Convective heat exchange

the lower efficiency of heat exchange processes in the cylindrical channels of tubular devices, compared with diffuser-confusor devices, is explained by an undesirably close approach of the internal flow and circular flow structures to the plug flow mode. The heat exchange efficiency in a diffuser-confusor device, at a2 otj, can be intensified by increasing the cooling agent flow rate w, which offers another tool for intensification and control of the heat transmission processes. 

M Barabash and N.N. Smirnov, Zhurnal Prikladnoi Khimii, 1994,67,2,196. [In Russian] 

Bajzenberger and D.H. Sebastian in Engineering Problems of Polymer Synthesis, Khimiya, Moscow, Russia, 1988. [In Russian] 

Braginskiy, V.I. Begachev and V.M. Barabash in Agitation of Liquid Media Physical Foundations and Engineering Methods of Calculation, Khimiya, Leningrad, Russia, 1984. [In Russian] 

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For each layer the energy conservation equation is solved. The individual terms are the absorbed radiation in the layer and the radiative and convective heat exchange to the adjacent panes, to the room, or to the exterior. 

Convective heat exchange The heat interchange by convection between the clothing surface or skin and the surrounding environment, C, in W m A... 

Convective heat exchange coefficient A complicated factor involving the surface ge... 

Convective heat exchange, globe The convective heat exchange that takes place between the surface of a globe thermometer and the surrounding air, C, in W m" . 

Design Procedure for Shell-Side Condensers and Shell-Side Condensation with Gas Cooling of Condensables, Fluid-Fluid Convection Heat Exchange... 

Convective heat exchange, natural or forced Radiation heat transfer, e.g. in furnaces Evaporation Condensation... 

Convective heat exchange, natural or forced Radiant heat transfer, e.g. furnaces Evaporation, e.g. in evaporators Condensation, e.g. in shell and tube heat exchanges Heat transfer to boiling liquids, e.g. in vaporizers, boilers, re-boilers ... 

The combustion products then pass through a series of convective heat exchangers which cool them to normal flue gas temperature. Samples extracted from the cool (400-500°K) combustion products are analyzed for major gaseous products and aerosol properties. 

The laboratory furnace, illustrated in Figure 1, has been described in detail elsewhere (19). The combustion chamber design is similar to that of Pershing and Wendt (20). It consists of a vertical cylinder 1.0 m long and 0.2 m inside diameter cast from alumina refractory cement. A series of convective heat exchangers, also 1.0 m long and 0.2 m inside diameter, are mounted directly below the combustor. The combustor is fired at a rate of 8 to 12 Kw, providing a residence time of 1 to 2 seconds in the combustion chamber. 

In continuous systems, the feed stream is not always at the same temperature as the reactor outlet. This temperature difference between the reactor feed (T0) and exit streams (Tf) results in a convective heat exchange with the surroundings. The heat flow is proportional to the heat capacity and the volume flow rate (i>) ... 

Numerous fin corrugations have been developed, each with its own special characteristics (Figure 15). Straight fins and straight perforated fins act like parallel tubes with a rectangular cross section. Convective heat exchange occurs due to the friction of the fluid in contact with the surface of the fin. The channels of serrated fins are discontinuous, and the walls of the fins are offset. For air flows,... 

Lobing and dissection (Fig. 7-llb) tend to decrease the effective length across a leaf in the direction of the wind and hence to reduce Sbl (Eq. 7.10), with a consequent increase of convective heat exchange. For instance, the heat convection coefficient hc (Eq. 7.17) increases with the depth of leaf serrations. In addition to differences in size, the greater lobing observed for sun leaves compared to shade leaves on the same plant further reduces the heating of sun leaves above air temperature. Also, heat convection is greater for a pinnate leaf with many leaflets than for a simple undivided (entire) leaf of the same area (Fig. 7-llb). 

Vx Velocity of convective heat exchange front (see Section lV,3,a)... 

However, since most of the plastic foams now produced commercially have a cell size below this value, the contribution of the convective heat exchange to the total heat... 

Fouling is the accumulation of mineral-derived ash on the superheater and reheater tubes in the convective (heat exchanger) section downstream from the furnace. Fouling restricts the flow of exhaust gases and impedes heat transfer through superheater tube walls and thereby reduces the amount of steam generated. 

Combustion air supply for inductive burners is similar to combustion air supply for natural suction burners. However, the draft in a combustion chamber is created by flue gas fan. This method is used whenever there is insufficient natural suction or if a pressure drop disables suction of a sufficient amount of combustion air (e.g., fhrough convective heat exchangers, filters, etc.). Installation of burners with an inductive supply of combustion air as opposed to natural draft burners is less common. 

If the initial calculations show that the convection heat exchange is not enough to establish the designed combustion intensity, the use of radiant burners becomes decisive. The radiative contribution of the mat is naturally predominant in the power range when flame develops within the mat itself. 

Convection heat exchange in the circulatory system can be found by summing all other components of a heat balance equation. 

For analysis of heat similarity Prandtl s criterion (Pr) is very important. It characterizes similarity of heat-carrying agents physical properties under convective heat-exchange processes [204] ... 

The following conclusions may be drawn out of results of convective heat-exchange investigation ... 

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