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Enhanced Building Performance Heat Transfer and Alternative Energy Systems Indoor Air Quality and Ventilation |
We identify and characterize new atmospherically-safe refrigerants and refrigerant mixtures that contribute to energy-efficient refrigerant applications. We also evaluate alternative refrigerant cycles, systems, and components that will operate efficiently with new refrigerants. Working with industry, we improve capabilities in determining the performance of alternative refrigerants and help refrigeration equipment manufacturers in designing refrigeration systems. In response to global warming concerns, we evaluate relative merits of ozone-safe hydrofluorocarbon (HFC) refrigerants, "natural" refrigerants, and their mixtures in a variety of refrigeration cycles. We perform laboratory tests and analytical evaluations through computer simulations. We study fluorocarbon and hydrocarbon mixtures in novel applications such as water-to-water heat pump. We evaluate performance merits of carbon dioxide in reference to HFC refrigerants in different comfort-cooling applications. We further develop some of our simulation models into public-domain simulation tools available to industry. These include vapor-compression cycle models, CYCLE-11.UA, CYCLE_D, and the leak/recharge simulation program for refrigerant mixtures, REFLEAK. To fully characterize
new refrigerants, we carry out fundamental pool-boiling, flow-boiling,
and condensation studies to determine heat transfer coefficients using
a variety of heat transfer surfaces. We also study the impact of additives
and lubricant content on the heat transfer mechanism using a novel fluorescence-spectroscopy
technique. Understanding the refrigerant-lubricant interaction may offer
an opportunity to formulate and select lubricants that improve the heat
transfer performance and system efficiency. Contact: Piotr A. Domanski We are fostering the development of more intelligent, integrated, and optimized building mechanical systems. We use a dynamic building heating, ventilating, and air-conditioning (HVAC) control system simulation program to study HVAC control system dynamics and interactions. We use our building management and controls laboratory to assist the building controls industry in the development, evaluation, and testing of communication protocol standards for the open exchange of information. NIST technologies serve as a basis for American Society of Heating, Refrigerating and Air-Conditioning Engineers standards to assist the control system manufacturers in developing interoperable systems and conformance testing methods. The application of "smart" control systems to buildings is a relatively new area of research that focuses on studying the integration and interaction of traditionally stand-alone building automation and control systems such as HVAC, fire, lighting, and security systems. This integration can occur within a single building or throughout multiple buildings connected through automation and control systems. Research topics include exploring how real-time models, on-line system identification, optimal control, and fault detection and diagnostics can be combined to improve control system performance, make control strategy decisions that optimize building operations, and advise the building operator or manager on building operations, equipment problems, or maintenance requirements. Our research on smart building control systems involves simulation and emulation studies, laboratory testing, and field studies in real buildings. Contact: Steven Bushby Heat Transfer and Alternative Energy Systems Buildings account for more than 40 percent of the U.S. energy consumption. A significant portion of this energy is used to provide space conditioning and water heating. We are developing basic data, measurement techniques, and performance prediction techniques to address barriers that impact the implementation of conservation and renewable energy resources. We assist industry by measuring the thermal conductivity of building and industrial thermal insulation materials using a 1-meter guarded hot plate, an apparatus that serves as the nation's standard. We have compiled a web database containing more than 70 years of thermal conductivity data to assist outside researchers and architects in the selection of appropriate insulation materials. We participated in international interlaboratory comparisons of thermal conductivity measurements that may lead to international measurement standards. The widespread use of building-integrated photovoltaics appears likely as a result of the continuing decline in photovoltaic manufacturing costs and the relative ease in which photovoltaics can be incorporated within the building envelope. However, designers, architects, installers, and consumers need more information and analysis tools to judge the merits of building-integrated solar photovoltaic products. In an effort to add to the knowledge base, we are collecting experimental electrical performance data on building-integrated photovoltaic products. The data will be used to validate computer models, currently under development, that will give architects and building owners the ability to make informed economic decisions regarding the role that photovoltaics can play in meeting energy needs. We also support the Department of Energy through the development of test methods for residential water heaters, heat pumps, and air-conditioners. These test methods are utilized in the calculation of the energy costs associated with each of these appliances. Contact: Hunter Fanney Indoor Air Quality and Ventilation Our research effort is focused on three areas: airflow and indoor air quality model development; ventilation and indoor air quality design methods; and impacts of indoor air quality control technologies. We are developing and applying improved, validated computer simulation programs to enable reliable performance prediction for research, development, design, and forensics. Model development activities are focused on the CONTAMW program, an internationally recognized multizone airflow and indoor air quality model, which predicts airflows and contaminant concentrations in buildings. We have used CONTAMW to study the indoor air quality impacts of heating, ventilating, and air-conditioning systems in single-family residential buildings, ventilation and infiltration in large mechanically ventilated office buildings, and radon entry and transport in large residential, office, and school buildings. In order to foster and facilitate the use of CONTAMW by the building industry, we provide information on multizone modeling, critical input data, supporting software, and discussion on various applications of multizone modeling on our Multizone Modeling website. Also, we are working
on new building design procedures that will enable true indoor air quality
design of buildings and systems, and advance the industry beyond current
prescriptive methods. We are developing design methods, software tools,
and supporting data to enable design approaches that move beyond tables
of ventilation rates and enable consideration of indoor contaminant levels
and technologies that can reduce these levels. These design methods are
based in part on the modeling techniques discussed above. We also are
conducting model validation efforts in residential and commercial buildings. In support of all of the above activities, we are developing and demonstrating measurement procedures to evaluate ventilation and indoor pollutant concentrations in buildings. These procedures range from sophisticated tracer gas methods used predominantly in building research efforts to less complex procedures that can be employed by building operators. One important result of our efforts is a unique database of building ventilation and indoor air quality performance. Contact: Andrew K. Persily Computer-Integrated Building Processes We are working collaboratively with the U.S. construction and building industries to establish an exemplary computer-integrated construction environment, based on open standards for the representation, access, exchange, use, and archiving of information. With these standards implemented in software systems, industry will be able to achieve its goal of seamlessly circulating information throughout its life-cycle work processes, all taking place in a loosely coupled, distributed, heterogeneous environment. Currently, we are concentrating on three areas: the integration of project information, the integration and automation of activities on the construction site, and the electronic commerce of technical information between supplier and project. The output of this research is prototype standards and protocols, measurement technologies, and testing procedures. Experiments to evaluate and demonstrate these outputs are conducted in a testbed that is open to industry and academia. Our near-term focus has been in support of the heavy industrial construction sector, dealing with capital projects such as chemical process plants. To ensure that our research is addressing industrial needs, we participate in industrial consortia, such as PlantSTEP Inc., Process Data Exchange Institute of the American Institute of Chemical Engineers, and in committees of the Construction Industry Institute. The focus is being broadened to other industry sectors as our research matures and as we establish industrial partnerships. We are exploring current and emerging information technologies, including traditional data-oriented and emerging object-oriented technologies, and new communication and collaboration technologies made possible by the Internet. A major theme of our research is the harmonization of different technologies to allow industry maximum flexibility in choosing technologies to meet its needs. Contact: Kent A. Reed
Date
created:
April 24, 2002 |