Numerical investigation of heat-transfer enhancement in helically coiled spiral grooved tube heat exchanger

Passive enhanced heat transfer technology considerably influences helically coiled tube (HCT) heat exchangers (HEs), which are typically used in nuclear power plants. Numerical investigations were performed to study the effects of various grooving methods and depths on the heat transfer characteristics of HCT HEs. The results revealed that grooving on the plain tube could enhance the comprehensive heat transfer performance and simultaneously increase the pressure drop of the fluid. The performance evaluation criterion (PEC) value of the helically coiled spiral grooved tube (HCSGT) HEs was 25% higher than the helically coiled plain tube (HCPT) HEs, whereas the PEC value of a helically coiled parallel grooved tube (HCPGT) HEs was 20% better than that of the HCPT HEs. Furthermore, the HCSGT HEs exhibited superior heat transfer enhancement ability. A comparison of the influences of various grooving depths on the heat transfer enhancement of HCSGT HEs revealed that the increase in the groove depth first increased the Nusselt number (Nu) and friction factor (f), followed by a subsequent decrease. The PEC value of the HCSGT HEs with 0.5 mm groove depth was observed to be maximal. Thus, grooved treatment can effectively improve the comprehensive heat transfer capacity of HEs.