Abstract
In the present work, numerical investigation is applied to study the thermal and hydraulic characteristics of a new type of helically coiled tube heat exchangers called “sector-by-sector heat exchangers”. The studied flow regime is turbulent. It was simulated using the realizable K-ε model. In addition to these types of the heat exchangers, the tube-in-tube helical coil are also investigated and compared. The model is validated by comparing the Nusselt number and friction factor with the predicted values which are obtained using the previous experimental correlations. The Reynolds number, sector angle and its orientation, dimensionless pitch and coil diameter effects on the Nusselt number and friction factor are analyzed. For each types of these heat exchangers, equations are suggested for the estimation of the Nusselt number and friction factor as functions of those mentioned parameters. Furthermore, the coefficient of the thermal and hydraulic performance of these heat exchangers are compared with an example. It was found, the semi-circular cross section sector-by-sector heat exchangers are more efficient than quadrant-circular cross section and tube-in-tube heat exchangers.
[Display omitted]
•New types of the helically coiled tube heat exchangers are introduced.•Correlations are proposed for the estimation of the Nusselt number and friction factor.•Application of the sector-by-sector heat exchangers with semi-circular cross section are highly recommended.