Effects of fin configuration on heat transfer rate in packed bed reactors for improvement of their thermal characteristics

Koichi Nakaso, Takuro Aoki, Jun Fukai

Research output: Chapter in Book/Report/Conference proceedingConference contribution

1 Citation (Scopus)

Abstract

Packed bed reactors are utilized for catalysts, chemical heat pumps, etc. Because the effective thermal conductivities of the packed beds of particles are generally low (≈10-1 W/mK), this matter often results in low performance and degradation of catalyst. Many heat transfer tubes with fins and/or much filler with high thermal conductivities are inserted in the packed bed reactors to improve heat transfer rate. In return to this, the volume of reactive particles packed into the reactors, or stored energy, decreases. In this study, the effect of fin configurations on the heat transfer rate in the reactors is numerically investigated. Three configurations of fins are studied. (1) "Sheet type" is a longitudinal fin attached on the heat transfer tubes. It is placed to connect between heat transfer tubes. (2) "Straight type" is several longitudinal fins in the half length of the tube pitch attached on the tube with radial structure. (3) "Spiral type" is many narrow rectangular fins attached on the tube with spiral structure. To discuss the effect of fin configuration on the heat transfer generally, the heat conduction equation in the packed bed around the tube is converted to the dimensionless form. The transient temperature responses in the packed bed and fins at a uniform temperature are calculated when the temperature of the tube surface is stepwise changes. In another analytical system, a homogeneous body around the tube is assumed. To evaluate the thermal performance of the fin, apparent thermal conductivity is defined as the thermal conductivity which gives the same thermal response as that calculated in the heterogeneous system. As a result, the spiral type rather than the straight and sheet types effectively increases apparent thermal conductivity. The apparent thermal conductivity of the spiral type is two-three times larger than the straight type, and ten times as large as the sheet type. This result indicates dispersion of fins in packed bed is essential to improve the thermal response in the reactors.

Original languageEnglish
Title of host publication2010 14th International Heat Transfer Conference, IHTC 14
Pages975-981
Number of pages7
Volume6
DOIs
Publication statusPublished - 2010
Externally publishedYes
Event2010 14th International Heat Transfer Conference, IHTC 14 - Washington, DC, United States
Duration: Aug 8 2010Aug 13 2010

Other

Other2010 14th International Heat Transfer Conference, IHTC 14
CountryUnited States
CityWashington, DC
Period8/8/108/13/10

Fingerprint

Fins (heat exchange)
Packed beds
Thermal conductivity
Heat transfer
Tubes (components)
Catalysts
Heat conduction
Temperature
Hot Temperature
Fillers
Pumps
Degradation

ASJC Scopus subject areas

  • Fluid Flow and Transfer Processes

Cite this

Nakaso, K., Aoki, T., & Fukai, J. (2010). Effects of fin configuration on heat transfer rate in packed bed reactors for improvement of their thermal characteristics. In 2010 14th International Heat Transfer Conference, IHTC 14 (Vol. 6, pp. 975-981) https://doi.org/10.1115/IHTC14-23175

Effects of fin configuration on heat transfer rate in packed bed reactors for improvement of their thermal characteristics. / Nakaso, Koichi; Aoki, Takuro; Fukai, Jun.

2010 14th International Heat Transfer Conference, IHTC 14. Vol. 6 2010. p. 975-981.

Research output: Chapter in Book/Report/Conference proceedingConference contribution

Nakaso, K, Aoki, T & Fukai, J 2010, Effects of fin configuration on heat transfer rate in packed bed reactors for improvement of their thermal characteristics. in 2010 14th International Heat Transfer Conference, IHTC 14. vol. 6, pp. 975-981, 2010 14th International Heat Transfer Conference, IHTC 14, Washington, DC, United States, 8/8/10. https://doi.org/10.1115/IHTC14-23175
Nakaso, Koichi ; Aoki, Takuro ; Fukai, Jun. / Effects of fin configuration on heat transfer rate in packed bed reactors for improvement of their thermal characteristics. 2010 14th International Heat Transfer Conference, IHTC 14. Vol. 6 2010. pp. 975-981
@inproceedings{7417415b3de7436496e3b398d012b93a,
title = "Effects of fin configuration on heat transfer rate in packed bed reactors for improvement of their thermal characteristics",
abstract = "Packed bed reactors are utilized for catalysts, chemical heat pumps, etc. Because the effective thermal conductivities of the packed beds of particles are generally low (≈10-1 W/mK), this matter often results in low performance and degradation of catalyst. Many heat transfer tubes with fins and/or much filler with high thermal conductivities are inserted in the packed bed reactors to improve heat transfer rate. In return to this, the volume of reactive particles packed into the reactors, or stored energy, decreases. In this study, the effect of fin configurations on the heat transfer rate in the reactors is numerically investigated. Three configurations of fins are studied. (1) {"}Sheet type{"} is a longitudinal fin attached on the heat transfer tubes. It is placed to connect between heat transfer tubes. (2) {"}Straight type{"} is several longitudinal fins in the half length of the tube pitch attached on the tube with radial structure. (3) {"}Spiral type{"} is many narrow rectangular fins attached on the tube with spiral structure. To discuss the effect of fin configuration on the heat transfer generally, the heat conduction equation in the packed bed around the tube is converted to the dimensionless form. The transient temperature responses in the packed bed and fins at a uniform temperature are calculated when the temperature of the tube surface is stepwise changes. In another analytical system, a homogeneous body around the tube is assumed. To evaluate the thermal performance of the fin, apparent thermal conductivity is defined as the thermal conductivity which gives the same thermal response as that calculated in the heterogeneous system. As a result, the spiral type rather than the straight and sheet types effectively increases apparent thermal conductivity. The apparent thermal conductivity of the spiral type is two-three times larger than the straight type, and ten times as large as the sheet type. This result indicates dispersion of fins in packed bed is essential to improve the thermal response in the reactors.",
author = "Koichi Nakaso and Takuro Aoki and Jun Fukai",
year = "2010",
doi = "10.1115/IHTC14-23175",
language = "English",
isbn = "9780791849415",
volume = "6",
pages = "975--981",
booktitle = "2010 14th International Heat Transfer Conference, IHTC 14",

}

TY - GEN

T1 - Effects of fin configuration on heat transfer rate in packed bed reactors for improvement of their thermal characteristics

AU - Nakaso, Koichi

AU - Aoki, Takuro

AU - Fukai, Jun

PY - 2010

Y1 - 2010

N2 - Packed bed reactors are utilized for catalysts, chemical heat pumps, etc. Because the effective thermal conductivities of the packed beds of particles are generally low (≈10-1 W/mK), this matter often results in low performance and degradation of catalyst. Many heat transfer tubes with fins and/or much filler with high thermal conductivities are inserted in the packed bed reactors to improve heat transfer rate. In return to this, the volume of reactive particles packed into the reactors, or stored energy, decreases. In this study, the effect of fin configurations on the heat transfer rate in the reactors is numerically investigated. Three configurations of fins are studied. (1) "Sheet type" is a longitudinal fin attached on the heat transfer tubes. It is placed to connect between heat transfer tubes. (2) "Straight type" is several longitudinal fins in the half length of the tube pitch attached on the tube with radial structure. (3) "Spiral type" is many narrow rectangular fins attached on the tube with spiral structure. To discuss the effect of fin configuration on the heat transfer generally, the heat conduction equation in the packed bed around the tube is converted to the dimensionless form. The transient temperature responses in the packed bed and fins at a uniform temperature are calculated when the temperature of the tube surface is stepwise changes. In another analytical system, a homogeneous body around the tube is assumed. To evaluate the thermal performance of the fin, apparent thermal conductivity is defined as the thermal conductivity which gives the same thermal response as that calculated in the heterogeneous system. As a result, the spiral type rather than the straight and sheet types effectively increases apparent thermal conductivity. The apparent thermal conductivity of the spiral type is two-three times larger than the straight type, and ten times as large as the sheet type. This result indicates dispersion of fins in packed bed is essential to improve the thermal response in the reactors.

AB - Packed bed reactors are utilized for catalysts, chemical heat pumps, etc. Because the effective thermal conductivities of the packed beds of particles are generally low (≈10-1 W/mK), this matter often results in low performance and degradation of catalyst. Many heat transfer tubes with fins and/or much filler with high thermal conductivities are inserted in the packed bed reactors to improve heat transfer rate. In return to this, the volume of reactive particles packed into the reactors, or stored energy, decreases. In this study, the effect of fin configurations on the heat transfer rate in the reactors is numerically investigated. Three configurations of fins are studied. (1) "Sheet type" is a longitudinal fin attached on the heat transfer tubes. It is placed to connect between heat transfer tubes. (2) "Straight type" is several longitudinal fins in the half length of the tube pitch attached on the tube with radial structure. (3) "Spiral type" is many narrow rectangular fins attached on the tube with spiral structure. To discuss the effect of fin configuration on the heat transfer generally, the heat conduction equation in the packed bed around the tube is converted to the dimensionless form. The transient temperature responses in the packed bed and fins at a uniform temperature are calculated when the temperature of the tube surface is stepwise changes. In another analytical system, a homogeneous body around the tube is assumed. To evaluate the thermal performance of the fin, apparent thermal conductivity is defined as the thermal conductivity which gives the same thermal response as that calculated in the heterogeneous system. As a result, the spiral type rather than the straight and sheet types effectively increases apparent thermal conductivity. The apparent thermal conductivity of the spiral type is two-three times larger than the straight type, and ten times as large as the sheet type. This result indicates dispersion of fins in packed bed is essential to improve the thermal response in the reactors.

UR - http://www.scopus.com/inward/record.url?scp=84860534275&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=84860534275&partnerID=8YFLogxK

U2 - 10.1115/IHTC14-23175

DO - 10.1115/IHTC14-23175

M3 - Conference contribution

AN - SCOPUS:84860534275

SN - 9780791849415

VL - 6

SP - 975

EP - 981

BT - 2010 14th International Heat Transfer Conference, IHTC 14

ER -