INDUSTRIAL VENTILATION DESIGN GUIDEBOOK

Series Fan Connection

In this case the outlet of the first fan is connected to the inlet of the second fan. With this arrangement, the total head developed at a given volume is equal to the sum of the total heads developed by the individual fans. Sometimes more than one fan is used in a duct arrangement. In […]

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Fan and Duct Network

In some instances the fan has a free discharge. Typical is the axial fan installed in a wall opening (wall fan). In most cases the fan is connected to a duct run; in this instance the total pressure difference and volume flow are determined from both the fan and duct network characteristics. Consider the thermodynamic […]

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Effect of Speed of Revolution

In the previous sections, the centrifugal and axial fans were investigated for a constant rotational speed. In this section, the rotational velocity is directly proportional to the rota­tional velocity n according to the equation u = irDn. The impeller blade an­gles remain the same regardless of the rotational velocity of the impeller. Hence, the inlet […]

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Axial Fans

Figure 9.43 shows the schematic diagram of an axial fan system. The air flows through a nozzle toward the impeller, where static pressure rises. The impeller is attached to a hub. The impeller is also called the propeller. The propeller is followed by a diffuser. When the aim is to build a cheap fan system […]

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Centrifugal Fan

In this type of fan, the gas flows initially in an axial direction toward the impeller. After this, in a part of the impeller blade, the gas flow becomes radial. To force the air to flow through the impeller blades of a centrifugal fan, a tangential force is needed. According to the momentum law this […]

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FANS General

The fan is the heart of a ventilation system. The industrial engineer requires a comprehensive working knowledge of the subject of fan engineering for the following reasons: 1. The designer must fully appreciate the correct fan selection, by ensuring that its duty meets the requirements of the task for which it is intended. 2. In […]

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Air Distribution

1.3.1.19 Introduction The aim of this section is to provide a basic introduction to the methods by which air may enter a space and be distributed and to consider the govern­ing equation for the determination of the air quantity and temperature. The governing equation relating to airflow patterns in a space is not covered in […]

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Humidification and Dehumidification

1.3.1.16 Introduction Humidification and dehumidification (drying) of air are required in many commercial and industrial applications for the following reasons: • The control of air moisture content within the occupied space to ensure the well-being of human, animal, or plant life • The control of air moisture content within a space for process control or […]

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N Solid-Fuel-Fired Heaters

Furnace-type air heaters are manufactured from cast iron or steel, and cased in brickwork or steel. The cast-iron heaters are sectional, cemented and bolted together. The steel type are welded or riveted. It is essentia] that the joints are airtight, so that the cold air can pass over the heated surfaces of the furnace and […]

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AIR-HANDLING PROCESSES Air-Heating Equipment

1.3.1.7Introduction Many different methods of heating the air for industrial ventilation purposes are possible. In all warm-air design applications, consideration must be given to the ef­fects of stratification in tall buildings. Stratification increases the roof and high-wall fabric losses and the air change rate by the stack effect, and hence the ventilation loss. These effects […]

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