Design of Passive Cooling Module for Metalhydride Vessel for Hydrogen Storage
Abstract
The article addresses the design and calculation of heat transfer in the program ANSYS CFX of passive cooling module for metal hydride low-pressure vessels, which main purpose is to store hydrogen used in mobile applications such as automobile or bus.
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Introduction
Hydrogen is most abundant element not just on earth but also in the universe and has very promising future as an energy carrier. The largest amount of hydrogen is of course bound in water and hydrocarbons. Hydrogen has a low bulk density, so it contains a relatively small amount of energy. To work with hydrogen several challenges must be addressed. First challenge is hydrogen production, second is distribution and third is storage. This article addresses the challenge of storage. Most abundant way of storing a hydrogen is by using high-pressure vessels, next is by using cryogenic vessels and lastly there is hydrogen storage in low-pressure vessels by absorbing hydrogen into metal alloy structure. Hydrogen storage in metal hydrides represents the possibility of storage in low pressures as well as in low temperatures. Used metalhydride in our vessel is based on elements La Ce Ni. The only disadvantage is low thermal conductivity of metallic alloys and generated heat from hydrogen storage. Since there is generated heat by hydrogen storage in low-pressure vessels, passive and active cooling modules must be present. This article solves the problem of implementing passive cooling module into low-pressure vessel.
Conclusion
Storing hydrogen in metal hydrides present very promising future since high pressures are not required. Only disadvantage of storing hydrogen in metal hydrides is requirement of heat dissipation, which is generated by metal hydride absorbing hydrogen. This is the main reason why active and passive cooling systems needs to be provided to the metal hydride pressure vessel. This article shows the design of passive cooling system implemented in metal hydride pressure vessel and heat transfer calculation. The results shows that auxiliary ribs do not dissipate heat efficiently which means, that metalhydride is overheated in those places. To get more satisfactory results, geometry of heat transfer exchanger needs to be changed. For instance, the placement of auxiliary lamellas can change the whole outcome of the simulation.