Page 129 - Applied Process Design For Chemical And Petrochemical Plants Volume III

66131_Ludwig_CH10D 5/30/2001 4:29 PM Page 95

Heat Transfer 95

where Table 10-19
C or c specific heat of fluid, Btu/(lb)(°F)
Approximate Film Coefficients, h i or h o
D inside diameter of tube, ft
2
G mass velocity, lb/hr (ft ) Film Coefficient,
g acceleration of gravity, ft/(hr ), or ft/sec/sec Btu/hr. (ft )(°F)
2
2
Depends on the system of units
2
H heat transfer film coefficient, Btu/(hr) (ft )(°F) No Change of Phase
Water 0300—2000
j H factor for heat transfer, dimensionless
Gases 03—50
2
k thermal conductivity, Btu/(hr) (ft )(°F/ft)
Organic solvents 060—500
L length, ft
Oils 010—120
t temperature difference for heat transfer, °F Condensing
v velocity, ft/hr Steam 1000—3000
viscosity, absolute, lb/(hr)(ft) Organic solvents 150—500
density, lb/ft 3 Light oils 200—400
2
k d diffusivity (volumetric), ft /hr Heavy oils (vacuum) 20—50
thermal coefficient of expansion, 1/°F Ammonia 0500—1000
Evaporation
Water 0800—2000
Gas and liquid heat transfer inside tubes has been studied
Organic solvents 100—300
by Sieder and Tate 101 and is represented by Figure 10-46. Ammonia 200—400
Also see references 270 and 271. Light oils 150—300
Heavy oils 10—50
Used by permission: Pfaudler, Inc., Bul. SB 95-500-1 ©1984.
Table 10-18A
1
Miscellaneous Heating Overall Heat Transfer Coefficient, U
Material Heating Overall Coeff. Controlling
Equipment Treated Agitation Surface Btu/hr (Ft )(°F) Resistance
2
Steam Paper drying rolls Paper Cast iron 20—58 Paper film*
Steam Yankee drying rolls Paper Cast iron 100 Metal wall*
Steam Jacketed kettle Paraffin wax None Copper 0027.4 Product
Steam Jacketed kettle Paraffin wax Scraper Cast iron 107 Product
Steam Jacketed kettle Boiling water None Steel 187 Product
DOWTHERM A (vapor phase) Jacketed kettle Varnish None Steel 20—50 Product
DOWTHERM A (vapor phase) Jacketed kettle Asphalt None Steel 08—20 Product
DOWTHERM A (vapor phase) Heat exchanger Fatty acids Forced circn. Steel 45—50 Product
DOWTHERM A (vapor phase) Heat exchanger Rosin Forced circn. Steel 40 Product
DOWTHERM A (vapor phase) Heat exchanger Asphalt Forced circn. Steel 25—50 Product
DOWTHERM A (vapor phase) Reboiler Fatty acids None 80 Product
DOWTHERM A (liquid phase) Jacketed kettle Varnish Forced circn. Steel 15—40 Product
DOWTHERM A (vapor phase) Heat exchanger Edible oil Forced circn. Steel 124—150 Product
DOWTHERM A (vapor phase) Heat exchanger Cocoa butter Forced circn. Steel 70—75 Product
Mercury vapor Heat exchanger DOWTHERM Forced circn. Steel 220—350 Product
A MEDIUM

Approximate Overall Design Coefficient 1
Hot Fluid Cold Fluid Overall U

Coolers Light organic Water 075–150
Heaters Steam Light organic 100–200
Exchangers Light organic Light organic 40–75
Heavy organic Light organic 30–60
Light organic Heavy organic 10–40
1 Values include dirt factors of 0.003 and allowable pressure drops at 5—10 psi on the controlling steam. DOWTHERM fluid would be included as light
organic. (Kern. Process Heat Transfer, 1 Ed., p. 840 ©1950.)
st
*Montgomery, A. E. “Heat Transfer Calens. In Paper Machine.” Paper Trade Journal, Oct. 3, 1946, p. 29.

Perry. Chemical Engineers Handbook, 3 Ed., p. 482, ©1950.
rd