What’s New in DOAS and Refrigerant Research?

From eSociety, June 2018

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The use of dedicated outdoor air systems (DOAS) for ventilation has become increasingly popular in all parts of the world. A well-designed system can ventilate a building at lower installed cost, reduce overall annual building energy use and improve indoor environmental quality.

A recently completed ASHRAE research project has developed a Design Guide for Dedicated Outdoor Air Systems (DOAS), which is now available in the ASHRAE bookstore. The intent of the guide is to compile existing knowledge into a single guide, focused on providing the working level HVAC designer with the tools needed to understand and design a DOAS. The project also drafted a chapter on DOAS for the HVAC Systems volume of the ASHRAE Handbook. This chapter will appear in the electronic version of the Handbook 2018 and in the 2020 print version.

1712-RP, Development of the ASHRAE Design Guide for Dedicated Outdoor Air Systems, was sponsored by TC 8.10, Mechanical Dehumidification Equipment and Heat Pumps. The principal investigator was Dr. Svein Morner with the Sustainable Engineering Group.

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With increased interest in low global warming potential (GWP) refrigerants, the industry is looking at HFCs that are flammable. ASHRAE Standard 34, Safety Standard for Refrigeration Systems and Designation and Classification of Refrigerants, references ASTM E681 to measure flammability and evaluate risk hazards.

An ASHRAE research project has studied ASTM E681 to improve repeatability and reproducibility. The final report details the setup of two experimental apparatuses: one meeting current guidelines of the standard, and one with alternate construction materials. New instrumentation has been added to both understand and quantify the behaviors of flame propagation, venting, quenching and flammability of concentration and initial test pressure.

The final report presents four improvements to the E681 that would significantly improve accuracy and reproducibility and are relatively easy to implement. A technical paper has been submitted for publication in a future edition of ASHRAE’s Science and Technology for the Built Environment.

1717-RP, Improve Accuracy and Reproducibility of ASTM-E681 Test Methods for Flammability Limit Measurement of 2L Flammable Refrigerants, was sponsored by TC 3.1, Refrigerants and Secondary Coolants. The principal investigator was Mr. Peter Sunderland with the University of Maryland.