JNTU B.Tech II THERMAL SCIENCE Previous Question Paper (April/May - 2018 - R13)

Explain the concept of macroscopic and microscopic approach.

Calculate the temperature at which the Celsius and Fahrenheit scales agree.

Define PMM1.

Define path and point functions.

Define clausius inequality.

Define the third law of thermodynamics.

Write the equation for the efficiency for diesel cycle.

Draw p-v and T-s diagrams for dual cycle.

Explain VTD for 4 stroke diesel engine.

What is the purpose of the carburetor?

State and differentiate between extensive, intensive and specific properties.

A non-flow system undergoes a frictionless process according to a law p v^1.4 = constant, where p is in bar and the volume υ is in m³/kg. During the process, the volume changes from 0.12m³/kg to 0.04 m³/kg and temperature increases by 133°C. The change in internal energy of the fluid is given as du=Cυ dT, where Cυ = 0.71 kJ/kg.K and dT is temperature change. Find out (i) heat transferred, and (ii) change in enthalpy. Assume a fluid quantity of 10 kg.

Show that work is a path function, not a state function.

What is a quasi-static process? Illustrate some common quasi-static process. Explain how you will execute a quasi-static process from an initial pressure Pin to the final pressure Pfin.

State and explain the zeroth law of thermodynamics.

What are the limitations of the first law of thermodynamics?

What is a constant volume gas thermometer? Why is it preferred to a constant pressure gas thermometer?

1 kg of fluid contained in a cylinder receives 150 kJ of work by paddle wheel together with 50kJ in the form of heat. At the same time, the piston in the cylinder moves in such a way that pressure remains constant at 200 kN/m² and fluid expands from 2m³ to 5m³. Estimate the change in internal energy and change in enthalpy.

Prove that the Kelvin Plank and Clausius’s statement of the second law of thermodynamics are equivalent to each other.

Three Carnot engines C1, C2 and C3 operate in series between two heat reservoirs, which are at temperatures of 1000 K and 400 K. Calculate the temperature of the intermediate reservoirs if the amount of work produced by these engines in the proportion of 5:4:3.

Define an adiabatic process. Show that a reversible adiabatic process for a given mass of a perfect gas is pV^γ = Constant.

A rigid tank of 0.2m³ capacity contains nitrogen at 350 kPa and 15°C. The tank is exposed to a constant temperature source at 170°C, which result in 50kJ of heat being transferred to nitrogen. Determine i) Final state of the gas, ii) Change in internal energy, iii) Change in entropy. Take Cv=743J/kg.K for Nitrogen.

Derive an expression for thermal efficiency of Otto cycle.

In an air-standard Diesel engine cycle with a compression ratio of 14, the condition of air at the start of the compression stroke are 1 bar and 300 K. after addition of heat at constant pressure, the temperature rises to 2775 K. Determine the thermal efficiency of the cycle, net work done per kg of air and the mean effective pressure.

Show that the efficiency of the Otto cycle depends only on the compression ratio.

An engine working on the Otto cycle has an air standard cycle efficiency of 56% and rejects 544kJ/kg of air. The pressure and temperature of air at the beginning of compression are 0.1MPa and 60°C respectively. Compute (i) the compression ratio of the engine, (ii) the work done per kg of air, (iii) the pressure and temperature at the end of compression, and (iv) the maximum pressure in the cycle.

Compare and contrast between two and four stroke engines.

Draw the line diagram and explain the working of a fuel injector.

Explain with the help of line diagrams, the modes of fuel admission to engine cylinder.

What are the different ignition systems used in I.C. engines and explain one of them?