Numerical investigation of heat transfer enhancement inside heat exchanger tubes fitted with perforated hollow cylinders

Nakhchi, M.E.; Esfahani, Javad Abolfazli

doi:10.1016/j.ijthermalsci.2019.106153

Cited by 49 publications

(22 citation statements)

References 31 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…[42] Scholars have developed a series of thermoelectric devices to absorb the heat of PV cells, which is called as PV-TE hybrid system. [42,43] Direct-coupled PV-TE hybrid system and indirectcoupled PV-TE hybrid system are two typical types. For directcoupled PV-TE hybrid system, the PV cell and TE are directly stacked.…”

Section: Methodsmentioning

confidence: 99%

See 1 more Smart Citation

Full-Spectrum Solar Energy Utilization and Enhanced Solar Energy Harvesting via Photon Anti-Reflection and Scattering Performance Using Nanophotonic Structure

Liang¹,

Wang²,

Cheng³

et al. 2020

ES Energy Environ.

View full text Add to dashboard Cite

Conventional Si photovoltaic cells cannot convert full solar energy spectrum (400~2 500 nm) into electricity owing to the mismatch between Si band gap and broad range of solar photon energies. Transparent silicon PV cell allows sunlight in the wavelength of 1 100~2 500 nm to transmit through itself and irradiate on the thermal absorber below. The traditional photon management method based on texturing silicon layer with nanostructures can enhance 400~1 100 nm absorptivity and 1 1002 500 nm transmittance of transparent silicon PV cell. However, an increase in charge carrier capture and a decrease in electricity generation efficiency are often observed with this. In this study, a novel spectral splitting method based on frontlocated wavelength-sized TiO 2 biomimetic moth-eye nanophotonic structure is put forward, which can inhibit the increase of charge carrier capture and recombination. The biomimetic moth-eye nanophotonic structure was optimized by using finitedifference time-domain (FDTD) method to achieve excellent photon anti-reflection and scattering properties. The calculation results indicated that the absorption factor and transmission factor of transparent silicon PV cell could be increased from 46% to 58% and from 11% to 14%; the relative power conversion efficiency enhancement rate and relative incident radiation power enhancement rate was 32% and 27% when the TiO 2 biomimetic moth-eye was adopted.

show abstract

Section: Methodsmentioning

confidence: 99%

“…Usually, the indirect-coupled PV-TE hybrid system has lower temperature in PV cell and higher efficiency and absolute feasibility. [43] The indirect-coupled PV-TE hybrid system is concerned in this study.…”

Section: Methodsmentioning

confidence: 99%

Full-Spectrum Solar Energy Utilization and Enhanced Solar Energy Harvesting via Photon Anti-Reflection and Scattering Performance Using Nanophotonic Structure

Liang¹,

Wang²,

Cheng³

et al. 2020

ES Energy Environ.

View full text Add to dashboard Cite

show abstract

“…Different methods have been employed for thermal performance intensification of these systems by considering size and cost reductions. To this end, several passive methods are suggested by scientists to improve the thermal efficiency of mechanical structures in the past few years, like twisted tapes [1,2], perforated turbulators [3,4], hollow cylinders [5], conical rings [6,7] and employing nanofluids [8][9][10] as the operating cooling fluid.…”

Section: Introductionmentioning

confidence: 99%

CFD approach for two-phase CuO nanofluid flow through heat exchangers enhanced by double perforated louvered strip insert

Nakhchi

Esfahani

2020

Powder Technology

Self Cite

View full text Add to dashboard Cite

In this study, turbulent flow characteristics of CuO-water nanofluid through heat exchanger pipe enhanced with louvered strips are numerically investigated. Nanoparticles volume fraction    varied from 0 to 2% . The louvered strips are mounted in single and double geometries. The slant angle    and the Reynolds number (Re) are within 15 25    and between 5,000 and 14,000, respectively. (RNG) k   model is employed based on the finite volume technique. The results illustrated that strong flow disturbance between the wall and the louvered strip is the main reason for turbulent kinetic energy increment. Besides, the nanoparticles improve the thermophysical properties of the working fluid, which results in better heat transfer. The Nu number increases 15.6% by using nanofluid instead of water at Re 14000  . The highest thermal enhancement parameter of 1.99 is obtained at Re 14000  by using double perforated louvered strip with 25    . The recirculating flow inside the holes can significantly improve the thermal performance.

show abstract

“…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

Esfahani

2020

J Therm Anal Calorim

Self Cite

View full text Add to dashboard Cite

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  

show abstract

Numerical investigation of heat transfer enhancement inside heat exchanger tubes fitted with perforated hollow cylinders

Cited by 49 publications

References 31 publications

Full-Spectrum Solar Energy Utilization and Enhanced Solar Energy Harvesting via Photon Anti-Reflection and Scattering Performance Using Nanophotonic Structure

Full-Spectrum Solar Energy Utilization and Enhanced Solar Energy Harvesting via Photon Anti-Reflection and Scattering Performance Using Nanophotonic Structure

CFD approach for two-phase CuO nanofluid flow through heat exchangers enhanced by double perforated louvered strip insert

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

Contact Info

Product

Resources

About