1,720,964 research outputs found
IMPROVEMENT OF SOLAR COOLING PLANT PERFORMANCE BASED ON SIMULATION AND EXPERIMENTAL ACTIVITIES
No full textSolar refrigeration for dry hot climates has been achieved by developing a novel concept of high temperature lift solar cooling system. A pilot plant based on this concept was designed and installed for a Tunisian beverage factory in spring 2008. The development of the system concept, the detailed design and the components sizing have been implemented through simulations of the system behaviour using the TRNSYS’s simulation platform. For this purpose mathematical models of the concentrating collector and the absorption chiller were developed and implemented. Results obtained from the monitoring activities of the system’s performance were utilized for the TRNSYS models validation. Therefore the validated models were used for further simulation campaign aiming to define the optimum operating points of the whole system and trace a path towards it’s the plant performance improvement
Modelling of a Commercial Absorption Heat Pump with Integral Storage
No full textThe thermo-chemical accumulator (TCA) is a closed absorption batch process that uses a working pair, not only in the liquid, vapor and solution phases but also with solid sorbent, so called triple state operation. It was patented in 2000 (Olsson et al., 2000). Since then the TCA process has been developed in a relatively short space of time by the Swedish company ClimateWell via five generations of prototypes and is now commercially available under the name ClimateWell 10 (CW10). The majority of the 500 machines sold since 2007 are for relatively complex solar heating and cooling systems in the Mediterranean. They provide cooling during summer, space heating during winter and hot water year round. Although in principle both common absorption and adsorption processes can include significant heat storage, this is not used in commercial products. The ClimateWell machine is the first thermally driven heat pump with integral storage on the market. It uses LiCl and water as the working pair. Several prototypes have been developed, with different characteristics and operating principles (Bales et al., 2004). The first simulation model was derived for the 3rd generation of prototypes (Bales and Nordlander, 2005; Bales, 2006).
The 4th generation of machines differs significantly from the previous generations, and was the first to be sold commercially, as from 2007. As a result the simulation model for the 3rd generation had to be rewritten. This paper describes the basic operating principles of the machine, the model as well as the identification of model parameters. Finally the paper describes a series of parametric studies highlighting the influence of a number of parameters on the COP and storage capacity of the machine
Assessment and Optimization of the Performance of a Novel Solar Refrigeration System Applied in Agro-Food Industry.
No full textIn solar cooling systems the selection of the thermal driven and solar collection technologies is mainly based on climate and load conditions analysis. Moreover in particular conditions (i.e., south part of the Mediterranean basin), energy (electricity, back-up fuel) and water costs and availability can be driving parameters in the design process.
The work presented in this paper falls within the activities carried out to evaluate the technical feasibility of solar cooling in the Mediterranean food & agro industry. In particular, a case study based on the application of a solar refrigeration system for a Tunisian Agro-food industry is presented.
This novel system consists in the series connection of a concentrating collector, a water-ammonia single effect air-cooled absorption chiller and a cold storage. This configuration is justified by the high temperature difference between the chilled refrigerant temperature about –5 °C and the ambient temperature which could exceed 40 °C.
The monitoring data obtained were analyzed in order to extract the performance figures recommended by the most up to date unified monitoring procedure proposed within Task 38-SHC of the International Energy Agency (IEA). These results showed a good operation of the system as well as they are reasonably comparable to the expected performance of the system. As well as they pointed out possible improvements of the system’s operation parameters
Solar Heating and Cooling System for Office Building in Italy; Description and Performance Assessment
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Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe 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
Variations on the Author
Full text link“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
Full text linkWe 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
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
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