Search results
Results From The WOW.Com Content Network
The airtightness of a building is often expressed in terms of the leakage airflow rate through the building's envelope at a given reference pressure (usually 50 pascal) [10] divided by the: Heated building volume V. At 50·Pa, it is called the air change rate at 50 Pa and usually noted n 50 (units: h −1). [13] [14] Envelope area A E.
The airflow, (Imperial in Cubic Feet / minute; SI in liters / second) at a given building-to-outside pressure differential, 50 pascal (Q 50). This standardized single-point test allows for comparison between homes measured at the same reference pressure. This is a raw number reflecting only the flow of air through the fan.
The relationship between pressure and leakage air flow rate is defined by the power law model between the airflow rate and the pressure difference across the ductwork envelope as follows: q L =C L ∆p n. where: q L is the volumetric leakage airflow rate expressed in L.s −1; C L is the air leakage coefficient expressed in L.s −1.Pa −n
The infiltration rate is the volumetric flow rate of outside air into a building, typically in cubic feet per minute (CFM) or liters per second (LPS). The air exchange rate, (I), is the number of interior volume air changes that occur per hour, and has units of 1/h. The air exchange rate is also known as air changes per hour (ACH).
A duct leakage tester is a diagnostic tool designed to measure the airtightness of forced air heating, ventilating and air-conditioning (HVAC) ductwork. A duct leakage tester consists of a calibrated fan for measuring an air flow rate and a pressure sensing device to measure the pressure created by the fan flow.
Displacement ventilation systems supply air directly to the occupied zone.The air is supplied at low velocities to cause minimal induction and mixing. This system is used for ventilation and cooling of large high spaces, such as auditorium and atria, where energy may be saved if only the occupied zone is treated rather than trying to control the conditions in the entire space.
Diffusers can be as a shape of round, rectangular, or can be as linear slot diffusers (LSDs). E.g., linear slot diffusers take the form of one or several long, narrow slots, mostly semi-concealed in a fixed or suspended ceiling with airfoils behind the slots directing the airflow in the desired direction.
Bleed air in aerospace engineering is compressed air taken from the compressor stage of a gas turbine, upstream of its fuel-burning sections.Automatic air supply and cabin pressure controller (ASCPC) valves bleed air from low or high stage engine compressor sections; low stage air is used during high power setting operation, and high stage air is used during descent and other low power setting ...