JNTU
JNTU B.Tech II THERMAL SCIENCE Previous Question Paper (November/December - 2018 - R16)
Note: This question paper contains two parts A and B. Part A is compulsory which carries 25 marks. Answer all questions in Part A. Part B consists of 5 Units. Answer any one full question from each unit.
Part A
What is meant by control volume?
Answer
A control volume is a fixed region in space or a defined volume through which mass and energy can flow. It is used in the analysis of open systems where the identity of the matter within the volume changes over time.
Why pressure can be considered as point function.
Answer
Pressure is considered a point function because it is a thermodynamic property that depends only on the state of the system at a specific instant, regardless of the path taken to reach that state. At any infinitesimal point within a fluid in equilibrium, the pressure exerts the same magnitude in all directions, making it a state variable defined by the local conditions.
What is the zeroth law of thermodynamics?
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What is displacement work?
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State the third law of thermodynamics.
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Why the entropy of universe goes on increase.
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Show the process of Otto cycle on T-s diagram.
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What do you mean by mean effective pressure?
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What is the working principle of two stroke engines?
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What are the different functions of carburetor?
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Part B
Explain the concept of thermodynamic equilibrium.
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What is meant by process? List out the reasons for irreversibility of the process.
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What is meant by system? Explain the different type of systems with neat sketches.
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Explain the Quasi-static process with an example.
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An air turbine forms part of an air craft refrigerating plant. Air at a pressure of 295 kPa and a temperature of 580 C flows steadily into the turbine with a velocity of 45 m/s. The air leaves the turbine at a pressure of 115kPa, a temperature of 20C, and a velocity of 150 m/s. The shaft work delivered by the turbine is 54 kJ/kg of air. Neglecting changes in elevation, determine the magnitude and sign of the heat transfer per unit mass of air flowing. For air, take Cp= 1.005 kJ/kg K and the enthalpy h= Cpt.
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Air flows steadily at the rate of 0.4 kg/s through an air compressor, entering at 6 m/s with a pressure of 1 bar and specific volume of 0.85 m3/kg, and leaving at 4.5 m/s with a pressure of 6.9 bar and a specific volume of 0.16 m3/kg. The internal energy of air leaving is 88 kJ/kg greater than that of air entering. Cooling water in a jacket surrounding the cylinder absorbs heat from the air at the rate of 59W. Calculate the power required to drive the compressor and the inlet and outlet cross sectional areas.
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Air of mass 0.5 kg as an ideal gas executes a Carnot cycle having a thermal efficiency of 50%. The heat transfer to the air during the isothermal expansion is 40 kJ. At the beginning of isothermal expansion the pressure is 7 bar and the volume is 0.12 m3. Determine (a) the maximum and minimum temperatures for the cycle, (b) the volume at the end of isothermal expansion (c) the work and heat transfer for each of the process.
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A heat engine is used to drive a heat pump. The heat transfers from the heat engine and the heat pump are used to heat the water circulating through the radiators of a building. The efficiency of the heat engine is 27% and the COP of the heat pump is 4. Evaluate the ratio of the heat transfer to the circulating water to the heat transfer to the heat engine.
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A diesel cycle operating on an air standard cycle has a compression ratio of 15. The pressure and temperature at the beginning of the compression are 1.04 bar and 150C. If the maximum temperature of the cycle is 2230 K, determine the thermal efficiency and the mean effective pressure.
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Calculate the thermal efficiency and the mean effective pressure of a dual combustion cycle when the maximum temperature is 15000C and the maximum pressure is 65 bar. The pressure and temperature at the start of compression are 1 bar and 170C respectively.
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Explain the working four stroke diesel engine with neat sketches.
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Explain the battery ignition system with neat sketch.
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Explain the working of simple carburetor with neat sketch.
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Explain the working of thermo syphon cooling system with neat sketch.
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