Multi-objective design optimization of hydride hydrogen storage reactor structured with finned helical tubes based on energetic and economic analyses

Abstract

Hydride-based systems are a potential alternative to hydrogen storage technologies due to their simple structure and ambient operating conditions. The optimization of hydride reactor design factors is highly correlated to the targeted application. This research focuses on optimizing the thermal-static performance of LaNi5-holding helically coiled hydride reactors employing combined response surface methodology, computational modeling, and a desirability approach. The structural geometric design optimization factors include the diameter of the helical tubes and shell, the number of helical tubes, the pitch, and the distance between two adjacent helical tubes. Responses comprise a dimensionless characteristic response – weight ratio (static performance) and 90 % absorption time with maximal heat extraction rate (thermal performance). The quadratic regression model outperformed the linear regression models in terms of accuracy and reliability, effectively reducing the number of computational runs by 83 % compared to the standard parametric study-based technique. Combinatorically assessing the weight ratio and thermal power to be set to the maximum at the quickest absorption time resulted in selecting the best helical reactor design. The optimal base case was further improvised by integrating fins, which were optimized using the proposed methodology. The optimal base case and finned helical reactor subjected to sensitivity analysis revealed that the latter exhibited an average 18 % fall in complete saturation time and a 16 % rise in thermal power despite the 5.66 % loss in weight ratio. The Levelized cost of hydrogen storage was substantially reduced by 18–23 % when operated at higher supply pressures and fluid inlet temperatures. Besides, when the price of the finned reactor to its base case ratio was cut from 1.5 to 1.1, the optimized finned reactor turned economical. Furthermore, the outcomes of a systematic literature comparative study demonstrated that the constructed finned helical reactor was superior to its equivalent, accounting for a 60–75 % drop in 90 % saturation time. As an upshot, this study aids the researchers in designing accurate and apt objective-based hydride reactors using the proposed statistical method: coupled quadratic regression-thermal modeling-desirability approach-based design optimization.