Heat transfer enhancement and optimization of a tube fitted with twisted tape in a fin-and-tube heat exchanger

Hajabdollahi, Zahra; Hajabdollahi, Hassan; Kim, Kyung Chun

doi:10.1007/s10973-019-08668-w

Cited by 13 publications

(4 citation statements)

References 32 publications

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“…Although the Pareto front proposes many potential optimal solutions, the selection of one to be implemented is guided by decision-making process tools [45,46] which encompass the TOPSIS, Shannon entropy, LINMAP and Fuzzy methods, etc. However, here we introduce a simple and yet robust statistical analysis that pinpoint the optimal design parameters.…”

Section: Optimization Resultsmentioning

confidence: 99%

Optimal Design of Combined Two-Tank Latent and Metal Hydrides-Based Thermochemical Heat Storage Systems for High-Temperature Waste Heat Recovery

2020

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The integration of thermal energy storage systems (TES) in waste-heat recovery applications shows great potential for energy efficiency improvement. In this study, a 2D mathematical model is formulated to analyze the performance of a two-tank thermochemical heat storage system using metal hydrides pair (Mg2Ni/LaNi5), for high-temperature waste heat recovery. Moreover, the system integrates a phase change material (PCM) to store and restore the heat of reaction of LaNi5. The effects of key properties of the PCM on the dynamics of the heat storage system were analyzed. Then, the TES was optimized using a genetic algorithm-based multi-objective optimization tool (NSGA-II), to maximize the power density, the energy density and storage efficiency simultaneously. The results indicate that the melting point Tm and the effective thermal conductivity of the PCM greatly affect the energy storage density and power output. For the range of melting point Tm = 30–50 °C used in this study, it was shown that a PCM with Tm = 47–49 °C leads to a maximum heat storage performance. Indeed, at that melting point narrow range, the thermodynamic driving force of reaction between metal hydrides during the heat charging and discharging processes is almost equal. The increase in the effective thermal conductivity by the addition of graphite brings about a tradeoff between increasing power output and decreasing the energy storage density. Finally, the hysteresis behavior (the difference between the melting and freezing point) only negatively impacts energy storage and power density during the heat discharging process by up to 9%. This study paves the way for the selection of PCMs for such combined thermochemical-latent heat storage systems.

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Section: Optimization Resultsmentioning

confidence: 99%

Optimal Design of Combined Two-Tank Latent and Metal Hydrides-Based Thermochemical Heat Storage Systems for High-Temperature Waste Heat Recovery

2020

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“…They found that the Nusselt number could be around 2.6 times of that in the circular tubes without inserts. Hajabdollahi et al [24] numerically examined the temperature distributions inside a fin and tube heat exchanger enhanced with twisted tapes. The outcome revealed that the twisted tape could significantly improve the heat transfer of the system compared to the circular ducts without turbulators under the same mass flow rates.…”

Section: Introductionmentioning

confidence: 99%

Entropy generation of turbulent Cu–water nanofluid flows inside thermal systems equipped with transverse-cut twisted turbulators

Nakhchi

Rahmati

2020

J Therm Anal Calorim

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“…There are various techniques for enhancing the heat transfer rate and thermal efficiency of these thermal systems, which also decrease the size of the heat exchangers. The following methods are popular in recent years because of simple installation and low costs: (i) using nanofluids as the working fluid [1,2], (ii) using twisted tapes (TTs) [3][4][5][6], (iii) conical rings [7,8], grooved surfaces [9], hollow cylinders [10], and (iv) combined use of vortex generators and nanofluids [11][12][13].…”

Section: Introductionmentioning
confidence: 99%

Numerical investigation of turbulent CuO–water nanofluid inside heat exchanger enhanced with double V-cut twisted tapes
Nakhchi
¹
,
Esfahani
²

2020
J Therm Anal Calorim
38
0
4
0
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This numerical investigation aims to study the turbulent characteristics and thermal enhancement parameter of CuO-water nanofluids through heat exchangers enhanced with double V-cut twisted tapes. The twist ratio of the twisted tapes is 5.25, and the cut ratio (b/c) is varied from 0 (conventional twisted tape) to 1.8. The Reynolds number is in the range of 5,000 to 15,000 and nanoparticles volume fraction is in the range of 0 1.5%The flow is fully turbulent and(RNG) k − ϵ turbulent model is used for the numerical analysis. The results reveal that strong turbulent kinetic energy and additional vortex flow through the cuts of the modified twisted tapes is the main reason for better fluid mixing and heat transfer enhancement. The heat transfer enhances about 14.5% for the case of 1.5%   . Furthermore, using double V-cut twisted tapes improves the Nusselt number of the nanofluid flow inside heat exchangers about 138% compared to conventional twisted tape without cuts. The maximum value of the thermal performance  

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Heat transfer enhancement and optimization of a tube fitted with twisted tape in a fin-and-tube heat exchanger

Cited by 13 publications

References 32 publications

Optimal Design of Combined Two-Tank Latent and Metal Hydrides-Based Thermochemical Heat Storage Systems for High-Temperature Waste Heat Recovery

Optimal Design of Combined Two-Tank Latent and Metal Hydrides-Based Thermochemical Heat Storage Systems for High-Temperature Waste Heat Recovery

Entropy generation of turbulent Cu–water nanofluid flows inside thermal systems equipped with transverse-cut twisted turbulators

Numerical investigation of turbulent CuO–water nanofluid inside heat exchanger enhanced with double V-cut twisted tapes

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