Neue Gleichungen für den Wärme- und den Stoffübergang in turbulent durchströmten Rohren und Kanälen

Gnielinski, Volker

doi:10.1007/bf02559682

Cited by 354 publications

(136 citation statements)

References 18 publications

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“…In fact, some well-known texts do not recognize that a Prandtl number less than 0.6 can occur for gas mixtures. Several relations have been reported which differ considerably from Colburn and are suggested for use over a wide range of Prandtl numbers, some as low as 0.1 [Kays, 1966;Petukhov, 1970;Sleicher and Rouse, 1975;Gnielinski, 1975;and Churchill, 1977]. The relations recommended by these investigators are tabulated in Table 1.…”

Section: Abstracmentioning

confidence: 99%

Internal forced convection to low-Prandtl-number gas mixtures

Taylor

Bauer

McEligot³

1988

International Journal of Heat and Mass Transfer

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Section: Abstracmentioning

confidence: 99%

Internal forced convection to low-Prandtl-number gas mixtures

Taylor

Bauer

McEligot³

1988

International Journal of Heat and Mass Transfer

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“…2. The initial-boundary value problem defined by equations (1)(2)(3)(4)(5)(6)(7)(8)(9)(10)(11)(12)(13)(14) applies to heat exchangers made of bare or finned tubes. For bare tubes, m f is equal to zero because there are no fins.…”

Section: T X T T X Y T Dymentioning

confidence: 99%

“…The correlation for the Nusselt number at the water side was taken in a form similar to the formulae developed by Petukhov & Kirillov [14] and Gnielinski [10]. …”

Section: Experimental Correlations For Water-and Air-side Nusselt Nummentioning

confidence: 99%

Modelowanie matematyczne pracy wymiennika ciepła z rur ożebrowanych dla zmiennych w czasie strumienia masy płynu i prędkości powietrza

Korzeń

Taler

2017

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Mathematical modelling of the unsteady operation of a plate and fin heat exchanger for the time-varying mass flow rate of liquid and air velocity Modelowanie matematyczne pracy wymiennika ciepła z rur ożebrowanych dla zmiennych w czasie strumienia masy płynu i prędkości powietrza AbstractThe mathematical simulation of a plate fin and tube heat exchanger is presented in this paper. The simulation of the transient operation of the heat exchanger was carried out using a general numerical model that was previously developed by the authors. The Reynolds number of the water flowing inside the tubes varied in the range from 4000 to 12000. A detailed analysis of the transient response of a heat exchanger to sudden increase in water mass flow rate and the simultaneous reduction in air flow velocity was modelled. Heat transfer correlations for air and water were determined based on the experimental data. Unknown parameters appearing in the relationships for the Nusselt numbers on the airand water-sides were estimated using the least squares method. A set of partial differential equations for the temperature of water, air, tube wall, and fins was solved using the finite volume method. The results of the numerical simulations of a heat exchanger using experimentally determined air and water-side heat transfer formulas for the calculation of heat transfer coefficients were compared with the experimental data. Excellent agreement between computation results (air and water temperatures at the outlet of the heat exchanger) and experimental results was obtained.Keywords: plate-fin and tube heat exchanger; experimental determination of heat transfer correlations; numerical modelling; transient response; transition tube flow StreszczeniePrzedstawiona została symulacja matematyczna wymiennika ciepła z rur ożebrowanych. Symulacja nieustalonej pracy wymiennika przeprowadzona została za pomocą modelu matematycznego opracowanego wcześniej przez autorów. Liczba Reynoldsa po stronie wody zmieniała się w zakresie od 4000 do 12 000. Szczegółowa analiza zmian temperatury została przeprowadzona dla przypadku nagłego wzrostu strumienia masowego płynu z jednoczesnym obniżeniem prędkości powietrza. Korelacje na współczynniki wnikania ciepła dla powietrza i wody określono na podstawie danych doświad-czalnych. Nieznane parametry, które pojawiają się w równaniach na liczbę Nusselta dla powietrza i wody wyznaczono za pomocą metody najmniejszych kwadratów. Układ równań różniczkowych cząstkowych umożliwiający wyznaczenie temperatury wody, powietrza, ścianki rury i żeber zostały rozwiązane z użyciem metody objętości skończonej. Wyniki numerycznej symulacji pracy wymiennika z użyciem współczynników wnikania ciepła wyznaczonych z korelacji na liczby Nusselta od strony powietrza i wody porównano z danymi eksperymentalnymi. Uzyskano bardzo dobrą zgodność wyników obliczeń i pomiarów.Słowa kluczowe: instalacje energetyczne, badania termowizyjne, termogram, emisyjność, temperatura odbicia

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“…The convective heat transfer coefficient is calculated according to the Gnielinski correlation [40], The latent heat transfers are calculated using the Lewis heat-mass transfer analogy. The former sensible heat (Eq.…”

Section: Numerical Modelmentioning

confidence: 99%

Experimental and numerical study of an earth-to-air heat exchanger for air cooling in a residential building in hot semi-arid climate

Khabbaz

Benhamou

Limam

et al. 2016

Energy and Buildings

111

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Experimental and numerical study of an earth-to-air heat exchanger for air cooling in a residential building in hot semi-arid climate, Energy and Buildings http://dx.doi.org/10. 1016/j.enbuild.2016.04.071 This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. 3 ABSTRACT This work deals with an experimental and numerical study of an Earth-to-Air Heat Exchanger (EAHX) for air cooling, connected to a residential building located in Marrakech (Morocco) which climate is a hot semi-arid one. The EAHX consists of three parallel PVC pipes of 72 m length each and 15 cm inside diameter, buried at 2.2-3.2 m depth. Each pipe is equipped with a fan, which blows treated air into the building. The experimental study consists of summer monitoring of the EAHX via measurements of air temperature and humidity throughout the exchanger, as well as at its inlet and outlet to the building for two fixed values of the airflow rate. The experimental results show that the EAHX is a good semipassive system for air refreshment, as the recorded blown air temperature into the building is quasi-constant at 25 °C with air humidity around 40%, even though the outside temperature reaches more than 40 °C. Furthermore, the reduction of daily and annual air temperature amplitudes is characterized by an exponential drop as a function of pipe length. The characteristic length is found to be around 20m and 70m respectively for the daily and annual air temperature amplitudes reduction. Moreover, it is shown that the design guidelines from literature cannot straightforwardly be applied to an EAHX which is subject to meteorological disturbance from the upper surface and/or which is not operated all year round, for which numerical simulation with a validated models remains necessary. 1 EXPERIMENTAL AND NUMERICAL STUDY OF AN EARTH-TO-AIR HEAT EXCHANGER FOR AIR COOLING INOn the other hand, dynamic simulations of the EAHX using TRNSYS software (TYPE 460) were performed with one pipe or three pipes continuously running. Good agreement was found between the simulation and experimental results. Simulation results show that the EAHX can perform a maximum drop of air temperature as high as 19.5 °C and 18.3 °C respectively for an EAHX with one and three pipes. The achieving specific cooling capacity is 58 W/m 2 (one pipe) and 55 W/m 2 (three pipes) obtained for air temperatures of 25 °C and 26 °C respectively, at the EAHX outlet and 44.6 °C at its inlet.

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Neue Gleichungen für den Wärme- und den Stoffübergang in turbulent durchströmten Rohren und Kanälen

Cited by 354 publications

References 18 publications

Internal forced convection to low-Prandtl-number gas mixtures

Internal forced convection to low-Prandtl-number gas mixtures

Modelowanie matematyczne pracy wymiennika ciepła z rur ożebrowanych dla zmiennych w czasie strumienia masy płynu i prędkości powietrza

Experimental and numerical study of an earth-to-air heat exchanger for air cooling in a residential building in hot semi-arid climate

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