Effect of Reduced Air Flow

Loss of air flow through a filmed tube air cooler bundle is a universal problem. The effect is to reduce the exchanger s cooling efficiency. To restore cooling, you might wish to try the Norm Lieberman method, which consists of reversing the polarity of the three-phase fan motor electric leads. The fan will now spin backward. Depending on the nature of the deposits, a portion of the accumulated dirt will be blown off the tubes— but all over the unit. Personnel should observe this procedure from a safe distance. 

A more socially acceptable option is to water-wash the tubes. Most of the effective washing must be underneath the tubes. Washing from the top down is relatively ineffective. In many cases, detergent must be added to the washwater to remove greasy dirt. Caution Hot tubes may be thermally shocked by this washing and pull out of the tube header box.) 

To effectively water-wash the deposits from the fins I will proceed as follows  

Tie off the fan blade with a rope to keep it from spinning in the wind. 

For water, use steam condensate or boiler feed water at 50 to 100 psig. 

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Air at 207 kPa and 200°C enters a 2.5-cm-ID tube at 6 m/s. The tube is constructed of copper with a thickness of 0.8 mm and a length of 3 m. Atmospheric air at 1 atm and 20°C flows normal to the outside of the tube with a free-stream velocity of 12 m/s. Calculate the air temperature at exit from the tube. What would be the effect of reducing the hot-air flow in half ... 

The cross-flow-tower manufacturer may effectively reduce the tower characteristic at very low approaches by increasing the air quantity to give a lower L/G ratio. The increase in air flow is not necessarily achieved by increasing the air velocity but primarily by lengthening the tower to increase the air-flow cross-sectional area. It appears then that the cross-flow fill can be made progressively longer in the direction perpendicular to the air flow and shorter in the direction of the air flow until it almost loses its inherent potential-difference disadvantage. However, as this is done, fan power consumption increases. 

High pass filter (8 Hz) reduces effects caused by air flow across heating of sensor. 

Bronchoconstriction results from the effects of acetylcholine, histamine, and inflammatory mediators released within the bronchial walls. The vagus nerve releases acetylcholine in response to stimulation of upper airway mucosa by irritants. Acetylcholine also triggers release of pulmonary secretions which further reduce air flow by plugging airways. Sympathomimet-ics (adrenergic agonists, cholinergic antagonists), methylated xanthines and corticosteroids reverse or reduce bronchoconstriction (Tables 5.1A and 5.1B). 

This invention relates generally to light weight covers used to increase the aerodynamic properties of wheels. More specifically, the present invention relates to covers for wheels capable of creating an aerodynamic effect by reducing the friction or drag across the surface of a wheel created by air flow. 

Two types of floater aozzles are curreafly ia use and they are based on two different principles. The Bernoulli principle is used ia the airfoil flotatioa aozzles, ia which the air flows from the aozzle parallel to the web and the high velocities create a reduced pressure, which attracts the web while keeping the web from touching the nozzles. The Coanda effect is used to create a flotation nozzle when the air is focused and thus a pressure pad is created to support the web as shown ia Figure 19. 

Free phenol is a major concern in the manufacture of novolac resins. This is true for several reasons. The strongest drivers are probably EPA classification of phenol as a Hazardous Air Pollutant and worker safety concerns. However, free phenol also has significant technical effects on such parameters as melt flow characteristics. In this role, free phenol may undermine the desired effects of a molecular weight design by increasing flow beyond the desired point. Since free phenol is often variable, the effects on flow may also cause variation in product performance from batch to batch. Fig. 18 shows the effects of free phenol on the flow across a series of molecular weights. Free phenol contents between 1 and 10% are commonly seen. In recent years, much work has been aimed at reducing the free phenol. 

The flow field created within the protection zone depends mainly on the density difference between supply air and room air (Fig. 10.90). With vertical flow the supply air should be isothermal or cooler than ambient air. If it were warmer, the extension of the controlled flow would be reduced due to buoyancy effects, resulting in the supply air not reaching the operator s breathing zone. As the. supply air cannot be used for heating, the operator s thermal comfort should be maintained, preferably with radiant heaters in cold environments. If the supply air temperature is lower than the room air, the denser supply air accelerates down to the operator, and for continuity reasons the supply flow contracts. Excessive temperature differences result in a reduced controlled flow area with thermal discomfort, and should only be used in special cases. 

Turbochargers use the expansion of exhaust gas to pump combustion air to an engine. Exhaust gas is directed through a set of nozzles to drive a turbine wheel. Directly connected to the exhaust turbine is an air compressor turbine that delivers combustion air to the power cylinders. Thus, back-pressure is put on the engine exhaust, reducing power slightly, but the net effect of the increase in air mass flow available for combustion i.s to increase horsepower. 

Frequently, coil data will he available for a design air flow, hut the system resistance reduces this flow to a lower value. There is a double effect the lowering of the In MTD and the lower heat transfer from the coil by convection. 

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