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HFC-134A and HCFC-22 supermarket refrigeration demonstration and laboratory testing. Phase I. Final report

Description: Aspen Systems and a team of nineteen agencies and industry participants conducted a series of tests to determine the performance of HFC-134a, HCFC-22, and CFC-502 for supermarket application. This effort constitutes the first phase of a larger project aimed at carrying out both laboratory and demonstration tests of the most viable HFC refrigerants and the refrigerants they replace. The results of the Phase I effort are presented in the present report. The second phase of the project has also been completed. It centered on testing all viable HFC replacement refrigerants for CFC-502. These were HFC-507, HFC-404A, and HFC-407A. The latter results are published in the Phase II report for this project. As part of Phase I, a refrigeration rack utilizing a horizontal open drive screw compressor was constructed in our laboratory. This refrigeration rack is a duplicate of one we have installed in a supermarket in Clifton Park, NY.
Date: April 1, 1996
Partner: UNT Libraries Government Documents Department

Hydrogen storage on activated carbon. Final report

Description: The project studied factors that influence the ability of carbon to store hydrogen and developed techniques to enhance that ability in naturally occurring and factory-produced commercial carbon materials. During testing of enhanced materials, levels of hydrogen storage were achieved that compare well with conventional forms of energy storage, including lead-acid batteries, gasoline, and diesel fuel. Using the best materials, an electric car with a modern fuel cell to convert the hydrogen directly to electricity would have a range of over 1,000 miles. This assumes that the total allowable weight of the fuel cell and carbon/hydrogen storage system is no greater than the present weight of batteries in an existing electric vehicle. By comparison, gasoline cars generally are limited to about a 450-mile range, and battery-electric cars to 40 to 60 miles. The project also developed a new class of carbon materials, based on polymers and other organic compounds, in which the best hydrogen-storing factors discovered earlier were {open_quotes}molecularly engineered{close_quotes} into the new materials. It is believed that these new molecularly engineered materials are likely to exceed the performance of the naturally occurring and manufactured carbons seen earlier with respect to hydrogen storage.
Date: November 1, 1994
Creator: Schwarz, J. A.
Partner: UNT Libraries Government Documents Department

Energy use and domestic hot water consumption - Phase 1. Final report

Description: New York State Energy Research & Development Authority has sponsored a project to develop comprehensive operating data on combined domestic hot water (DHW) and heating systems to be used in system design and specifications. The new, more precise DHW flow data (broken down on a per capita basis) result in a better foundation for sizing decisions. Thirty New York City multifamily buildings with combined steam heating and DHW plants were instrumented to monitor apartment, outdoor, boiler and DHW temperatures, and burner on-off times. In nine buildings, which had been upgraded, additional data collected were: stack temperature, DHW flow in 15-minute increments, oil and boiler make-up water flows, and DHW temperature before and after the mixing valve and on the return line. The data set collected for 14 months amounts to a data base of over 110 megabytes. This report presents DHW demand patterns, seasonal variations, weekday vs. weekend consumption, consumption vs. occupancy levels, coincidence of 15-, 60-, 120-, and 180- minute demand periods, and average vs. peak demand levels, as well as figures for energy to generate DHW. The format of guidelines presented in this report differs from those currently in use. The {open_quotes}Low - Medium - High{close_quotes} (LMH) users set of guidelines provide a range, rather than a specific, singular gallonage standard. By providing LMH tables and guidelines for their application the design engineer or contractor can then use these as a tool from which to select the appropriate level that matches the site being served. Values are presented for both New York sizing guidelines (developed from this study), as well as a set of {open_quote}National{close_quote} figures (derived from a compilation of studies conducted in other cities). The LMH approach and {open_quote}National{close_quote} guidelines were adopted for inclusion in the 1995 ASHRAE Handbook revision.
Date: November 1, 1994
Creator: Goldner, F. S.
Partner: UNT Libraries Government Documents Department

Leachate treatment system using constructed wetlands, Town of Fenton sanitary landfill, Broome County, New York. Final report

Description: Municipal sanitary landfills generate leachate that New York State regulations require to be collected and treated to avoid contaminating surface water and groundwater. One option for treating leachate is to haul it to municipal wastewater treatment facility. This option may be expensive, may require excessive energy for transportation, and may require pretreatment to protect the receiving facility`s processes. An alternative is on-site treatment and discharge. Personnel from the Town of Fenton, New York; Hawk Engineering, P.C.; Cornell University; and Ithaca College designed, built, and operated a pilot constructed wetland for treating leachate at the Town of Fenton`s municipal landfill. The system, consisting of two overland flow beds and two subsurface flow beds has been effective for 18 months in reducing levels of ammonia (averaging 85% removal by volatilization and denitrification) and total iron (averaging 95% removal by precipitation and sedimentation), two key constituents of the Fenton landfill`s leachate. The system effects these reductions with zero chemical and energy inputs and minimal maintenance. A third key constituent of the leachate, manganese, apparently passes through the beds with minimal removal. Details and wetland considerations are described.
Date: November 1, 1993
Partner: UNT Libraries Government Documents Department

Uncertainty analysis of the Measured Performance Rating (MPR) method. Final report

Description: A report was commissioned by the New York State Energy Research and Development Authority and the Electric Power Research Institute to evaluate the uncertainties in the energy monitoring method known as measured performance rating (MPR). The work is intended to help further development of the MPR system by quantitatively analyzing the uncertainties in estimates of the heat loss coefficients and heating system efficiencies. The analysis indicates that the MPR should detect as little as a 7 percent change in the heat loss coefficients and heating system efficiencies. The analysis indicate that the MPR should be able to detect as little as a 7 percent change in the heat loss coefficient at 95 percent confidence level. MPR appears sufficiently robust for characterizing common weatherization treatments; e.g., increasing attic insulation from R-7 to R-19 in a typical single-story, 1,100 sq. ft. house resulting in a 19 percent reduction in heat loss coefficient. Furnace efficiency uncertainties ranged up to three times those of the heat loss coefficients. Measurement uncertainties (at the 95 percent confidence level) were estimated to be from 1 to 5 percent for heat loss coefficients and 1.5 percent for a typical furnace efficiency. The analysis also shows a limitation in applying MPR to houses with heating ducts in slabs on grade and to those with very large thermal mass. Most of the uncertainties encountered in the study were due more to the methods of estimating the ``true`` heat loss coefficients, furnace efficiency, and furnace fuel consumption (by collecting fuel bills and simulating two actual houses) than to the MPR approach. These uncertainties in the true parameter values become evidence for arguments in favor of the need of empirical measures of heat loss coefficient and furnace efficiency, like the MPR method, rather than arguments against.
Date: November 1, 1993
Partner: UNT Libraries Government Documents Department

Laboratory for Laser Energetics annual report, 1 October 1991--30 September 1992. Inertial Fusion Program and National Laser Users Facility Program

Description: This is an annual report covering research progress on laser fusion and the OMEGA Upgrade design and development. In laser fusion, line-spectroscopy methods were demonstrated to be useful in diagnosing the core temperature and densities of polymer-shell targets; a theoretical analysis of nonlocal heat transport effects on filamentation of light in plasmas confirms that the principle mechanism driving filamentation is kinetic thermal rather than ponderomotive; a new method (spatial beam deflection) to produce laser pulses of arbitrary shape was developed; laser-plasma x-ray emission was measured using photodiode arrays; experiments on long-scale-length plasmas have shown that smoothing by spectral dispersion has proven effective in reducing Raman scattering; a method for increasing the gas-retention time of polymer shell targets was developed by overcoating them with aluminum. Experiments relating to the OMEGA Upgrade are described.
Date: January 1, 1993
Partner: UNT Libraries Government Documents Department

Evaluation and demonstration of decentralized space and water heating versus centralized services for new and rehabilitated multifamily buildings. Final report

Description: The general objective of this research was aimed at developing sufficient technical and economic know-how to convince the building and design communities of the appropriateness and energy advantages of decentralized space and water heating for multifamily buildings. Two main goals were established to guide this research. First, the research sought to determine the cost-benefit advantages of decentralized space and water heating versus centralized systems for multifamily applications based on innovative gas piping and appliance technologies. The second goal was to ensure that this information is made available to the design community.
Date: June 1, 1993
Creator: Belkus, P. & Tuluca, A.
Partner: UNT Libraries Government Documents Department

Methanol fuel vehicle demonstration: Exhaust emission testing. Final report

Description: Ford Motor Company converted four stock 1986 Ford Crown Victoria sedans to methanol flexible fuel vehicles (FFVs). During 143,108 operational miles from 1987 to 1990, the FFVs underwent more than 300 dynamometer driving tests to measure exhaust emissions, catalytic activity, fuel economy, acceleration, and driveability with gasoline and methanol blend fuels. Dynamometer driving tests included the Federal Test Procedure (FTP), the Highway Fuel Economy Test, and the New York City Cycle. Exhaust emission measurements included carbon dioxide, carbon monoxide (CO), nitrogen oxides (NO{sub x}), non- oxygenated hydrocarbons, organic material hydrocarbon equivalent (OMHCE), formaldehyde, and methanol. Catalytic activity was based on exhaust emissions data from active and inactive catalysts. OMHCE, CO, and NO{sub x} were usually lower with M85 (85% methanol, 15% gasoline) than with gasoline for both active and inactive catalysts when initial engine and catalyst temperatures were at or near normal operating temperatures. CO was higher with M85 than with gasoline when initial engine and catalyst temperatures were at or near ambient temperature. Formaldehyde and methanol were higher with M85. Active catalyst FTP OMHCE, CO, and NO{sub x} increased as vehicle mileage increased, but increased less with M85 than with gasoline. Energy based fuel economy remained almost constant with changes in fuel composition and vehicle mileage.
Date: July 1, 1993
Creator: Hyde, J. D.
Partner: UNT Libraries Government Documents Department

Fresh Kills leachate treatment and minimization study. Volume 1, Characteristics and treatment alternatives: Final report

Description: The New York City Department of Sanitation is developing a comprehensive landfill leachate management plan for the Fresh Kills Landfill. The leachate was first analyzed for conventional and priority pollutants. The leachate was well buffered at pH 7 to 8 with an alkalinity of 5,000 to 6,000 mg/L. The BOD was low, usually less than 100 mg/L, but the COD was as high as 1,800 mg/L. Ammonia concentrations were around 700 mg/L and the color resembled strong tea at 3,000 colorimetric units. Only few of the priority pollutants were present, and at extremely low concentrations. Based on the chemical characteristics of the leachate, the primary environmental impact would be on the oxygen balance of the receiving surface waters.
Date: September 1, 1993
Creator: Fillos, J. & Khanbilvardi, R.
Partner: UNT Libraries Government Documents Department

Fresh Kills leachate treatment and minimization study: Volume 2, Modeling, monitoring and evaluation. Final report

Description: The New York City Department of Sanitation is developing a comprehensive landfill leachate management plan for the Fresh Kills landfill, located on the western shore of Staten Island, New York. The 3000-acre facility, owned and operated by the City of New York, has been developed into four distinct mounds that correspond to areas designated as Sections 1/9, 2/8, 3/4 and 6/7. In developing a comprehensive leachate management plan, the estimating leachate flow rates is important in designing appropriate treatment alternatives to reduce the offsite migration that pollutes both surface water and groundwater resources.Estimating the leachate flow rates from Sections 1/9 and 6/7 was given priority using an available model, hydrologic evaluation of landfill performance (HELP), and a new model, flow investigation for landfill leachate (FILL). The field-scale analysis for leachate flow included data collection of the leachate mound-level from piezometers and monitoring wells installed on-site, for six months period. From the leachate mound-head contours and flow-gradients, Leachate flow rates were computed using Darcy`s Law.
Date: September 1, 1993
Creator: Fillos, J. & Khanbilvardi, R.
Partner: UNT Libraries Government Documents Department

Attic ventilation and air sealing: A technical review of the issues. Final report

Description: This report was commissioned by the New York State Energy Research and Development Authority and the New York State Department of State to review the history and state-of-the-art of attic ventilation and air sealing. It includes a mathematical model that is used to examine the complex relationships between such variables as attic bypass leakage area, outside air temperature, household moisture production, and venting area. The primary recommendation is to reduce heat and moisture flows into the attic by permanently sealing all air leakage paths between the house and attic, especially in climate areas that experience sustained periods of low wintertime temperatures. It concludes that current attic ventilation codes, which omit reference to considerations of climate zones, are of marginal utility to the building or retrofit industry and are in need of revision. Recommendations for further research are included.
Date: September 1, 1993
Partner: UNT Libraries Government Documents Department

New York state high-speed surface transportation study: Final report

Description: In 1990, New York State Governor Mario M. Cuomo created an interagency task force under the leadership of Lt. Governor Stan Lundine to investigate the potential of high speed ground transportation (HSGT) systems. Building on information from previous agency activities, including consultant efforts contracted by the New York State Energy Research and Development Authority (NYSERDA), the New York State Thruway Authority (NYSTA), and in-house analyses performed by New York State Department of Transportation (NYSDOT), the task force focused on the corridor between New York City and the Niagara Frontier. In December 1991, NYSERDA issued a contract for a study of high speed ground transportation options for New York State. The study`s objective was to assess potential rights-of-way, ridership, energy and environmental impacts, economic benefits, capital, operating, and maintenance costs, and financial viability of HSGT systems. This study builds upon and supplements previous and on-going HSGT activities conducted by the members of the interagency task force. These activities include: Maglev Technical and Economic Feasibility Study (NYSERDA); Maglev Demonstration Site Investigation (NYSTA); and New York/Massachusetts High Speed Ground Transportation Study (NYSDOT). This study is intended to verify and refine previous information and analyses and provide supplemental information and insights to be used in determining if additional investigation and activities involving HSGT are desirable for New York State. This study evaluates HSGT technologies capable of speeds significantly higher than those achieved with the present rail system. Three HSGT categories are used in this study: incremental rail improvement, very high-speed rail, and Maglev.
Date: August 1, 1994
Partner: UNT Libraries Government Documents Department

Early-warning process/control for anaerobic digestion and biological nitrogen transformation processes: Batch, semi-continuous, and/or chemostat experiments. Final report

Description: The objective of this project was to develop and test an early-warning/process control model for anaerobic sludge digestion (AD). The approach was to use batch and semi-continuously fed systems and to assemble system parameter data on a real-time basis. Specific goals were to produce a real-time early warning control model and computer code, tested for internal and external validity; to determine the minimum rate of data collection for maximum lag time to predict failure with a prescribed accuracy and confidence in the prediction; and to determine and characterize any trends in the real-time data collected in response to particular perturbations to feedstock quality. Trends in the response of trace gases carbon monoxide and hydrogen in batch experiments, were found to depend on toxicant type. For example, these trace gases respond differently for organic substances vs. heavy metals. In both batch and semi-continuously feed experiments, increased organic loading lead to proportionate increases in gas production rates as well as increases in CO and H{sub 2} concentration. An analysis of variance of gas parameters confirmed that CO was the most sensitive indicator variable by virtue of its relatively larger variance compared to the others. The other parameters evaluated including gas production, methane production, hydrogen, carbon monoxide, carbon dioxide and methane concentration. In addition, a relationship was hypothesized between gaseous CO concentration and acetate concentrations in the digester. The data from semicontinuous feed experiments were supportive.
Date: September 1, 1992
Creator: Hickey, R.
Partner: UNT Libraries Government Documents Department

Energy savings in one-pipe steam heating systems fitted with high-capacity air vents. Final report

Description: Multifamily buildings heated by one-pipe steam systems experience significant temperature gradients from apartment to apartment, often reaching 15{degrees}F. As a result, many tenants are to cold, or if the heating system output is increased so as to heat the coldest apartment adequately, too hot. While both are undesirable, the second is particularly so because it wastes energy. It was thought that insufficient air venting of the steam pipes contributed to the gradient. Theoretically, if steam mains and risers are quickly vented, steam will reach each radiator at approximately the same time and balance apartment temperatures. The project`s objective was to determine if the installation of large-capacity air vents at the ends of steam mains and risers would economically reduce the temperature gradient between apartments and reduce the amount of space heating energy required. The test was conducted by enabling and disabling air vents biweekly in 10 multifamily buildings in New York City between December 1992 to May 1993. The temperatures of selected apartments and total space heating energy were compared during each venting regime. There was no difference in energy consumption between ``vents on`` and ``vents off`` periods (see Tables 2 and 5); however, there was a reduction in the maximum spread of apartment temperatures.
Date: September 1, 1994
Partner: UNT Libraries Government Documents Department

Reduced gas pressure operation of sludge digesters: Expanded studies. Final report

Description: Previous investigations strongly suggested that the municipal anaerobic sludge digestion process could be enhanced by reactor operation with subatmospheric headspace pressures. Enhanced solids destruction and methane production along with increased process stability were observed in these earlier studies. However, due to the small scale of the anaerobic reactors used ( {approx}1.5 L), definitive steady-state measurements could not be obtained. These expanded studies were undertaken to verify and define the magnitude of the benefits that might be obtained with vacuum operation of sludge digesters. Four reactors ({approx}15.0 L) were fed municipal sludge at three different organic loading rates while being maintained with a 15-day solids retention time. One reactor had a constant headspace pressure of 1.02 atm; a second was maintained at 0.75 atm; and the remaining two reactors were operated for the majority of the day at 1.02 atm, and for part of the day with a 0.75 atm headspace pressure. Additional small-scale, batch experiments were performed to help identify controlling digestion mechanisms. The results of these expanded studies indicate that vacuum operation did not yield significant advantages over the organic loading range investigated (0.088 to 0.352 lb VSS/ft{sup 3}{center_dot}d).
Date: September 1, 1993
Partner: UNT Libraries Government Documents Department

LLE 1994 annual report, October 1993--September 1994

Description: This is the 1994 annual report for the University of Rochester, Laboratory for Laser Energetics. The report is presented as a series of research type reports. The titles emphasize the breadth of work carried out. They are: stability analysis of unsteady ablation fronts; characterization of laser-produced plasma density profiles using grid image refractometry; transport and sound waves in plasmas with light and heavy ions; three-halves-harmonic radiation from long-scale-length plasmas revisited; OMEGA upgrade status report; target imaging and backlighting diagnosis; effect of electron collisions on ion-acoustic waves and heat flow; particle-in-cell code simulations of the interaction of gaussian ultrashort laser pulses with targets of varying initial scale lengths; characterization of thick cryogenic fuel layers: compensation for the lens effect using convergent beam interferometry; compact, multijoule-output, Nd:Glass, large-aperture ring amplifier; atomic force microscopy observation of water-induced morphological changes in Y{sub 2}O{sub 3} monolayer coatings; observation of longitudinal acceleration of electrons born in a high-intensity laser focus; spatial intensity nonuniformities of an OMEGA beam due to nonlinear beam propagation; calculated X-ray backlighting images of mixed imploded targets; evaluation of cosmic rays for use in the monitoring of the MEDUSA scintillator-photomultiplier diagnostic array; highly efficient second-harmonic generation of ultra-intense Nd:Glass laser pulses multiple cutoff wave numbers of the ablative Rayleigh-Taylor instability; ultrafast, all-silicon light modulator; angular dependence of the stimulated Brillouin scattering in homogeneous plasma; femtosecond excited-state dynamics of a conjugated ladder polymer.
Date: January 1, 1995
Partner: UNT Libraries Government Documents Department

Spectral correction of silicon photodiode solar radiation detectors

Description: The multi-filter rotating shadowband radiometer (MFRSR) is a ground- based instrument that uses a silicon photodiode sensor to measure shortwave global and diffuse horizontal irradiance from which direct normal irradiance is calculated. Besides this multiplexing advantage, silicon sensors are rugged, stable and have a fast time response. On the other hand, silicon sensors are both thermally and spectrally sensitive. They, as do all pyranometric sensors, have an imperfect cosine response, especially at high solar-zenith angles. In the MFRSR two of these problems are solved. The MFRSR`s cosine response is measured and corrected. An automatic heater maintains the MFRSR detector at a constant temperature near 40 {degree}C. This paper describes a correction scheme, based on sky conditions, to account for the remaining spectral bias. The data base for these corrections was collected in Albany, New York, during 1993. The MFRSR and WMO firstclass thermopile instruments were sampled every 15 seconds and 5- minute averages were compared. The differences in time response between silicon and thermopile instruments contributes substantially to the remaining root-mean-square error reported.
Date: December 31, 1994
Creator: Zhou, C. & Michalsky, J.
Partner: UNT Libraries Government Documents Department

Confidential data in a competitive utility environment: A regulatory perspective

Description: Historically, the electric utility industry has been regarded as one of the most open industries in the United States in sharing information but their reputation is being challenged by competitive energy providers, the general public, regulators, and other stakeholders. As the prospect of competition among electricity power providers has increased in recent years, many utilities have been requesting that the data they submit to their utility regulatory commissions remain confidential. Withholding utility information from the public is likely to have serious and significant policy implications with respect to: (1) consumer education, the pursuit of truth, mutual respect among parties, and social cooperation; (2) the creation of a fair market for competitive energy services; (3) the regulatory balance; (4) regional and national assessments of energy-savings opportunities; (5) research and development; and (6) evaluations of utility programs, plans, and policies. In a telephone survey of all public utility commissions (PUCs) that regulate electric and gas utilities in the U.S., we found that almost all PUCs have received requests from utility companies for data to be filed as confidential, and confidential data filings appear to have increased (both in scope and in frequency) in those states where utility restructuring is being actively discussed. The most common types of data submitted as confidential by utilities dealt with specific customer data, market data, avoided costs, and utility costs.
Date: August 1, 1996
Creator: Vine, E.
Partner: UNT Libraries Government Documents Department

LLE Review: Quarterly report, July--September 1994. Volume 60

Description: This volume contains articles on efficient generation of second-harmonic radiation from short-pulse lasers; calculation of the stabilization cutoff wave numbers for the Rayleigh-Taylor instability; a high-frequency silicon optical modulator; the angular dependence of stimulated Brillouin scattering; and femtosecond dynamics of ladder polymers. Three of these articles--second-harmonic generation, Rayleigh-Taylor cutoff wave numbers, and angular dependence of Brillouin scattering--are directly related to the OMEGA Upgrade, currently under construction. A summary of the status of the OMEGA Upgrade laser facility and the NLUF News for FY94 are included in this volume.
Date: December 31, 1994
Creator: Knauer, J.P.
Partner: UNT Libraries Government Documents Department

LLE review: Quarterly report, April--June 1996. Volume 67

Description: This volume contains articles detailing several nonlinear processes associated with lasers and their use, as well as an article describing the computer control systems necessary to maintain and operate a large laser system such as the 60-beam OMEGA laser. The specific topics discussed in this issue include stimulated scattering in laser plasmas, power exchange between interacting laser beams, charged particles interacting with a laser pulse, thermal equilibration of optically excited states, an overview of the laser control system software in OMEGA, and a technique for cancellation of the nonlinear phase accumulation in short-pulse lasers.
Date: November 1, 1996
Creator: Skeldon, M.D.
Partner: UNT Libraries Government Documents Department

LLE review. Volume 66. Quarterly report, January--March 1996

Description: This volume of the LLE Review, covering the period January-March 1996, contains three articles related to spherical implosions and their diagnosis, one article that provides an analysis of laser-plasma interactions, and three articles on advanced technologies developed at LLE.
Date: June 1, 1996
Creator: Boehly, T.R.
Partner: UNT Libraries Government Documents Department

LLE 1995 annual report, October 1994--September 1995

Description: The fiscal year ending September 1995 (FY95) concluded the third year of the cooperative agreement (DE-FC03-92SF19460) with the U.S. Department of Energy (DOE). This report summarizes research at the Laboratory for Laser Energetics (LLE) and reports on the successful completion of the OMEGA Upgrade. Previous annual reports describe the OMEGA Upgrade design. The preliminary design for the system was complete in October 1989 and the detailed design started in October 1990. The original 24-beam OMEGA system was decommissioned in December 1992 as construction for the OMEGA Upgrade began. We discuss the initial performance results (p. 99) of the upgraded OMEGA laser system. All acceptance tests were completed, and we demonstrated that all 60 beams can irradiate a target with more energy and better beam balance than was required by DOE`s acceptance criteria. We are most proud that all program milestones were met or exceeded, and that the system was completed on time and on budget.
Date: January 1, 1996
Partner: UNT Libraries Government Documents Department

Time-dependent behavior of Mount Pinatubo aerosol

Description: The 15--16 June 1991 eruption of Mount Pinatubo delivered approximately 20 million metric tons of SO{sub 2} to the stratosphere. The SO{sub 2} plume from Mount Pinatubo straddled the equator resulting in a more symmetrical global distribution of the H{sub 2}SO{sub 4}-H{sub 2}O aerosol that results from the photochemical conversion of the SO{sub 2}. This paper follows the aerosol optical depth change over three-northern mid-latitude sites for the first sixteen months following the eruption. The technique to derive volcanic aerosol optical depth from ground-based measurements (which are, by their nature, total column aerosol optical depth measurements) follows the technique developed in an earlier parer to examine El Chichon aerosol. The three sites` time-dependent behavior is discussed and compared. Comparison of El Chichon and Mount Pinatubo aerosol optical depth change with time is also discussed for the one site that operated before, through, and after both eruptions.
Date: November 1, 1993
Creator: Michalsky, J. & Larson, N.
Partner: UNT Libraries Government Documents Department

Development of a demand defrost controller. Final report

Description: The purpose of this project was to develop and commercialize a demand defrost controller that initiates defrosts of refrigeration systems only when required. The standard method of control is a time clock that usually defrosts too often, which wastes energy. The controller developed by this project uses an algorithm based on the temperature difference between the discharge and return of the display case air curtain along with several time settings to defrost only when needed. This controller was field tested in a supermarket where it controlled defrost of the low-temperature display cases. According to test results the controller could reduce annual energy consumption by 20,000 and 62,000 kWh for hot gas and electric defrost, respectively. The controller saves electric demand as well as energy, is adaptable to ambient air conditions, and provides valuable savings throughout the year. The savings are greatest for low-temperature systems that use the most energy. A less tangible benefit of the demand controller is the improvement in food quality that results from fewer defrosts.
Date: October 1, 1993
Creator: Borton, D. N. & Walker, D. H.
Partner: UNT Libraries Government Documents Department