A diffuser is a device for reducing the velocity and increasing the static pressure of a fluid passing through a system."[1][2] The static pressure of the liquid passes through a conduit which is commonly known as pressure recovery. In contrast, a nozzle is used with the intention of increasing the discharge velocity and lowering the pressure, while the direction of flow runs in a particular direction.
Friction effects during the analysis period can sometimes be important, but are generally neglected. Conduits containing low-velocity fluids can generally be analyzed using Bernoulli's principle. Analysis of higher velocity flowing conduits with "mach numbers" in excess of 0.3 generally require compressible flow ratios.[3].
A typical subsonic diffuser is a duct that increases in size in the direction of flow. As the conduit increases in size, the fluid velocity decreases and the static pressure rises.
Both mass flow rate and Bernoulli's principle are responsible for these changes in pressure and velocity.
Supersonic diffusers
A supersonic diffuser is a duct that decreases in size in the direction of flow. As the conduit decreases in size, the fluid temperature, pressure, and density increase, while velocity decreases. Compressible flow is responsible for these changes in pressure, velocity, density, and temperature. Shock waves can also play an important role in a supersonic diffuser.
HVAC
Diffusers are very common in heating, ventilation and air conditioning systems.[4] Diffusers are used in both all-air and air-water HVAC systems, as part of the room air distribution subsystems, and serve several purposes:
• - To dispense air conditioning and ventilation.
• - Evenly distribute the air flow in the desired direction.
• - To improve the room air mixing, when the primary air is being discharged.
• - Often, because of the air jet(s) it is used to attach to a ceiling or other surface, taking advantage of the Coandă effect.
• - To create low velocity air circulation in the occupied part of the room.
• - Perform the above while the minimum amount of noise is produced.
Linear diffusers
Introduction
A diffuser is a device for reducing the velocity and increasing the static pressure of a fluid passing through a system."[1][2] The static pressure of the liquid passes through a conduit which is commonly known as pressure recovery. In contrast, a nozzle is used with the intention of increasing the discharge velocity and lowering the pressure, while the direction of flow runs in a particular direction.
Friction effects during the analysis period can sometimes be important, but are generally neglected. Conduits containing low-velocity fluids can generally be analyzed using Bernoulli's principle. Analysis of higher velocity flowing conduits with "mach numbers" in excess of 0.3 generally require compressible flow ratios.[3].
A typical subsonic diffuser is a duct that increases in size in the direction of flow. As the conduit increases in size, the fluid velocity decreases and the static pressure rises.
Both mass flow rate and Bernoulli's principle are responsible for these changes in pressure and velocity.
Supersonic diffusers
A supersonic diffuser is a duct that decreases in size in the direction of flow. As the conduit decreases in size, the fluid temperature, pressure, and density increase, while velocity decreases. Compressible flow is responsible for these changes in pressure, velocity, density, and temperature. Shock waves can also play an important role in a supersonic diffuser.
HVAC
Diffusers are very common in heating, ventilation and air conditioning systems.[4] Diffusers are used in both all-air and air-water HVAC systems, as part of the room air distribution subsystems, and serve several purposes:
• - To dispense air conditioning and ventilation.
• - Evenly distribute the air flow in the desired direction.
• - To improve the room air mixing, when the primary air is being discharged.
When possible, dampers, extractors, and other flow control devices should not be placed near the inlet diffusers (neck), they are not used at all because they are far away cause above. They have been shown to dramatically increase noise production. A rated performance diffuser, in a straight section of duct are necessary to serve a diffuser. An elbow, or bent flexible duct (just before the diffuser) often lead to poor air distribution and increased noise.
The diffusers can be round, rectangular, or linear slot in shape.
Occasionally, diffusers are generally used in reverse, as air inlets or returns. But more commonly, "Reja (architecture)" grilles are used as return or exhaust air inlets.
[4] ↑ Designer's Guide to Ceiling-Based Air Diffusion, ASHRAE, Inc., Atlanta, GA, USA, 2002.
• - Often, because of the air jet(s) it is used to attach to a ceiling or other surface, taking advantage of the Coandă effect.
• - To create low velocity air circulation in the occupied part of the room.
• - Perform the above while the minimum amount of noise is produced.
When possible, dampers, extractors, and other flow control devices should not be placed near the inlet diffusers (neck), they are not used at all because they are far away cause above. They have been shown to dramatically increase noise production. A rated performance diffuser, in a straight section of duct are necessary to serve a diffuser. An elbow, or bent flexible duct (just before the diffuser) often lead to poor air distribution and increased noise.
The diffusers can be round, rectangular, or linear slot in shape.
Occasionally, diffusers are generally used in reverse, as air inlets or returns. But more commonly, "Reja (architecture)" grilles are used as return or exhaust air inlets.