JAWAHARLAL NEHRU TECHNOLOGICAL UNIVERSITY HYDERABAD
JAWAHARLAL NEHRU TECHNOLOGICAL UNIVERSITY HYDERABAD B.Tech II Year THERMAL ENGINEERING – I Previous Question Paper (December - 2018 - R15)
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. Each question carries 10 marks and may have a, b, c as sub questions.
Part A
What is gas power cycle?
Answer
A gas power cycle is a thermodynamic cycle in which the working fluid remains in the gaseous state throughout the entire process, typically used to convert thermal energy into mechanical work in engines like the Otto, Diesel, or Brayton cycles.
Define mixture strength.
Answer
Mixture strength is the ratio of the actual fuel-air ratio to the chemically correct (stoichiometric) fuel-air ratio required for complete combustion of the fuel. It indicates whether the mixture is rich (ratio > 1) or lean (ratio < 1).
What is the function of a governor in I.C Engines?
Answer
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Define cetane number.
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Define the terms compression ratio and cutoff ratio.
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What is scavenging in IC engines?
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What are the various types of compressors?
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Define degree of reaction.
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Define: COP.
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What is net refrigerating effect of a refrigerant?
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Part B
Explain with a neat sketch the working principle of a four stroke engine with a line sketch.
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What is the need of a cooling system in an automobile engine? Explain the general type of cooling system used in four wheeled vehicles.
Answer
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What do you mean by pre ignition? How can it be detected?
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What is meant by ignition delay? Explain the causes of knock in C.I. Engines.
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Explain the method used for the measurement of indicated power of multi cylinder engine.
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Find out the expression for the work saved per kg of air in a three stage compressor, if the perfect inter cooling is used during the compression process.
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Explain the working of Roots blower with a line diagram and find the expression for its efficiency.
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Explain with a line sketch the working principle of centrifugal compressor.
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Explain the construction and working of vapour absorption refrigeration system.
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A simple saturation refrigeration cycle developing 15 tons of refrigeration using R12 operates with a condensing temperature of 35°C and an evaporator temperature of -6°C. Calculate: (a) The refrigerating effect, (b) Refrigerant flow rate (c) The power required to drive the compressor, (d) COP.
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