mcq: Convection CONVECTION 1 MARK OBJECTIVE QUESTIONS Convective heat transfer takes place between Two solid surfaces in physical contact Between a solid surface and a fluid Between two fluids None Ans: (b) Select the correct formula for the convective rate of heat transfer Q. =–kA (tl–th) Q. = hA (th—tl) Q. = σA (Th4—Tl4) None […]
Interview Short Question Answers on Conduction and Convection Q . Define Biot number and its significance. Biot number is Bi= conductive resistance/convective resistance = hLc/ksolid Where h is convective heat transfer coefficient W/m2K Lc is the characteristic length= volume/surface area =δ/2 for a plane wall, =r/2 for a cylinder =r/3 for a sphere = side/6 for […]
Interview Short Question Answers on Conduction and Convection-2 Q. Critical thickness of insulation. The thickness of insulation for which rate of heat transfer is maximum, is called critical thickness of insulation. Adding insulation to a wall type surface always reduces the rate of heat transfer because thermal resistance (Rth=x/KA) increases. While in case […]
Free and Forced Convection Heat Transfer CONVECTION HEAT TRANSFER It takes place in fluids (liquids, vapors and gases). It is due to the bulk motion of the fluid. It is at macro level i.e. visible to the naked eye. Driving force is temperature difference. It takes place from higher temperature to lower temperature. It is […]
Free and Forced Convection Free Convection TABLE: (i) CRITERIA FOR LAMINAR FLOW & TURBULENT FLOW IN FREE CONVECTION (ii) THE IMPERICAL CORRELATION in Free Convection Free Convection Laminar condition Turbulent condition Over a horizontal flat plate with hot surface upwards Gr Pr < 109 Nu=0.54 […]