The evaluation and the improvement on the contact thermal resistance between fin collar and pipe making by mechanical expanding were investigated numerically and experimentally.
The main results obtained in this paper are as follows :
(1) By obtaining the calibration curves of temperature differences vs. thermal resistance (thermal conductance) between fin collar arid pipe surface, it may be possible to evaluate thecontact resistance by the simple experiment.
(2) Futhermore, by measuring the contact length between fin collar and pipe, it is clear that the optimum expansion ratio of pipe exist on the fin type heat exchanger.
(3) It has been confirmed experimentally that the better contact state between fin collar and pipe than the case employing flared collar was obtained by using straight collar removed flare part.