PRODUCTION OF HEAT EXCHANGER ELEMENT

摘要

PURPOSE:To subject a tentatively fixed member consisting of two sheets of plates coated with a flux over the entire surface and a corrugated sheet material fitted therebetween to aluminum brazing and surface coating without sagging and defects by preheating said member, dipping the member into an aluminum bath vessel etc. and cooling the member in a non-oxidative neutral fused salt kept at a low temp. CONSTITUTION:The element 7 fixed tentatively with two sheets of the plates 8 and the corrugated sheet material 9 by a spot welding or press machine is dipped into the flux 2 consisting of AlF3 and KF at 600 deg.C by which the element is coated with the flux over the entire surface and is preheated. The element is then dipped into the bath vessel 3 contg. pure aluminum 4 kept at 700 deg.C and is thereby brazed with the aluminum and is coated with the aluminum over the entire surface. The element is dipped into the non-oxidative neutral fused salt 6 consisting of KNO3 and NaNO3 at a low temp. of about 300 deg.C and is cooled in succession thereto. No sagging is generated owing to the specific gravity relation and the thermal impact and distortion are decreased. The satisfactory and uniform brazing and coating over the entire surface are thus made possible without exfoliation.