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Cabin heater, Caetano, EF Calcium carbonate, fouling of heat exchangers by, Calcium sulphate, fouling of heat exchangers by, CALFLO, heat transfer media, Calorically perfect gas, CANDU Reactor, fouling problems in, Carbon dioxide: Carbon disulfide: Carbon monoxide: Carbon steel: Carbon-manganese steels Carbon-molybdenum steels, Carbon tetrachloride: Carbonyl sulfide: Carboxylic acids: Carnot cycle in refrigeration, Carnot factor, Carreau fluid (non-Newtonian), Carryover of solids in fluidized beds, Cashman, B L, Cast iron, thermal and mechanical properties, Cavitation as source of damage in heat exchangers, Cell method, for heat exchanger effectiveness, Cement kilns, CEN code for pressure vessels, Centrifugal dryer, Ceramics Certification of heat exchangers, Chan, S H, Channel emissivity, Chapman-Rubescin formula for viscosity variation with temperature, Chemical exergy, Chemical formulas of commonly used fluids Chemical industry, fouling of heat exchangers in, Chemical reactions, exergy analysis of, Chemical reaction fouling, Chen correlation for forced convective boiling, Chen method, for enthalpy of vaporisation, Chenoweth, J M, Chevron troughs as corrugation design in plate heat exchangers, Chillers, construction features of, Chilton-Colburn analogy, Chisholm, D Chisholm correlations: Chlorine: Chloroacetic acid: Chlorobenzene: Chlorobutane: Chlorodifluoromethane (see Refrigerant 22) 1-Chloro-1,1-difluoroethane (Refrigerant 142b): Chloroethane (Refrigerant 160): Chloromethane (Refrigerant 40): Chloropentane: 1,2-Chloropentafluoroethane (Refrigerant 115): Chloroprene (2-Chloro-1,3-butadiene): 1-Chloropropane: 2-Chloropropane: m-Chlorotoluene: o-Chlorotoluene: Chlorotrifluoroethylene: Chlorotrifluoromethane (see Refrigerant 13) Chromium-molybdenum steels, Chudnovsky, Y, Chugging flow (gas-liquid), in shell-and-tube heat exchangers, Chung et al method, for viscosity of low pressure gases, Church and Prausnitz methods: Churchill, S W, Churchill and Chu correlations for free convective heat transfer: Churn flow, regions of occurrence of, Circles, radiative heat transfer shape factors between parallel coaxial, Circular girth flanges, design according to ASME VIII code, Circulating fluidized beds, Circulation, modes of in free convection: in enclosures heated from below, CISE correlations for void fractions, Clausius-Clapeyron relationship: Cleaning: Climbing film evaporator, Closed circuit cooling towers, Coalescence of bubbles in fluidized beds, Coatings for corrosion protection Cocurrent flow: Codes, mechanical design: Cogeneration Colburn and Drew method for binary vapor condensation, Colburn and Hougen method for condensation in presence of noncondensable gases Colburn equation for single-phase heat transfer outside tube banks, Colburn j factor: Colebrook-White equation for friction factor in rough circular pipe, Coles, law of the wake, Collier, J G, Combined free and forced convection heat transfer: Combined heat and mass transfer, Combining flow, loss coefficients in, Combustion model for furnaces, Compact heat exchangers (see Plate fin heat exchangers) Compartment dryers, Composite curves, in the pinch analysis method for heat exchanger network analysis: Compressed liquids, density of: Compressible flow: Compression, exergy analysis of Compressive stress, in heat exchanger tubes, Computer-aided design, of evaporators, Computer program for Monte Carlo calculations of radiative heat transfer, Computer simulation, of fouling, Computer software for mechanical design, Concentration, choice of evaporator type for, Concentric spheres, free convective heat transfer in, Concurrency corrections in plate heat exchangers, Condensation: Concrete, lightweight, submerged combustion system for, Condensation curves: Condenser/preheater tubes, in multistage flash evaporation, Condensers: Conduction, heat: Conductors, thermal conductivity of, Cones, under internal pressure, EN13445 guidelines for, Cones, vertical: Conical shells, mechanical design of: Conjugate radiation interactions Connors equation for fluid elastic instability, Conservation equations: Constantinon and Gani method, for estimating normal boiling point, Contact angle, Contact resistance: Continuity equation: Continuum model, for fluids, Continuum theories, for non-Newtonian fluids, Contraction, sudden, pressure drop in: Control: Control volume method, in finite difference solutions for conduction, Convection, interaction of radiation with, Convection effects, on heat transfer in kettle reboilers, Convective heat transfer, single-phase:
around immersed bodies: single bodies, augmentation of, in combined free and forced convection (see Combined free and forced convection) effect of radiation on, in fixed beds, in flow over tube banks, forced convection in ducts, in free convection: immersed bodies, with impinging jets,
Impinging Jets
in liquid metal systems, with non-Newtonian fluids, in agitated beds, to moving granular solids,
Conversion factors: Conveyor, gravity: Cooling curves, in condensation, Cooling towers: Cooling water fouling, Cooper correlation, for nucleate boiling, Cooper, Anthony, Copper, thermal and mechanical properties, Copper alloys, Correlation, general nature of, Corresponding states principle Corrosion: Corrugation design, for plate heat exchangers Costing of heat exchangers: Countercurrent flow: Coupled thermal fields, in transient conduction, Cowie, R C, Crank-Nicolson differencing scheme, in finite difference method, Creeping flow, in combined free and forced convection around immersed bodies, m-Cresol: o-Cresol: p-Cresol: Crevice corrosion, in stainless steels, Critical constants Critical density, of commonly used fluids, Critical flow, in gas-liquid systems, Critical heat flux: Critical pressure: Critical Rayleigh number, in free convection, Critical temperature: Critical velocity, in stratification in bends and horizontal tubes, Critical volume (see also Critical density) Cross counterflow heat exchangers, Crossflow: Crude oil, fouling of heat exchangers: Cryogenic plant, entropy generation in, Crystallization Crystallization fouling, Curved ducts: Cut-and-twist factor, in enhancement of heat transfer in double pipe heat exchangers, C-value method for heat exchanger costing, Cycling, of expansion bellows, Cyclobutane: Cyclohexane: Cyclohexanol: Cyclohexene: Cyclopentane: Cyclopentene: Cyclopropane: Cylinders: Cylindrical contacts, thermal contact resistance in, Cylindrical coordinates, finite difference equations for conduction in, Cylindrical shell, analytical basis of code rules for,

Index

HEDH
A B C
Cabin heater, Caetano, EF Calcium carbonate, fouling of heat exchangers by, Calcium sulphate, fouling of heat exchangers by, CALFLO, heat transfer media, Calorically perfect gas, CANDU Reactor, fouling problems in, Carbon dioxide: Carbon disulfide: Carbon monoxide: Carbon steel: Carbon-manganese steels Carbon-molybdenum steels, Carbon tetrachloride: Carbonyl sulfide: Carboxylic acids: Carnot cycle in refrigeration, Carnot factor, Carreau fluid (non-Newtonian), Carryover of solids in fluidized beds, Cashman, B L, Cast iron, thermal and mechanical properties, Cavitation as source of damage in heat exchangers, Cell method, for heat exchanger effectiveness, Cement kilns, CEN code for pressure vessels, Centrifugal dryer, Ceramics Certification of heat exchangers, Chan, S H, Channel emissivity, Chapman-Rubescin formula for viscosity variation with temperature, Chemical exergy, Chemical formulas of commonly used fluids Chemical industry, fouling of heat exchangers in, Chemical reactions, exergy analysis of, Chemical reaction fouling, Chen correlation for forced convective boiling, Chen method, for enthalpy of vaporisation, Chenoweth, J M, Chevron troughs as corrugation design in plate heat exchangers, Chillers, construction features of, Chilton-Colburn analogy, Chisholm, D Chisholm correlations: Chlorine: Chloroacetic acid: Chlorobenzene: Chlorobutane: Chlorodifluoromethane (see Refrigerant 22) 1-Chloro-1,1-difluoroethane (Refrigerant 142b): Chloroethane (Refrigerant 160): Chloromethane (Refrigerant 40): Chloropentane: 1,2-Chloropentafluoroethane (Refrigerant 115): Chloroprene (2-Chloro-1,3-butadiene): 1-Chloropropane: 2-Chloropropane: m-Chlorotoluene: o-Chlorotoluene: Chlorotrifluoroethylene: Chlorotrifluoromethane (see Refrigerant 13) Chromium-molybdenum steels, Chudnovsky, Y, Chugging flow (gas-liquid), in shell-and-tube heat exchangers, Chung et al method, for viscosity of low pressure gases, Church and Prausnitz methods: Churchill, S W, Churchill and Chu correlations for free convective heat transfer: Churn flow, regions of occurrence of, Circles, radiative heat transfer shape factors between parallel coaxial, Circular girth flanges, design according to ASME VIII code, Circulating fluidized beds, Circulation, modes of in free convection: in enclosures heated from below, CISE correlations for void fractions, Clausius-Clapeyron relationship: Cleaning: Climbing film evaporator, Closed circuit cooling towers, Coalescence of bubbles in fluidized beds, Coatings for corrosion protection Cocurrent flow: Codes, mechanical design: Cogeneration Colburn and Drew method for binary vapor condensation, Colburn and Hougen method for condensation in presence of noncondensable gases Colburn equation for single-phase heat transfer outside tube banks, Colburn j factor: Colebrook-White equation for friction factor in rough circular pipe, Coles, law of the wake, Collier, J G, Combined free and forced convection heat transfer: Combined heat and mass transfer, Combining flow, loss coefficients in, Combustion model for furnaces, Compact heat exchangers (see Plate fin heat exchangers) Compartment dryers, Composite curves, in the pinch analysis method for heat exchanger network analysis: Compressed liquids, density of: Compressible flow: Compression, exergy analysis of Compressive stress, in heat exchanger tubes, Computer-aided design, of evaporators, Computer program for Monte Carlo calculations of radiative heat transfer, Computer simulation, of fouling, Computer software for mechanical design, Concentration, choice of evaporator type for, Concentric spheres, free convective heat transfer in, Concurrency corrections in plate heat exchangers, Condensation: Concrete, lightweight, submerged combustion system for, Condensation curves: Condenser/preheater tubes, in multistage flash evaporation, Condensers: Conduction, heat: Conductors, thermal conductivity of, Cones, under internal pressure, EN13445 guidelines for, Cones, vertical: Conical shells, mechanical design of: Conjugate radiation interactions Connors equation for fluid elastic instability, Conservation equations: Constantinon and Gani method, for estimating normal boiling point, Contact angle, Contact resistance: Continuity equation: Continuum model, for fluids, Continuum theories, for non-Newtonian fluids, Contraction, sudden, pressure drop in: Control: Control volume method, in finite difference solutions for conduction, Convection, interaction of radiation with, Convection effects, on heat transfer in kettle reboilers, Convective heat transfer, single-phase:
around immersed bodies: single bodies, augmentation of, in combined free and forced convection (see Combined free and forced convection) effect of radiation on, in fixed beds, in flow over tube banks, forced convection in ducts, in free convection: immersed bodies, with impinging jets,
Impinging Jets
in liquid metal systems, with non-Newtonian fluids, in agitated beds, to moving granular solids,
Conversion factors: Conveyor, gravity: Cooling curves, in condensation, Cooling towers: Cooling water fouling, Cooper correlation, for nucleate boiling, Cooper, Anthony, Copper, thermal and mechanical properties, Copper alloys, Correlation, general nature of, Corresponding states principle Corrosion: Corrugation design, for plate heat exchangers Costing of heat exchangers: Countercurrent flow: Coupled thermal fields, in transient conduction, Cowie, R C, Crank-Nicolson differencing scheme, in finite difference method, Creeping flow, in combined free and forced convection around immersed bodies, m-Cresol: o-Cresol: p-Cresol: Crevice corrosion, in stainless steels, Critical constants Critical density, of commonly used fluids, Critical flow, in gas-liquid systems, Critical heat flux: Critical pressure: Critical Rayleigh number, in free convection, Critical temperature: Critical velocity, in stratification in bends and horizontal tubes, Critical volume (see also Critical density) Cross counterflow heat exchangers, Crossflow: Crude oil, fouling of heat exchangers: Cryogenic plant, entropy generation in, Crystallization Crystallization fouling, Curved ducts: Cut-and-twist factor, in enhancement of heat transfer in double pipe heat exchangers, C-value method for heat exchanger costing, Cycling, of expansion bellows, Cyclobutane: Cyclohexane: Cyclohexanol: Cyclohexene: Cyclopentane: Cyclopentene: Cyclopropane: Cylinders: Cylindrical contacts, thermal contact resistance in, Cylindrical coordinates, finite difference equations for conduction in, Cylindrical shell, analytical basis of code rules for,
D E F G H I J K L M N O P Q R S T U V W X Y Z
C Convective heat transfer, single-phase: with impinging jets,
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Impinging Jets

DOI 10.1615/hedhme.a.000173

2.5.6 Impinging Jets

H. Martin and W. Schabel

A. Introduction

Heating or cooling of large-surface-area products is often carried out by means of arrays of round or slot nozzles. A fluid (typically, air) impinges upon the product surface. Impinging flow devices allow short flow paths to the surface small boundary layers and, therefore, relatively high heat and mass transfer rates. For these reasons impinging jets are used in the fields of paper drying, the drying of functional films, thin film coating applications (such as optical foils), battery electrodes, and many other industrial applications. The fluid temperature, fluid flow rate, diameter (or slot width) of the impingement nozzles, distance to the surface, and spacing and alignment between the nozzles are the main variables, which can be adjusted for a given heat or mass transfer problem. As shown by Schrader (1961), Glaser (1962 and 1963), and other authors (Lohe, 1967; Petzold, 1968; Kumada and Mabuchi, 1970; Romanenko and Davidzon, 1970), the flow pattern of impinging jets from single round and slot nozzles can be subdivided into three characteristic regions: the free jet region, the stagnation flow region, and the region of lateral (or radial) flow outside the stagnation zone, also called the wall jet region after the basic theoretical work of Glauert (1956). The velocity field of an impinging jet is shown schematically in Figure 1. The free jet, at the exit of the nozzle, a, with diameter D or slot width B, in general will be turbulent (for typical industrial application conditions). By intensive exchanger of momentum with the surrounding gas over the free boundaries, b, the jet broadens linearly with its length, z', up to a limiting distance, zg, from the solid surface, c. The velocity profile, d, being nearly rectangular at the nozzle exit, spreads toward the free boundaries and, for sufficient length of the free jet, approaches a bell shape. Toward a substrate, stagnation flow begins relatively close to the surface [ according to Schrader (1961), limiting distance zg is about 1.2 times the nozzle diameter ]. Here, the vertical velocity component is decelerated and transformed into an accelerated horizontal one. Analytical solutions of the Navier–Stokes equations are known for the idealized limiting case of the infinitely extended plane and axisymmetric laminar stagnation flows [ see Schlichting (1958), pp. 76–81 ]. Because of the finite range of the jet and the exchange or momentum with its motionless surroundings, the accelerated stagnation flow finally must transform to a decelerated wall jet flow. Thus, the wall parallel velocity component wg (wr), initially increasing linearly from zero, must reach a maximum value at a certain distance xg (rg) from the stagnation point, and finally tends to zero with xn (rn) in the fully developed wall jet. Exponent n is about −0.5 for the plane (Glauert, 1956; Seban and Back, 1961; Schwartz and Cosart, 1961) and about −1 for the axisymmetric (Glauert, 1956; Seban and Back, 1961; Bakke, 1957) turbulent wall jet. While the stabilizing effect of acceleration keeps the boundary layer laminar in the stagnation zone, transition to turbulence generally will occur immediately after xg (or rg) in the decelerating flow region. The wall boundary layer and free jet boundary grow together, forming the typical wall jet profile where the boundary layer, σ, is defined as the locus of the maxima of the velocity [ z(wx,max) ] (see f in Figure 1). In principle, the impinging flow from arrays of nozzles shows the same three flow regions: free jet, stagnation zone, and wall jet. However, in addition to that, secondary stagnation zones occur where the wall jets of neighboring nozzles impinge upon each other. These secondary stagnation zones are characterized by boundary layer separation and eddying of the flow at the substrate position where the neighboring jets interact.

Figure 1 Velocity field of impinging flow

B. Local Heat and Mass Transfer Coefficients

(a) Single Round Nozzles (SRNs) and Single Slot Nozzles (SSNs)

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