Numerical analysis of the influence of spherical turbulence generators on heat transfer enhancement of flat plate solar air heater

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Abstract

This paper presents the influence of spherical turbulence generators on thermal efficiency and thermohydraulic performance of flat plate solar air heater. The analysis is carried out for the Reynolds number range of 4000–25000. The thermal performance is investigated for various diameter (D) of sphere consisting of 5,10,15,20 and 25�mm and relative roughness pitch (P/D) of 3, 6 and 12. The simulation is carried out using solar insolation as heat input at 12 noon conditions for the global position of Manipal (74.786�E, 13.343�N) obtained through the solar load model, a feature available in the software tool used for the analysis and Discrete Ordinates radiation model is used to compute the radiation heat interactions within the computational domain. The CFD results for the base model are validated against experimental results and are found to have good agreement. The thermal efficiency is found to increase with increasing sphere diameter and reducing relative roughness pitch. The maximum average percentage increase in thermal efficiency is found to be about 23.4% as compared to the base model for D�=�25�mm and P/D�=�3. The highest increase in the Nusselt number is found to be 2.5 times higher as compared to the base model for D�=�25�mm and P/D�=�3�at Re�=�23560. The analysis shows that the relative roughness pitch and size of the spherical turbulator have significant influence on the thermohydraulic performance of solar air heater.

Original languageEnglish
Pages (from-to)616-630
Number of pages15
JournalEnergy
Volume121
DOIs
Publication statusPublished - 01-01-2017

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Numerical analysis
Turbulence
Heat transfer
Air
Surface roughness
Incident solar radiation
Heat radiation
Nusselt number
Computational fluid dynamics
Reynolds number
Hot Temperature
Radiation

All Science Journal Classification (ASJC) codes

  • Civil and Structural Engineering
  • Building and Construction
  • Pollution
  • Mechanical Engineering
  • Industrial and Manufacturing Engineering
  • Electrical and Electronic Engineering

Cite this

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title = "Numerical analysis of the influence of spherical turbulence generators on heat transfer enhancement of flat plate solar air heater",
abstract = "This paper presents the influence of spherical turbulence generators on thermal efficiency and thermohydraulic performance of flat plate solar air heater. The analysis is carried out for the Reynolds number range of 4000–25000. The thermal performance is investigated for various diameter (D) of sphere consisting of 5,10,15,20 and 25{\"i}¿½mm and relative roughness pitch (P/D) of 3, 6 and 12. The simulation is carried out using solar insolation as heat input at 12 noon conditions for the global position of Manipal (74.786{\"i}¿½E, 13.343{\"i}¿½N) obtained through the solar load model, a feature available in the software tool used for the analysis and Discrete Ordinates radiation model is used to compute the radiation heat interactions within the computational domain. The CFD results for the base model are validated against experimental results and are found to have good agreement. The thermal efficiency is found to increase with increasing sphere diameter and reducing relative roughness pitch. The maximum average percentage increase in thermal efficiency is found to be about 23.4{\%} as compared to the base model for D{\"i}¿½={\"i}¿½25{\"i}¿½mm and P/D{\"i}¿½={\"i}¿½3. The highest increase in the Nusselt number is found to be 2.5 times higher as compared to the base model for D{\"i}¿½={\"i}¿½25{\"i}¿½mm and P/D{\"i}¿½={\"i}¿½3{\"i}¿½at Re{\"i}¿½={\"i}¿½23560. The analysis shows that the relative roughness pitch and size of the spherical turbulator have significant influence on the thermohydraulic performance of solar air heater.",
author = "Manjunath, {M. S.} and Karanth, {K. Vasudeva} and Sharma, {N. Yagnesh}",
year = "2017",
month = "1",
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doi = "10.1016/j.energy.2017.01.032",
language = "English",
volume = "121",
pages = "616--630",
journal = "Energy",
issn = "0360-5442",
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T1 - Numerical analysis of the influence of spherical turbulence generators on heat transfer enhancement of flat plate solar air heater

AU - Manjunath, M. S.

AU - Karanth, K. Vasudeva

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PY - 2017/1/1

Y1 - 2017/1/1

N2 - This paper presents the influence of spherical turbulence generators on thermal efficiency and thermohydraulic performance of flat plate solar air heater. The analysis is carried out for the Reynolds number range of 4000–25000. The thermal performance is investigated for various diameter (D) of sphere consisting of 5,10,15,20 and 25�mm and relative roughness pitch (P/D) of 3, 6 and 12. The simulation is carried out using solar insolation as heat input at 12 noon conditions for the global position of Manipal (74.786�E, 13.343�N) obtained through the solar load model, a feature available in the software tool used for the analysis and Discrete Ordinates radiation model is used to compute the radiation heat interactions within the computational domain. The CFD results for the base model are validated against experimental results and are found to have good agreement. The thermal efficiency is found to increase with increasing sphere diameter and reducing relative roughness pitch. The maximum average percentage increase in thermal efficiency is found to be about 23.4% as compared to the base model for D�=�25�mm and P/D�=�3. The highest increase in the Nusselt number is found to be 2.5 times higher as compared to the base model for D�=�25�mm and P/D�=�3�at Re�=�23560. The analysis shows that the relative roughness pitch and size of the spherical turbulator have significant influence on the thermohydraulic performance of solar air heater.

AB - This paper presents the influence of spherical turbulence generators on thermal efficiency and thermohydraulic performance of flat plate solar air heater. The analysis is carried out for the Reynolds number range of 4000–25000. The thermal performance is investigated for various diameter (D) of sphere consisting of 5,10,15,20 and 25�mm and relative roughness pitch (P/D) of 3, 6 and 12. The simulation is carried out using solar insolation as heat input at 12 noon conditions for the global position of Manipal (74.786�E, 13.343�N) obtained through the solar load model, a feature available in the software tool used for the analysis and Discrete Ordinates radiation model is used to compute the radiation heat interactions within the computational domain. The CFD results for the base model are validated against experimental results and are found to have good agreement. The thermal efficiency is found to increase with increasing sphere diameter and reducing relative roughness pitch. The maximum average percentage increase in thermal efficiency is found to be about 23.4% as compared to the base model for D�=�25�mm and P/D�=�3. The highest increase in the Nusselt number is found to be 2.5 times higher as compared to the base model for D�=�25�mm and P/D�=�3�at Re�=�23560. The analysis shows that the relative roughness pitch and size of the spherical turbulator have significant influence on the thermohydraulic performance of solar air heater.

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