# Reconsideration of data and correlations for plate finned-tube heat exchangers

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## Abstract

This paper deals with heat exchangers having plain finned tubes in staggered (triangular) pattern. The objective of this paper is to provide the heat transfer and friction factor correlation which can be used in engineering practice. For this purpose, the experimental data of several (most cited) authors who deal with this type of heat exchangers are used. The new correlations are established to predict the air-side heat transfer coefficient and friction factor as a function of the Reynolds number and geometric variables of the heat exchanger – tube diameter, tube pitch, fin spacing, tube rows, etc. In those correlations the characteristic dimension in Reynolds number is calculated by using the new parameter – volumetric porosity. Also, there are given the errors of those correlations.

## Nomenclature

*d*_{c}collar diameter, m

*d*_{h}hydraulic diameter, m

*f*Fanning friction factor

*H*height of a heat exchanger channel, m

*j*_{H}Colburn heat transfer factor

*L*length of the heat exchanger, m

- \( \dot{m} \)
fluid flow rate, kg/s

*N*_{l}number of tube rows

- Nu
Nusselt number

- Pr
Prandtl number

- Re
Reynolds number based on hydraulic diameter

*s*_{f}fin pitch, m

*S*_{HE}air side heat exchange surface area (total outside surface area), m

^{2}*s*_{l}longitudinal tube pitch, m

*s*_{t}transversal tube pitch, m

*S*_{uf}unfined surface area (area of bare tubes between fins), m

^{2}*s*_{V}specific surface, m

^{2}/m^{3}- \( \dot{V} \)
fluid volume flow rate, m

^{3}/s*V*_{f}heat exchanger free volume, m

^{3}*V*_{HE}volume of heat exchanger chamber, m

^{3}*W*width of a heat exchanger channel, m

*w*_{f}air velocity at the front of the heat exchanger, m/s

*w*_{ε}air velocity reduced to the porous cross-section of the exchanger, m/s

*z*number of experimental regimes (runs)

## Greek

*α*heat transfer coefficient, W/(m

^{2}∙K)*∆p*_{HE}pressure drop, Pa

*δ*fin thickness, m

*ε*volumetric porosity, m

^{3}/m^{3}*λ*thermal conductivity, W/(m∙K)

*μ*dynamic viscosity, Pa∙s

*ρ*average fluid density, kg/m

^{3}*ξ*Weisbach (Dracy) friction factor

## Abbreviations

- PD
pressure drop

- HT
heat transfer

## Notes

## References

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