September 2009

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BFRL Researchers Characterize Air Flow Distribution Through Air-to-Refrigerant Heat Exchanger

In cooperation with and partial sponsorship by the Air- Conditioning and Refrigeration Technology Institute, BFRL completed a comprehensive experimental and analytical study in which they characterized the air flow distribution through a finned-tube, air-to-refrigerant heat exchanger. The HVAC&R industry has long been aware of the performance degradation of heat exchangers due to nonuniform air distribution and the consequent impact on the overall energy use by air-conditioning and refrigeration equipment. However, air velocity distributions have been left uncharacterized because of the difficulty in obtaining accurate data using conventional measurement instruments.

The researchers from the BFRL’s HVAC&R Equipment Performance Group used particle image velocimetry to make detailed measurements of the air flow approaching and leaving a heat exchanger under various operating conditions, and used these measurements as the basis for developing a computational fluid dynamics predictive method. The results of these measurements and simulations showed large regions of highly maldistributed air flow. The nature of the measured flow patterns indicated the possibility to achieve significant efficiency improvements by implementing design changes, some of which would also reduce manufacturing costs.

CONTACT:
David Yashar
301-975-5868

ISO Adopts New Version of BACnet Standard for Building Automation and Control Devices

The International Organization for Standardization (ISO) has adopted a revised version of the BACnet (building automation and control networks) communication protocol standard. The BACnet standard, developed by BFRL researchers in close collaboration with industry and the American Society of Heating, Refrigerating, and Air- Conditioning Engineers (ASHRAE), enables the integration of a broad range of building automation and control devices.

This revision to the standard includes a number of new BACnet features that expands capabilities for applications such as physical access control systems, Web service interfaces to link building automation information with business management tools, and reducing peak electrical loads. A revised version of a companion standard that serves as the basis for product testing was also adopted. More than 30 countries had adopted the previous version of BACnet as a national standard. It is expected that they will now adopt the newly revised version.

SHRAE has a standing committee that maintains and enhances the capability of the BACnet standard under a “continuous maintenance” process. This action by ISO aligns the ISO version of BACnet with recent revisions to the ASHRAE standard.

CONTACT:
Steven Bushby
301-975-5873

CYCLE_D: Refrigerant Screening Database Released

A new version of NIST Standard Reference Database 49 CYCLE_D: NIST Vapor Compression Cycle Design Program was recently released. The simulation model facilitates screening of refrigerants, both singlecompound fluids and mixtures, for application in different vapor compression-based space conditioning and refrigerating systems. S. Brown (Catholic University of America), Piotr Domanski (BFRL) and Eric Lemmon (CSTL) cooperated on this release.

The new Version 4.0 of CYCLE_D is a complete revision of the database. The simulation capabilities were expanded beyond the single-stage subcritical cycle of the previous versions to allow industry users to explore advanced cycle options such as two-stage cycle with intercooling, and two-stage and three-stage cycles with an economizer in their attempts to improve system efficiencies. In addition, other new simulation options include single-stage supercritical cycle for evaluating the performance of carbon dioxide, an alternative to currently used hydrofluorocarbon (HFC) refrigerants.

CYCLE_D uses the latest version of REFPROP, NIST's Standard Reference Database 23 (www.nist.gov/ srd/nist23.htm) for representation of the thermophysical properties of the refrigerants. To the greatest extent possible, CYCLE_D has become compatible with REFPROP from the user’s point of view by mimicking REFPROP’s management of refrigerant data files, by implementing similar steps as REFPROP for refrigerant selection, and by REFPROP-like graphical representation of the simulation results. Further information on CYCLE_D is available at the Standard Reference Data Program Web site at www.nist.gov/srd/nist49V04.htm.

CONTACT:
Piotr Domanski
301-975-5877

NIST Smart Grid Workshop Maps Actions Plans

The NIST Smart Grid Interoperability Standards Project continues to make significant progress. On Aug. 3-4, 2009, it convened a workshop to engage standards development organizations and other Smart Grid stakeholders to review and begin responding to action plans that address 14 standards-related priorities. The meeting succeeded in forging consensus agreements on paths forward in each area that, together, will enable accelerated development and adoption of Smart Grid standards.

The Energy Independence and Security Act of December 2007 called on NIST to coordinate the development of a framework “to achieve interoperability of smart grid devices and systems…” NIST has since then worked closely with federal and industry partners to identify relevant existing standards and to define gaps and priority issues. This most recent workshop follows two others, one on identifying key existing standards and the other on setting priorities for new standardization efforts. Altogether, more than 1,500 people have participated in these public workshops. In June 2009, the Electric Power Research Institute, or EPRI (under contract to NIST), issued its Report to NIST on the Smart Grid Interoperability Standards Roadmap. The 14 priority actions plans developed by NIST for review at the recent workshop drew significantly from the report. The refined priority action plans resulting from the current workshop, including sets of assigned tasks, with target dates, for nearly all priorities will be integrated into the NIST Smart Grid Framework and Standards Roadmap, version 1.0, which NIST intends to release in September 2009. This will be a living document, necessary to guide development and implementation of the hundreds of standards that ultimately will be needed to build a modern electric power grid that is secure and fully interoperable, end to end.

The August 2009 workshop addressed standards issues, including: role of Internet Protocol (IP), wireless communications, customer access to meter data, pricing data model, demand response, electric vehicle interconnection, storage data models, transmission and distribution communication standards harmonization, and standard meter data profiles. As an example of accomplishments, the pricing data model breakout session produced an action plan that calls on the Organization for the Advancement of Structured Information Standards (OASIS) and the North American Energy Standards Board to lead a cross-domain activity to address: highlevel price communication requirements, survey of existing price communications, and development of a data model with a draft pricing specification within the OASIS Energy Market Information Exchange Technical Committee, due in six months. This work involves stakeholders from financial, regulatory, utility, transmission operator, and end-use sectors (residential and large customers). Details on the results from the workshop and ongoing progress are available via the NIST Smart Grid Web site at: www.nist.gov/smartgrid.

CONTACT:
David Holmberg
301-975-6450

BFRL and CSTL Organize International Refrigeration Conference

BFRL and CSTL partnered with the International Institute of Refrigeration, (IIR) to organize the 3rd IIR Conference on Thermophysical Properties and Transfer Processes of Refrigerants, June 23-26, 2009, in Boulder, Colo. The conference was held jointly with the 17th Symposium on Thermophysical Properties, which is organized by CSTL in Boulder every third year. BFRL’s Piotr Domanski and CSTL’s Mark McLinden co-chaired the conference.

Increased concerns about climate change places a discussion focus on refrigerants as greenhouse gases and on refrigeration systems as energy users responsible for CO2 emissions from power plants. In response, the search for new refrigerants continues and new technological solutions are sought. Accurate knowledge of thermophysical properties and in-depth understanding of heat and mass transfer phenomena are essential to accurately model these processes, and optimize refrigeration systems and their components. In this context, the conference covered the areas of research that are prerequisites for advancing refrigeration technology.

The conference was attended by 110 researchers from 20 countries. The program listed 77 presentations in 19 sessions (including sessions held jointly with the 17th symposium). The topics included measurement and modeling of thermophysical properties, current issues in heat transfer, and concepts for improving system efficiency. Three sessions covered CO2 systems and CO2 heat transfer. Of particular interest were three sessions devoted to the properties and applications of novel fluids with a low global warming potential.

CONTACT:
Piotr Domanski
301-975-5877

BFRL Contributes to International Effort on Sustainability Performance Metrics

On July 23, 2009, BFRL’s Bobbie Lippiatt delivered a plenary talk at the Organisation for Economic Cooperation and Development (OECD) Workshop on Best Practices in Assessing the Environmental and Economic Sustainability of Biobased Products. She was invited by the OECD Directorate for Science, Technology, and Industry to give a talk about BFRL’s sustainability performance metrics and tool known as BEES (Building for Environmental and Economic Sustainability). With over 25,000 users worldwide, the popular science-based tool for evaluating the business case for “green” products is required by federal rulemaking for use in the USDA preferred procurement program known as BioPreferred. BioPreferred was created by the 2002 Farm Bill, and expanded by the 2008 Farm Bill, to increase the purchase and use of biobased products (commercial or industrial products composed of biological products or renewable domestic agricultural materials or forestry materials). USDA requires BEES evaluation of biobased products prior to “designation” by rulemaking for preferred purchasing.

TheThe OECD Task Force on Industrial Biotechnology decided in November 2008 that best practices for sustainability performance measurement are needed. OECD considers BEES a best practice in the United States, having just published a report featuring BEES, Metrics to Support Informed Decision-Making for Consumers of Biobased Products, co-authored by the USDA Office of the Chief Economist, BFRL, and the DOE Office of the Biomass Program. The purpose of the workshop was to provide expert input to either a medium-impact OECD report on emerging international best practices in assessing the sustainability of biobased products or a highimpact OECD policy instrument on biobased product sustainability measurement requiring OECD member countries to agree to implement its recommendations.

CONTACT:
Bobbie Lippiatt
301-975-6133

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