Simulations of the thermal effects during adsorption cycles are valuable tools for the design of efficient adsorption-based systems such as gas storage, gas separation and adsorption-based heat pumps. An analytical representation of the measured adsorption data over the wide operating pressure and temperature swing of the system is necessary for the calculation of complete mass and energy conservation equations. In Part 1, the Dubinin-Astakhov (D-A) model is adapted to model hydrogen, nitrogen, and methane adsorption isotherms on activated carbon at high pressures and supercritical temperatures assuming a constant microporous adsorption volume. The five parameter D-A type adsorption model is shown to fit the experimental data for hydrogen (30 to 293 K, up to 6 MPa), nitrogen (93 to 298 K, up to 6 MPa), and for methane (243 to 333 K, up to 9 MPa). The quality of the fit of the multiple experimental adsorption isotherms is excellent over the large temperature and pressure ranges involved. The model's parameters could be determined as well from only the 77 K and 298 K hydrogen isotherms without much reducing the quality of the fit.

An investigation of active magnetic regenerators ͑AMRs͒ has been performed near room temperature using helium as a heat transfer fluid and a magnetic field of 2 T. To evaluate the impact of the operating conditions, the performance of two reciprocating 90 g gadolinium packed bed regenerators was mapped as a function of the fluid flux and cycle frequency. In addition, two multilayer regenerators of similar mass and dimensions, composed of a layer of gadolinium and a layer of a gadolinium-terbium alloy, were tested and compared to the performance of the Gd-only regenerators. The multilayer regenerators produced a larger temperature span and cooling power compared to the single material regenerators of equivalent mass and geometry ͑temperature spans of about 20 and 16 K, respectively͒. Theses results validate the concept of a multilayer AMR, provide useful data for magnetic refrigerator design, and provide better understanding of active magnetic refrigeration.

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Simulations of the thermal effects during adsorption cycles are a valuable tool for the design of efficient adsorption-based systems such as gas storage, gas separation and adsorption-based heat pumps. In this paper, we present simulations of the thermal phenomena associated with hydrogen, nitrogen and methane adsorption on activated carbon for supercritical temperatures and high pressures. The analytical expressions of adsorption and of the internal energy of the adsorbed phase are calculated from a DubininAstakhov adsorption model using solution thermodynamics. A constant adsorption volume is assumed. The isosteric heat is also calculated and discussed. Finally, the mass and energy rate balance equations for an adsorbate/adsorbent pair are presented and are shown to be in agreement with desorption experiments.

in Wiley InterScience (www.interscience.wiley.com).Using modeling and thermal simulations, the feasibility of an adsorption-based hydrogen storage system for vehicles is evaluated. The storage capacity of a 150 L tank filled with a high surface-area activated carbon is mapped for temperatures from 60 to 298 K and pressures up to 35 MPa. The thermal simulations are verified using experiments. For a storage capacity target of 5 kg, the adsorption-based storage system will offer a storage advantage over the cryogenic gas storage if the residual mass of hydrogen in the tank is retrieved by heating. For a discharge rate of 1.8 g/s, the required heat is of the order of 500 W. The net energy requirements for the refueling has contributions from compression, precooling and tank cooling and can approach that for liquid hydrogen storage. With a good insulation and a maximum tank pressure of 35 MPa, the dormancy period can be extended to several weeks. V