Numerical study of a metal hydride heat transformer for low-grade heat recovery

Yang, Fusheng; Zhang, Z.X.; Wang, Geoff; Bao, Zewei; Costa, João C. Diniz da; Rudolph, Victor

doi:10.1016/j.applthermaleng.2011.04.047

Cited by 29 publications

(7 citation statements)

References 19 publications

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“…Table 5 shows the performance comparison of the present study with similar studies. It is observed that the COP of the present study is higher than the COP reported by Yang et al 17 and Sekhar et al 16 The higher COP is achieved because of more hydrogen transfer between coupled MH beds. Apart from this, the present system stores 243.67 kJ kg À1 of heat which is lower than the study conducted by Satya Sekhar et al 37 and the reason behind this high heat storage is the reaction enthalpy of Mg material which is far greater than the materials used in the present study.…”

Section: Performance Comparisoncontrasting

confidence: 77%

Performance investigations on hydrogen‐based thermochemical energy storage system through finite volume method and thermodynamic simulation

Choudhari

Sharma

2021

Int J Energy Res

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In the present work, thermodynamic simulation and numerical modelling (through a finite volume approach) are carried out to investigate the performance of hydrogen-based thermochemical energy storage (H-TCES) system with the application of LaNi 4.6 Al 0.4 -La 0.9 Ce 0.1 Ni 5 metal hydride (MH) pair. Thermodynamic equations are used to evaluate the H-TCES performance whereas the continuity, energy and pressure equations are solved with the help of the computational fluid dynamics (CFD) approach to predict the heat and mass transfer behaviour of MH beds. The numerical code is validated by comparing the predicted pressure concentration isotherms (PCIs) with the experimentally measured PCIs, which are observed to be in good agreement. The experimental PCI data are used for the performance prediction of H-TCES system operating at 25 C, 100 C, 130 C and 150 C as ambient-, regeneration-, storage-and output temperature respectively. It is found that the energy storage density of the H-TCES system is 243.67 kJ with a COP of 0.48. The overall cycle time is predicted as 2200 seconds, which includes heat storage, heat output, sensible heating and sensible cooling processes. The generated temperature contours illustrate the effect of an increase and decrease in bed temperature during absorption and desorption processes.

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Section: Performance Comparisoncontrasting

confidence: 77%

Performance investigations on hydrogen‐based thermochemical energy storage system through finite volume method and thermodynamic simulation

Choudhari

Sharma

2021

Int J Energy Res

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“…Several studies on the performance analyses of sorption thermodynamic systems are conducted using different MH pairs. Kang and Yabe gave attention to metal hydride heat transformers for the effective use of industrial waste heat.…”

Section: Introductionmentioning

confidence: 99%

“…Moreover, the system performance can be enhanced with rectifications in reactor designs. Yang et al employed LaNi 5 /LaNi 4.7 Al 0.3 pair for MHHT and performance was investigated using ambient and waste heat sources through two‐dimensional unsteady model solved by finite volume method. Yang et al tried to account the realistic application for which they introduced a new dynamic index called true temperature boost for better assessment.…”

Section: Introductionmentioning

confidence: 99%

Performance investigation of metal hydride based heat transformer

et al. 2019

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Energy is one of the major inputs for the economic development of any country. However, for developing countries energy is essential for economic growth, which calls for the development of clean and sustainable energy source/carrier. Among all the possible options, hydrogen has been considered as a promising clean energy carrier, which is associated with major challenges of its storage and application. Hydrogen can be stored safely in the form of metal hydrides whose formation and decomposition involve high heat interaction, which can be used for the development of thermodynamic systems like sorption heat pumps, which can transform waste heat to useful high‐grade heat. In the present work, the performance of metal hydride based heat transformer (MHHT) is investigated in terms of variation in MH bed temperature and hydrogen interaction between coupled reactors during hydrogen transfer processes, in addition to thermodynamic performance (ie, Coefficient of Performance (COP), heating capacity, and so on) for the operating temperature of TL = 303 K, TM = 383 K, and TH = 423 K. A pair of La0.9Ce0.1Ni5 and LaNi4.6Al0.4 is chosen for present study based on author's previous work. In the present study, user‐defined functions are employed in ANSYS Fluent, which consist of pressure, mass, and energy variation equations. The results are derived in the form of contours and graphical representations of variations in bed temperature and hydrogen concentration. It is observed that the system produces 40 kJ of upgraded heat with heating capacity of 0.1 kW and COP of 0.46 at 880 seconds of hydrogen transfer time for 250 g of each alloys.

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“…The selection of a particular heat exchanger, especially for experimental studies, is driven mainly by the availability of the single components rather than the result of an optimization analysis [15,[21][22][23]. Simple and complex computational models have been applied to describe the performance of complete thermal cycles in terms of the coefficient of performance (COP) but often lack general insights into the selection criteria for the heat exchanger [14,20,24,25]. Furthermore, most studies refer to a specific metal hydride pair, making the comparison between MHHPs configurations material dependent.…”

Section: Introductionmentioning

confidence: 99%

Heat exchanger selection and design analyses for metal hydride heat pump systems

Mazzucco

Voskuilen

Waters

et al. 2016

International Journal of Hydrogen Energy

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This study presents a design analysis for the development of highly efficient heat exchangers within stationary metal hydride heat pumps. The design constraints and selected performance criteria are applied to three representative heat exchangers. The proposed thermal model can be applied to select the most efficient heat exchanger design and provides outcomes generally valid in a pre-design stage. Heat transfer effectiveness is the principal performance parameter guiding the selection analysis, the results of which appear to be mildly (up to 13%) affected by the specific Nusselt correlation used. The thermo-physical properties of the heat transfer medium and geometrical parameters are varied in the sensitivity analysis, suggesting that the length of independent tubes is the physical parameter that influences the performance of the heat exchangers the most. The practical operative regions for each heat exchanger are identified by finding the conditions over which the heat removal from the solid bed enables a complete and continuous hydriding reaction. The most efficient solution is a design example that achieves the target effectiveness of 95%.

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Numerical study of a metal hydride heat transformer for low-grade heat recovery

Cited by 29 publications

References 19 publications

Performance investigations on hydrogen‐based thermochemical energy storage system through finite volume method and thermodynamic simulation

Performance investigations on hydrogen‐based thermochemical energy storage system through finite volume method and thermodynamic simulation

Performance investigation of metal hydride based heat transformer

Heat exchanger selection and design analyses for metal hydride heat pump systems

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