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Completed Research—May 2018

A recently completed ASHRAE research project quantifies the sound attenuation of acoustically lined sheet metal ducts of varying lengths. The goal was to better predict attenuation and improve the tools currently available in the ASHRAE Handbook, which assume a simple linear relationship. The study looked at various duct shapes fittings, sizes and lining materials and presents empirical equations to a better approximation of the insertion loss.  

These new equations were compared with current methods of insertion loss prediction and shown to be significantly different. Two technical papers on this project have been submitted for future publication in ASHRAE Transactions.

1408-RP, The Effect of Lining Length on the Insertion Loss of Acoustical Duct Liner in Sheet Metal, was sponsored by TC 2.6, Sound and Vibration. The principle investigator was Dr. Douglas Reynolds with the University of Nevada, Las Vegas.

Shell and tube style flooded evaporators are commonly utilized as liquid cooler heat exchangers in HVAC chiller and refrigeration applications. An ASHRAE research project set out to better understand and characterize refrigerant flow into, through and out of the evaporator. This can have potential to correctly size evaporators, reduce design lengthy design times and improve system efficiency.

The final report details efforts to experimentally determine the size distribution, velocity and outflow and drop back of liquid refrigerant droplets emerging from the top of the tube bundle in a flooded evaporator. A parametric study was carried out to quantify the effects of surface geometry, fluid properties, and operating conditions on the droplet size distribution, velocity and egress and regress. A technical paper has been submitted for future publication in Science and Technology for the Built Environment.

1556-RP, Characterization of Liquid Refrigerant Flow Emerging From a Flooded Evaporator Tube Bundle, was sponsored by TC 1.3, Heat Transfer and Fluid Flow. The principle investigator was Dr. Steven Eckels with Kansas State University.