Self-hea­ting pro­ces­ses

Rese­arch of self-hea­ting pro­ces­ses of modern bulk mate­ri­als

Bulk solid mate­ri­als can spon­ta­neous­ly reach high tem­pe­ra­tures and even catch fire. The reasons for this are inter­nal chemical/physical reac­tions, which gene­ra­te more heat than the bulk can emit through their sur­roun­dings. Con­ven­tio­nal com­bus­ti­ble bulk solids are straw, coal and house­hold was­tes. Bio­lo­gi­cal pro­ces­ses and oxi­da­ti­on reac­tions are respon­si­ble for self-hea­ting in the­se cases.

The iden­ti­fi­ca­ti­on of the respon­si­ble reac­tions and their kine­tics can be mea­su­red using dif­fe­rent methods. At the Chair of Ther­mal Pro­ces­sing Tech­no­lo­gy, we mea­su­re pro­duct gases with a labo­ra­to­ry dif­fe­ren­ti­al loop reac­tor to descri­be the che­mi­cal kine­tics of the exo­ther­mic reac­tions.

In view of the cur­rent cli­ma­te chan­ges, e. g. in car­bon-based pro­duc­tion or ener­gy sto­rage, many new or reco­ver­ed mate­ri­als are con­side­red to be sub­sti­tu­tes for com­mon pro­ducts. Such pro­ducts may have dan­ge­rous poten­ti­al for self-hea­ting and need to be eva­lua­ted. In two of our latest rese­arch pro­jects, we inves­ti­ga­te the che­mi­cal kine­tics of the reoxi­da­ti­on of hydro­gen-direct redu­ced iron (DRI) and the kine­tics of exo­ther­mic reac­tions in shred­ded nickel-metal hydride bat­tery was­te. Both mate­ri­als play an important role in miti­ga­ti­on cli­ma­te chan­ge in indus­try, but also for us end-con­su­mers.

Pho­to © John­Seb