PERIODICAL TEST – I

BRANCH/ YEAR/SEM : BIOTECH / II /IVSUBJECT : UNIT OPERATIONSTIME : 9.30AM - 11.30AMMax Ma !" : #0 Ma !"

ANS$ER ALL THE %UESTIONS &# ' 10 ( #0 Ma !")

1. Discuss the effects of various parameters on the thermal conductivity of solids.OR

2. Derive expressions for temperature distribution , under one dimensional steady state heatconduction, for the following systems. A. omposite !all ". omposite ylinder.

#. A furnace is constructed with 22$ mm thic% of fire bric% & % ' 1.( !)m*+ , 12 mm of insulating bric% & % ' .2 !)m*+ and 22$ mm of building bric% & % ' .- !.m * +. he inside temperature is 12 * and the outside temperature is # *. /ind the heat loss per unit area and the temperature of the 0unction of the fire bric% and insulating bric%.

OR (. An exterior wall of a house may be approximated by a .1 m layer of common bric% & % ' .-

!)m o + followed by a . (m layer of gypsum plaster & % ' .( !)m o+ . !hat thic%ness of loosely pac%ed roc% wool insulation & % ' . $ !)m o + should be added to reduce the heatloss or gain through the wall by percent.

$. A steam pipe& * ' ($ !)m o+ having - mm inside diameter and $mm outside diameter is lagged with two insulation layers3 the layer in contact with the pipe is #$mm asbestos& %' .1$ !)m o+ and is covered with 2$mm thic% magnesia insulation & % ' . -$ !)m o +.he heat transfer coefficients from the inside and outside surfaces are 22 !)m2 and .$!)m 2 respectively. 4f the temperature of steam is #$o and the ambient temperature is #o

, calculate i+ he steady loss of heat for $ mm length of pipe and ii+ the overall heat transfer coefficients based on inside and outside surfaces of the lagged steam main.

OR . A steel rod type fin & % ' #2 !)mo+, 12 mm in diameter and mm long, with an insulated

end is to be used a pin type fin. 4t is exposed to surroundings with a temperature of o and aheat transfer coefficient of $$ !)m2. he temperature at the base of the fin is 5$ o.Determine i+ the fin efficiency, ii+ the temperature at the end of the fin, iii+ the heatdissipation.

-. 6xplain the 7echanism of "oiling heat transfer with neat s%etch.OR

. !ater is to be boiled at atmospheric pressure in a polished copper pan by means of an6lectric heater. he diameter of the pan is .# m and is %ept at 11$8 . alculate the following 1. 9ower re:uired to boil the water.2. Rate of evaporation, #. ritical heat flux

S*a++ I, a HOD

PERIODICAL TEST – I

BRANCH/ YEAR/SEM : BIOTECH / II /IVSUBJECT : UNIT OPERATIONSTIME : 9.30AM - 11.30AMMax Ma !" : #0 Ma !"

ANS$ER ALL THE %UESTIONS &# ' 10 ( #0 Ma !")

1. Air at 2 ; at atmospheric pressure flows over a flat plate at a velocity of #m)s. 4f the plate is 1m wide and ; , alculate the following at x ' # mm.

a. <ydrodynamic boundary layer thic%ness b. hermal boundary layer thic%nessc. =ocal friction co>efficientd. Average friction co>efficiente. =ocal heat transfer co>efficientf. Average heat transfer co>efficientg. <eat transfer

OR

2. Air at pressure of %?)m 2 and a temperature of 2$ 8 flows over flat plate .#m wide and 1m long at a velocity of m)s. 4f the plate is to be maintained at a temperature of - 8 , estimate rate of heat to be removed continuously from the plate.

#. A vertical tube of $mm outside diameter and 1.$m long is exposed to steam at atmospherics pressure. he outer surface of the tube is maintained at a temperature of 8 by circulating cold water through the tube. alculate the following 1. he rate of heat transfer to the coolant., 2. he rate of condensation of steam.

OR

(. 6xplain the 7echanism of "oiling heat transfer with neat s%etch.$. 6xplain condensation and its types with neat s%etch.

OR

. Alac% body at # * emits radiation. calculate the following@

a. 7onochromatic emissive power at 1 m wave length b. !ave length at which emission is maximumc. 7aximum emissive power d. otal emissive power e. alculate the total emissive of the furnace if it is assumed as a real surface having

emissivitye:ual to . $

-. A furnace wall emits radiation at 2 *. reating it as blac% body radiation, calculate &i+ monochromatic radiant flux density at 1 B m wavelength. &ii+ !avelength at whichemission is maximum and the corresponding emissive power. &iii+ otal emissive power.

OR

. Alloy steel ball of 1.$cm diameter heated to - 8 and :uenched in a bath at 1 8 . he material properties of the ball are thermal conductivity * ' 2 *C)mhr8 , density ' - $%g)mE, thermal diffusivity F ' . mG)h, specific heat p '.($*C)%g8 , convective heat transfer co>efficient h '1( *C)hr mG8 . Determine the temperature of the ball after 1 seconds.

S*a++ I, a HOD