1,720,969 research outputs found
Ecological sanitation, organic animal farm, and cogeneration: Closing the loop in achieving sustainable development-A concept study with on-site biogas fueled trigeneration retrofit in a 900-bed university hospital
No full textKilkis, Birol/0000-0003-2580-3910WOS: 000383811100010Healthcare facilities mostly consume natural gas or fuel oil, utilize grid power, and are the second most energy intensive sector in the USA. Besides their high fossil fuel expenditures, hospital buildings generate large amounts of plumbing wastes and others, such that they are the largest producer of GHG emissions in the building sector. Energy costs are consuming up to 15% of their annual profits. In this paper the overall environmental and economic problems that may be associated especially with large healthcare facilities are addressed by showing ways to convert their energy and environmental disadvantages into advantages. In this respect, a concept study with ecological sanitation and formation of an energy, water, food, and education nexus by primarily employing a trigeneration system operating with biogas at an optimum fuel share with natural gas for retrofitting an existing 900-bed University hospital is presented. This case study covers two scenarios. The first scenario is the base scenario, which utilizes three trigeneration engines, with one 1,25 MWe, and two 2,2 MWe capacity each, all running on natural gas with a total capacity of 5,65 MWe. The second scenario includes three stages. The first stage mixes natural gas with biogas, which is to be produced on-site by primarily using plumbing wastes, for driving the 1,25 MWe engine, which satisfies the constant base load of the hospital for 24h a day. The second stage produces biogas by making use of the widely available surrounding free land of the hospital in a new eco-farm development and replaces the fuel input of the first 2,2 MWe engine, which operates 16 h a day on average. In the third stage the second trigeneration unit with 2,2 MWe capacity remains on natural gas fuel input and operates approximately 8 h a day (peaking engine). Both scenarios have an absorption cooling system with the same capacity and an 8 MWc-h ice tank. This common base of identical power, heat, and cold capacities was aimed to independently focus on the environmental and economic benefits of biogas substitution covering a ten-year operational period. The next system for stage two involves a new organic 6000 livestock-animal organic farm and a dairy factory to be owned by the University, which completes the food, water, energy, education and environment nexus and serves as a full-scale hands-on farm for the Department of Agriculture students and provide an R&D platform. It has been shown that such an application closes the loop towards sustain ability. The organic venture is expected to have a large economic impact and important contributions also on the dietary needs of the patients. The organic farm is envisioned to incorporate greenhouses, wind, and solar farms. Yet this study only covers the impact of the biogas supply to the trigeneration system: CO2 emissions from biogas generation is assumed to be captured and utilized for dry ice production. Analyses show that the additional cost of on-site biogas anaerobic digester and its ancillaries of the. first-stage (1,25 MWe) may pay back themselves in four years. The corresponding prediction for the second stage biogas trigeneration system with biogas fuel (2,2 MWe) is also four years. Total reduction in CO2 emissions attributable to the biogas conversion of the trigeneration system is 161558,2 t CO2 over a ten-year period, taking into account the additional reductions due to improvements in rational exergy management of the energy resources. The net total savings from biogas conversion in two stages is expected to be about 4 M(sic) for a ten-year period. (C) 2016 Elsevier B.V. All rights reserved
Lessons Learned from Labyrinth Type of Air Preconditioning in Exergy-Aware Solar Greenhouses
Get PDFAn exergy-based model hypothesizes that labyrinth-type ground-to-air heat exchangers are responsible for carbon dioxide emissions if the exergy of power demand concerning ancillaries like fans and pumps exceeds the thermal exergy gain. This hypothesis was analyzed for a novel solar greenhouse proposal in northern Holland, primarily using heat pipes. Minimum electrical power demand without any need for fossil fuels were the main findings on a holistic basis. New definitions, namely nearly-zero-exergy greenhouse and nearly-zero carbon greenhouse, were developed with new metrics to quantify the hypothesis. Results show that the exergy approach provides crucial insight for the design of labyrinth-type ground-to-air heat exchangers and sets new constraints about limited environmental benefits
A Parametric Study for Integrated Design Optimization of Low-Energy Buildings
No full textBeyond a low-energy and low-exergy building concept, the mechanical system that converts energy resources to useful mechanical power and HVAC functions need to be optimized for maximum efficiency with minimum energy waste and exergy destruction. This paper provides a new analytical algorithm, which optimizes the CHP, absorption chiller, heat pump, alternative energy and power systems like wind and solar, TES, PES, and HVAC terminal unit combinations and capacities for a given building. A case study is presented for several mechanical system scenarios. Results show that lower CO(2) impact buildings are possible even when fossil fuels are used.</p
Exergy-Optimum Coupling of Heat Recovery Ventilation Units with Heat Pumps in Sustainable Buildings
Get PDFThis study shows that as a result of exergy destructions in heat recovery ventilation units, additional but avoidable carbon dioxide emissions take place due to the imbalance between the unit exergy of thermal power recovered and the unit exergy of fan power required to overcome the additional pressure drop. Therefore, special attention needs to be paid in the design and control of heat recovery ventilation units to minimize such carbon dioxide emissions responsibility by a proper exergy-rational balance between the heat recovered and power required. The potential improvements about the exergy
rationality of the heat recovery ventilation units were investigated for several alternatives. These alternatives were: heat recovery ventilation-only (base case), coupling with an airto- air heat pump in tandem or parallel to the heat recovery ventilation unit, and a heat
pump-only case. To carry out such an investigation, a new exergy-optimum design and dynamic control model was developed. Under typical design conditions, this model showed that a heat pump in parallel configuration does not improve the exergy rationality
unless its coefficient of performance is over 11, which is not practical with today’s technology. Instead, passive solar and wind energy systems have been discussed and recommended. Results were also compared with condensing boiler, micro-cogeneration unit, fuel cell, and electric resistance heating cases. It has been shown that heat recovery ventilation with an air-to-air heat pump in tandem is the best in terms of the exergy-based coefficient of performance. Additional comparisons were made concerning avoidable and direct carbon dioxide emission responsibilities, climate warming-potential and
ozone-depleting potential, embodied energy, embodied exergy, and carbon dioxide recovery periods. A new composite index, which recognizes the direct relationship between the ozone layer depletion and the greenhouse gas emissions has also been introduced for comparing system alternatives in terms of their atmospheric footprint
A Parametric Study for Integrated Design Optimization of Low-Energy Buildings
No full textBeyond a low-energy and low-exergy building concept, the mechanical system that converts energy resources to useful mechanical power and HVAC functions need to be optimized for maximum efficiency with minimum energy waste and exergy destruction. This paper provides a new analytical algorithm, which optimizes the CHP, absorption chiller, heat pump, alternative energy and power systems like wind and solar, TES, PES, and HVAC terminal unit combinations and capacities for a given building. A case study is presented for several mechanical system scenarios. Results show that lower CO2 impact buildings are possible even when fossil fuels are used
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
A Parametric Study for Integrated Design Optimization of Low-Energy Buildings
No full textBeyond a low-energy and low-exergy building concept, the mechanical system that converts energy resources to useful mechanical power and HVAC functions need to be optimized for maximum efficiency with minimum energy waste and exergy destruction. This paper provides a new analytical algorithm, which optimizes the CHP, absorption chiller, heat pump, alternative energy and power systems like wind and solar, TES, PES, and HVAC terminal unit combinations and capacities for a given building. A case study is presented for several mechanical system scenarios. Results show that lower CO2 impact buildings are possible even when fossil fuels are used
Variations on the Author
Get PDF“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Get PDFWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
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