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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.
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.
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).
Variable air volume (VAV) is a type of heating, ventilating, and/or air-conditioning system. Unlike constant air volume (CAV) systems, which supply a constant airflow at a variable temperature, VAV systems vary the airflow at a constant or varying temperature.
An HVAC system that has a stable supply-air temperature, and varies the air flow rate to meet the temperature requirements. Compared to constant air volume systems, these systems conserve energy through lower fan speeds during times of lower temperature control demand. Most new commercial buildings have VAV systems.
The process does no pressure-volume work, since such work is defined by =, where P is pressure. The sign convention is such that positive work is performed by the system on the environment. If the process is not quasi-static, the work can perhaps be done in a volume constant thermodynamic process. [1]
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.
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.