REALISATION D'UN ECHANGEUR THERMIQUE BI-TUBE COAXIAUX RENFORCE DE FILS CIRCULAIRES BOBINES

Abstract

In this study, a heat exchanger was made with two concentric tubes removable, in order to insert a coiled wire around the inner tube’s outer surface of the heat exchanger. Tests have been made for a smooth wall tube, and with a coiled wire. Three types of coiled wires are used, a copper wire with a circular section of 1.5mm diameter, a copper wire with a circular section of 2.5mm diameter, and an insulated wire with a circular section of 2.5mm diameter mm, with the use of water as a working fluid, for Reynolds numbers (5166, 11380, 17059) in both cases of fluid flow (co-current) and (countercurrent). Experimental results reveal that the use of coiled wires results in a large increase in heat transfer coefficients compared to a smooth wall tube for both arrangements. Increasing the pitch of the same wire causes the increase of the heat transfer coefficient to reach a certain limit beyond this limit the increase in the pitch of the wound wire becomes ineffective. The heat transfer is increased with increasing the diameter of the coiled wire. The copper increases the heat transfer coefficient and the efficiency compared to the insulated wire. Key words: heat exchanger, two concentric tubes, coiled wire, heat transfer coefficient, efficiency.