State of the Art in Development of Heat Exchanger Geometry Optimization and Different Storage Bed Designs of a Metal Hydride Reactor

Abstract

The efficient operation of a metal hydride reactor depends on the hydrogen sorption and desorption reaction rate. In this regard, special attention is paid to heat management solutions when designing metal hydride hydrogen storage systems. One of the effective solutions for improving the heat and mass transfer effect in metal hydride beds is the use of heat exchangers. The design of modern cylindrical-shaped reactors makes it possible to optimize the number of heat exchange elements, design of fins and cooling tubes, filter arrangement and geometrical distribution of metal hydride bed elements. Thus, the development of a metal hydride reactor design with optimal weight and size characteristics, taking into account the efficiency of heat transfer and metal hydride bed design, is the relevant task. This paper discusses the influence of different configurations of heat exchangers and metal hydride bed for modern solid-state hydrogen storage systems. The main advantages and disadvantages of various configurations are considered in terms of heat transfer as well as weight and size characteristics. A comparative analysis of the heat exchangers, fins and other solutions efficiency has been performed, which makes it possible to summarize and facilitate the choice of the reactor configuration in the future.

A Minimum Entropy Production Approach to Optimization of Tubular Chemical Reactors with Nature-Inspired Design

“…The minimum entropy production approach was successfully applied to optimization of the methanol synthesis via the carbon dioxide hydrogenation reactor [54], the ammonia synthesis reactor [55], the SO 2 oxidation reactor [30], small modular reactors [1,4], tubular steam reformer [35,56,57], the reverse water-gas shift reactors [58,59], dimethyl ether synthesis reactors [60], catalytic combustion of air pollutants with Pd/Al 2 O 3 catalyst [37], polymer electrolyte membrane fuel cells (FC) with Fermat spiral [61], biomimetic [62] and fractal-type [63] flow-fields, solid oxide FC [64], in ammonia-methane fueled microcombustor for thermophotovoltaic applications [65], in hydrocarbon synthesis reactor with carbon dioxide and hydrogen [66], CO 2 hydrogenation [67], isothermal crystallization processing [68], in the Fickett-Jacob cycle [69], diabatic distillation [70], in hydrogen iodide decomposition reactors heated by high-temperature helium [71], ideal reactors and practical industrial reactors [60,72], stirred tank and plug flow reactors [72], thermoelectric modules [73], heaters [13,74,75], and chillers [76]. Based on the minimum entropy production approach, a nanofluid-based tubular reactor was optimized to the elliptic shape with the axes ratio 5:3 that gave up to 16.82% reduction in the entropy production and rise in the thermal efficiency from 74% to 80% [77].…”

“…The optimization of a chemical unit may need optimization of the cooling system. Choices include set of fins, cooling tubes, and use of materials with higher thermal conductivity [13].…”

“…The chemical reactions could be endo-or exothermic, and the corresponding heating or cooling system must be mounted at the sur face of the tube. The heat produced in exothermal chemical reactions can be used as an energy source for other purposes, making it an important issue for design optimization as well [2,4,6,13].…”

Fast Design and Numerical Simulation of a Metal Hydride Reactor Embedded in a Conventional Shell-and-Tube Heat Exchanger

“…Because metal hydride materials have low thermal conductivity, more efficient heat transfer can be realized by expanding their heat transfer area or raising their heat transfer coefficient. In recent years, numerous studies on the reactor are focused on the structure of shell-and-tube heat exchanger, the number of heat exchanger tubes increases, and the shape of the heat exchanger tube is also continuously optimized [19][20][21]. To improve the heat transfer of hydride materials, various heat-conducting matrices like fins, aluminum foam, and natural graphite can be added.…”

“…To improve the heat transfer of hydride materials, various heat-conducting matrices like fins, aluminum foam, and natural graphite can be added. Then, their parameters can be further optimized [19,[22][23][24]. Bai et al [22] studied a tree-finned reactor using genetic algorithms, which reduced the hydrogen absorption time by 20.7% compared to radial fins.…”