Electrically powered micro-heat exchangers built from foils containing microchannels and from spacer blocks with electrical heater cartridges were compared for water throughputs of up to 64 kg/h and for electrical powers up to 3 kW. A reference design and two variations of this design were characterised with regard to their power conversion efficiency, and to the correlation between the maximum heater cartridge temperature and the outlet temperature. The design variation with shortened microchannels showed improved thermal conversion for flow rates around 2 kg/h. The other design variation, replacing straight microchannels with curved meanders, exhibited significantly improved properties for the evaporation of water and overheating of the steam.
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