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This work presents a Computational Fluid Dynamics model of helically wound fin tube bundles and demonstrates its predictive capability for thermal-hydraulic performance. A consistent validation against experimental data is given for four different fin tube geometries, two with plain fins and two with serrated fins. Predicted heat transfer and pressure drop data are within, or very close to, the experimental uncertainty, with maximum root mean square errors of 13.8 % and 14.4 % respectively. The modeled fin temperature distribution is used to evaluate three fin efficiency models, revealing that correction equations can be in significant error for tall plain fins. Three sets of semi-empirical correlations for Nusselt and Euler numbers are also evaluated, showing non-conservative predictions for several of the tested geometries. Results from the study confirm the efficacy of reduced domain modeling, whereby geometric periodicity of the heat exchanger array is exploited to reduce computational cost.

While the main barrier for the development of hydrogen adsorption type storage systems remains the material development, an improved thermal management may offer solutions to minimize the penalties in the amount of stored gas during fast-filling and the residual amount of hydrogen during discharging operations. The emphasis of this work was to experimentally investigate the dynamical thermal behavior of a hydrogen cryoadsorption storage system during fast-filling operations. The experiments were conducted with granulated activated carbon and MOF adsorbents. The influence of the charge pressure and the gas flow rate on the temperature elevations and the amount of filled hydrogen gas was analyzed. The heat generated in the storage vessel originates from the released heat of adsorption, gas compression work and thermal energy transfer that takes place when high pressure gas at the ambient temperature is introduced to the tank. A typical average temperature increase observed during the charging of the test tank, filled with the activated carbon (NORIT R0.8 extra), to 2 MPa was about 21 K. Such temperature elevation leads to a significant decrease in adsorption storage capacity.

The fabrication and performance of wicks for vertical flat heat pipe applications produced by compression of nickel foams has been investigated. The permeabilities and the effective pore radii for the wicks were estimated from rate-of-rise experiments, using the model fluid heptane. The porosities of the wicks were measured using isopropanol. The results, which are new and of vital importance for optimum use of such wicks, show that the permeabilities and the effective pore radii are in the upper range for heat pipe use. The joining pressure required during the sintering of the wicks was determined, and it was discovered that the nickel foams turned hydrophilic during the sintering.