Cyclic steam generation from a novel zeolite–water adsorption heat pump using low-grade waste heat

Cyclic steam generation experiments from a novel zeolite–water adsorption heat pump were carried out to demonstrate the feasibility of recycling hot water and low-grade waste gas. A direct heat exchange approach was introduced to enhance heat transfer and decrease system size. The experimental steam generation rate per unit mass of zeolite is 2.44 × 10−5 (kg-steam/kg-zeolite)/s at regeneration for 1200 s, which is 10% larger than that for 3600 s. A one-dimensional model describing transport phenomena during regeneration was developed to estimate temperature distributions and local water content in zeolite at the end of regeneration. Based on the numerical results, the mass of steam generated in the subsequent process was calculated. Then, the cyclic steam generation rate can be estimated. Calculated results on steam generation rate agree with the two sets of experimental data. The calculation reveals a maximum in the steam generation rate with the change in regeneration time. Predictions also show the possibility of high-pressure steam generation from this system.

► Experiments prove adsorption heat pump for steam generation with low-grade heat.
► Calculations on steam generation rate agree with experiments and reveal a maximum.
► Predictions show possibility of high-pressure steam generation from this system.