency of a reversible engine operating between two given constant temperature is the maximum. [6] Q2). A Carnot engine E1 operates between temperatures T1 and T2, rejects its waste heat at its sink temperature T2 to Carnot engine E2 which operates between the temperatures limits T2 and T3. Set up an expression relating the thermal efficiency of engines E1 and E2 to that of a Carnot engine E3 operating directly between temperatures T1 and T3. [3+4] Q3). A heat pump working on a reversed Carnot cycle takes in energy from a reservoir maintained at 3°C and delivers it to another reservoir where temperature is 77°C. The heat pump drives power fir its operation from a reversible engine operating within the higher and lower temperature limits of 1077°C and 77°C. For 100kJ/s of energy supplied to the reservoir at 77°C, estimate the energy taken from the reservoir at 1077°C. [7] __________X__________




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(Session: 2010-11)


Roll No.



Q.1) In a counter flow heat exchanger 0.25 Kg/s of water is heated from 30 °C to 60 °C by hot gases which enter at 180° C and leave at 80 °C. Make calculations for the mass flow of gases, heat transferred and loss of available energy due to this heat transfer. Take Cp for gases=1.08kJ/kg K and ambient temperature =27°C. (Q. No.7} (2+2+1) Q.2) A heat engine operates between source at 600 K and sink at 300 K. Heat supplied by source is 500 kcal/s. Evaluate feasibility of engine and nature of cycle for the following conditions: (a) heat rejected being 200 kcal/s, (b) heat rejected being 400 kcal/s, and (c)heat rejected being 250 kcal/s. {Q.No.10} (5) Part – B [20 Marks] Q.1) Comment on the statement: “The entropy of the universe is increasing” and explain the difference between isentropic &adiabatic process. (3+2) Q.2) Is the adiabatic mixing of fluids irreversible? If yes, explain. And why the 2nd law efficiency is needed in analysis of any system? (5+2) Q.3) One kg of water at 273 K is brought into contact with a heat reservoir at 373 K. When the water has reached 373 K, Find the(a) entropy change of the water ,of the reservoir, and of the universe, (b) if the water is heated from 273 K to 373 K by first bringing in contact with a reservoir at 323 K and then with the reservoir at 373 K, what will the entropy change of universe be, (c) explain how water might be heated from 273 K to 373 K with almost no change in the entropy of the universe. (3+3+2) _________X__________




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(Session: 2010-11)


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Q.1) The connections of a reversible engine to three sources at 400 K, 300 K and 200 K are as shown in fig. The engine draws 1200 kJ from source at 400 K and produces 200 kJ of work. Determine (a) the amount and directions of heat interactions with the other heat sources, (b) the entropy changes due to each of the heat interactions with the engine, and (c) How much entropy change occur for the cycle. {Q. No 4} (2.5+2.5) Q.2 Determine the second law efficiency of a heat engine operating between 700C and 30C. The heat engine has efficiency of 0.40. {Q. No. 12} (5) Part – B [20Marks] Q.1) Comment on the statement: “The entropy of the universe is increasing” and explain the difference between isentropic &adiabatic process. (3+2) Q.2) Is the adiabatic mixing of fluids irreversible? If yes, explain. And why the 2nd law efficiency is needed in analysis of any system? (5+2) Q.3) One kg of water at 273 K is brought into contact with a heat reservoir at 373 K. When the water has reached 373 K, Find the(a) entropy change of the water ,of the reservoir, and of the universe, (b) if the water is heated from 273 K to 373 K by first bringing in contact with a reservoir at 323 K and then with the reservoir at 373 K, what will the entropy change of universe be, (c) explain how water might be heated from 273 K to 373 K with almost no change in the entropy of the universe. (3+3+2) ]




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(Session: 2010-11)


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Q.1) Find the entropy change of 5 kg of a perfect gas whose temperature varies from 150 C to 200 C during a constant volume process. The specific heat varies linearly with absolute temperature and is presented by the relation: Cv= (0.45+0.009T) kJ/kg K. {Q. No. 3} (5) Q.2) Determine the entropy change of universe, if two copper blocks of 1 kg & 0.5 kg at 150° and 0°C are joined together. Specific heats for copper at 150°C and 0°C are 0.393kJ/kg K and 0.381 kJ/kg K respectively. {Q. No. 8} (5)

Part – B [20 Marks] Q.1) Comment on the statement: “The entropy of the universe is increasing” and explain the difference between isentropic &adiabatic process. (3+2) Q.2) Is the adiabatic mixing of fluids irreversible? If yes, explain. And why the 2nd law efficiency is needed in Analysis of any system? (5+2) Q.3) One kg of water at 273 K is brought into contact with a heat reservoir at 373 K. When the water has reached 373 K, Find the(a) entropy change of the water ,of the reservoir, and of the universe, (b) if the water is heated from 273 K to 373 K by first bringing in contact with a reservoir at 323 K and then with the reservoir at 373 K, what will the entropy change of universe be, (c) explain how water might be heated from 273 K to 373 K with almost no change in the entropy of the universe. (3+3+2) _________X__________




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(Session: 2010-11)


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Q.1)1 m3 of air is heated reversibly at constant pressure from 290 K and 580 K, and is then cooled reversibly at constant volume back to initial temperature. If the initial pressure is 1bar, work out of the net heat flow and overall change in entropy. Represent the processes on T- S plot. Take Cp=1.005kJ/kg K and R=287J/kg K. {Q. No.2} (1.5+1.5+2) Q.2) Determine the change in entropy of universe if a copper block of 1 kg at 150°C is placed in sea water at 25°C. Take heat capacity of copper as 0.393 kJ/kg K. {Q. No. 9} (5) Part – B [20 Marks] Q.1) Comment on the statement: “The entropy of the universe is increasing” and explain the difference between isentropic &adiabatic process. (3+2) Q.2) Is the adiabatic mixing of fluids irreversible? If yes, explain. And why the 2nd law efficiency is needed in analysis of any system? (5+2) Q.3) One kg of water at 273 K is brought into contact with a heat reservoir at 373 K. When the water has reached 373 K, Find the(a) entropy change of the water ,of the reservoir, and of the universe, (b) if the water is heated from 273 K to 373 K by first bringing in contact with a reservoir at 323 K and then with the reservoir at 373 K, what will the entropy change of universe be, (c) explain how water might be heated from 273 K to 373 K with almost no change in the entropy of the universe. (3+3+2) _________X__________




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(Session: 2010-11)


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Q.1) A piston cylinder arrangement contains 1 kg of air at pressure 1 bar and temperature 300 K. When 10kJ of work is done on air, its parameter change to 2.5 bar and 310 K. If the piston- cylinder assembly exchanges heat only with a reservoir maintained at 300 K, make calculations for entropy change of the air, entropy change of the reservoir and heat transfer from the air. Comment on the truth or falsehood of the claim. Take Cp=1.005kJ/kg K and R= 0.287kJ/kg K for air. {Q. No. 1} (2+2+1) Q.2) Find the entropy change of 5 kg of a perfect gas whose temperature varies from 150 C to 200 C during a constant volume process. The specific heat varies linearly with absolute temperature and is presented by the relation: Cv= (0.45+0.009T) kJ/kg K. {Q. No. 3) (5) Part – B [20 Marks] Q.1) Comment on the statement: “The entropy of the universe is increasing” and explain the difference between isentropic &adiabatic process. (3+2) Q.2) Is the adiabatic mixing of fluids irreversible? If yes, explain. And why the 2nd law efficiency is needed in analysis of any system? (5+2) Q.3) One kg of water at 273 K is brought into contact with a heat reservoir at 373 K. When the water has reached 373 K, Find the(a) entropy change of the water ,of the reservoir, and of the universe, (b) if the water is heated from 273 K to 373 K by first bringing in contact with a reservoir at 323 K and then with the reservoir at 373 K, what will the entropy change of universe be, (c) explain how water might be heated from 273 K to 373 K with almost no change in the entropy of the universe. (3+3+2) _________X__________



EME-303/Ms. Dolly Singh Date: 12 / 11 /2011

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(Session : 2011-12)

THERMODYNAMICS Time:1 Hour (EME-303) Max.Marks:30

Roll No.

(To be filled by the Student) Note: Attempt all questions


Q1. A 4-stroke petrol engine having six cylinders is to operate with compression ratio 6 and deliver 300kW brake power when running at 2400 rev/min. Determine,(a)bore and stroke of the engine,(b)fuel consumption in kg/hr, and(c) specific fuel consumption in kg/kWh. The following data may be assumed: stroke =1.25times of the bore, mechanical efficiency =0.8, indicated mean effective pressure =10bar, relative efficiency=0.5 and calorific value of fuel used=44MJ/kg (Q-3) [2+2+1] Q 2. Determine the enthalpy, volume, internal energy and entropy of superheated stem at 15 bar pressure and 220°C. The volume of water may be neglected and take specific heat of superheat equal to 2.2 kJ/kg K. (Q-6) [1+1+2+1]

Part – B [20 Marks] Q1 Steam at a pressure of 14 bar with 80 K of superheat is throttled to a pressure of 8.5 bar. Determine the temperature of steam after throttling. The specific heat of superheated steam may be assumed as 2.2 kJ/kg K. [5] Q2 During a test of single cylinder of oil engine , working on the four stroke cycle and fitted with a rope brake, the following readings are taken: Effective diameter of brake wheel=630mm, Dead load on brake=200 N. spring balance reading =30N, Speed=450rpm, Area of indicator diagram=420mm2, Length of indicator diagram =60mm, Spring scale=1.1 bar/mm, Diameter of the cylinder=100mm, Stroke=150mm, Quantity of oil used=0.815kg/h, calorific value of oil=42000kJ/kg. Calculate brake power, indicated power, mechanical efficiency, brake thermal efficiency and brake specific fuel consumption. [2+2+1+1+1] Q3 (A) What is the use of heat of heat balance sheet of an engine? Mention the various items to be determined to complete the heat balance sheet. [2+2] (B)What kind of steam is called wet saturated, dry saturated and superheated? [4]



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Q1. The following data was recorded during a test run made on a single cylinder, four stroke engine having a compression ratio of 6;Bore and stroke =10cm and 12.5cm respectively, Dead load and spring balance reading =60N and 20N, Effective radius of brake drum=40cm, Fuel consumption=1.2kg/hr and calorific value of fuel is 42500kJ/kg. if the engine turns 2000rev/min and the indicated mean effective pressure is 0.25MPa ,Determine its indicated &brake power and mechanical ,overall and relative efficiencies. (Q-2) [1+1+1+1+1] Q 2. Wet steam at 20 bar pressure and 0.9 dryness fraction is heated reversibly at constant pressure to a temperature of 300°C. Make calculate for the work done, heat supplied and changes in internal energy and entropy. Represent the process on T-S diagram and indicated there upon the area which represents the heat interaction. (Q-7) [1+1+1+1+1] Part – B [20 Marks]

Q1 Steam at a pressure of 14 bar with 80 K of superheat is throttled to a pressure of 8.5 bar. Determine the temperature of steam after throttling. The specific heat of superheated steam may be assumed as 2.2 kJ/kg K. [5] Q2 During a test of single cylinder of oil engine , working on the four stroke cycle and fitted with a rope brake, the following readings are taken: Effective diameter of brake wheel=630mm, Dead load on brake=200 N. spring balance reading =30N, Speed=450rpm, Area of indicator diagram=420mm2, Length of indicator diagram =60mm, Spring scale=1.1 bar/mm, Diameter of the cylinder=100mm, Stroke=150mm, Quantity of oil used=0.815kg/h, calorific value of oil=42000kJ/kg. Calculate brake power, indicated power, mechanical efficiency, brake thermal efficiency and brake specific fuel consumption. [2+2+1+1+1] Q3 (A) What is the use of heat of heat balance sheet of an engine? Mention the various items to be determined to complete the heat balance sheet. [2+2] (B)What kind of steam is called wet saturated, dry saturated and superheated? [4]



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(Session : 2011-12)


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Q1. The following data was recorded during a test run made on a single cylinder, four stroke engine having a compression ratio of 6;Bore and stroke =10cm and 12.5cm respectively, Dead load and spring balance reading =60N and 20N, Effective radius of brake drum=40cm, Fuel consumption=1.2kg/hr and calorific value of fuel is 42500kJ/kg. if the engine turns 2000rev/min and the indicated mean effective pressure is 0.25MPa ,Determine its indicated &brake power and mechanical ,overall and relative efficiencies. (Q-2) [1+1+1+1+1] Q 2. Wet steam at 20 bar pressure and 0.9 dryness fraction is heated reversibly at constant pressure to a temperature of 300°C. Make calculate for the work done, heat supplied and changes in internal energy and entropy. Represent the process on T-S diagram and indicated there upon the area which represents the heat interaction. (Q-7) [1+1+1+1+1] Part – B [20 Marks]




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(Session : 2011-12)


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Q1. Two boilers A and B are delivering steam in equal proportion to a common main. Both the boilers operate at a pressure of 14 bar which is also the pressure of steam in the main. The boiler A is fitted with a superheater and supplies steam at 300C. If the temperature of the resulting mixture in the steam main is 235C, estimate the quality of steam supplied by the boiler B which is without a superheater. Proceed to determine the net change in the entropy of the arrangement. Take Cps=2.25kJ/kg K for the superheated steam. (Q-4) [2.5+2.5] Q 2. Find the internal energy of 1 kg of superheated steam at a pressure of 10 bar and 280°C. If this steam be expanded to a pressure of 1.6 bar and 0.8 dry, determine the change in internal energy. Assume specific heat of superheated steam as 2.1 kJ/ kg K. (Q-8)[5] Part – B [20 Marks]


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(Session : 2011-12)


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Q1. A vessel of 0.05m3 capacity contains a mixture of saturated steam and water at a temperature of 300C, the mass of liquid water being 10kg. Determine the pressure, mass, enthalpy ,specific volume, internal energy and entropy of contents present in the vessel. (Q-5) [1+1+1+1+1] Q 2. The steam consumption of a steam engine is 20 tones per shift of 8 hours when developing 220 kW. Dry and saturated steam enters the engine at 10 bar pressure and leaves it at 0.1 bar pressure. Estimate the Rankine efficiency and the thermal efficiency of the engine. (Q-11) [2.5+2.5]





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b.tech. [sem iii (me)] quiz test-1 - being...

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