Heat and Mass Transfer Exam 1 QUESTIONS & ANSWER 100% VERIFIED

Heat and Mass Transfer Exam 1 QUESTIONS & ANSWER 100% VERIFIED What is heat transfer? - ANSWER-Thermal energy in transit due to a spatial temperature difference assumptions of qx" = k(T1-T2)/L = k∆T/L - ANSWER-Steady state, temperature distribution is linear What is the thermal boundary layer? - ANSWER-Region between the surface and the free stream with temperature gradients and heat fluxes. Where convection heat transfer occurs What is Newton's law of cooling? - ANSWER-q" = h(Ts-Tinf) Which type of convection heat transfer results in the highest amount of heat transferred? - ANSWER-Convection with phase change; boiling or condensation Which will typically have a larger h value, Free convection or Forced convection? Why? - ANSWER-Forced convection will have a larger h value, because the an external force is acting on the flow, increasing the heat flux with a by increasing the contact of the surface compared to free flow Why is there a negative sign in the equation for Fourier's law? - ANSWER-the ∆T value is negative if we consider that heat travels from a hot to cold body so T2 will always be less than T1. The addition of a negative in the equation keeps answers reasonable and positive like the area and temperature What is the relative orientation between the isotherm and the direction of heat transfer? - ANSWER-The isotherm is normal to the direction of heat transfer What is an isotherm - ANSWER-Area where the temperature is the same What is an isotropic material? Does k vary with x? - ANSWER-Isotropic means the material is uniform in all directions. K is independent of x Does the mean free path of the energy carriers increase or decrease as the thermal conductivity increases - ANSWER-Increases Relationship between thermal diffusivity (α) and k - ANSWER-α = k/rho*cp What does b in van der waals equation account for? - ANSWER-finite size of molecules