Convection & Heat Transfer Coefficients Convection carries the heat through fluids — explore how heat transfer happens via moving air or liquid, and test your grasp of Newton’s law of cooling and boundary layer theory. 1 / 20 The local heat transfer coefficient is highest At The Trailing Edge At The Leading Edge Of A Flat Plate Midway Independent Of Position Near the leading edge, temperature gradient is steepest, increasing heat flux. 2 / 20 The boundary layer thickness grows Against Flow Along The Flow Direction On A Plate Independent Of Flow Decreases With Distance As fluid travels, more of it is affected by surface friction, thickening the layer 3 / 20 Dropwise condensation provides Higher Heat Transfer Rate Lower Heat Transfer Same As Film No Transfer Droplets expose more surface area, increasing heat flux. 4 / 20 Film condensation occurs when Vapor Remains Static Boiling Starts Condensate Forms A Continuous Liquid Film Droplets Form On Surface Continuous liquid film creates resistance to heat transfer. 5 / 20 Boiling and condensation are examples of Phase Change Convection Radiation Pure Conduction Steady State Transfer Heat transfer occurs during change of state with latent heat involvement 6 / 20 The film coefficient of heat transfer increases with Fluid Velocity And Turbulence Surface Roughness Alone Temperature Decrease Low Pressure Faster fluid motion improves heat transfer between surface and fluid 7 / 20 The Grashof number relates Heat Transfer To Velocity Reynolds To Prandtl Density To Conductivity Buoyancy To Viscous Forces It determines the significance of natural convection effects 8 / 20 Natural convection strongly depends on Velocity Gradient Temperature Difference And Gravity Pressure Only Density Only Buoyancy due to temperature differences drives motion in natural convection. 9 / 20 In turbulent flow, the heat transfer coefficient is Higher Than Laminar Flow Same As Laminar Lower Zero Mixing in turbulence increases temperature uniformity and enhances heat transfer. 10 / 20 Reynolds number helps determine Type Of Flow Amount Of Heat Transfer Heat Capacity Thermal Conductivity It predicts laminar or turbulent flow regime in a fluid. 11 / 20 When Prandtl number is small, it indicates Low Thermal Diffusivity High Viscosity Poor Conductivity High Thermal Diffusivity The smaller the Pr, the faster heat diffuses compared to momentum. 12 / 20 For gases, the Prandtl number is approximately 0.7 1.5 2.0 10.0 Gases generally have Pr ≈ 0.7 because heat and momentum diffuse similarly. 13 / 20 The Prandtl number is the ratio of Specific Heat To Viscosity Density To Viscosity Momentum Diffusivity To Thermal Diffusivity Thermal Conductivity To Density It shows how momentum and heat spread through a fluid 14 / 20 In laminar flow over a flat plate, Nusselt number depends on Viscosity Alone Reynolds And Prandtl Numbers Only Temperature Plate Length Both flow type and fluid properties influence convective performance. 15 / 20 The Nusselt number represents the ratio of Convective To Conductive Heat Transfer Viscous To Buoyant Forces Conductive To Convective Kinetic To Potential Energy It indicates the effectiveness of convection compared to conduction. 16 / 20 Free (natural) convection occurs due to Chemical Reaction Radiation External Mechanical Devices Density Differences Caused By Temperature Variation Buoyancy forces move the fluid in natural convection. 17 / 20 Forced convection occurs when Fluid Motion Is Induced By External Means Fluid Is Stationary Buoyancy Acts Alone Conduction Is Dominant Fans, pumps, or blowers drive the flow in forced convection. 18 / 20 The unit of heat transfer coefficient is W/m·K J/kg·K W/m²·K J/m·s·K It defines the amount of heat transferred per square meter per degree temperature difference. 19 / 20 Newton’s law of cooling relates heat transfer rate with Temperature Difference Heat Capacity Specific Heat Density The rate of convective heat transfer is proportional to the temperature difference between surface and fluid. 20 / 20 Convection is the mode of heat transfer that occurs through solid medium stationary fluid moving fluid radiation Convection happens when fluid particles move and carry heat energy with them. Your score isThe average score is 20% 0% Restart quiz
