HEAT TRANSFER IN RECTANGULAR CHANNELS WITH A SERIES OF NORMALLY IN-LINE POSITIONED PLATES

Abstract

Periodically fully developed flow and heat transfer were numerically studied for a rectangular channel with normally in-line positioned plates along the axis. The governing equations were solved using a finite volume technique. Consideration was given only to laminar flow with uniform heat flux heating conditions at the channel walls. The independent governing parameters were identified as flow Reynolds number (Re), Prandtl number (Pr), pitch ratio of the plates (L / H), channel blockage ratio (B / H), plate thickness to height ratio (t / B), and the ratio of the thermal conductivity of the plate to the fluid (K). Calculations were made for the following range of independent parameters: Re ≤ 500, 0.7 ≤ Pr ≤ 12, 0.5 ≤ L / H ≤ 5.0, 0.2 ≤ B / H ≤ 0.8, 0.1 ≤ t / B ≤ 0.3, and 8 ≤ K ≤ 80,000. Heat transfer at the channel walls increased with a decrease in L / H; however, for L / H > 5.0, the impact of L / H on heat transfer was found to be minimal. Heat transfer increased with an increase in B / H, but the increase in pressure drop was prohibitively high for B / H ≥ 0.6. The thermal conductivity ratio (K) was found to have no impact on heat transfer at the channel walls. Correlations were established for heat transfer ratio (N^∗) and friction factor ratio (F^∗), along the channel walls, as a function of Re with the above independent governing parameters.