Cleaning Methods for Flux Pollution Measurement in Automotive Coolant Loop Components

摘要

For the worldwide technology of heat exchangers, Nocolok flux is used to remove aluminium oxide during brazing under controlled atmosphere. This flux is known to react with corrosion inhibitors from coolant by creating silicate paste. Coolant flows in heat exchangers: several temperature cycles, coolant ageing, inhibitors consumption will enhance this phenomenon. By this way, heat exchangers are losing thermal performance. That is the reason why car manufacturers ask to reduce residual flux amount. This presentation deals with different existing methods to evaluate heat exchangers cleanliness: how can be measured the residual flux amount? Different processes used by Valeo to reduce the initial flux amount will be also presented. The main difficulty of this study is to minimize the flux quantity while maintaining a good brazing quality. Flux amount reduction cannot be done by sacrificing heat exchangers robustness and reliability. Customer's specifications are staying at a high requirement level.