6,806 research outputs found

    Techno-economic projections for advanced small solar thermal electric power plants to years 1990-2000

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    Advanced technologies applicable to solar thermal electric power systems in the 1990-200 time-frame are delineated for power applications that fulfill a wide spectrum of small power needs with primary emphasis on power ratings less than 10MWe. Projections of power system characteristics (energy and capital costs as a function of capacity factor) are made based on development of identified promising technologies and are used as the basis for comparing technology development options and combinations of these options to determine developmental directions offering potential for significant improvements. Stirling engines, Brayton/Rankine combined cycles and storage/transport concepts encompassing liquid metals, and reversible-reaction chemical systems are considered for two-axis tracking systems such as the central receiver or power tower concept and distributed parabolic dish receivers which can provide efficient low-cost solar energy collection while achieving high temperatures for efficient energy conversion. Pursuit of advanced technology across a broad front can result in post-1985 solar thermal systems having the potential of approaching the goal of competitiveness with conventional power systems

    Air Conditioning Hybrid Electric Vehicles while Stopped in Traffic

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    HEVs idle their engine during the stops to meet the cooling and heating needs. But, idling decreases fuel economy and increases engine wear and emissions. The report explores alternative strategies for air conditioning the HEV during the stop times. Simulation analyses are used to identify fundamental differences and new technology tradeoffs encountered in HEVs. An analysis of cooling and heating loads on a car under typical weather and driving conditions is combined with efficiency estimates for an advanced a/c system to compare different cooling strategies in terms of fuel usage and overall system COP. Options considered include belt and electrically driven compressors, with thermal and electrical storage technologies. The results of this parametric analysis narrow the range of cooling and heating strategies to be considered for detailed analysis and prototype testing.Air Conditioning and Refrigeration Project 14

    The ridiculous sublime in Don DeLillo’s White Noise and Cosmopolis

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    The sublime figures significantly in Don DeLillo’s novels. Transformed into what has been termed postmodern sublime - disposing of transcendence in favor of immanence - it is considered to be more of a hollow, confusing and overwhelming phenomenon rather than an elevating and empowering one. Moreover, the multiplicity of prior representations and the exhaustion of the possible have undermined the authenticity and power of the sublime, turning it into pseudo-sublime and mock-sublime. As such, it has moved ever closer to the realm of the ridiculous to the point where it is rather a question of co-existence and coimplication between them rather than an opposition. This can be phrased the ridiculous sublime. This paper focuses on DeLillo’s White Noise (1984) and Cosmopolis (2003) by drawing on major theorists of the sublime like Kant, Jameson, Zizek and, most notably, Lyotard, in an attempt to shed light on the modality of the merging of the sublime and the ridiculous. Our analysis shows that in DeLillo’s fiction, White Noise and Cosmopolis, the events and phenomena that transpire to convey a sense of sublimity are almost always interrupted and tarnished by an implication of the grotesque and the ridiculous. This transformation of the concept of the sublime reflects the decline of metanarratives and the exhaustion of possible experiences as the hallmarks of the postmodern era

    TRANSIENT PERFORMANCE EVALUATION OF AUTOMOTIVE SECONDARY LOOP SYSTEMS

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    Automotive air-conditioning is a high impact technology where improvements in energy consumption and environmental performance can make a significant difference in fuel efficiency and comfort. The mandatory phase out of R134a as refrigerant in the European Union has set the stage for new systems and alternative refrigerants. While some of these refrigerants, such as R152a or R290, have a low Global Warming Potential, their flammability requires secondary loop systems to be used. The added thermal mass of such systems may increase power consumption and delay cool down while benefitting thermal comfort during start/stop operation. The recent revival of electric vehicles, as well as the associated focus on air-conditioning energy consumption, provides new challenges and opportunities. This research focuses on the performance evaluation of refrigerants R152a and R290 during transient operation in secondary loop systems, quantification of thermal storage benefits for start/stop operation, and investigation of energy saving potentials in electric vehicles through the use of advanced air-conditioning system controls and cabin preconditioning. A test facility was built to dynamically test secondary loop systems over a wide range of pull down conditions and drive cycles using a passenger cabin model and associated controls. It was shown that R290 is a viable alternative in secondary loop systems and system performance may be on par or better compared to R134a direct expansion systems. The preservation of cooling capacity and thermal comfort during off-cycle periods were quantified for a secondary loop system, as well as a combined ice storage system. System efficiency increases with longer off-cycle periods compared to direct expansion systems. Advanced compressor control strategies and the use of cabin preconditioning can make use of this characteristic and improve energy efficiency by more than 50%. Ice storage may be used in combination with cabin preconditioning to preserve comfort for an extended driving time with reduced use of the vapor compression cycle. A Modelica model of the secondary loop system was developed and validated with experimental data. The model enables dynamic simulation of pull-down and drive cycle scenarios and was used to study the effects of coolant volume and coolant concentration on transient performance

    Dynamics of Consumer Demand for New Durable Goods

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    Most new consumer durable goods experience rapid prices declines and quality improvements, suggesting the importance of modeling dynamics. This paper specifies a dynamic model of consumer preferences for new durable goods with persistently heterogeneous consumer tastes, rational expectations, and repeat purchases over time. We estimate the model on the digital camcorder industry using panel data on prices, sales and characteristics. We find that the one-year elasticity in response to a transitory industry-wide price shock is about 25% less than the one-month elasticity. Standard cost-of-living indices overstate welfare gain in later periods due to a changing composition of buyers.

    Heat and Mass Transfer Technological Center

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    Travel Demand Growth: Research on Longer-Term Issues. The Potential Contribution of Trip Planning Systems

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    INTRODUCTION 1.1 The growth in demand for travel Over the 20 years hm 1965, National Travel Survey (NTS) data shows a 61% growth in total person - km of travel. More detailed analysis suggests that this is made up roughly as follows:- due to increased population 4% due to more journeys 22% due to longer journeys 35% This implies that around 60% of the growth in travel has been due to people travelling further, rather than making more journeys. It is interesting to note, too, that the same phenomenon occurs even in the most congested areas. Between 1975 and 1985, NTS shows an 11% growth in person -km by London residents, at a time when population fell by 5%. In this case, the growth is made up roughly as follows:- due to lost population -5% due to more journeys 4% due to longer journeys 12% It is of course difficult to estimate the extent to which future growth in travel will be generated by longer journeys. The NRTF, which predicts a growth in car-km of between 120% and 180% between 1985 and 2025, is not based on a procedure which enables the effects of journey making and journey length to be separated. However, it is worth noting that if the same pattern were to exist at a national level in future, the predicted growth in car travel due to longer journeys could be equivalent to between 75% and 100% of today's car travel. It seems appropriate to ask whether it is a wise use of scarce resources to provide the infrastructure and energy needed to enable people to carry out their activities further from home. (Continues...
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