B.TECH - Semester 4 thermal engineering Question Paper 2020 (sep)
Practice authentic previous year university questions for better exam preparation.
Sample Questions
- Sketch the line diagram of a steam plant working on Rankine Cycle with reheat and name the components.
- Derive an expression for the velocity of steam leaving a nozzle.
- Define calorific value of a fuel. Distinguish between lower colarific value and higher colarific value.
- What are the causes of knock in Cl engines?
- Describe the MANN combustion chamber.
- Explain gas turbine with inter cooling and reheating.
- List out eight uses of compressed air.
- Explain reheat factor. Why its magnitude is always greater than unity?
- Give the advantages of gas turbines over steam turbines.
- Give four advantages of centrifugal compressors over axial flow compressors. ( $\mathbf{1 0} \boldsymbol{\times} \mathbf{4} \boldsymbol{=} \mathbf{4 0}$ Marks) P.T.O. Answer one questions from each Module.
- (a) What is the effect of friction of critical pressure ratio of a nozzle?
- (b) A nozzle is to be designed to expand dry saturated steam from 7.5 bar to 0.25 bar. The mass flow rate of steam is $3 \mathrm{~kg} / \mathrm{sec}$. Calculate the throat and exit areas required. The isentropic index of expansion may be taken as 1.3...
- (a) Explain the various methods of governing of steam turbines giving merits and demerits of each method.
- (b) In a Parsons reaction turbine, the fixed and moving blades are of same shape. The moving blade angles at entry and exit are $35^{\circ}$ and $20^{\circ}$ respectively. Determine the power developed for a steam flow rate of 2.2 $\mathrm{kg} / \mat...
- (a) What are the important properties of fuels used in IC engines?
- (b) An unknown hydrocarbon fuel has the following Orsat analysis. $\mathrm{CO}_{2}-12.5 \%: \mathrm{CO}-0.3 \% ; \mathrm{O}_{2}-3.1 \%$. Determine the A/F ratio, fuel composition on mass basis stoichiometric A/F ratio and percentage of excess air, if...
- (a) Explain the working of an open cycle gas turbine plant.
- (b) Air enters at 1 bar and $15^{\circ} \mathrm{C}$ into the compressor of a constant pressure open cycle gas turbine plant and leaves the compressor at 6 bar. Temperature of the gases entering the turbine $=700^{\circ} \mathrm{C}$; pressure loss in ...
- (i) The power output per kg of air (ii) The thermal efficiency of the cycle Take $\gamma=1.4$ and $\mathrm{C}_{\mathrm{p}}=1 \mathrm{~kJ} / \mathrm{kg} \mathrm{K}$ for air and gas
- (a) Explain the working of various types of compressors:
- (b) A single acting compressor with bore and stroke of 15 cm and 20 cm respectively run at 220 rpm . Air is drawn at 1 bar and delivered at 6 bar . The law of compression is $\mathrm{PV}^{1.2}=\mathrm{C}$. Determine the power require to drive the com...
- (a) Prove that for maximum efficiency of two stage compression, the inter cooler pressure must be the geometric mean of the initial and final pressures.
- (b) Air at a temperature of 290 K flows in a centrifugal compressors running at 20000 rpm . Slip factor $=0.80$; Isentropic efficiency $=0.75$; Outer diameter of blade tip $=500 \mathrm{~mm}$. Assume the absolute velocities of air at inlet and exit o...