计算圆管内部湍流对流换热系数 强迫

Forced Convection Heat Transfer Coefficient Correlations (S.I. units)

1. Turbulent Flow Inside a Circular Tube

Inputs Calculations

Fluid = water Reynolds Number, Re =17,745 Ave. Fluid Temp, T b =20o C Prandtl Number, Pr = 5.7

Pipe Diam., D =20mm Correlation #1, the Dittus Boelter Correlation

Pipe Diam., D =0.020m T wall > T fluid:Nu o =115

(calculated)

h o =12055

Ave. Velocity, V =0.7m/s3348.522921

T wall < T fluid:Nu o =110

Fluid Density, r =995kg/m3

h o =11456

Fluid viscosity, m =0.000785N-s/m23182.24

f =0.02697

Fluid Sp. Heat, C p = 4.19kJ/kg-K

Correlation #2:

Fluid Thermal

Conductivity, k =0.58W/m-K Nu o =123

Fluid Thermal h o =12817

Conductivity, k =0.00058kJ/s-m-K3560.349172

Fluid Thermal Correlation #3:

Conductivity, k = 2.088kJ/hr-m-K

Nu o =123

Pipe Length, L = 1.5m

h o =12818

3560.522493 Correction for Temperature Variation: ( h = h o(m b/m w)0.14

Inputs Calculations

Ave. Fluid Temp, T b =30o C Correlation #1, the Dittus Boelter Correlation Fluid Visc. at T b, m b =0.000785N-s/m2T wall > T fluid:h =12607

Ave. Wall Temp, T w =50o C T wall

Fluid Visc. at T w, m w =0.00057N-s/m2Correlation #2:

h =13405

Correlation #3:

h =13405

Equations for Forced Convection Flow inside Pipes

oelter Correlation Correlation #1, the Dittus Boelter Correlation

kJ/hr-m2-K

w/m2-K

Correlation #2, Convection H.T., Turb. Pipe Flow kJ/hr-m2-K

w/m2-K

kJ/hr-m2-K Correlation #3, Convection H.T., Turb. Pipe Flow

w/m2-K

kJ/hr-m2-K

w/m2-K

oelter Correlation

kJ/hr-m2-K3501.971w/m2-K

kJ/hr-m2-K3328.07w/m2-K

kJ/hr-m2-K3723.504w/m2-K

kJ/hr-m2-K3723.686w/m2-K