The effect of rotating magnetic turbulators on the convective heat transfer and pressure drop through a circular tube: Experimental investigation
In this study, forced convective heat transfer inside a tube is investigated by introducing a novel active method that uses an external rotational magnetic field to rotate magnetic spheres in a tube under constant heat flux. To generate the rotating magnetic field, an electric signal generator with...
Saved in:
| Main Authors: | , , |
|---|---|
| Format: | Article |
| Language: | English |
| Published: |
Elsevier
2025-03-01
|
| Series: | International Journal of Thermofluids |
| Subjects: | |
| Online Access: | http://www.sciencedirect.com/science/article/pii/S2666202725000564 |
| Tags: |
Add Tag
No Tags, Be the first to tag this record!
|
| _version_ | 1832087409639030784 |
|---|---|
| author | Seyyed Morteza Mansouri Mohamad Ali Bijarchi L Siamak K Kazemzadeh Hannani |
| author_facet | Seyyed Morteza Mansouri Mohamad Ali Bijarchi L Siamak K Kazemzadeh Hannani |
| author_sort | Seyyed Morteza Mansouri |
| collection | DOAJ |
| description | In this study, forced convective heat transfer inside a tube is investigated by introducing a novel active method that uses an external rotational magnetic field to rotate magnetic spheres in a tube under constant heat flux. To generate the rotating magnetic field, an electric signal generator with adjustable frequencies is used along with a Rodin star coil. The rotation of the magnetic spheres on the inner surface of the tube and simultaneously around themselves disrupts the hydraulic and thermal boundary layers. Hence, the flow regime shifts from laminar to turbulent, leading to an increase in both convective heat transfer and pressure drop inside the tube, which are respectively, favorable and undesirable impacts. The effect of the location and number of the rotating and non-rotating spheres, as well as their presence and absence, and their rotation direction relative to each other on the local and average Nusselt numbers, friction coefficient, and thermal performance factor is studied. Results show that the existence of the rotating magnetic spheres leads to a remarkable elevation in the local Nusselt number after the sphere. Hence, the average Nusselt number is increased significantly in the case of rotating spheres compared to the simple tube. By increasing the number of rotating spheres, locating the rotating spheres closer to the upstream, or rotating the spheres opposite to each other, the average Nusselt number increases, while the enhancement of friction coefficient is negligible. Hence the thermal performance factor elevates up to 24% compared to a simple tube. |
| format | Article |
| id | doaj-art-a69faefa553c401a8296803880d5c749 |
| institution | Kabale University |
| issn | 2666-2027 |
| language | English |
| publishDate | 2025-03-01 |
| publisher | Elsevier |
| record_format | Article |
| series | International Journal of Thermofluids |
| spelling | doaj-art-a69faefa553c401a8296803880d5c7492025-02-06T05:12:49ZengElsevierInternational Journal of Thermofluids2666-20272025-03-0126101108The effect of rotating magnetic turbulators on the convective heat transfer and pressure drop through a circular tube: Experimental investigationSeyyed Morteza Mansouri0Mohamad Ali Bijarchi1L Siamak K Kazemzadeh Hannani2Center of Excellence in Energy Conversion (CEEC), Department of Mechanical Engineering, Sharif University of Technology, Tehran, IranCorresponding author.; Center of Excellence in Energy Conversion (CEEC), Department of Mechanical Engineering, Sharif University of Technology, Tehran, IranCenter of Excellence in Energy Conversion (CEEC), Department of Mechanical Engineering, Sharif University of Technology, Tehran, IranIn this study, forced convective heat transfer inside a tube is investigated by introducing a novel active method that uses an external rotational magnetic field to rotate magnetic spheres in a tube under constant heat flux. To generate the rotating magnetic field, an electric signal generator with adjustable frequencies is used along with a Rodin star coil. The rotation of the magnetic spheres on the inner surface of the tube and simultaneously around themselves disrupts the hydraulic and thermal boundary layers. Hence, the flow regime shifts from laminar to turbulent, leading to an increase in both convective heat transfer and pressure drop inside the tube, which are respectively, favorable and undesirable impacts. The effect of the location and number of the rotating and non-rotating spheres, as well as their presence and absence, and their rotation direction relative to each other on the local and average Nusselt numbers, friction coefficient, and thermal performance factor is studied. Results show that the existence of the rotating magnetic spheres leads to a remarkable elevation in the local Nusselt number after the sphere. Hence, the average Nusselt number is increased significantly in the case of rotating spheres compared to the simple tube. By increasing the number of rotating spheres, locating the rotating spheres closer to the upstream, or rotating the spheres opposite to each other, the average Nusselt number increases, while the enhancement of friction coefficient is negligible. Hence the thermal performance factor elevates up to 24% compared to a simple tube.http://www.sciencedirect.com/science/article/pii/S2666202725000564Forced convection heat transfer coefficientActive methodExternal magnetic fieldRotating magnetic spheresRodin star coil |
| spellingShingle | Seyyed Morteza Mansouri Mohamad Ali Bijarchi L Siamak K Kazemzadeh Hannani The effect of rotating magnetic turbulators on the convective heat transfer and pressure drop through a circular tube: Experimental investigation International Journal of Thermofluids Forced convection heat transfer coefficient Active method External magnetic field Rotating magnetic spheres Rodin star coil |
| title | The effect of rotating magnetic turbulators on the convective heat transfer and pressure drop through a circular tube: Experimental investigation |
| title_full | The effect of rotating magnetic turbulators on the convective heat transfer and pressure drop through a circular tube: Experimental investigation |
| title_fullStr | The effect of rotating magnetic turbulators on the convective heat transfer and pressure drop through a circular tube: Experimental investigation |
| title_full_unstemmed | The effect of rotating magnetic turbulators on the convective heat transfer and pressure drop through a circular tube: Experimental investigation |
| title_short | The effect of rotating magnetic turbulators on the convective heat transfer and pressure drop through a circular tube: Experimental investigation |
| title_sort | effect of rotating magnetic turbulators on the convective heat transfer and pressure drop through a circular tube experimental investigation |
| topic | Forced convection heat transfer coefficient Active method External magnetic field Rotating magnetic spheres Rodin star coil |
| url | http://www.sciencedirect.com/science/article/pii/S2666202725000564 |
| work_keys_str_mv | AT seyyedmortezamansouri theeffectofrotatingmagneticturbulatorsontheconvectiveheattransferandpressuredropthroughacirculartubeexperimentalinvestigation AT mohamadalibijarchi theeffectofrotatingmagneticturbulatorsontheconvectiveheattransferandpressuredropthroughacirculartubeexperimentalinvestigation AT lsiamakkkazemzadehhannani theeffectofrotatingmagneticturbulatorsontheconvectiveheattransferandpressuredropthroughacirculartubeexperimentalinvestigation AT seyyedmortezamansouri effectofrotatingmagneticturbulatorsontheconvectiveheattransferandpressuredropthroughacirculartubeexperimentalinvestigation AT mohamadalibijarchi effectofrotatingmagneticturbulatorsontheconvectiveheattransferandpressuredropthroughacirculartubeexperimentalinvestigation AT lsiamakkkazemzadehhannani effectofrotatingmagneticturbulatorsontheconvectiveheattransferandpressuredropthroughacirculartubeexperimentalinvestigation |