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Constant air volume (CAV) is a type of heating, ventilating, and air-conditioning system. In a simple CAV system, the supply air flow rate is constant, but the supply air temperature is varied to meet the thermal loads of a space. [1] Most CAV systems are small, and serve a single thermal zone.
Air is drawn from the workplace, around the worker and into the front of the hood, and is then exhausted out of the laboratory. Most laboratory hoods are described as constant air volume (CAV) hoods because they draw air constantly at all times. Rising energy costs have made these hoods exceptionally expensive to operate.
Again, a centrifugal fan is a constant volume device that will move the same amount of air at two different temperatures. If, for example, a centrifugal fan moves 1,000 CFM at 70°F it will also move 1,000 CFM at 200°F. The air volume delivered by the centrifugal fan is not affected by density.
Pages in category "Heating, ventilation, and air conditioning" The following 200 pages are in this category, out of approximately 248 total. This list may not reflect recent changes .
[38]: 12 The air going through the hood maintains a constant volume no matter where the sash is positioned and without changing fan speeds. As a result, the energy consumed by CAV fume hoods (or rather, the energy consumed by the building HVAC system and the energy consumed by the hood's exhaust fan) remains constant, or near constant ...
This mechanism is found very commonly in everyday life, including central heating and air conditioning and in many other machines. Forced convection is often encountered by engineers designing or analyzing heat exchangers, pipe flow, and flow over a plate at a different temperature than the stream (the case of a shuttle wing during re-entry, for example).
Doing this work, air inside the cylinder will cool to below the target temperature. To return to the target temperature (still with a free piston), the air must be heated, but is no longer under constant volume, since the piston is free to move as the gas is reheated. This extra heat amounts to about 40% more than the previous amount added.
If specific heat is expressed per mole of atoms for these substances, none of the constant-volume values exceed, to any large extent, the theoretical Dulong–Petit limit of 25 J⋅mol −1 ⋅K −1 = 3 R per mole of atoms (see the last column of this table).