▁that ▁heat ▁transfer ▁in ▁firing ▁systems ▁neither ▁takes ▁place ▁through ▁radiation ▁nor ▁by ▁contact . ▁In ▁those ▁days , ▁this ▁theory ▁was ▁strongly ▁doubt ed ▁among ▁the ▁exper ts ▁– ▁never theless , ▁his ▁th esis ▁could ▁not ▁be ▁ref uted ▁and ▁Sch ack ▁gained ▁wide ▁recognition ▁in ▁the ▁world ▁of ▁science . ▁▁ ▁In ▁ 1 9 2 9 , ▁the ▁pione er ▁work ▁“ Der ▁industri elle ▁W är me ü berg ang ” ▁ ▁( The ▁Indust rial ▁He at ▁Transfer ) ▁was ▁published . ▁This ▁educational ▁book ▁providing ▁practical ▁knowledge ▁for ▁engine ers ▁was ▁continu ously ▁re vised ▁and ▁extended ▁in ▁the ▁following ▁years . ▁▁ ▁On ▁July ▁ 1 4 , ▁ 1 9 3 1 , ▁Sch ack ▁established ▁the ▁company ▁Re ku per ator ▁K G ▁Dr .- In g . ▁Sch ack ▁& ▁Co ., ▁with ▁the ▁support ▁of ▁Dem ag ▁AG . ▁Due ▁to ▁the ▁economic ▁de pression ▁the ▁first ▁time ▁was ▁quite ▁difficult . ▁However , ▁the ▁break through ▁came ▁when ▁in ▁ 1 9 3 5 ▁the ▁company ▁Rö ch ling - W er ke ▁awarded ▁to ▁Sch ack ▁the ▁order ▁to ▁construct ▁a ▁huge ▁steel ▁recuper ator , ▁which ▁went ▁into ▁history ▁as ▁it ▁was ▁the ▁largest ▁plant ▁of ▁its ▁kind ▁ever ▁built ▁at ▁that ▁time . ▁Other ▁important ▁units ▁followed , ▁such ▁as ▁the ▁first ▁S iem ens - Martin ▁furn ace ▁with ▁recuper ator ▁he ating ▁and ▁in ▁ 1 9 3 9 ▁the ▁first ▁hot ▁bl ast ▁furn