.ICHANICAL INGINIIAING
II


SECTION A

Answer any three of the folloWlng parts (Answer to each part should not exceed 200 words) 20x3=60 The ratio 0 f heal transfer to work transfer 1n the process of an atf compressor reapra eating type is If the compreSSiOn follows pv" constant, whatlS the value of Denve the equation that you use In such a compreSSiOn process the work reqUired is 200 lI!kg and the speCIfic heal at constant volume is 0.75 kJ/kg K. What me of temperature is expecled at the end of compreSSiOn process?
01

1 -10atm.

p. 1 alm.
•
K


5
What lS the available enefll!.e., the maximum amount of work that can be obtamed 110m 1 kg of alf at slale poml 1 1n the figure? The dead slale 1S also marked 1n the figure?

What are the fan laws? Discuss alleast three methods which are used to control fan oUllul

1n a power pI ant


Show thalm a 50% reaction II!Ibme stage, the maXimum stile efficlency is glven by,


2 cos'

where, a is the nozzle angle


A power generating station has a maXimum demand of 20 MW The daily load on the station
is as follows

6 lIN 15 IN
B HI lo 12 NOON
12 NOON to 1 PM
1PMIt/5PM
5PMlo1PM
1111to9PM
9 PM II PM

11II 105AM

load, lIN

"

15•
"



"

•

Draw the load curve and 10 ad duration curve for the plant
Deade the cap acity and number of
Prep are the operating schedu! e of the urnts

Determme the load factor, pI ant cap acity factor anti pI ant use factor 0f the station
Develop the Clapeyron equation for the pure substance changmg the phase. Hence find the enthalpy of evaporation for R-22 at _10°C and compare the same with the tabulated value
What 1s the percentage error lnvolved?
01H_22





n1nlsfkg
01400
ll0929 0.'7587
0._
i O.04n
h"


220,331
213.136
205.369


A four cylinder engme 0f a truck has been converted to run on propane fuel A dry anal ym of the engme exhaust giVes the followmg volumetric percentages

CO, 90 CO -9.79 and -245
Calculate the eqUivalence ratio at which the engme lS operating



Explam the followmg


Rich miXture lS used dunng ldlmg


As the engine speed mcreases, the 19nition tinung should be advanced
S.1. engmes are generally not supercharged



Two stroke G. E. engines find Wide applications m manne propubon




A three liter V 6 S 1. engine operates on a four stroke cycle at 3600 rpm. The compressiOn ratio lS 9.5, the length of the connecting rod is 16.6 cm and the engine lS square (bore stroke). At this speed, the combustion ends at200 ATDC Calculate


cylmder bore and stroke length


average plSton speed
clearance volume of one cylinder



plSton speed at the end of combustion


distance the plSton has travelled from TDC at the end of combustion


volume m the combustion chamber at the end of combustion




Denve an expreSSiOn for the alr-fuel ratio delivered by a Simple carburellor. Discuss ltS limitations. What are the systems lncorporated to overcome the limitations of a Simple carburellor?


SECTION B
Answer any three ofthe folloWing parts (Answer to each part should not exceed 200 words)

Show that vol umelnc clearance efficlency 0f a reaprocating compressor lS given by

el (c1
where ellS c1 earance ratio and suffix d s refer to eli scharge and suction pressures



Discuss and show on the skeleton psychometric chart, the process for the alr passmg through alr washers with three types of spray recalculated chilled and heated water


"

How, m a refrigeration system usmg ammorua, the compressor could be replaced by another sUltable set 0f eqUlpments?


Show that Nu (Pr)"lB Re


"
Calculate the cop power reqUlrement and cooling capacity ofa CO, compressor working between 22 68 bar and 64 32 bar pressures. The liqUid m the condenser gets cooled, by another system, to 15°C before entenng the expanSiOn valve. The system lS assumed to work on wet-compresS! on with x 0.9 The compressor data stroke volume 500 c. c., rp.m 500 and'lwl 0.85. Property values are: sp. heat of CO, vapour 2.4 kJ/kgOC and
9nlhllipy II<J/kgj
liq. yap.
22bl:lI4';1.62 322.86
50.92 127.75 308.US:
64.32 164.]7 28363


v(m'lloo!J
5
liq ""p.
I"CI
h".

O.lYJlOl 0016610. " 1.2567
0.00130 0,0066
1.0959
15
000147 0.0042
0,5903

"


In an atr-conditiorung plant eqUlpment elmts for reheating the alr before supply to aroom to be malntalned at 25° dbt with 55% RH. The RSHL, 150,000 W and RLHL 222,000 W The discharge from coolmg coillS 22°C 95% RH Calculate


the supply alr state and rate


reheating, If any




A 3 m long 25 mm dia tube lS held at 100°C by steam Jacketing Water flows through the tube 180 kgihr at 20°C. Calculate the rate of heat transfer from the tube to water For water r:p 4 178 kJikg k 0.66 p 983 kgim3 and 0.47 x 10.3 kg/ms



The surface of two arcular discs parallel to each other, each with 1 m 2 area, are exchangmg thermal radiation with each other and with the surrounding walls. The temperatures of disc disc 2 and the walls are 800K, 500 K and 300 K respectively. The shape factor between discs lS 05 Compute Wl th help 0f network analySiS the net radiative heat transfer between the two discs

The velocity of steam entenng a Simple Impulse turbme lS 1000 WS and the nozzle angle is 20° The mean peripheral velocity of blades lS 400 m/s. The blades are asymmetncal. If the steam lS to enter the blades without shock, that will be the blade angles?
Neglecting the friction effects on the blades, calculate the tangential force on the blades and
the diagram power for a mass flow of 0,75 kg/s. Calculate the axial thrust and diagram
effiaency

Clearly explatn as to how the circulation lS malntalned m modem boilers havmg operating
pressures 100 bar, 180 bar and 240 bar respectively? WhatlS Clfculation ratio? WhatlS the nonnal range of circulation ratio m case 0f utility boilers and mdustnal boilers?