Measured performance of conventional and high-velocity distribution systems in attic and space locations

Residential distribution systems are inherently inefficient at delivering heated or cooled air to the conditioned space as the result of poor design and installation practices. Examples of some of the more common problems include heat loss/gain in unconditioned spaces and leakage through supply and return ducts. These defects can result in significantly increased energy consumption, poor thermal comfort, and high peak electricity demand. Efforts to improve distribution systems

A duct performance model that includes the effects of leakage

A model for air flow inside ducts with leakages has been established from the equations governing the variation of total pressure and velocity along the duct. It was found that duct performance could be expressed as a function of two dimensionless constants, allowing the calculation of the required total pressure and velocity in the duct.

Response of low velocity thermal anemometers to step-up and step-down changes of velocity

Three methods : step-up velocity change, step-down velocity change, and the cut-off frequency method were tested for the dynamic response of two low velocity thermal anemometers.This paper had the objective to identify whether those methods recommended in the standards and guidelines always succeed in determining accurately the frequency response curves and the time constant of low velocities anemometers.

Correlations between the indoor airflow and thermal comfort criteria

Influences of architectural parameters , solar heat gain of glazing envelopes, thermal inertia on opaque walls indoor air velocity and physiological parmeters has been taken in account to estimate indoor thermal comfort for occupants.

Modeling of complex air diffuser for CFD simulation. Part 1 : experiment and numerical simulation of a complex air diffuser under isothermal condition

Part 1 of this paper gives first an outline of the experiment (full-scale measurement of the air velocity carried under isothermal condition), then discusses the 2 modeling methods - the BOX method and the P.V. method - used for CFD simulation.The results of calculations with the 2 methods showed good agreement with the experimental data.

Flow behaviour in a ventilated room - Measurements and simulations -

Disturbances from the surroundind environment and boundary conditions can influence very much the flow pattern , particles concentration and temperature distribution in a room.This report confirms the importance of working with measurements and simulations in parallel. Simulations of indoor air quality need to be validated . Guidelines on how to combine results are discussed in the paper.

The effect of enclosure size on turbulence in axisymmetric jets

The paper presents the results of the measurement of turbulence intensity in jets issued into enclosures of different size. The test results confirm the relation between the velocity distribution coefficient and turbulence parameters.

Analysis of thermal plumes generated by a seated person, a thermal manikin and a dummy

The experiment shows that the temperature and velocity fields generated above a seated person are comparatively better approached by a thermal manikin rather than a cylindrical dummy.

The effect of enclosure size on the air velocity distribution in axisymmetric jets

The paper presents the results of experimental tests : the enclosure size and background turbulence in the surroundings of the jet have an influence on the air velocity distribution in axisymmetric jets

Modeling of complex air diffuser for CFD simulation. Part 2 : air diffuser model based on airflow data obtained by unstructured CFD simulation

In this paper the application of CFD simulation with unstructured fine elements system was carried out to obtain airflow data for the boundary conditions for an air flow.Tthe results were compared with the measured data.