English

When ASHRAE Standard 52.2-1999 was written, Standard Project Committee 52.2 recognized that the first dust loading step, also called the conditioning step, was not fully adequate for revealing the drop in efficiency that electret filters undergo during actual use. This is pointed out in the standards

Current models and test methods for determining filter efficiency ignore filter bypass, the air that circumvents filter media because of gaps around the filter or filter housing. In this paper, we develop a general model to estimate the size-resolved particle removal efficiency, including bypass, of HVAC filters. The model applies the measured pressure drop of the filter to determine the airflow through the bypass cracks and accounts for particle loss in the bypass cracks. We consider a particle

This paper presents a comprehensive discussion about past, present and future research focused on air curtain performance optimization. The past reserach mostly relies on simplified analytical solutions for jets. The present approach takes a more comprehensive step toward understanding and quantification of all major parameters that affect the air curtain flow field by utilization of modern analytical/computational and experimental techniques. The goal of future work is a systematic approach to map optimum air curtain performance as a function of the major design parameters.

A research project is being conducted at the National Research Council of Canada (NRC) to evaluate the effectiveness of current emergency ventilation strategies to control smoke spread in the event of a fire in two road tunnels. The research study includes numerical and experimental phases. The numerical phase uses computational fluid dynamics (CFD) models to study smoke ventilation in the tunnels. The experimental phase is used to calibrate and to partially validate
the chosen CFD models and to provide the necessary initial and boundary conditions.

This paper compares CFD models and field-measured data from four large enclosed locomotive facilities. For each facility, CFD models were built using two computational fluid dynamics programs. These included a commercially available software package using a revised Reynolds Averaged Navier-Stokes (RANS) k-epsilon model and a public domain large eddy simulation model. This paper discusses the development of the models, compares their predictions with field measurements,

The air performance effects expected due to inlet velocity distortion for axial fans is predicted based on basic airfoil data. This expectation is compared with the test data gathered in RP-1010. Sound data for various inlet configurations are also presented to help understand the test data.

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.

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.

With sponsorship from the US Department of Energy, a research project has designed, fabricated, and tested improvements to an air conditioner’s outdoor unit fan system. The primary objective was to improve condenser fan performance while reducing motor po