Experimental and numerical characterization of single-phase pressure drop and heat transfer enhancement in helical corrugated tubes

The internal flow in corrugated tubes of different helical pitch, covering from the laminar to turbulent regime, was studied order characterize three-dimensional and influence corrugation geometry on pressure drop convective heat transfer. With water as working fluid an imposed wall flux, ranging around 4 33 kW/m2, a numerical model developed with CFD commercial software, where k?? SST used turbulence. Experimental tests were performed Reynolds numbers range 300 up 5000, which allowed identify transition region validate model. results show that due swirl induced by corrugation, critical number for start is reduced. thermal performance factor, quantifies transfer enhancement at expense drop, compare against reference case smooth tube. Based this, all investigated geometries better than tube, except low (Re<500) regime. Overall, tube lowest pitch showed clearly intermediate (1000<Re<2300), being optimal choice wider operating conditions transitional regimes.