An experimental study of the air-side performance of a novel louver spiral fin-and-tube heat exchanger

We studied the effect of fin patterns on the air-side performance of a novel type of heat exchanger, namely louver spiral fin-and-tube heat exchangers (LSFTHXs). We investigated three types of fin patterns—radial, curved, and mixed-louver spiral fins—and compared their characteristics with plain spiral fin. We fabricated heat exchangers with a crimped aluminum fin base, two rows of steel tubes, and a fin pitch of 8.45 mm. All heat exchangers had both multipass parallel and counter cross-flow arrangements. The average heat transfer rate (Qave), heat transfer coefficient (ho), and pressure drop (ΔP) increased along with frontal air velocity. The louver-spiral fin provided greater Qave and ho than plain-spiral fin by about 9.7–15.6% and 13.4–27.1%, respectively. The j factors (Colburn factors) of louver-spiral fins were greater by approximately 10.4–13.1% (for mixed LSFTHX), 7.7–8.8% (for radial LSFTHX), and 2.1–5.1% (for curved LSFTHX) compared with the plain SFTHXs. Additionally, we found no significant difference in ΔP or f factor (friction factor) between louver-spiral and plain-spiral fins. LSFTHX configurations increased ho and j.