Air distribution systems

Minimization of pollutants from the combustion chamber. This approach consists of designing the engine with improved fuel-air distribution systems, ignition timing, fuel-air ratios, coolant and mixture temperatures, and engine speeds for minimum emissions. The majority of automobiles sold in the United States now use an electronic sensor/control system to adjust these variables for maximum engine performance with minimum pollutant emissions. 

Particulate filtration removes suspended liquid or solid materials whose size, shape, and mass allow them to remain airborne at the air velocity conditions present. Filters are available in a range of efficiencies, with higher efficiency indicating removal of a greater proportion of particles and of smaller particles. Moving to medium efficiency pleated filters is advisable to improve lAQ and increase protection for equipment. However, the higher the efficiency of the filter, the more it will increase the pressure drop within the air distribution system and reduce total airflow (unless other adjustments are made to compensate). It is important to select an appropriate filter for the specific application and to make sure that the HVAC system will continue to perform as designed. Filters are rated by different standards which measure different aspects of performance. 

Note Air distribution systems are not ventilation or air conditioning systems. For example, mixing air distribution and displacement air distribution are methods to bring the supply air to the treated space. 

Diffuser jet interaction is a common case when air is supplied into ventilated rooms through multiple air diffusers (e.g., sidewall-mounted grills or ceiling-mounted air diffusers) or using speciality air distribution systems. Interacting jets can be supplied... 

TABLE 9.10 Airtightness Classes as Defined in the EUROVENT Guidelines HI Air Leakage Rate in Sheet Metal Air Distribution Systems... 

Eurovent 2/2. Air leakage in sheet metal air distribution systems. 

To give the designer some advice, many recommendations exist in literature. Some general recommendations can be found in prEN 13779 for designing the air distribution system for low energy consumption. These include giving a certain target level for power consumption [the so-called SEP class. SEP means specific fan power, the ratio between the input power of fan mo tors and the total airflow, in W/(m s" )]. 

These issues are covered in more detail in DGB, Volumes B and C. Here, just a few basic tools have been introduced as guidance toward energy efficient air distribution systems in industry. 

Dampers in air handling units and air distribution systems Attention has to be paid to reducing the leakages, in accordance with EN 1751. Dampers used in mixing sections of air-handling units must fulfill additional requirements, in accordance with prEN 13053. 

Mixing in air-handling units and air distribution systems Some main principles are presented in Section 9.4. However, air mixing is a complicated process under srrong development. Also, the need for major improvements in the equipment has been identified very recently in connection with the standardization work in CEN (prEN 13053). 

Duct sealing Measures taken to ensure that the air distribution system has an airtight seal. 

Room air distribution system The method by which air is distributed within a space. 

A house is a complex system of interacting parts that contribute to overall performance including comfort, energy use, health, maintenance, and longevity. For example, a common air distribution system utilizes supply ducts running through the attic and return ducts tied directly to the air handler inside the home. If the ductwork is not properly sealed and there are combustion appliances in the home, this configuration can lead to health and fire hazards because the... 

Jump, D. A. Walker, I. S. Modera, M. P. (1996). Field Measurements of Efficiency and Duct Retrofit Effectiveness in Residential Forced Air Distribution Systems. In Proceedings of the ACEEE 1996 Summer Study on Energy Efficiency in Buildings, Vol. 1, pp. 147-155. Washington, DC American Council for an Energy Efficient Economy. 

Murphy, J. R., Air Products-HRI, The Development of Feed and Air Distribution Systems in Fluid Catalytic Cracking, presented at the 1984 Akzo Chemicals Symposium, Amsterdam, The Netherlands... 

Compressed air invariably contains water and usually oil from the compressor. It is also likely to pick up dirt and rust from the distribution line. For use in the laboratory, the air must be clean, particularly if it is to be used in instruments. One laboratory operator suggested the use of corrosion resistant pipes for the air distribution system in a building. This was turned down because of its high cost. The result was a heavy load of rust which began to accumulate in air filters after only a few months of operation. 

FCC feed, sulfur compounds in, 11 716 FCC unit emissions, 11 714 controlling, 11 689-694 FCC unit regenerators, 11 713 air distribution systems in, 11 726 catalyst emissions from, 11 714—715 CO2 emissions from, 11 720—721 configuration and mechanical hardware in, 11 722-731 cyclones in, 11 726-728 design of, 11 722-723 flue gas handling in, 11 729 fluidization in, 11 723-725 nitrogen oxide emissions from,... 

Aheam DG, Crow SA, Simmons RB, et al. 1996. Fungal colonization of fiberglass insulation in the air distribution system of a multi-story office building VOC production and possible relationship to a sick building syndrome. J Ind Microbiol 16 280-285. 

NOTE This method relies on either of two commercially available instruments that consist of a means of controlling sample temperature (maintained at 0.1 °C), an air distribution system, conductivity tubes, stoppers and probes, and electronics or software for measuring conductivity and determining induction period. The following steps are generally applicable to both the Rancimat and the Oxidative Stability Instrument however, some variations exist due to differences in hardware and models available. Consult the manufacturer s instructions for additional detail. 

Position the instrument in a well ventilated room or exhaust hood and connect compressed air source with water and hydrocarbon traps to the air distribution system of the instrument. 

Connect silicone tubing from air distribution system to sample tube. 

Start the determination. Place sample tubes into the heating block and connect the tubing from the air distribution system to the sample tubes, and from the sample tubes to the conductivity tubes. Position the aeration tubes 5 mm from the bottom of the sample tubes and the conductivity tubes. 

This section discusses the concentration levels of individual VOCs found in typical tropical office buildings, their potential health effects and possible sources. Eight buildings, considering their age, location and air distribution system were selected for the purpose of detailed characterization of VOCs. At the outset, the choice of selecting a measurement floor on the basis of its association with a dedicated air handling unit (AHU) was emphasized. A measurement floor was chosen such... 

---