RadOnFan: Fans and electric heating – Influence of heating coils on fan design

Pro­mo­ti­on of Indus­tri­al Rese­arch (IGF), 1 Decem­ber 2025 – 31 May 2028

Project description

In many modern indus­tri­al fur­naces, a recir­cu­la­ti­on fan ensu­res that hot gases flow over the pro­duct at high speed, trans­fer­ring heat main­ly by con­vec­tion. When con­ver­ting from gas bur­ners to elec­tric hea­ting coils, the­se must be instal­led very clo­se to the fan for space reasons. The sur­face tem­pe­ra­tures of the elec­tric hea­ting wires are often 300–400 °C abo­ve the gas tem­pe­ra­tu­re and typi­cal­ly reach around 1,100–1,150 °C.

This results in a strong radia­ti­on exch­an­ge bet­ween the hea­ting coil and the fan rotor, which can rai­se the actu­al rotor tem­pe­ra­tu­re signi­fi­cant­ly abo­ve the tem­pe­ra­tu­re of the sur­roun­ding flu­id. Preli­mi­na­ry inves­ti­ga­ti­ons show that the tem­pe­ra­tu­re dif­fe­rence bet­ween the flu­id and the impel­ler can increase by over a hundred Kel­vin, depen­ding on the distance and ope­ra­ting tem­pe­ra­tures. This redu­ces the ser­vice life of the fan, increa­ses the risk of fail­ure and has so far requi­red a very con­ser­va­ti­ve, cost-inten­si­ve design.

Project goals

RadOn­Fan aims to sys­te­ma­ti­cal­ly inves­ti­ga­te the radia­ti­on exch­an­ge bet­ween elec­tric hea­ting regis­ters and fan impel­lers and to uti­li­se this infor­ma­ti­on in the design of fans for elec­tri­cal­ly hea­ted ther­mal pro­ces­sing systems.

Spe­ci­fi­cal­ly, the aim is to

  • quan­ti­fy the addi­tio­nal ther­mal loads on fans cau­sed by hea­ting coils,
  • iden­ti­fy opti­mal arran­ge­ments of hea­ting coils and fans with the lowest pos­si­ble impel­ler temperature,
  • eva­lua­te the effects of increased tem­pe­ra­tures on the ser­vice life of the impellers,
  • pro­vi­de prac­ti­cal design rules and sim­pli­fied cal­cu­la­ti­on approa­ches for com­pa­nies, espe­ci­al­ly SMEs.

 

The pro­ject thus lays the foun­da­ti­on for the safe and eco­no­mic­al elec­tri­fi­ca­ti­on of con­vec­tion-domi­na­ted indus­tri­al furnaces.

The rese­arch approach com­bi­nes expe­ri­men­tal inves­ti­ga­ti­ons on a hot gas test rig, in which the influence of dif­fe­rent hea­ting regis­ter posi­ti­ons and ope­ra­ting para­me­ters on flow and impel­ler tem­pe­ra­tu­re is sys­te­ma­ti­cal­ly mea­su­red. In par­al­lel, a 3D CFD and FEM model is being deve­lo­ped and vali­da­ted with the mea­su­re­ment data in order to cal­cu­la­te tem­pe­ra­tu­re dis­tri­bu­ti­ons, heat flows and the resul­ting mecha­ni­cal stress and ser­vice life of the fans.

Contact

Julius Wilker, M.Sc.

 

+49 241 80–25965

Nico Rademacher, M.Sc.

 

+49 241 80–25939

Funding

The RadOn­Fan rese­arch pro­ject (pro­ject no. 01IF24638N) was sub­mit­ted with the sup­port of the Rese­arch Asso­cia­ti­on for Indus­tri­al Fur­nace Con­s­truc­tion (FOGI) via the Rese­arch Coun­cil for Mecha­ni­cal Engi­nee­ring (FKM). It is finan­ci­al­ly sup­port­ed by the Ger­man Aero­space Cent­re (DLR) as part of the pro­gram­me for the pro­mo­ti­on of indus­tri­al joint rese­arch and deve­lo­p­ment (IGF) by the Fede­ral Minis­try for Eco­no­mic Affairs and Ener­gy (BMWE) on the basis of a reso­lu­ti­on of the Ger­man Bundestag.