“…Schlager et al, 1990;Ishikawa et al, 2002;Col et al, 2002), but the singlephase heat transfer and flow characteristics of micro-fin tubes are not well established as results reported are scarce and non-consistent, thus leading to a serious lack of single-phase design data. For example, in the turbulent flow region Khanpara et al's (1987) single-phase heat transfer data indicate that Nu number is proportional to Re 1.7 Pr 0.4 whereas Al-Fahed et al (1993) and Chiou et al (1995) report a Nu number proportionality of Re 0.8 Pr 0.4 , while Copetti et al (2004) reports a Nu number proportionality of Re 1.1 Pr 0.4 . Moreover, in a singlephase heat transfer study by Brognaux et al (1997) it was concluded that the Prandtl number exponent should be near 0.56-0.57 as opposed to 0.4 as reported by many authors.…”