Download DBATU B.Tech 2019 Oct-Nov Mech 5th Sem Heat Transfer Question Paper

Download DBATU (Dr. Babasaheb Ambedkar Technological University) B Tech 2019 Oct-Nov (Bachelor of Technology) Mech 5th Sem Heat Transfer Question Paper

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DR. BABASA'HEB AMBEDKAR TECHNOLOGICAL UNIVERSITY, LONERE '
1 1 2 Mid Semester Examination ? Sept./Oct. 2019 ,
COurse: TY Mech- I 311d 11 . . Sem: Vth
. 'Suhject: Heat Transfer Subject Code: BTMEC501
' Maxi Marks? 20 ~ ' Date:? 23/09/19 Duration:- 1 Hr.
Instruetions to the Students: ' I I
1. *Draw ?gures wherever possible.
2. Assume?suitable data if required.
'. I ' Level Marks
Q.1 ? Answer the following questions 6 -
? , 1. State different modes of heat transfer. ? L-l
' ' 2. Write equation of ?Newton? s law of heating/cooling?. L?l
_ 3. Write an application of ?Extended Surfaces 0r Fins?. L?2
4. Write equation/formula of Reynolds Number and Prahdle Number. L-l
1 5. De?ne ?Critical Radius of Insulation? L-l
6. State any two factors which affects thermal conductivity of material L-2
Q.2 Solve Any Two of the following. 3 X 2
(A) Write short note 'on ?Hydrodynamic Boundary Layer?. L-2
(B) A-?hollow cylinder of 50mm inner dia and 80mm outer diameter is 5m long. The ,L-3
' thermal conductivity bf cylinder material is 110 W/m-OC. If the inner and outer ?
surfaees of cylinder are at 2100C and 300C, determine the rate of heat loss from the
. cylinder.
(C) A wall Of furnace is made up of inside layer of silica brick 120 mm thick covered L-3
with a layer of magnesite brick 240mm thick. The temperatures at the? inside
surface of silica brick wall and outside surface of magnesite brick wall are 7300C
and" 105?C resp. The contact?thermal resistance between two wall at the interface is
, 0.0035'0C/W'per unit area. If thermal conductivities 0f Silica-and magnesite brick
. are 1.7 W/m-OC and 5.8 W/m-"C, calculate a) The rate of heat loss per unit wall . ?
, ' area. b) Temperature drop ?at interface. ?.
Q.3 Solve Any One of the following. , 8
(A) Derive generalized three dimensional conduction eqhation in Cartesian co- L-3
" ordinates and reduce it to various forms. 1
(B) Twelve thin hrass ?ns (, K='65 W/m-0C) of 0.8 mm thick are placed axially on a '5 L-3
- .cm dia cylinder which stands vertically and is surrounded by air at 40?C. The ?ns
extend 3.5 cm from the cylinder surface. What 1s the rate of heat transfer to air per
meter length of cylinder when its surface 18 at 1500C? Take h= 20 Wlm2 C.
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