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Q1::A- The absolute pressure in water at a depth of 5 m is read to be 145 kPa. Determine the absolute pressure at a depth of 5 m in a liquid whose density 900 kg/m3 at the same location? B- A 650 MW thermal power plant has an overall efficiency of 43% consumped natural gas fue

Q1::A- The absolute pressure in water at a depth of 5 m is read to be 145 kPa. Determine the absolute pressure at a depth of 5 m in a liquid whose density 900 kg/m3 at the same location? B- A 650 MW thermal power plant has an overall efficiency of 43% consumped natural gas fue

Elements Of Electromagnetics
Elements Of Electromagnetics
7th Edition
ISBN:9780190698614
Author:Sadiku, Matthew N. O.
Publisher:Sadiku, Matthew N. O.
ChapterMA: Math Assessment
Section: Chapter Questions
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University of Technology Mechanical Engineering Mid Examination 2020/2021 Year: 1" Stage Subject: physics 2 Examiners: Thermodynamics group Exam Time: 2 Hrs. Date: 22 /6/ 2021 Answer four questions only Q1:: A- The absolute pressure in water at a depth of 5 m is read to be 145 kPa. Determine the absolute pressure at a depth of 5 m in a liquid whose density 900 kg/m3 at the same location? B- A 650 MW thermal power plant has an overall efficiency of 43% consumped natural gas fuel (heating value-45 MJ/kg).Calculate the saving in fuel when the fuel type change to gasoil (heating value=50 MJ/kg) in kg/hr. Q2 A perfect gas is contained in a rigid vessel at 2 bar and 315°C is cooled at constant volume to pressure of 1 bar ,and then expanded isothermally until the pressure falls to 0.5 bar; the gas has a molar mass of 26 kg/kmol and value of y=1.37.Calculate the net work and heat transferred per unit mass. Q3: - In a gas turbine installation, the gases enter the turbine at the rate of 5 kg/s with a velocity of 50 m/s and enthalpy of 900 kJ/kg and leave the turbine with 150 m/s and enthalpy of 400 kJ/kg. The loss of heat from the gases to the surroundings is 25 kJ/kg. Assume R = 0.285 kJ/kgK, Cp = 1.004 kJ/kgK and inlet conditions to be 100 kPa and 27 C. Determine the diameter of the inlet pipe. Q4 A- Answer false or true and correct: 1. When a closed system undergoes a process between two specified states, the change in temperature between the end states is dependent of details of the process. 2. If the volume of a given mass of a gas is doubled without changing its temperature the pressure of the gas is Reduced to 1/4of the initial value 3. Volume is an intensive property of a thermodynamic system. 4. The heating and expanding of a gas is called thermodynamic states. 5. An increase in enthalpy leads to an decrease in internal energy. B- The gas in an internal combustion engine initially at temperature of 1400°C expands polytropically to five times its initial volume and( 1/7) its initial pressure. Calculate 1-The index of expansion n. Q5: A-Steam enters a turbine with a velocity of 47 m/s and specific enthalpy 2690 kJ/kg. the steam leaves the turbine with a velocity of 25 m/s and specific enthalpy 1200 kJ/kg. the heat lost to the surroundings as the steam passes through the turbine is 25 kJ/kg .the steam flow rate is 32400kg/h determine the work output from the turbine in kilowatts. B- 0.016 m' gas at a pressure of 3.070 Kpa expands to a pressure of 0.00207 bar according to the law pV-C .Determine a- the final volume b- the work heat transferred during the expansion. Take (the molecular weight of the gas =28 and specific heat at constant volume =0.866 kJ/kg .K).
Transcribed Image Text:University of Technology Mechanical Engineering Mid Examination 2020/2021 Year: 1" Stage Subject: physics 2 Examiners: Thermodynamics group Exam Time: 2 Hrs. Date: 22 /6/ 2021 Answer four questions only Q1:: A- The absolute pressure in water at a depth of 5 m is read to be 145 kPa. Determine the absolute pressure at a depth of 5 m in a liquid whose density 900 kg/m3 at the same location? B- A 650 MW thermal power plant has an overall efficiency of 43% consumped natural gas fuel (heating value-45 MJ/kg).Calculate the saving in fuel when the fuel type change to gasoil (heating value=50 MJ/kg) in kg/hr. Q2 A perfect gas is contained in a rigid vessel at 2 bar and 315°C is cooled at constant volume to pressure of 1 bar ,and then expanded isothermally until the pressure falls to 0.5 bar; the gas has a molar mass of 26 kg/kmol and value of y=1.37.Calculate the net work and heat transferred per unit mass. Q3: - In a gas turbine installation, the gases enter the turbine at the rate of 5 kg/s with a velocity of 50 m/s and enthalpy of 900 kJ/kg and leave the turbine with 150 m/s and enthalpy of 400 kJ/kg. The loss of heat from the gases to the surroundings is 25 kJ/kg. Assume R = 0.285 kJ/kgK, Cp = 1.004 kJ/kgK and inlet conditions to be 100 kPa and 27 C. Determine the diameter of the inlet pipe. Q4 A- Answer false or true and correct: 1. When a closed system undergoes a process between two specified states, the change in temperature between the end states is dependent of details of the process. 2. If the volume of a given mass of a gas is doubled without changing its temperature the pressure of the gas is Reduced to 1/4of the initial value 3. Volume is an intensive property of a thermodynamic system. 4. The heating and expanding of a gas is called thermodynamic states. 5. An increase in enthalpy leads to an decrease in internal energy. B- The gas in an internal combustion engine initially at temperature of 1400°C expands polytropically to five times its initial volume and( 1/7) its initial pressure. Calculate 1-The index of expansion n. Q5: A-Steam enters a turbine with a velocity of 47 m/s and specific enthalpy 2690 kJ/kg. the steam leaves the turbine with a velocity of 25 m/s and specific enthalpy 1200 kJ/kg. the heat lost to the surroundings as the steam passes through the turbine is 25 kJ/kg .the steam flow rate is 32400kg/h determine the work output from the turbine in kilowatts. B- 0.016 m' gas at a pressure of 3.070 Kpa expands to a pressure of 0.00207 bar according to the law pV-C .Determine a- the final volume b- the work heat transferred during the expansion. Take (the molecular weight of the gas =28 and specific heat at constant volume =0.866 kJ/kg .K).
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