Heat transfer in a channel with ribbed twisted tapes

The results of a study on heat transfer in a channel with a ribbed twisted tape with $s/d = 2.5$–$4$ are presented. Ribs $0.5$, $1.0$, or $1.5$ mm high installed on tapes with different pitches $(t = 40$–$120$ mm) against the flow were studied. The effect of the geometry and operating conditions on the heat-transfer rate was analyzed, and a generalized dependence has been derived to calculate the heat-transfer to a water or refrigerant R134a flow in the Reynolds number range of $\rm Re = 10^4$–$2 \times 10^5$.