INTERNATIONAL INSTITUTE OF MANAGEMENT & TECHNICALSTUDIESProgramme Name: Professional Graduate Programme In Mechanical EngineeringSubject: Thermal Science EngineeringGuideline –• Please ensure to solve all the question in series.• Please do not copy past answers from internet or any other material, as it will lead to rejection of answer sheets.Faculty will use Plagiarism tool to check the answer sheet• Please make sure to write enough length of answers & a descriptive answer whenever require to do as per theirweightage of marks.• Please highlight more relevant case studies and practice examples.• Please Submit answer sheet in standard format described at the end of the format(Annexure-A).• Please make sure to be in time limits while submitting answer sheets on portal to avoid rejection of submissionafter deadline.• Answer sheets must be submitted on portal only & answer sheets submitted through mail or any other sourcewill be rejected.• In case of hand written answer sheet submission please be assure of sober writing and cleanliness of answersheet.• Do take care of numerical and diagrammatical representation up to the mark if applicable.Max. Marks:100Max. Marks: 100Answer any FIVE Questions All Questions Carry Equal Marks (5 x 20 = 100)Question No 1 a.) What are Heisler charts? Explain its significance.b.) A short cylindrical aluminium bar, having thermal conductivity, 200W/m.K and thermal diffusivity, 8.4 X10-5 m2 /s of diameter 6 cm and height 3 cm is initially at a uniform temperature of 175°C. Suddenly thesurfaces are subjected to convective cooling with a heat transfer coefficient of 250 W/m2 .K into an ambient at25°C. Calculate the center temperature of the cylinder one minute after the start of cooling.Question No 2 a.) Explain Dirichlet and Newmann Boundary conditions as applied to conduction with examples.b.) Write the finite difference form of the two dimensional steady state heat conduction equation with internalheat generation at a constant rate ‘g’ for a region 0.03m X 0.03m by using a mesh size ∆x=∆y= 0.01 m for amaterial having thermal conductivity 25 W/m.K and heat generation rate, 107 W/m3 . All the boundary surfacesare maintained at 100C. Express the finite difference equations in matrix form for the unknown nodetemperatures.OrQuestion No 3. a.) Discuss the assumptions made in the Nusselts theory of film condensation on a vertical plate.b.) Prove that by using dimensional analysis Nusselt number is a function of Reynolds number and Prandtlnumber in forced convection.Question No 4. a.) Explain in detail, the differences between implicit and explicit methods.b.) By using approximate integral boundary layer analysis, derive the equation for the local heat transfer coefficient forthe flow over flat plate in terms of the Reynolds number.Question No.5. a.) Explain and discuss the significance of (i) Rayleigh number and (ii) Nusselt number in naturalconvection.b.) Air at 200C flowing at 25 m/s passes over a flat plate, the surface of which is maintained at 270°C. Calculate the rateat which heat is transferred from both the sides of the plate per unit width over a distance of 0.25 m from the leadingedge. Properties of air at 145°C are Prandtl number = 0.687; Viscosity = 2.8 X 10-5 m2/s and thermal conductivity = 3.49X 10-5 kW/m.K.OrQuestion No 6. a.) Write short notes on Gas radiation.b.) A 15 cm outer diameter steel pipe lies 2m vertically and 8 m horizontally in a large room with an ambienttemperature of 300C. If the pipe surface is at 2500C, calculate the total rate of heat loss from the pipe to the atmosphere.Properties of air at 1400C are density = 0.854 kg/m3 ; specific heat, cp= 1.01 kJ/kg.K; thermal conductivity = 0.035W/m.K; Prandtl number = 0.684 and viscosity = 27.8 X 10-6 m2 /sQuestion No 7. Draw the radiation network for a specular diffuse surface losing heat to a large enclosure. Obtain anexpression for the heat transfer under these circumstances. How does this heat transfer compared with that which wouldbe lost by a completely diffuse surface with the same emissivity.OrQuestion No 8. a Define Schmidt and Lewis numbers. Discuss the significances of each.b Assuming laminar film condensation, calculate the ratio of condensing heat transfer coefficient on a vertical tube tothat of a horizontal tube of same diameter and length.Annexure-A:-

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