THERMODYNAMICS 2018 Question Paper — Government College of Engineerin…

The 2018 THERMODYNAMICS previous year question paper (Government College of Engineering and Technology, Jammu), with every question and its marks.

Instructions

Q1. (a) State the First Law of Thermodynamics and prove that for a non-flow process, it leads to the energy equation $Q = \Delta U + W$. (b) Explain the concept of continuum with a suitable example. [20 marks]
Q2. A Carnot cycle operates between source and sink temperatures of $250^\circ\text{C}$ and $15^\circ\text{C}$. If the system receives $90\text{ kJ}$ from the source, find : (i) Efficiency of the system (ii) The net work transfers (iii) Heat rejected to sink. [20 marks]
Q3. (a) Give the following statements of Second Law of Thermodynamics : (i) Clausius Statement (ii) Kelvin-Planck Statement. (b) Calculate the change of entropy of $1\text{ kg}$ of air expanding polytropically in a cylinder behind a piston from $6.3\text{ bar}$ and $550^\circ\text{C}$ to $1.05\text{ bar}$. The index of expansion is $1.3$. [20 marks]
Q4. (a) Explain Throttling process as an application of steady flow energy equation. (b) $5\text{ kg}$ of air is compressed in a reversible steady flow polytropic process from $100\text{ kPa}$ and $40^\circ\text{C}$ to $1000\text{ kPa}$ following the process given by : $PV^{1.25} = C$ Determine : (a) Total shaft work (b) Heat transferred. [20 marks]

Q5. Superheated steam at a pressure of $10\text{ bar}$ and $400^\circ\text{C}$ is supplied to a steam engine. Adiabatic expansion takes place to release point at $0.9\text{ bar}$ and it exhausts into a condenser at $0.3\text{ bar}$. Neglecting clearance determine for a steam flow rate of $1.5\text{ kg/s}$ : (i) Quality of steam at the end of expansion and the end of constant volume operation (ii) Power developed (iii) Specific steam consumption (iv) Modified Rankine cycle efficiency. [20 marks]
Q6. An engine of $250\text{ mm}$ bore and $375\text{ mm}$ stroke works on Otto cycle. The clearance volume is $0.00263\text{ m}^3$. The initial pressure and temperature are $1\text{ bar}$ and $50^\circ\text{C}$. If the maximum pressure is limited to $25\text{ bar}$, find the following : (i) The air standard efficiency of the cycle (ii) The mean effective pressure for the cycle. [20 marks]
Q7. What amount of heat would be required to produce $4.4\text{ kg}$ of steam at a pressure of $6\text{ bar}$ and temperature of $250^\circ\text{C}$ from water at $30^\circ\text{C}$ ? Take specific heat for superheated steam as $2.2\text{ kJ/kg K}$. [20 marks]
Q8. Write short notes on : (i) Free expansion process (ii) IC Engine Performance parameters. [20 marks]