For 200 years, convective heat flux q has been calculated by multiplying heat transfer coefficient h times boundary layer temperature difference ΔT. Since h times ΔT equals q, h must be a symbol for (q/ΔT) because (q/ΔT) times ΔT equals q. h (ie q/ΔT) is generally calculated from correlations derived from experiments in which q data and ΔT data are used to obtain (q/ΔT){ΔT} correlations-ie h{ΔT} correlations. (It is not possible to obtain h data because h is not a parameter. h is the ratio of two parameters). Heat transfer coefficients are unnecessary and undesirable. It is self-evident that any problem that can be solved using q, q/ΔT (ie h), and ΔT can also be solved using only q and ΔT. Therefore h (ie q/ΔT) is unnecessary. h (ie q/ΔT) is undesirable because, when q is a nonlinear function of ΔT (as in free convection, condensation, and boiling), h (ie q/ΔT) is an extraneous variable, and it greatly complicates problem solutions. When h has been abandoned, convective heat flux is determined from q{ΔT} correlations that result from q data and ΔT data, or from the transformation of h{ΔT} correlations. (Transformation from h{ΔT} correlations to q{ΔT} correlations requires that h be replaced by q/ΔT, and that q and ΔT be separated.). The text includes example problems that validate the conclusion that h (ie q/ΔT) is unnecessary and undesirable, and demonstrate that the solution of nonlinear problems is much simpler if h is abandoned.

dimensional homogeneity, heat transfer coefficient, law of convection heat transfer, nonlinear problems, parameter symbols