efficient cooling to ambient conditions should be enough to recapture a significant amount of the supplied water in the humidifier thereby recycling most of the water and reducing losses this also reduces the amount of water needed to be supplied to the vehicle at the time of fuel u201c fill ups u201d fig8 shows example psychrometrics of the supply air to the fuel cell under conventional un heated adiabatic humidification air enters the humidifier at 20 u00b0 c dry bulb 0 0006 kg kg dry air humidity ratio state point 1 and leaves the humidifier at 13 5 u00b0 c 0 0009 kg kg state point 2 one embodiment of the instant invention in fig3 provides a means for isothermal humidification wherein the air conditions leaving the humidifier are 20 u00b0 c 0 013 kg kg state point 3 thereby improving the moisture content humidity ratio and dry bulb temperature of the supply air for improved fuel cell performance another embodiment of the instant invention in fig5 and 7 preheats the supply air to 25 u00b0 c state point 4 and then isothermally humidifies the air to 25 u00b0 c 0 018 kg kg state point 5 thereby further improving the moisture content of the supply air for greater fuel cell performance a unique feature is the use of the carbon foam to capture waste heat from onboard systems such.