Under an ESA Contract EADS SPACE Transportation GmbH has designed and built an advanced Stainless Steel Condensing Heat Exchanger (CHX) Spare as part of the Environmental Control and Life Support Subsystem (ECLSS) of the European Columbus Module that shall be docked to the ISS in early 2007.
Lessons learnt from both, ground and space applications of condensing heat exchangers were to be considered, for risk mitigation, in a CHX alternative design.
The slurper section is equipped with a sophisticated capillary suction feature that supports an adequate condensate removal and transport through the slurper holes to the water separator assembly even at low airflow condition.
The air fin surface is covered with a hydrophilic coating that did pass qualification for 10 years' exposure to the various contaminants specified respectively determined in the ISS atmosphere so far. The biocidal additive of such coating is qualified for fungus growth prevention, accordingly.
Furthermore, the CHX is prepared for the late installation of a buffer volume downstream the condensate outlet that is actually in qualification. In case - for whatever reason- the accumulation of condensate in the CHX core would increase beyond the level that was achieved during successful CHX lifetime qualification, such buffer equipment shall intermediately store and thus flatten consequential condensate slugs to the interfacing water separator.
A dedicated control algorithm applied on the CHX' bypass valve limits the worst case accumulation of condensate in the CHX core to a level tolerated by the system, without compromising liquid carry over or temperature control requirements, respectively.
The paper describes the implementation & qualification of the above addressed advanced design features into the EADS-ST built CHX flight spare Figure 1, that shall now be installed into the European Columbus Module as part of the baseline ECLSS.