Complete Suggestion for Theoretical Questions ****************************************************** কোর্সের নামঃ হিট এন্ড মাস ট্রান্সফার (মেকানিক্যাল ইঞ্জিনিয়ারিং) ১/ Describe the basic modes of heat transfer with proper sketches and examples. Write their proper formula and discuss. 10 Marks September-2007 ২/ Derive the general equation for one dimensional heat conduction in a plane and in a cylindrical wall and discuss. 10 Marks September-2007 October-2011 ৩/ State the laws of thermal radiation with proper sketches and examples and discuss. 20 Marks September-2007 April-2008 September-2006 April-2003 October-2011 April-2011 April-2009 ৪/ Name the general methods that are available for evaluation of convection heat transfer and discuss. 10 Marks September-2007 April-2008 ৫/ What do you mean by LMTD? Why is it so important? Derive an expression for LMTD of a heat exchanger. 8 Marks September-2007 April-2009 ৬/ Describe the working principle of a cooling tower. 5 Marks September-2007 October-2011 ৭/ Write down the three dimensional heat conduction equation in a cylindrical coordinate and discuss. 10 Marks April-2008 ৮/ Derive the steady flow energy equation for low velocity and incompressible flow and discuss. 10 Marks April-2008 ৯/ Explain the role of extended surfaces in heat transfer. Also briefly mention about their performance parameters. 8 Marks April-2007 ১০/ State the Wein’s displacement law. Derive this from Planck’s law of electromagnetic radiation. 8 Marks April-2007 ১১/ At what wavelength has the sun its maximum emissive power? At what wavelength has the earth? 6 Marks April-2007 September-2003 ১২/ Consider an enclosure of hemisphere of diameter D and a flat surface of the same diameter. Determine the relevant view factors. 6 Marks April-2007 ১৩/ Write a short notes on heat transfer coefficient. Name and explain the non-dimensional parameter associated with heat transfer coefficient during forced convection. 8 Marks April-2008 ১৪/ Distinguish between forced convection and free convection. 5 Marks April-2007 ১৫/ Classify heat exchangers on the basis of different aspects. 6 Marks April-2007 ১৬/ For flow of a liquid metal through a circular tube, the velocity and temperature profiles at a particular axial location may be approximated as u(r)= c_1 and T(r)= T_s+ c_2 (1-(r/r_0 )^2 ) respectively, where c_1 and c_2 are constants and T_s is the surface temperature. What is the value of the Nusselt number N_ud at this location? 15 Marks April-2007 ১৭/ Write short notes on (i) Bulk Temperature and Film Temperature 8 Marks April-2007 (ii) NTU and Its physical significance 6 Marks April-2007 (iii) Fick’s law of diffusion. 6 Marks April-2007 ১৮/ Define fin effectiveness and fin efficiency. 8 Marks September-2006 ১৯/ What is meant by lumped capacity? What are the physical assumptions necessary for a lumped capacity unsteady state analysis to apply? 8 Marks September-2006 October-2013 April-2012 ২০/ Briefly mention about the nature of radiation transport. Why radiation from a solid/liquid is considered a surface phenomenon? 8 Marks September-2006 ২১/ Distinguish between the following: (i) Black body and Gray body (ii) Specular and diffuse surfaces (iii) Irradiation and Radiasity. 12 Marks September-2006 ২২/ Discuss with a neat sketch a developing flow and developed flow inside a circular pipe. 8 Marks September-2006 ২৩/ What is Grashof number? Write down its physical significance. 6 Marks September-2006 ২৪/ Why a counter flow heat exchanger is more effective than a parallel flow heat exchanger? 8 Marks September-2006 ২৫/ Define Schmidt, Sherwood and Lewis Numbers. What is the physical significance of each? 10 Marks September-2006 ২৬/ What is Fick’s law of diffusion? Discuss its application. A wet garment dries up quickly in dry season. Explain with proper equation and sketches. 10 Marks September-2006 ২৭/ What is the semi-infinite solid? Describe the significance of using error function in a semi-infinite solid in transient state. 10 Marks September-2006 ২৮/ Derive expressions for temperature distribution and heat dissipation in a straight fin of rectangular profile with insulated tip. Briefly discuss on this. 12 Marks September-2006 ২৯/ What is shape factor? Describe its physical significance in heat transfer. 4 Marks September-2006 October-2011 ৩০/ Determine the shape factor for the following: (i) From the base of a cube to each of the five surfaces (ii) Between the surfaces of two concentric spheres with A_1 and A_2 surface area. 8 Marks September-2006 ৩১/ What is meant by “Dimensional Analysis”? Show that for forced convection heat transfer Nu=f (R_e,P_r), where the symbols have their usual meanings. 10 Marks September-2006 September-2003 April-2009 ৩২/ Discuss the following terms as used in heat exchanger analysis: (i) LMTD (ii) Correction Factor (iii) NTU. (iv) Effectiveness of Heat exchanger. 8 Marks September-2006 September-2005 ৩৩/ What are the different modes of mass transfer? Discuss. 5 Marks September-2006 ৩৪/ Describe the following equation in relation to forced convection mass transfer in a tube Sh=0.023 R_e^0.83 〖(Sc)〗^0.44. 5 Marks September-2006 October-2011 ৩৫/ Explain what is meant by “negligible internal resistance”. What is the measure of the ratio of internal to external resistance as applied in transient heat flow? 6 Marks September-2005 ৩৬/ With necessary diagrams discuss briefly the differences among black body, gray body and real surfaces regarding emission, absorption and reflection of radiation. 10 Marks September-2005 ৩৭/ Two tea cups, one having very reflective surface another is dark brown,. With necessary equation and justification comment in which one tea will remain hotter for longer period of time and why. 10 Marks September-2005 ৩৮/ What is meant by a “hydrodynamic boundary layer”. Note down the assumptions and the associated continuity, momentum and the energy equations for the laminar boundary layer on a flat plate. ৩৯/ Define Pradtl number. What is its physical significance? Draw necessary graph to show the effect of Pradtl number on the temperature profile for turbulent flow in a long pipe. 12 Marks September-2005 ৪০/ What do you understand by critical thickness of insulation on a cylinder? Derive an expression for critical thickness of insulation on a cylinder exposed to constant temperatures inside and outside the insulation. 10 Marks March – 2004 April-2012 ৪০/ Derive an expression of one dimensional conductive heat flow and temperature distribution across a wall with uniform heat generation. 10 Marks March – 2004 ৪১/ Give two examples of fins being used in practice. Derive an expression of one dimensional heat conduction across a fin of uniform cross-section considering negligible heat losses from the fin tip. 10 Marks March – 2004 ৪২/ What do you understand by transient heat transfer? Briefly explain the lump capacitance method of evaluating transient heat conduction. What is its limitation? 10 Marks March – 2004 ৪৩/ Define heat radiation. What is meant by Blackbody and gray body radiation? 5 Marks March – 2004 ৪৪/ Define radiation shape factor (angle factor). Briefly explain the reciprocity rule. 5 Marks March – 2004 October-2010 ৪৫/ Derive an expression of the radiation shape factor of a small area located on the axis of a circular disc surface at a parallel distance of S. 10 Marks March - 2004 ৪৬/ Define Reynold’s number and Nusselt Number. Briefly explain their physical significance. 8 Marks March – 2004 ৪৭/ Define forced and natural convection heat transfer. How can you determine whether a convective heat transfer is forced or natural? 6 Marks March – 2004 ৪৮/ Answer briefly: (i) What is conduction heat transfer? (ii) Draw an elemental volume for three dimensional heat conduction analysis in Cartesian coordinate system and make the energy balance. 8 Marks September-2003 ৪৯/ For a semi-infinite solid with constant temperature boundary, prove that the heat flow at the surface is Q_s (t)=KA(T_s-T_i)√παt, where T_s is the surface temperature, T_i is the initial temperature and t is the time. 10 Marks September-2003 ৫০/ Answer briefly the following: (i) What is thermal radiation? How does it differ from the other types of radiation? (ii) What are the factors that determine the rate of radiative exchange between surfaces? 10 Marks September-2003 ৫১/ Answer briefly the following: (i) Write what you know about film temperature and bulk temperature mentioning their importance in convection heat transfer. (ii) List the parameters that influence the forced convection heat transfer in a pipe. Also mention about different dimensionless groups and their functional relationship. 8 Marks September-2003 ৫২/ Mention some applications where heat transfer by free convection occur. 3 Marks September-2003 ৫৩/ What is Grashof number? Explain Its role in free convection. 6 Marks September-2003 ৫৪/ Answer briefly the following: (i) Explain fouling and fouling factor. (ii) Explain NTU and its physical significance in heat exchanger analysis. (iii) When is the LMTD method for heat exchanger design? 12 Marks September-2003 ৫৫/ Explain Fick’s law of diffusion. 8 Marks September-2003 October-2013 ৫৬/ Using the Fourier heat conduction equation. Develop a general equation for describing the temperature distribution in a cylindrical heat conducting solid. 5 Marks April-2003 October-2002 ৫৭/ Give the sketch of a Heisler chart and explain its usage. 5 Marks April-2003 ৫৮/ Discuss the similarity behavior between heat and mass transfer phenomenon. 6 Marks April-2003 ৫৯/ Discuss the Sherwood number and Schmidlt number and their functional relationship. 6 Marks April-2003 ৬০/ Develop an expression for the rate of diffusion of water vapour from the bottom of a cylindrical vessel to dry air flowing over the top of vessel. Make necessary drawings and assumptions. 8 Marks April-2003 ৬১/ Why is the one-dimensional heat-flow assumption important in the analysis of pin fins? Define fin efficiency and fin effectiveness. 10 Marks April-2003 October-2011 ৬২/ Based on Plank’s law, discuss briefly with figure the hemispherical spectral emissive power of a blackbody at different temperatures and hence discuss Wein’s displacement law. 10 Marks April-2003 ৬৩/ Sketch the temperature and velocity profiles in free convection on a vertical wall and discuss. 7 Marks April-2003 ৬৪/ Define the effectiveness of a heat exchanger. Name and explain the dimensionless parameters upon which the effectiveness depends. 10 Marks April-2003 ৬৫/ Define mass transfer coefficient. How does it differ from heat transfer coefficient? Discuss the physical significance of Sherwood and Schmidlt number. 10 Marks April-2003 October-2011 ৬৬/ With a neat sketch explain the boundary layer information for the flow around a curved body and the flow separation. 8 Marks October-2013 ৬৭/ Deduce the dimensionless temperature profile for forced convection in a circular tube in the hydrodynamically and thermally developed region under the constant heat flux condition. Hence calculate the Nusselt number. 10 Marks October-2013 ৬৮/ What do you mean by Fick’s Law of diffusion? Describe the mechanism of mass transfer in equimolar counter diffusion of two gases. 10 Marks October-2013 ৬৯/ How does a cross-flow heat exchanger differ from a counter-flow one? What are the differences between mixed and unmixed fluids in cross flow? 8 Marks October-2013 ৭০/ When the outlet temperatures of the fluids in a heat exchanger are not known. Is it still practical to use LMTD method? Explain. 4 Marks October-2013 ৭১/ What is Reynold’s analogy? Show that st= f/8, where the symbols have their usual meanings. 10 Marks October-2013 October-2011 April-2011 ৭২/ Show that for free convection heat transfer Nu=f(Gr,Pr) where the symbols have their usual meanings. 10 Marks October-2013 October-2011 ৭৩/ Starting with energy balance on a cylindrical shell volume element, determine the steady one dimensional heat conduction equation for a long cylinder with constant thermal conductivity in which heat is generated at a rate of q. 10 Marks October-2013 ৭৪/ What do you mean by equimolar counter diffusion of two gases? Explain. 10 Marks April-2012 October-2011 April-2009 ৭৫/ Derive Stefan’s law for diffusion of an ideal gaseous component through a stagnant and ideal constituent of the binary system. 10 Marks April-2012 ৭৬/ State and derive the reciprocity relation for radiation heat exchange. 10 Marks April-2012 ৭৭/ Define and explain mixed and unmixed fluids in a heat exchanger. Why does a mixed and unmixed fluid arrangement influence heat exchanger performance? 10 Marks April-2012 ৭৮/ Derive Reynolds-Colburn analogy for laminar flow on a flat plate. Explain the significance of the relation. 10 Marks April-2012 ৭৯/ Derive the expression for the temperature distribution in a hollow cylinder with uniformly distributed heat source and constant thermal conductivity. State necessary assumptions and boundary conditions. 10 Marks April-2012 ৮০/ Explain the following terms: (i) R-value and U-Factor (ii) Thermal Diffusity (iii) Hydrodynamic and thermal boundary layer. 9 Marks April-2012 April-2010 ৮১/ What are the physical significances of Prandit, Nusselt Number and Peclet number? 6 Marks April-2012 ৮২/ Explain free convection. Discuss the problem of combined free and forced convection. 5 Marks April-2012 ৮৩/ What are the different modes of mass transfer? Discuss. 5 Marks October-2011 ৮৪/ What do you mean by semi-infinite solids? When does it apply satisfactorily to heat-conduction problem? 5 Marks October-2011 ৮৫/ Describe with sketches the use of a Heisler’s chart in transient heat conduction problem. 5 Marks October-2011 ৮৬/ Derive expressions for temperature distribution and heat dissipation in a straight fin of rectangular profile with insulated tip. Discuss. 10 Marks October-2011 ৮৭/ Sketch the temperature and velocity profile in the vicinity of a vertical flat plate and discuss. 8 Marks April-2011 April-2009 ৮৮/ Name the factors that one should consider during design of a modern heat exchanger and discuss. 4 Marks October-2011 ৮৯/ What do you mean by radiating wall? State and prove the reciprocity theorem of view-factor in thermal radiation heat transfer. 10 Marks April-2011 ৯০/ Derive the most generalized form of energy equation and modify it for low velocity incompressible flow. 10 Marks April-2011 ৯১/ Derive the heat diffusion equation for a homogeneous, isotropic solid in cylindrical co-ordinate system. 10 Marks October-2010 April-2010 ৯২/ Write a note on thermal diffusivity. 6 Marks October-2010 ৯৩/ Explain what you know about R-value and U-factor commonly used for heat transfer through walls, windows and roofs. 8 Marks October-2010 ৯৪/ Prove that the temperature distribution in a semi-infinite solid is given by (T(s,t)-T_i)/(T_S-T_i )=erfc(x/√4αt) Where T_s is the surface temperature, T_i is the initial temperature of the solid. 12 Marks October-2010 ৯৫/ Name different types of conservation equations needed to analyze convective heat transfer. 6 Marks October-2010 ৯৬/ For fully developed laminar flow in a circular tube subjected to constant heat flux, prove that Nu=4.36. 14 Marks October-2010 ৯৭/ Distinguish between LMTD and effectiveness NTU methods of heat exchanger analysis. 8 Marks October-2010 ৯৮/ What is thermal radiation? Explain its importance in Engineering? 5 Marks October-2010 ৯৯/ What is spectral emissive power? How does it vary with wavelength for black body? 5 Marks October-2010 ১০০/ Define B_i and F_0 and explain its role in heat conduction. 4 Marks April-2010 ১০১/ For a semi-infinite solid, prove that the transient surface heat flux is given by q_s (t)=(K(T_s-T_i))/√παt Where T_s is the surface temperatures, T_i is the initial temperature and others have their usual meaning. ১০২/ What is free convection? Briefly explain its important dimensionless number. 6 Marks April-2010 ১০৩/ Briefly explain emission, irradiation and Radiosity. 6 Marks April-2010 ১০৪/ Prove that ρ+α+τ=1, where symbols have their usual meaning. 6 Marks April-2010 ১০৫/ Briefly explain the factors responsible for radiation exchange between two surfaces. 6 Marks April-2010 ১০৬/ Write short notes on the following: Fin performance parameter October-2010 April-2010 Heisler charts October-2010 April-2010 Critical Insulation October-2010 Fick’s law of insulation October-2010 April-2010 Black body radiation October-2010 Irradiation and Radiosity. 30 Marks October-2010 Thermal Diffusivity. April-2010 Reynolds analogy. April-2010 Wein’s Displacement law. April-2010 Solar radiation. April-2010 ১০৭/ Derive an expression for the temperature distribution in a solid cylinder of radius r with uniform heat generation and constant surface temperature. Make necessary assumptions and boundary conditions. 10 Marks October-2009 ১০৮/ Discus about the development of two types of boundary layers over a flat plate and a tube. Why is it so important in convection heat transfer studies? 10 Marks October-2009 ১০৯/ For a laminar tube flow, prove that u=T(r)= 2u_0 (1-(r/r_0 )^2 ) where the symbols have their usual meanings. Make necessary assumptions. 5 Marks October-2009 ১১০/ Distinguish between Laminar flow and Turbulent Flow. 5 Marks October-2009 ১১১/ Write down 3-D heat conduction equation in a rectangular and cylindrical geometrics and discuss each terminology. 5 Marks October-2009 ১১২/ Why dimensionless parameters are so important in convection heat transfer studies? 5 Marks October-2009 ১১৩/ What are the physical significances of Nusselt number, Pradtl number and Biot number? 6 Marks October-2009 ১১৪/ What is Dittus-Boelter equation and discuss it. 3 Marks October-2009 ১১৫/ Discuss about the thermal radiation heat transfer phenomenon. 5 Marks October-2009 ১১৬/ What is Radiosity? Discuss the role of view factor. 3 Marks October-2009 ১১৭/ Illustrate a mixed heat transfer problem for a particular case and comment on it. 5 Marks October-2009 ১১৮/ Discuss the relation ∆P=1/2 〖ρu〗^2 4L/d_h f where the symbols have their usual meanings. 4 Marks October-2009 ১১৮/ What is the Blasius equation for a circular duct? And discuss it. 4 Marks October-2009 ১১৯/ Explain the following terms: (i) Overall heat transfer coefficient (ii) Fully developed flow (iii) thermal diffusivity. 12 Marks October-2009 ১২০/ Distinguish between plate and shell & tube heat exchanger? 5 Marks October-2009 ১২১/ What is fouling factor? How do you control fouling in heat exchanger? 5 Marks October-2009 ১২২/ Write down one dimensional and two dimensional heat conduction equation and discuss. 5 Marks April-2009 ১২৩/ Derive an expression for the temperature distribution in a plane wall in which there are uniformly distributed heat sources which vary according to the linear relation q=q_w [1-β(t-t_w)] where q_w is the constant equal to the heat generated per unit volume at the wall temperature t_w. Both sides of the wall are maintained at t_w and the wall thickness is 2 L. Make necessary assumptions and discuss. 20 Marks April-2009 ১২৪/ Discuss the relation h/h_m =ρ C_p 〖(S_C/P_r )〗^(2/3), where the symbols have their usual meanings. 8 Marks April-2009 বিশেষ নির্দেশনাঃ হিট এন্ড মাস ট্রান্সফার কোর্সের প্রস্তুতিতে সিলেবাস, বিগত বছরের প্রশ্ন এবং একটি নির্দিষ্ট টেক্সটবই ফলো করে পড়াশুনা সম্পন্ন করার নির্দেশনা দেওয়া হলো । টেক্সটবই শুরু থেকে ধারাবাহিকভাবে প্রতিটি অধ্যায় পড়তে হবে, কিন্তু বিগত বছরের প্রশ্ন অনুসরণ করে প্রতি দিন বা প্রতি সপ্তাহে অন্তত “এক টার্মের (এপ্রিল বা অক্টোবর টার্ম)” প্রশ্নপত্র মুখস্থ করতে হবে, গাণিতিক সমস্যাসমূহ অনুশীলন করতে হবে । তাই আমরা, প্রত্যেক ক্লাসেই কিছু প্রশ্ন নিয়ে আলোচনা করে থাকি, শিক্ষার্থীদের পাশের লক্ষ্য পূরণের জন্য । একই সাথে জ্ঞানার্জনের উদ্দেশ্য পূরণের জন্য অধ্যায়ভিত্তিক ধারাবাহিক টপিকস নিয়ে আলোচনা করা হয়ে থাকে । প্রত্যেক শিক্ষার্থীকেই এই লক্ষ্যসমূহ খেয়াল রেখে পড়াশুনা করতে হবে ধারাবাহিকভাবে । এখানে প্রদত্ত ১২৬ টি প্রশ্ন প্রত্যেক শিক্ষার্থীকে তাদের নিজস্ব নোট খাতায় নোট করতে নির্দেশনা প্রদান করা হলো । এই প্রশ্নসমূহের উত্তর সংগ্রহের জন্য আর কে রাজপুত, চেঞ্জেল, ইনক্রোপেরা বা হলম্যানের বই ফলো করা যেতে পারে । একজন শিক্ষার্থীকে নোট তৈরি করার সময় অধ্যায়ভিত্তিক জ্ঞান আহরণ প্রতি খেয়াল রাখতে হবে । নোট তৈরি করতে সময় লাগলেও, যে নিজের পরীক্ষার প্রস্তুতির অংশ হিসেবে নোট তৈরি করে, তার জানাশোনার পরিমাণ অন্য শিক্ষার্থীদের তুলনায় বেশি থাকে ।
Posted on: Thu, 26 Jun 2014 08:33:12 +0000
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