Natural drafts, airflow

The constructed wetland was composed of the two tanks connected in series the one is the aerobic tank and the other is the anaerobic/anoxic one (Figure 1). The former tank could remain aerobic owing to the continuous supply of air through the natural draft system (Figure 2) whose driving force for airflow was the temperature difference between the... 

Upon fan failure, increased capacity compared to forced-draft coolers, since the airflow is designed for natural draft... 

Chimney-assisted natural draft towers also do not have fans, as shown in Figure 9.17(b). Most have tall chimneys, a fill that occupies a small percentage of the tower and no fan. They depend on a stack or chimney to induce the airflow through the tower. The hyperboloidal shape has greater strength for a given wall thickness. 

The basic approach to improving simple biomass stoves is to enclose the combustion zone and vent to the ontside through a flue/chimney. Unfortunately, such designs can sometimes actually lower total efficiency because of the high airflow induced by natural draft in the flue reduce heat transferto the pot. Shutting back the airflow with dampers can lead to a rise in total efficiency, but at the same time may reduce combustion efficiency sufficiently to actually increase PIC (pollutant) emissions per meal. If vented out-... 

A furnace can be classified as natural, induced, forced, or balanced draft. The pressure inside a warm furnace is typically lower because of buoyancy differences between air inside the furnace and the cooler outside air. A natural-draft furnace can operate using this approach however, when fans are used to push or pull air through the furnace, greater heat transfer rates can be achieved. A natural-draft fired heater is severely limited in contrast to these systems. Figure 9-13 shows the four different systems used to control airflow. 

Naturally, there is no reverse airflow on an induced-draft fan. That can occur only in a forced-draft fan. Reverse airflow can be observed with a forced-draft fan, by seeing which portions of the screen, shown in Fig. 14,2, will not allow a dollar bill to stick to the underside of the... 

Cooling towers—devices used by industry to remove heat from water. In a typical tower, a boxshaped collection of multilayered slats and louvers directs airflow and breaks up water as it cascades from the top of the water distribution system. Cooling towers are classified by the way they produce airflow and by the way the air moves in relation to the downward flow of water. Basic designs include atmospheric, natural, forced, and induced draft. 

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