Why heat transfer coefficients are unnecessary and undesirable, and how heat transfer problems are solved without them.

Heat transfer coefficients (h) are unnecessary and undesirable . They are unnecessary because heat transfer problems are readily solved without them. They are undesirable because they greatly complicate problems that concern nonlinear thermal behavior. In order to understand why heat transfer coefficients are unnecessary and undesirable, it is necessary to know precisely what h is. The nomenclature in every heat transfer text should state “ h is a symbol for q/ D T ”. (Note that q = h D T and h = q/ D T are identical .) Problems in convection heat transfer are conventionally solved using q, h, and D T —ie using q, q/ D T, and D T . It is self-evident that any problem that can be solved using q, q/ D T , and D T can also be solved using only q and D T . Therefore h (ie q/ D T ) is unnecessary. h (ie q/ D T ) is undesirable because, when q is a nonlinear function of DT (as in free convection, condensation, and boiling), h (ie q/ D T ) is a third variable , and it greatly complicates problem solutions. The text includes example problems that support the conclusion that h (ie q/ D T ) is unnecessary and undesirable.