Microscale Heat Transfer of Confined Miniature Jets

An experimental study of the microscale heat transfer characteristics of a 1.22 mm confined miniature jet is presented for both air and water. The experimental apparatus utilises infrared thermography to measure the temperature profiles on the underside of a heated thin-foil upon which the jet is impinging. The local heat transfer coefficient calculations account for lateral conduction within the foil, which, in contrast to conventional practice, has been shown to be non-negligible. The tests are carried out over a jet Reynolds number range of 5000–20000 and non-dimensional jet to target spacing (H/d) range of 2–5. Results are presented in terms of local heat transfer coefficients. It has been determined that (i) lateral heat conduction effects are significant for the air jet measurements but are negligible for the water jet results, and (ii) the two fluids display hugely different heat transfer coefficient profiles for ostensibly the same non-dimensional flow conditions.