Improvement of the performance of metal hydride pump by using phase change heat exchanger

Miled, Amel; Mellouli, Sofiene; Mâad, Hatem Ben; Askri, Faouzi

doi:10.1016/j.ijhydene.2017.08.118

Cited by 22 publications

(6 citation statements)

References 48 publications

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“…Therefore, at that temperature, the melting fraction is equal to 0.5. This is consistent with different PCM models proposed in the literature [47][48][49][50]. Taking into account this above discussion and the following assumptions, the energy balance of the PCM can be written:…”

Section: Phase Change Materialssupporting

confidence: 87%

Metal Hydride Beds-Phase Change Materials: Dual Mode Thermal Energy Storage for Medium-High Temperature Industrial Waste Heat Recovery

2019

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Heat storage systems based on two-tank thermochemical heat storage are gaining momentum for their utilization in solar power plants or industrial waste heat recovery since they can efficiently store heat for future usage. However, their performance is generally limited by reactor configuration, design, and optimization on the one hand and most importantly on the selection of appropriate thermochemical materials. Metal hydrides, although at the early stage of research and development (in heat storage applications), can offer several advantages over other thermochemical materials (salt hydrates, metal hydroxides, oxide, and carbonates) such as high energy storage density and power density. This study presents a system that combines latent heat and thermochemical heat storage based on two-tank metal hydrides. The systems consist of two metal hydrides tanks coupled and equipped with a phase change material (PCM) jacket. During the heat charging process, the high-temperature metal hydride (HTMH) desorbs hydrogen, which is stored in the low-temperature metal hydride (LTMH). In the meantime, the heat generated from hydrogen absorption in the LTMH tank is stored as latent heat in a phase change material (PCM) jacket surrounding the LTMH tank, to be reused during the heat discharging. A 2D axis-symmetric mathematical model was developed to investigate the heat and mass transfer phenomena inside the beds and the PCM jacket. The effects of the thermo-physical properties of the PCM and the PCM jacket size on the performance indicators (energy density, power output, and energy recovery efficiency) of the heat storage system are analyzed and discussed. The results showed that the PCM melting point, the latent heat of fusion, the density and the thermal conductivity had significant impacts on these performance indicators.Energies 2019, 12, 3949 2 of 27 or combined cooling heating and power (CCHP), have been the predominant waste-heat recovery methods in power plants. These multi-generation processes allow for an improvement of thermal energy efficiency of up to 80%. On the other hand, for industrial process heat, the organic Rankine cycle (ORC), thermoelectric generators, heat pumps, and heat storage have been reviewed as potential methods for waste heat recovery [2]. However, the efficacy of either heat recovery method depends on the conditions at which heat is discharged (especially the temperature). There are mainly three factors affecting the implementation of waste heat recovery: the availability, the heat amount and quality (which is the temperature range). The temperature range depends on the waste heat source which ranges from thermal power plants (diesel engines, fossil fuels-fired power plants, PEM, and solid oxide fuel cells) to industrial processes (steel, cement, etc). On the one hand, if the heat is available at a constant temperature, therefore the selection of ORC and thermoelectric generators for heat recovery can improve the overall energy efficiency by generating extra electricity to the end-users. On the oth...

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Section: Phase Change Materialssupporting

confidence: 87%

Metal Hydride Beds-Phase Change Materials: Dual Mode Thermal Energy Storage for Medium-High Temperature Industrial Waste Heat Recovery

2019

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“…Equations (1) and (2) give

P_{italicsp} = P_{italiceq} - P_{a} + ρ_{w} {italicgh}_{s}

The equilibrium pressure,

p_{italiceq},

is given by 24

p_{italiceq} = \exp [\frac{italicΔH}{R_{g} T} - \frac{italicΔS}{R_{g}} + f_{s} tg [π (\frac{X_{eq} - \frac{X_{s}}{2}}{X_{s}})]]

where,

f_{s}

: the slope factor;

X

: hydrogen concentration in the MH.…”

Section: Mathematical Model and Numerical Methodsmentioning

confidence: 99%

“…Phase change materials (PCMs) are an extremely interesting method for heat storage due to their high‐energy storage density 23 . Miled et al 24 studied numerically a low‐temperature MHP integrating a PCM. They found that an 88% reduction in pumping time and an 8‐times increase in efficiency can be achieved as a result of using PCM.…”

Section: Introductionmentioning

confidence: 99%

Enhancement of the metal hydride hydraulic pump efficiency by integrating a phase change material

Alqahtani

2022

Intl J of Energy Research

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Summary The combination of a metal hydride (MH) with a water pump has gained significant interest recently. However, the efficiency of such a system is low, as it requires a substantial quantity of heat from an external source to initiate the desorption process. Storing the heat generated by the absorption reaction (exothermic reaction) in a phase change material (PCM) and reusing it during the dehydration reaction (endothermic reaction) is a viable method to enhance the pump's efficiency. Thus, in the present study, the mathematical modeling and numerical simulation of a new configuration of a MH pump (MHP) equipped with a latent heat exchanger were investigated. The obtained results showed that using a PCM with MHP, as energy storage material, considerably enhances the performance of the pump. For example, with a heat transfer coefficient of 50 W/m2.K, an MH's thermal conductivity of 5.32 W/m. K, a PCM's thermal conductivity of 3 W/m. K, and pumping head of 25 m, it was noted that using Ba(OH)2‐8H2O with the pump as PCM decreases the pumping time by approximately 59% and allows for 17 times increase in overall efficiency over the case without PCM.

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“…Temperature control strategy is required to meet the requirements under different operating conditions and environmental conditions. There are many studies on the control strategy of cooling system, but the influence of hydrogen supply from hydrogen supply system on fuel cell stack cannot be ignored [9][10][11][12]. Zhu [13] and others give full consideration to the metal hydrogen storage vessel thermal control integration for hydrogen and fuel cell system of energy of the coupling relationship between each other, who put forward a kind of thermal management strategy based on PID controller to control the supply of hydrogen flow rate.…”

Section: Optimization Of Control Strategiesmentioning

confidence: 99%

Fuel Cell Vehicle Thermal Management Research

Guo

Wang

Liang

et al. 2022

Advances in Transdisciplinary Engineering

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The vehicle’s thermal management system is critical to the safety, durability, performance and passenger comfort of fuel cell vehicles, and is also one of the core technologies of fuel cell vehicles. The thermal management system needs to meet the thermal balance of the vehicle under the operating limit conditions and balance the working temperature of different components. This paper analyzes the structure and control strategy of the thermal management system of different vehicle models through the research summary of the current thermal management technology of fuel cell vehicles, summarizes the impact of different parameters on thermal efficiency, and deeply analyzes the technical research field and development in this direction. The direction gives some methods to improve the performance of the thermal management system during the selection of the R&D technology route and the development process of the enterprise.

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Improvement of the performance of metal hydride pump by using phase change heat exchanger

Cited by 22 publications

References 48 publications

Metal Hydride Beds-Phase Change Materials: Dual Mode Thermal Energy Storage for Medium-High Temperature Industrial Waste Heat Recovery

Metal Hydride Beds-Phase Change Materials: Dual Mode Thermal Energy Storage for Medium-High Temperature Industrial Waste Heat Recovery

Enhancement of the metal hydride hydraulic pump efficiency by integrating a phase change material

Fuel Cell Vehicle Thermal Management Research

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