High potency of application on an open direct-contact thermal storage using humid air

To reuse low-temperature wasted heat as a thermal resource for high temperature, a direct-contact adsorption thermal storage was focused using humid air and zeolite 13X particles as the working fluid and adsorbent, respectively. Only a few previous studies have chosen the working fluid in gaseous form because it is unavailable for latent heat in generating heat sources. Recovering waste heat in humid air to generate hotter steam is unique and becomes an originality of our present work. The time required to regenerate zeolite particles and the maximum temperature of the generated steam were investigated assuming a warm-up device for a vehicle. The time required to regenerate zeolite was investigated by changing the dew point, temperature, and superficial velocity of the inlet humid air. It was mainly affected by the temperature of the inlet air. The absorbent was regenerated within 30 min when the humid air preheated to 200 °C was supplied. On the other hand, the maximum steam temperature was investigated by changing the superficial velocity and temperature of saturated inlet humid air. As one of the significant and novel finding in this work, the steam of >200 °C was obtained as a high-temperature heat source even with saturated humid air unavailable latent heat. Moreover, as theoretical knowledge, it was revealed that the maximum temperature of the heat source can be estimated by the relationship between the heat balance on the packed bed and adsorption equilibrium.