A semi‐analytical solution for time‐varying latent heat thermal energy storage problems

Safdari, Mojtaba; Sadeghzadeh, Sadegh; Ahmadi, Rouhollah

doi:10.1002/er.5078

Cited by 8 publications

(5 citation statements)

References 34 publications

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“…In the previous article, 37 we introduced this method for phase change problems only in one phase. Then in another article, 36 we used it practically and evaluated various materials that can be used as PCM in thermal management systems.…”

Section: Discussionmentioning

confidence: 99%

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Two‐region semi‐analytical solution for latent heat thermal energy storage systems

Safdari

Sadeghzadeh

Ahmadi

et al. 2021

Intl J of Energy Research

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Problems with latent heat thermal storage (LHTS) often contain several boundary conditions that an exact solution cannot solve. Therefore, novel methods to tackle such issues could fundamentally change the design of innovative energy storage systems. This study concentrates on the reformulation of the generalized differential quadrature method (GDQM) for the two-region freezing/melting Stefan problem as an essential LHTS challenge. Comparison and convergence show that there is sufficient confidence in the proposed approach. By monitoring the precision of the suggested approach for the LHTS problem, it was indicated that this method's error depends on Stefan's number. The maximum error of all Stefan numbers up to 0.3 is less than 6%. For such applications in a standard array of LHTS (Stefan numbers between 0 and 0.2), the proposed method is appropriate as it predicts the answers with a maximum of 4.2% error. In comparison to the heat capacity method, GDQM delivers a more precise result at higher processing times. Additionally, this GDQM priority is accompanied by a low computational cost, which is unquestionably superior.

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Section: Discussionmentioning

confidence: 99%

“…In other articles, 36,37 the authors of this article solved the Stefan problem, which deals with the problem of phase change as one region, using this method (GDQ). The results showed that using this method to solve the issues of phase change material (PCM) can quickly and accurately predict these materials' behavior.…”

Section: Introductionmentioning

confidence: 99%

Two‐region semi‐analytical solution for latent heat thermal energy storage systems

Safdari

Sadeghzadeh

Ahmadi

et al. 2021

Intl J of Energy Research

Self Cite

View full text Add to dashboard Cite

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“…Also, Guo et al 26 experimentally evaluated the performance of TES, which consists of fin and PCM with metal foam combinations. Some research papers developed analytical techniques to analyze the TES system 27,28 . On the other hand, research related to PCM implementation in building envelopes is investigated by Ji et al 29 Besides, Asker et al 30 computed energetic performance and CO 2 emission for building‐wall integrated with PCM using actual weather data for Izmir city.…”

Section: Introductionmentioning

confidence: 99%

“…Some research papers developed analytical techniques to analyze the TES system. 27,28 On the other hand, research related to PCM implementation in building envelopes is investigated by Ji et al 29 Besides, Asker et al 30 computed energetic performance and CO 2 emission for building-wall integrated with PCM using actual weather data for Izmir city. Some research focused on the use of TES in electric vehicles.…”

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confidence: 99%

Performance assessment of a phase change charging mode in a vertical thermal energy storage system

Asker

Akal

Ezan

2022

Intl J of Energy Research

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Summary In this work, the performance of a charging mode of a thermal energy storage system is investigated numerically, and results are assessed considering the first law and second law perspectives. The storage unit comprises parallel plates positioned vertically, and the heat transfer fluid flows within the spacing between the plates. The melting process of phase change material inside a rectangular enclosure is simulated considering the natural convection using an in‐house model codded in C++. The proposed model is validated with the numerical and experimental research from the literature. A parametric analysis is carried out to explore the influence of heat transfer inlet temperature and aspect ratio on the unit's first law and second law performance indicators. Analyses are also conducted by disregarding the natural convection to assess the convective mode of heat transfer on the time‐wise variation of the storage effectiveness and stored exergy. The results revealed that for the highest inlet temperature of the heat transfer fluid, the stored energy value increases from 133.85 to 250 kJ then drops to 240 kJ by varying the aspect ratio from 0.25 to 0.50 and from 0.50 to 1.00, respectively, for the natural convection dominated melting. On the other hand, regarding effectiveness, both with and without natural convection modes show the same aspect ratio variations trend. The effectiveness reduces from 0.9 to 0.40 by increasing the aspect ratio from 0.25 to 1.00 for the natural convection‐dominated melting mode. The effectiveness drops from 0.62 to 0.16 for the same variation in the aspect ratio for the conduction‐dominated melting mode. Besides, it is found that the highest stored exergy is observed in Case 9 w/NC situation with a stored exergy value of 13.3 kJ. The exergy efficiency changes approximately between 65% and 81% for all cases.

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“…It is a more energy‐efficient method than conventional accumulation 8 . The utilization of the PCM has been found to be useful for different applications including thermal management in building, 9‐11 performance enhancement in solar collectors, 12,13 and thermal energy storage 14,15 . There is an increasing research interest in using nanoparticles and fins for enhancing the thermal performance of the heat storage units 16‐19 …”

Section: Introductionmentioning

confidence: 99%

Thermal performance of an accumulator unit using phase change material with a fixed volume of fins

2021

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Summary Melting rate enhancement inside an accumulator unit for a phase change material (PCM) has been numerically investigated in a shell‐and‐tube (S‐T) arrangement that incorporates the circular type of fins, considering a fixed total volume of fins. The number of fins was chosen as the design parameter. The heat transfer fluid (HTF) was chosen as water that flows through the selected accumulator unit during the process of melting. The computational fluid dynamics (CFD) technique has been utilized for the simulation of the accumulator using ANSYS FLUENT software by considering a two‐dimensional axisymmetric cylindrical accumulator in a vertical direction. During the melting process, two heat transfer mechanisms were considered, namely, conduction and convection. The HTF flow was 5 L/min with a flow temperature of 358 K for charging. The predicted complete melting time of the PCM decreased by 53.125%, 65.625%, 71.875%, and 71.875% for fins numbering 6, 18, 30, and 36, respectively, compared with the S‐T without fins where it took approximately 480 minutes to melt completely. The optimal fin parameters are recommended in this study as follows: number of fins N = 30, thickness t/d = 0.01858, interval d/L = 0.03227, and aspect ratio t/h = 0.015. These recommended values maximize the thermal performance of the selected accumulator unit. The effects of changing the flow rate of the heat transfer fluid and its inlet temperature have been found to be significant on the PCM melting rate. The total melting time of the PCM is found to be reduced by about 57% when the inlet flow temperature is increased from 343 to 358 K. Moreover, the total melting time reduces by about 70.5% with an increase in the heat transfer fluid mass flow rate from 0.15 to 5 L/min. Furthermore, increasing the HTF flow rate from 0.15 to 5 L/min leads to a reduction of about 61.1% in the predicted total time that is required for solidification. The temperature differences for low flow rates are greater than those for high flow rates. The novelty of this study is in investigating the performance at a fixed total volume of fins.

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A semi‐analytical solution for time‐varying latent heat thermal energy storage problems

Cited by 8 publications

References 34 publications

Two‐region semi‐analytical solution for latent heat thermal energy storage systems

Two‐region semi‐analytical solution for latent heat thermal energy storage systems

Performance assessment of a phase change charging mode in a vertical thermal energy storage system

Thermal performance of an accumulator unit using phase change material with a fixed volume of fins

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