Numerical investigation on the heat transfer enhancement of a latent heat thermal energy storage system with bundled tube structures

Li, Jiajia; Xu, Chao; Jü, Xing; Yang, Bingbin; Ren, Yaoyu; Du, Xiaoze

doi:10.1016/j.applthermaleng.2016.10.144

Cited by 35 publications

(12 citation statements)

References 26 publications

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“…13 illustrates the experimental calculated values of Nu-Ra for charging cycles at varied operating conditions. Rayleigh numbers for charging cycles have ranged from 5.63x10 10 -1.37x10 11 , which indicates that the melt front movement in upward direction is turbulent in nature. Moreover, the vertical orientation of longitudinal fins reinforces and supports natural convection in paraffin.…”

Section: Energy Efficiencies Of the Lhs Systemmentioning

confidence: 99%

“…For instance, geometrical orientation of the container, inclusion of extended surfaces with heat exchangers, addition of thermal conductive additives and encapsulation techniques are extensively examined [8][9][10]. This article will discuss literature concerning shell-and-tube heat exchangers with extended surfaces due to their relatively higher heat transfer potential, minimal design complexity and easier integration to practical applications [11,12].…”

Section: Introductionmentioning

confidence: 99%

“…The impact of design configurations of the shell-and-tube heat exchanger with vertical orientation of longitudinal fins on natural convection is evaluated by calculating Nu-Ra at varied operating conditions. Rayleigh number has ranged from 5.63x10 10 -1.37x10 11 , which signifies the turbulent nature of melt front movement in upward direction. Moreover, it is noticed that with an increase in temperature gradient, the Rayleigh number is significantly enhanced and consequently, the Nusselt number and heat transfer coefficient are augmented.…”

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confidence: 99%

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Thermodynamic performance of a novel shell-and-tube heat exchanger incorporating paraffin as thermal storage solution for domestic and commercial applications

Khan

2019

Applied Thermal Engineering

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This article is focused to evaluate thermal performance of commercial grade paraffin in a novel shell-and-tube heat exchanger with multi-tube passes and longitudinal fins as latent heat storage (LHS) system. Thermal performance assessments of latent heat storage system are conducted with respects to charging/discharging power, accumulative thermal energy storage/retrieval, thermal efficiencies and effectiveness, heat transfer characterisation and nature of melt front propagation. The average charging and discharging powers are significantly enhanced by 75.53% and 27.04% with an increase in temperature gradient between paraffin and inlet water from 52 o C-62 o C and 15 o C-5 o C, respectively. Likewise, the maximum charging and discharging powers are augmented from 2.15 kW-2.63 kW and 5.18-10.37 kW with an increase in flow rate from 1.5-3 l/min, respectively. Furthermore, the average effectiveness, Nu-Ra and heat transfer coefficient are significantly improved with an increase in temperature gradient and moderately reduced with upgrading volume flow rate. The range of Rayleigh numbers for charging cycles have indicated turbulent nature of melt front movement and supportive behaviour of longitudinal fins orientations towards natural convection. Empirical correlations for average effectiveness and Nu-Ra are developed from experimental results to facilitate design estimation for employment of proposed LHS systems in domestic and commercial applications. These empirical correlations, to evaluate feasibility and employability of LHS systems in practical applications such as domestic hot water supply and space heating to maintain control room temperature, have been successfully implemented in real operating conditions.

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Section: Energy Efficiencies Of the Lhs Systemmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

mentioning

confidence: 99%

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Thermodynamic performance of a novel shell-and-tube heat exchanger incorporating paraffin as thermal storage solution for domestic and commercial applications

Khan

2019

Applied Thermal Engineering

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“…The effect of an internal void on the melting of various sized cylindrical EPCM capsules with an exterior convective boundary condition was investigated by Elmozughi et al Their results showed that the presence of an internal void profoundly affects the internal heat transfer. An investigation of the effect of different initial void locations on the evolution of the melting front was conducted by Solomon et al Most recently Liu et al numerically compared the performance of staggered and parallel tubes, as well as a flat plate type TES system using air as the HTF. They reported that the staggered tube arrangement performed best and that the overall melting rate can be increased by utilizing internal fins which are attached to the interior tube wall.…”

Section: Introductionmentioning

confidence: 99%

Analysis of an encapsulated phase change material-based energy storage system for high-temperature applications

et al. 2018

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The capability of an encapsulated phase change material (EPCM)-based thermal energy storage (TES) system to store a large fraction of latent energy at high temperatures was examined. A 3-dimensional simulation of a prototype heat exchanger was conducted employing sodium nitrate as the phase change material (PCM). The k-ω SST model was used to capture the turbulent flow of the HTF, while the melting front was tracked using the enthalpy-porosity method.The results show that the use of metal deflectors yields a nearly constant heat transfer coefficient over the capsule's surface. Despite this, the presence of the void in the capsule and natural convection within the molten PCM influenced the storage characteristics of the system affecting the shape of the isotherms and melting front. Furthermore, the EPCM capsules consecutively undergo the same heat transfer starting from the capsule closest to the inlet. The EPCM capsules store 80% of the energy lost by the HTF. The 17.7 kg of sodium nitrate stores 14.5 MJ of energy where 20% of the energy stored is via latent heat. Of the energy released by the heat transfer fluid, 80% was absorbed by the EPCM capsules with the remaining energy going into the test section walls. A total of 14.5 MJ of energy was stored by the 17.7 kg of NaNO 3 , of which 20% is attributed to the latent heat. The fraction of energy stored as latent heat would be larger if a smaller operating temperature range was used. Thus, an EPCM-based latent heat TES system is capable of storing a large fraction of the supplied energy and presents efficient means of storing thermal energy for hightemperature applications. Additionally, the strong agreement between the numerical and experimental works demonstrates that the numerical methods employed can predict the behavior of an EPCM capsule not only within a single capsule but on the system scale as well. Therefore, the applied numerical methods can be used for further design and optimization of EPCM-based latent heat TES systems.

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“…Ismail et al [11] measurements on the solidification of PCM along a horizontal tube by using the boundary immobilization technique. Liu et al [12] performed a charging transient simulations based on a two dimensional numerical model, the melting processes of the storage units with staggered tube bundle structure and parallel tube bundle structure are compared with that of flat plate structure. Sugawara et al [13] investigated a freezing/melting of water/ice around a horizontal cylinder placed in a square cavity of the inner side length numerically.…”

Section: Introductionmentioning

confidence: 99%

Numerical & Experimental Investigation of Solidification Thickness around Cylindrical Surfaces for HVAC Cold Storage Systems

Abbas¹,

Tina²,

Badran³

2018

IJAERS

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Numerical investigation on the heat transfer enhancement of a latent heat thermal energy storage system with bundled tube structures

Cited by 35 publications

References 26 publications

Thermodynamic performance of a novel shell-and-tube heat exchanger incorporating paraffin as thermal storage solution for domestic and commercial applications

Thermodynamic performance of a novel shell-and-tube heat exchanger incorporating paraffin as thermal storage solution for domestic and commercial applications

Analysis of an encapsulated phase change material-based energy storage system for high-temperature applications

Numerical & Experimental Investigation of Solidification Thickness around Cylindrical Surfaces for HVAC Cold Storage Systems

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