The experimental study determined the degradation in performance of large axial fans caused by close inlet walls. Three fans with hub to tip ratios of 0.30, 0.49 and 0.74 were each tested at four blade angles and over the flow rate range of wide open to near shutoff. The closest walls, 0.5.D front clearane and OD side clearance, caused only modest loss in flow rate, up to 3,5 % and less than a 5 % loss of efficiency in the O.49 H/T fan. The other two fans had only minor decreases in flow rate and in efficiency for the closest walls.

Fan energy use in variable-air-volume (VAV) systems can be reduced by resetting the supply duct pressure. The standard way to reset duct pressure is by controlling the most open terminaldamper to a nearly open position. This strategy is rarely used because of a variety of issues including sensing limitations, network bandwidth, and stability. This paper describes the development of a new method of determining the critical supply duct pressure for VAV systems.

Air-to-air energy recovery can be used to reduce ventilation loads for small commercial buildings. Enthalpy exchangers are one approach to energy recovery that is commonly employed. An alternative technology involves the use of a heat pump that operates between the ventilation and exhaust streams. In this paper, the performance of a ventilation heat pump heat recovery unit was studied through simulation. A model of the heat pump was developed and validated using

This paper evaluates the operating cost savings and overall economics associated with these two different ventilation load reduction technologies : demand-controlled ventilation (DCV) and enthalpy exchangers. A specialized simulation tool was developed and used to perform the evaluations. For both technologies, the savings potential and economic payback are better in more extreme climates., particularly in cold climates because the ventilation load is a larger portion of the overall load.

This paper shows how a combined air-to-air heat and energy recovery system design problem can be formulated for HVAC cabinet units and solved for the least life-cycle cost system while still retaining a small time period payback. Mathematical expressions are presented to address the complicating interaction between the components of the unit to facilitate the design process. The design process is illustrated for the city of Chicago where both large heating and cooling loads occur in HVAC applications.

A stereoscopic particle image velocimetry (SPIV) system was used to measure airflow characteristics in an irregularly shaped test room. These measurements were compared with air velocity measurements obtained by a sonic anemometer instrument, hot-wire instrument, and draft instrument. All of the measurements were taken at five measurement locations along the center plane of the test room. For each measuement location, numerous pairs of SPIV, sonic, hot-wire, and draft data were collected and averaged to determine the average velocity.

An initial study to develop a numerical tool using CFD methods for investigating the potential of disease transmission in commercial aircraft is completed. To gain insight of the general airflow pattern, a detailed CFD model of a small section in the passenger cabin of a B767-300 passenger cabin was built and a Reynolds-averaged Navier-Stokes (RANS) simulation was performed. By comparing with the available test date, the RANS simulation substantially underpredicted the turbulence intensity, especially in and around the breathing zone.

An initial study to develop a numerical tool using CFD methods for investigating the potential of disease transmission in commercial aircraft is completed. To gain insight of the general airflow pattern, a detailed CFD model of a small section in the passenger cabin of a B767-300 passenger cabin was built and a Reynolds-averaged Navier-Stokes (RANS) simulation was performed. By comparing with the available test date, the RANS simulation substantially underpredicted the turbulence intensity, especially in and around the breathing zone.

A hot and uncomfortable kitchen contributes to productivity loss, employee turnover, and eventually profit loss for the restaurant operator. Using thermal displacement ventilation in kitchen environment allows for a reduction in space temperature without increasing the air-conditioning system capacity. Application of two systems is compared in a typical kitchen environment using CFD modeling. Often kitchen exhaust hoods are provided with untempered makeup air.

Designers of HVAC systems serving educational facilities face considerable acoustical challenges in applying equipment that complies with the acoustical levels specified in ANSI/ASA Standard S12.60-2002. Like all ANSI standards, the imposition of S12.60 is voluntary, therefore, its evolution as a regulatory document is likely to be a gradual process. However, the lobby that led to its adoption over many industry concerns is strong and will likely speed its integration and the need for HVAC systems that comply with its mandated space noise levels.