fan

Within the Belgian Radon Programme the Belgian Building Research Institute is responsible for theinvestigation of techniques for prevention and mitigation of radon problems in dwellings. One of themost regular actions is the installation of a sub-slab depressurisation (SSD) system. As there are noready-to-use systems available on the Belgian market, a system has to be designed for every specificsituation.

This study examines the way of utilizing a ceiling fan for airflow control in a large air-conditionedroom. Although it seems that CFD simulation is useful in predicting the airflow around a ceiling fan, modeling of a ceiling fan as a body of rotation is very complicated. Therefore, in this study, airflow of a ceiling fan is modeled as boundary conditions of air velocity data measured near the ceiling fan.

Research has shown that highly efficient solar powered ceiling fans improve thermal comfort and potentially provide health benefits when air conditioning or conventional ceiling fans are not available, such as during the 2003 summer heat waves in Europe, and in many undeveloped areas of the world. Ceiling fans can improve the spatial effectiveness of heating, ventilation and air conditioning (HVAC) systems. They can reduce air conditioning energy use if occupants increase thermostat set-points and reduce frequency of operation, and if waste heat from the fan motor is minimized.

Part of the task in the design of ventilation systems involves selection and specification of system components - components sizes and expected performance characteristics or criteria to achieve specific ventilation objectives for anticipated environmental conditions. Careful selection of these components is required to ensure that they are able to react to changes in environmental conditions.

This paper provides an overview of the benefits of plenum fans and a detailed discussion of some of the pitfalls. After covering some of the benefits leading to extensive use of plenum fans, included is a brief discussion of the major complaint expressed about plenum fans, which is that plenum
fans are less efficient than housed fans. Finally, the bulk of the paper covers problems that can result from poor design practices, sloppy construction, and careless handling.

The analytical model described in the first part of the paper is partially validated here by comparing the theoretical results to experimental data collected in a series of model test experiments in an open-jet anechoic wind tunnel. The emphasis is on the validation of the trailing-edge noise model. A comparison is made with existing numerical computations in the literature. The transfer function is found to be roughly invariant with respect to flow conditions encountered on an isolated airfoil. Furthermore, a first application of the model to a cooling fan is presented.

This paper, the first of 2 parts, is dedicated to the analytical modeling of the broadband noise radiated by subsonic fans, such as encountered in HVAC or engine cooling applications. A fan noise prediction scheme is proposed on the basis of single-airfoil linearised unsteady aerodynamics theories. Spanwise distributed sources only are investigated, corresponding to three basic mechanisms, namely the noise from impingement of upstream turbulence, the trailing edge noise associated with turbulent boundary layer scattering, and vortex shedding noise.

This paper is a description of the design process of a new generation low noise axial fan. The emphasis is on the practical use of acoustic knowledge issued from published work and engineer know-how. The use of date issued from numerical simulation is also presented.

This paper presents a comparison of the predicted and measured acoustic system effect induced by a box with a lateral opening at the inlet of an axial flow fan. The objective of this study carried out on an academic configuration, is to develop and validate prediction models for real cases.

Energy efficient operation of variable speed fans in Variable Air Volume (VAV) systems ishighly dependent on both the type of duct design as well as the type of control strategy thathas been implemented in association with the volume flow demand profiles of each individualzone in the building. The quantification of energy savings due to duct design and the effects offan control have generally been poorly understood, even with very simplistic types of controlstrategies, e.g. static pressure P + I control which have often been employed.