Integration of phase change materials in compressed hydrogen gas systems: Modelling and parametric analysis

Abstract

A dynamic fueling model is built to simulate the fueling process of a hydrogen tank with an integrated passive cooling system. The study investigates the possibility of absorbing a part of the heat of compression in the high latent-heat material during melting, with the aim of saving the monetary and energy resources spent at the refueling station to cool the gas prior to tank filling. This is done while respecting the technical constraint of keeping the walls below the critical temperature of 85 °C to ensure the mechanical stability of the storage system even when the gas is fueled at ambient temperature. Results show that a 10-mm-thick layer of paraffin wax can absorb enough heat to reduce the adiabatic temperature by 20 K when compared to a standard Type IV tank, but its influence on the hydrogen peak temperature that occurs at the end of refueling is modest. The heat transfer from the gas to the phase change material, mainly occurs after the fueling is completed, resulting in a hydrogen peak temperature higher than 85 °C and a lower fueled mass than a gas-cooled system. Such a mass reduction accounts for 12% with respect to the case of a standard tank system fueled at -40 °C. A parametric analysis that embraces the main thermal properties of the heat-absorbing material as well as the major design parameters is here carried out to determine possible solutions. It is found that the improvement of a single thermal property does not provide any significant benefit and that the most effective strategy consists in augmenting the heat transfer area by employing extended surfaces or the encapsulation technique.Keywords: phase change material; hydrogen storage; hydrogen fueling; dynamic model; heat transfer.International Journal of Hydrogen Energy, Vol. 41, No. 12, 2016, p. 1060-1073 IntroductionRecent interest has raised for phase change materials (PCMs) as attractive options to store the thermal energy coming from intermittent sources and enable a continuous availability of the stored heat. Their use provides considerable advantages when compared to technologies that are based on sensible cooling/heating processes. Indeed, great convenience arises from the possibility of using their high energy storage densities to store large amounts of heat in a reduced space, as well as the capability of absorbing and releasing the heat via isothermal heat transfer. These aspects have made PCMs promising candidates for a large variety of applications, including solar energy storage, air conditioning of buildings and spacecrafts, passive cooling of electronics, textiles and fabrics [1]- [9]. A considerably less explored area of study is hydrogen storage. In such a field, research has mainly focused on employing PCMs to absorb the heat that originates during hydrogen fueling in metal hydride tanks for stationary applications [10], [11].In this study, our interest is to investigate the potential advantages and drawbacks of integrating an adequate PCM into compressed gaseous hydrogen (CHG) storage systems for light duty veh...

The development of a computational platform to design and simulate on-board hydrogen storage systems

“…These two parameters are used together with p amb and T amb to determine the appropriate refueling protocol, which, in turn, defines the fueling pressure ramp for CHG storage systems according to SAE J2601 as discussed in Ref. [7].…”

“…In the tank model all the equations concerning energy and mass balances, kinetics and heat transfer are solved (see Appendix B and Refs. [6], [7]). This occurs according to the model setup that the user defines.…”

“…Reliable computational models are developed to describe hydriding and dehydriding reactions as well as melting and solidification processes that occur in the metal hydride tank and novel compressedhydrogen vessel respectively [6], [7]. For the former, these models are used to quantify the main design parameter, being the critical metal hydride thickness, for the tank/heat-exchanger system as described in the Heat exchanger designs Section and in more detail in Ref.…”

“…Only the main results that refer to the MHSS are here presented, as the analysis of the CHG system was discussed in Ref. [7].…”

Use of MWNTs‐COOH to improve thermal energy storage and release rates of capric–palmitic–stearic acid ternary eutectic/polyacrylonitrile form‐stable phase change composite fibrous membranes

“…Among these forms, latent heat storage using phase change materials (PCMs) is considered as one of the most efficient technologies to store and release large amounts of thermal energy. At present, PCMs has achieved wide application in the fields of energy storage and thermal insulation such as solar energy utilization (e.g., solar thermal collectors ), building energy conservation (e.g., lightweight building envelopes , PCM wallboards , and roofs ), battery thermal management , passive cooling systems , soilless greenhouse systems , conventional refrigeration systems , and smart textiles due to their excellent advantages such as high latent heat values and steady phase change temperatures .…”