Abstract
Heat transfer measurements with superheated steam have been performed in the pressure range of 10.5–33.3 bar, steam temperatures: 229–470 °C and heat fluxes: 2.6·104–5.7·105 W/m2. The measured data with steam flowing in an electrically heated tube of 10 mm inner diameter and 1 m length could be correlated with two different expressions, the mean steam temperature resp. the film temperature being used as reference for physical properties. The results of measurements in annular channels, with a heated rod of 14 mm outer diameter and channel diameters of 21 and 28 mm, were 10–15% lower than the proposed tube correlations. This could be explained by the differences in velocity and temperature distributions between tubes and annular channels. A satisfactory agreement was achieved between the tube correlations and transformed annular channel results.
Zusammenfassung
Wärmeübergangsmessungen an überhitztem Wasserdampf wurden im folgenden Bereich durchgeführt: Druck: 10,5–33,3 bar, Dampftemperatur: 229–470 °C, Wärmestromdichte: 2,6 · 104-5,7 · 105 W/m2. Die Eesultate der in einem elektrisch beheizten Rohr von 10 mm Innendurchdurchmesser und 1 m Länge durchgeführten Meß-Serie konnten durch zwei verschiedene Beziehungen je nach Bezugstemperatur der thermodynamischen Stoffwerte des Kühlmittels beschtieben werden. Als Bezugsgröße wurde die mittlere Dampf — temperatur bzw. die Filmtemperatur verwendet. Messungen, die in einem Ringspalt mit einem beheizten Stab von 14 mm Außendurchmesser und mit einem Kanaldurchmesser von 21 bzw. 28 mm durchgeführt wurden, ergaben 10–15% niedrigere Wärmeübergangszahlen, als die vorgeschlagenen Gleichungen für Rohrgeometrie. Dies kann durch den Unterschied der Geschwindigkeitsverteilungen in Rohren und Ringspalten erklärt werden. Die auf Rohrgeometrie umgerechneten Resultate der Ringspaltmessungen zeigten gute Übereinstimmung mit den vorgeschlagenen Gleichungen.
This is a preview of subscription content, log in via an institution to check access.
Similar content being viewed by others
Abbreviations
- A m2 :
-
surface area
- C :
-
constant
- c p J/kg °C:
-
heat capacity
- D m:
-
channel outer wall diameter
- d m:
-
channel inner wall diameter
- F m2 :
-
flow area
- f :
-
friction coefficient
- h W/°C m2 :
-
heat transfer coefficient
- k W/°C m:
-
thermal conductivity
- L, l m:
-
lenght
- m kg/s:
-
mass flow
- m :
-
exponent ofRe-number
- n :
-
exponent of Pr-number
- p N/m2, bar:
-
pressure
- Q W:
-
power
- q W/m2 :
-
heat flux
- r m:
-
radius
- t °C:
-
temperature
- w m/s:
-
velocity
- \(x = \frac{{t_x - t_S }}{{t_W - t_S }}\) :
-
dimensionless factor for reference temperature
- y :
-
exponent of the temperature ratio
- z :
-
exponent of the temperature ratiot w/t s
- \(Nu = \frac{{h \cdot d_h }}{k} \) :
-
Nusselt-Number
- \(Pr = \frac{{\eta \cdot c_p }}{k}\) :
-
Prandtl-Number
- \(Re = \frac{{w \cdot d_h }}{v} = \frac{{d_h }}{F}\frac{{\dot m}}{\eta }\) :
-
Reynolds-Number
- \(St = \frac{{Nu}}{{Re \cdot Pr}} = \frac{h}{{\varrho \cdot w \cdot c_p }}\) :
-
Stanton-Number
- δ B m:
-
boundary layer thickness
- η kg/ms:
-
dynamic viscosity
- Λ W/°C m:
-
heat conductivity including the influence of turbulence
- θ=t w−t s°C:
-
temperature difference
- ν m2/s:
-
kinematic viscosity
- ϱ kg/m3 :
-
density
- τ N/m2 :
-
shear stress
- B:
-
boundary layer
- F:
-
film
- S:
-
steam
- SS:
-
stainless steel
- T:
-
turbulent core
- W:
-
wall
- a:
-
outside
- h:
-
hydraulic
- i:
-
inside
- x :
-
based on reference temperaturet x
- 0:
-
based on zero shear surface
- 1:
-
based on inner subchannel of an annulus
- 2:
-
based on outer subchannel of an annulus
- -:
-
(over a symbol): average
- *:
-
(over a symbol): transformed
References
Heinemann, J. B.: An experimental investigation of heat transfer to superheated steam in round and rectangular channels. ANL-6213, Sept. 1960.
Sutherland, W. A.: Heat transfer to superheated steam. GEAP-4258, May 1963.
Bishop, A. A., F. J.Krambeck and R. O.Sandberg: Forced convection heat transfer to superheated steam at high pressure and high Prandtl numbers. WCAP-2056, Part III, July 1964.
McAdams, W. H., W. E.Kennel and J. N.Addoms: Heat transfer to superheated steam at high pressure. Trans. ASME 72, May 1950.
Collier, J. G., A. W.Bennet and P. M. C.Lacey: Heat transfer to mixtures of high pressure steam and water in an annulus. Part I: Single phase experiments: Superheated steam, AERE-R 3653, Febr. 1961.
Kütükçüoğlu, A.: Wärmeübergangsmessungen mit überhitztem Wasserdampf im Rohr und konzentrischen Ringkanal. EIR-Bericht Nr. 155, Würenlingen, Juni 1969.
Schmidt, E.: VDI-Wasserdampftafeln, 6. Aufl., Ausgabe B, Springer 1963.
Pickering, A. R.: Turbulent heat transfer to fluids with variable physical properties — a review: AEEW-R 290, Febr. 1964.
Kaul, V., andM. von Kiss: Forced convection heat transfer and pressure drop in artificially roughened flow passages. Neue Technik 6 (1964) Nr. B6, pp. 297/309.
Hall, W. B.: Heat transfer in channels having rough and smooth surfaces, J. Mech. Eng. Sci. 4 (1962) Nr. 3, pp. 287/291.
Kays, W. M., andE. Y. Leung: Heat transfer in annular passages, hydrodynamically developed turbulent flow with arbitrarily prescribed heat flux. Intern. J. Heat Transfer 6 (1963) pp. 537/557.
Kjellström, B., and S.Hedberg: On shear stress distributions for flow in smooth or partially rough annuli. E.A.E.S. Heat Transf. Symp., 31. Aug.–3. Sept. 1966, Bern.
Author information
Authors and Affiliations
Rights and permissions
About this article
Cite this article
Kütükçüoğlu, A. Heat transfer to superheated steam flowing in tubes and annular channels. Wärme- und Stoffübertragung 3, 174–184 (1970). https://doi.org/10.1007/BF01006693
Received:
Issue Date:
DOI: https://doi.org/10.1007/BF01006693