JNTU
JNTU B.Tech II THERMAL SCIENCE Previous Question Paper (February - 2024 - R16)
Note: i) Question paper consists of Part A, Part B. ii) Part A is compulsory, which carries 25 marks. In Part A, Answer all questions. iii) In Part B, Answer any one question from each unit. Each question carries 10 marks and may have a, b as sub questions.
PART - A
What is point function and path function?
Answer
A point function is a property that depends only on the state of the system and not on the path taken to reach that state. Its differential is exact, meaning the change in the property between two states is independent of the process, such as pressure, temperature, and volume.
A path function is a quantity that depends on the specific process or path taken to transition between two states. Its differential is inexact, and its value is determined by the history of the process, such as work and heat transfer.
Explain the concept of macroscopic and microscopic approach.
Answer
The macroscopic approach, or classical thermodynamics, considers a system as a whole without regard to the behavior of individual molecules. It focuses on time-averaged properties that can be measured experimentally, such as pressure, temperature, and volume. This approach is sufficient for most engineering applications as it requires no knowledge of the underlying atomic structure.
The microscopic approach, or statistical thermodynamics, is based on the behavior of individual molecules and their interactions. It uses statistical methods to predict the average behavior of a large number of particles. This approach is primarily used to explain the behavior of matter at the molecular level and to derive macroscopic properties from kinetic theory, though it is mathematically more complex for practical engineering design.
Define PMM1.
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Define the first law of thermodynamics.
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What is entropy?
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Explain the Carnot cycle and its specialties.
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Draw P-v and T-s diagrams for Otto cycle.
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What do you meant by actual Air standard cycle?
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What are the different stokes of four stoke engine?
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What is the purpose of the carburetor?
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PART - B
Explain the concept of Continuum with neat sketch? Why is it so important in thermodynamic system?
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Show that heat is path function not a state function.
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Explain about different types of systems with suitable examples.
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State and differentiate between extensive and intensive properties.
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State and explain the zeroth law of thermodynamics with neat sketch.
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2 kg of fluid contained in a cylinder receives 300kJ of work by paddle wheel together with 70kJ in the form of heat. At the same time, the piston in the cylinder moves in such a way that pressure remains constant at 200kN/m2 and fluid expand from 2m3 to 4m3. Estimate the change in internal energy and change in enthalpy?
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What are the limitations of the first law of thermodynamics?
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What is a constant volume gas thermometer? Why is it preferred to a constant pressure gas thermometer?
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Prove that the Kelvin Plank and Clausius’s statement of the second law of thermodynamics are equivalent to each other.
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A rigid tank of 0.3m3 capacity contains nitrogen at 300 kPa and 200°C. The tank is exposed to a constant temperature source at 1600°C, which result in 50kJ of heat being transferred to nitrogen. Determine: i) Final state of gas. ii) Change in internal energy. iii) Change in entropy. Take Cv=743J/kg. K for Nitrogen.
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Define an adiabatic process. Show that a reversible adiabatic process for a given mass of perfect gas is PVγ =Constant.
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How is the entropy change of a reversible process estimated? Will it be different for an irreversible process between the same end states?
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An air standard Otto cycle operates with a compression ratio 8. At the beginning of the compression the air is at 1.01 bar and 350°C, and during the heat addition process the pressure is tripled. Calculate (a) the thermal efficiency of the cycle and (b) the efficiency of the Carnot engine operating between the same overall temperature limits.
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An engine working on dual cycle has bore of 20 cm and stroke of 40 cm. compression ratio is 14.5 and pressure ratio at constant volume heat addition process is 1.5. The constant volume heat addition cut-off takes place at 4.9 % of the stroke. Assuming γ = 1.4, find the air standard efficiency.
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Show that the efficiency of the Otto cycle depends only on the compression ratio.
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Write down the differences between two and four stroke engines.
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Explain with the help of line diagrams, the modes of fuel admission to engine cylinder.
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Explain the working of Four stroke engines with neat sketch.
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Explain the working of fuel injector with neat sketch.
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