Navigation by alphabet

A B C D E F G H I J K L M N O P Q R S T U V W X Y Z
Rabas and Taborek correlation, for heat transfer in banks of low fin tubes, Rackett equation (modified) for liquid density Radiation: Radiation shields, in radiation heat transfer, Radiation source analysis, Radiative heat transfer: Radiators, automotive, construction, Radiometers, application in gas radiation property measurement, Radiosity, Stephan's law for, Radiosity-irradiation formulations in radiative heat transfer, Rankine cycle in refrigeration, Rao, B K Raoult's law for partial pressure, Rating of heat exchangers, Rayleigh instability, in free convection, Rayleigh number Reay, D Reboilers: Reciprocal mode integrating sphere, for reflection and transmission measurements in radiation, Rectangles: Rectangular ducts: Rectangular enclosures, free convective heat transfer in: Rectangular fins, for plate fin exchangers Reduced pressure, correlations for pool boiling using, Reference temperature: Refinery processes, fouling in, Reflection, of thermal radiation, from solid surfaces: Reflectivity, of solid surfaces, Reflectometer, heated cavity, Reflux condensers, Refractories, density of, Refractory surfaces, Refrigerants: Refrigerant 11 (Trichlorofluoromethane): Refrigerant 12 (Dichlorodifluoromethane): Refrigerant 13 (Chlorotrifluoromethane): Refrigerant 21 (Dichlorofluoromethane): Refrigerant 22 (Chlorodifluoromethane): Refrigerant 116: Refrigerant plant, entropy generation in, Refrigeration, heat transfer in, Regenerators and thermal energy storage, Regimes of heat transfer, in ducts, single phase flow, Reidel method, for predicting enthalpy of vaporisation, Reinforcing rings, for expansion bellows, Relaminarization, of turbulent flow, Reichenberg method, for effect of pressure on gas viscosity, Relief system design for shell-and-tube heat exchangers with tube side failure, Removal of fouling deposits: Renewable fuels, properties of, Renotherm, heat transfer medium, Repair, of expansion bellows, Residence times, in dryers: Resistance network analysis, Resistance (thermal) due to fouling: Reversible (minimum) work, in Reynolds number, Reynolds stress models, for turbulence, Rheologically complex materials, properties of: Rheological properties of drag reducing agents Rheology, shear flow experiments used in, Rhine, J M, Ribatski, G, Riblets for drag reduction, Richardson number, Richie, J M, Ring cells, in free convection, RODbaffles, in tube bundles with longitudinal flow, Rod bundles: Rohsenow correlation, for nucleate boiling, Roll cells, in free convection, Roller expansion, of tubes into tube sheets, Rose, J W, Rossby number, Rotary dryer, Rotating drums, heat transfer to particle bed in, Rotating surface, in an annular duct Rotation, as device for heat transfer augmentation, Roughness, surface: Rough walled passages, radiative heat transfer down, Rubber (sponge) balls, in fouling mitigation, Ryznar index for water quality,

Index

HEDH
A B C D E F G H I J K L M N O P Q R
Rabas and Taborek correlation, for heat transfer in banks of low fin tubes, Rackett equation (modified) for liquid density Radiation: Radiation shields, in radiation heat transfer, Radiation source analysis, Radiative heat transfer: Radiators, automotive, construction, Radiometers, application in gas radiation property measurement, Radiosity, Stephan's law for, Radiosity-irradiation formulations in radiative heat transfer, Rankine cycle in refrigeration, Rao, B K Raoult's law for partial pressure, Rating of heat exchangers, Rayleigh instability, in free convection, Rayleigh number Reay, D Reboilers: Reciprocal mode integrating sphere, for reflection and transmission measurements in radiation, Rectangles: Rectangular ducts: Rectangular enclosures, free convective heat transfer in: Rectangular fins, for plate fin exchangers Reduced pressure, correlations for pool boiling using, Reference temperature: Refinery processes, fouling in, Reflection, of thermal radiation, from solid surfaces: Reflectivity, of solid surfaces, Reflectometer, heated cavity, Reflux condensers, Refractories, density of, Refractory surfaces, Refrigerants: Refrigerant 11 (Trichlorofluoromethane): Refrigerant 12 (Dichlorodifluoromethane): Refrigerant 13 (Chlorotrifluoromethane): Refrigerant 21 (Dichlorofluoromethane): Refrigerant 22 (Chlorodifluoromethane): Refrigerant 116: Refrigerant plant, entropy generation in, Refrigeration, heat transfer in, Regenerators and thermal energy storage, Regimes of heat transfer, in ducts, single phase flow, Reidel method, for predicting enthalpy of vaporisation, Reinforcing rings, for expansion bellows, Relaminarization, of turbulent flow, Reichenberg method, for effect of pressure on gas viscosity, Relief system design for shell-and-tube heat exchangers with tube side failure, Removal of fouling deposits: Renewable fuels, properties of, Renotherm, heat transfer medium, Repair, of expansion bellows, Residence times, in dryers: Resistance network analysis, Resistance (thermal) due to fouling: Reversible (minimum) work, in Reynolds number, Reynolds stress models, for turbulence, Rheologically complex materials, properties of: Rheological properties of drag reducing agents Rheology, shear flow experiments used in, Rhine, J M, Ribatski, G, Riblets for drag reduction, Richardson number, Richie, J M, Ring cells, in free convection, RODbaffles, in tube bundles with longitudinal flow, Rod bundles: Rohsenow correlation, for nucleate boiling, Roll cells, in free convection, Roller expansion, of tubes into tube sheets, Rose, J W, Rossby number, Rotary dryer, Rotating drums, heat transfer to particle bed in, Rotating surface, in an annular duct Rotation, as device for heat transfer augmentation, Roughness, surface: Rough walled passages, radiative heat transfer down, Rubber (sponge) balls, in fouling mitigation, Ryznar index for water quality,
S T U V W X Y Z

Laminar Flow Surfaces

DOI 10.1615/hedhme.a.000300



3.9.5 Laminar flow in plain surface geometries

It was previously noted that very compact surfaces (small hydraulic diameter) may operate at Reynolds numbers well within the laminar flow region. In the laminar regime, surface geometries designed to produce boundary layer interruptions may be of little benefit. Therefore, plain fin surfaces are likely candidates for very compact designs operating in the laminar regime. Laminar flow plate-fin geometries are also used in rotary regenerators, discussed in Section 3.15. For fully developed laminar flow, Nu and fRe are independent of Reynolds number. But Nu and fRe are dependent on the cross-sectional shape of the flow channel. Because of the small hydraulic diameter of the flow channels, their L /Dh may be sufficiently large that fully developed laminar flow solutions are applicable. For most channel shapes. the mean Nusselt number and friction factor will be within 10% of the fully developed for gases if L /Dh > 0.2 Re.

Table 1 [from Webb and Kim (2005)] gives fully developed laminar flow solutions for 11 channel shapes of interest in compact heat exchanger design. The tables give NuH  (constant heat input per unit length with uniform peripheral temperature) and NuT  (constant wall temperature). The ratio j /f (for Pr = 0.7) is proportional to the required flow channel frontal area for a specified αA and friction power. The hydraulic entrance length Lhy+ = (X /Dh) /Re is the dimensionless length required for the centerline velocity to attain 99% of its fully developed value. The constant K() defines the pressure drop increment to be added to account for the increased friction in the flow development region. The pressure drop, accounting for the flow development region, is

\[\label{eq1} \Delta p=\left[\frac{4f_{fd}L}{D_{h}}+K(\infty)\right]\frac{G^{2}_{c}}{2\rho} \tag{1}\]

Table 1 Fully developed laminar flow solutions a

ajH and jT for Pr = 0.7. T constant temperature. H heat flux, heat flux with uniform peripheral temperature.
GeometryNuHNuTfReK(∞)jH /fjT /fLhy+
     8.2357.541240.6860.3860.3540.0056
  6.4905.59720.5850.8790.3550.3060.0094
  6.0495.13719.7020.9450.3460.2940.0110
  5.3314.43918.2331.0760.3290.2740.0147
      4.3643.65716.001.240.3070.2580.038
  4.1233.39115.5481.3830.2990.2450.0255
  3.6083.09114.2271.5520.2860.2360.0324
  3.1112.4713.3331.8180.2630.2090.0398
  3.0142.3912.6301.7390.2690.2140.0408
  2.882.2213.0261.9910.2490.1920.0443
2.601.9912.6222.2360.2320.1780.0515

... You need a subscriptionOpen in a new tab. to view the full text of the article. If you already have the subscription, please login here