177,078 research outputs found
Performance Analysis of the R290 Variable Geometry Gas Ejector Application for Other Refrigerants
No full textEjector refrigeration systems are promising alternative to standard vapour compression refrigeration systems. They can be driven with low-grade heat or solar systems, which make them even more renewable solution aligned with global energy transition. By implementing the controllable ejector, it can adapt to variable operating conditions, ensuring the high efficiency of both the device and the overall performance of the system. However, as it is fluid-driven device, its geometry has to be designed for particular fluid and typically requires redesigning when being applied for new applications. The R290 variable geometry gas ejector has been thoroughly tested for various spindle positions which ensured its highly efficient operation at different conditions. In this study, the same geometry was tested for other natural refrigerants of similar thermodynamic properties, i.e.R600a and R1270. The CFD analysis was based on a set of operating points for ejector-based air conditioning system working during the summer period with characteristic temperatures at evaporator and condenser. The controllable ejector was simulated for all the points with similar motive and suction nozzle parameters and the critical temperature at the outlet was determined. The analysis showed that the ejector can be used with other refrigerants maintaining high efficiency without any changes in geometry but for lower number of spindle positions. The obtained critical temperature indicates that with all the tested refrigerants the ejector-based cycle is able to work for cooling purposes during typical summer conditions for a wide range of temperatures
About the need to extend the scope of interlocutory appeal control over certain decisions regarding the rights of the accused – selected problems concerning the implementation of EU directives in Polish criminal trials
No full textThe Treaty of Lisbon from 13.12.2007, opened up new directions and methods for the harmonization of criminal procedures in EU Member States, implemented by using directives of the European Parliament and of the Council. The article analyses the nature of obligations imposed on the Member States in directives 2010/64/EU, 2012/13/EU, 2013/48/EU, 2016/343/EU, 2016/800 and 2016/1919, especially the meaning of the term “adequate and effective remedy”. Given the obligation to incorporate the directives in national legal systems, it is important to mention that some provisions of the Polish Code of Criminal Procedure do not provide for the minimum standards laid down in the directives and therefore require legislative intervention by extending complaint control over certain decisions concerning the rights of the accused. In particular, this includes issues relating to the right of the accused to translation and interpretation, access to the case file, restrictions on contact with counsel and lack of counsel during the first [email protected] Fingas – doktor nauk prawnych, adiunkt w Katedrze Prawa Karnego Procesowego i Kryminalistyki Uniwersytetu Gdańskiego, adwokat.Maciej Fingas – Ph.D. in law, lecturer at the Gdansk University, a practising attorney.Uniwersytet GdańskiBoratyńska K.T., Górski A., Sakowicz A., Ważny A., Kodeks postępowania karnego. Komentarz, Warszawa 2012.Cieślak M., Polska procedura karna. Podstawowe założenia teoretyczne, Warszawa 1984.Doda Z., Zażalenie w procesie karnym, Warszawa 1985.Doda Z., Gaberle A., Kontrola odwoławcza w procesie karnym, Warszawa 1997.Fingas M., Glosa do wyroku Sądu Apelacyjnego w Gdańsku z 30.11.2011 r., II AKa 349/11, „Palestra” 2013, nr 1-2.Garlicki L. (red.), Degener R., Hofmański P., Kondak I., Krzyżanowska-Mierzewska M., Ryngielewicz K., Wróbel A., Konwencja o Ochronie Praw Człowieka i Podstawowych Wolności. Komentarz do artykułów 19-59 oraz do Protokołów dodatkowych, Warszawa 2011.Górski A., Toruński M., Zmiany w treści prawa do tłumaczenia w postępowaniu karnym według dyrektywy komisji i rady 2010/64/UE, „Białostockie Studia Prawnicze” 2014, nr 15.Grzelak A., Królikowski M., Sakowicz A. (red.), Europejskie prawo karne, Warszawa 2012.Kalisz A., Multicentryczność systemu prawa polskiego a działalność orzecznicza Europejskiego Trybunału Sprawiedliwości i Europejskiego Trybunału Praw Człowieka, „Ruch Prawniczy, Ekonomiczny i Socjologiczny” 2007, nr 4.Klamczyńska A., Ostropolski T., Prawo do adwokata w dyrektywie 2013/48/UE – tło europejskie i implikacje dla polskiego ustawodawcy, „Białostockie Studia Prawnicze” 2014, nr 15.Krysztofiuk G., Zasada wzajemnego uznawania orzeczeń w sprawach karnych w Traktacie Lizbońskim, „Prokuratura i Prawo” 2011, nr 7-8.Łętowska E., Multicentryczność współczesnego systemu prawa i jej konsekwencje, „Państwo i Prawo” 2005, nr 4.Marszał K., Proces karny, Katowice 1998.Sakowicz A. (red.), Kodeks postępowania karnego. Komentarz, Warszawa 2016.Skorupka J. (red.), Kodeks postępowania karnego. Komentarz, Warszawa 2016.Steinborn S. (red.), Kodeks postępowania karnego. Komentarz do wybranych przepisów, Lex/el 2016.Świecki D. (red.), Kodeks postępowania karnego. Komentarz, t. 1, Warszawa 2015.Wąsek-Wiaderek M., Dostęp do akt sprawy oskarżonego tymczasowo aresztowanego i jego obrońcy w postępowaniu przygotowawczym – standard europejski a prawo polskie, „Palestra” 2003, nr 3-4.Wąsek-Wiaderek M., Stosowanie tymczasowego aresztowania po zmianach wprowadzonych do kodeksu postępowania karnego nowelizacją z dnia 11 marca 2016 r., „Ius et Administratio” 2016, nr 3.Wiliński P., Odmowa dostępu do akt sprawy w postępowaniu przygotowawczym, „Prokuratura i Prawo” 2006, nr 11.231476
Appropriate Similarity Measures for Author Cocitation Analysis
No full textWe 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
"Closing the R&D Gap, Evaluating the Sources of R&D Spending"
No full textBoth spending and tax policies have been implemented in the United States with the goal of stimulating private sector research and development (R&D). Karier questions whether current R&D policy, especially the research and experimentation tax credit, can contribute to closing the gap between nondefense expenditures on R&D in the United States and such expenditures in other countries, such as Japan and Germany. He also explores possible changes to our current R&D policy to make it more effective.
Experimental analysis of the air-to-water ejector-based R290 heat pump system for domestic application
No full textThe aim of this study was to analyze and compare the performance of an 8 kW ejector-based R290 heat pump system for hot water heating applications that operates with two different expansion devices: a throttling valve and a two-phase ejector. The vapor compression system was designed to compare the unit operating in direct expansion and ejector-based working modes under similar operating conditions. The test results were assessed for overall system performance measured by COP and heating capacity and for single-component operation. The ejector mode allowed operation at the same range of ambient temperatures as direct expansion mode with the potential to completely replace the expansion valve. The COP of ejector system was up to 2.6, which was 38% higher than direct expansion when working under similar conditions for an ambient temperature of -12.8 degrees C. Moreover, the COP in direct expansion mode decreased significantly along the decrease of ambient temperature, whereas for the ejector mode this decrease was considerably smaller
Going Beyond Counting First Authors in Author Co-citation Analysis
No full textThe 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
Numerical investigation of the expansion devices applied in modern vapour compression refrigeration unit considering specific entropy and entropy generation analyses
No full textEjector-based refrigeration cycles working with natural refrigerants have already gained industry attention. Replacing throttling valve with an ejector in vapour-compression cycles brings high improvement of the cycle efficiency due to the ejectors potential of recovering part of throttling losses. With the rapidly growing market for heat pumps, they are also being implemented in those cycles, but this requires redesigning the ejector geometry for new natural working fluids for different operating conditions and applications. Typical approach to perform the ejector shape optimization is to use the ejector mass entrainment ratio or overall efficiency as an objective function. However, an entropy generation analysis seems to be more efficient. For this reason, the aim of this work was to perform the numerical analysis of the entropy generation of two two-phase ejectors for R744 and R290 refrigerants in order to assess its potential as a tool for efficiency improvement in the shape optimization algorithms. The ejectorPL approach utilizing the HEM approach was complemented with the entropy generation model and implemented using an additional transport equation to the CFD software. The CFD models were validated based on experimental results obtained from ejectors working in R744 transcritical refrigeration system and R290 heat pump. Each ejector was simulated for set of operating conditions representing the system working in both supercritical and near critical point conditions. The CFD results of the mass flow rates for both devices were used for validation purposes. The results of the pressure and temperature were compared with experimental data. The entropy generation module allowed for the entropy generation analysis in terms of maximum values and their location showing critical areas of irreversibility characterizing different working fluids usage and ejector applications
Experimental analysis of the R290 variable geometry ejector with a spindle
No full textThe aim of this work was to experimentally analyze the variable geometry gas ejector with a spindle designed for operation with the natural working fluid propane (R290). The performance of the ejector was evaluated based on the mass entrainment ratio and critical temperature, being the most crucial parameters for optimizing the cooling capacity in ejector refrigeration systems, as well as the ejector efficiency using common literature notation. Additionally, local pressure drop measurements allowed for the determination of pressure profiles inside for different spindle positions used for capacity regulation. The experimentally defined ejector efficiency curves demonstrated the ability to control the ejector capacity by means of the spindle, irrespective of the unfavorable operating conditions. By decreasing the effective throat area using spindle, the ejector mass entertainment ratio increased by 35%. Spindle movement allowed for the decrease of the motive nozzle flow rate by up to 65%, while still maintaining the suction of the secondary flow of the ejector. Moreover, the behavior of a slight increase in suction nozzle flow with a decrease in motive nozzle flow has been observed for the initial movement of the spindle followed by a huge drop for further reduction of the effective throat area, confirming the previous conclusions shown in the literature
The experimental analysis of ejector‐based R290 heat pump system for domestic applications
No full textThe preliminary experimental study of a novel ejector‐based air‐source R290 heat pump was performed. The two‐phase bypass ejector was installed in a R290 heat pump unit and a number of modifications were introduced to the baseline system. The adaptions included implementation of the internal heat exchanger, increasing the superheat at the compressor suction port, and a liquid separator for handling the two‐phase flow at the ejector outlet. The performance evaluation of the system was based on COP and system heating capacity. Additionally, the comparative analysis with the R290 heat pump utilizing standard expansion valve for five typical operating points was carried out. The system working with an ejector as a throttling device allowed for up to 30% of COP improvement over the system utilizing an expansion valve. Additionally, the ejector implementation resulted in decreased pressure ratio of the compressor, which increased the system heating capacity by up to 12%
The comparative analysis of the R290 heat pump system working with standard expansion valve and two-phase ejector
No full textThe heat pump systems play a significant role in the global energy transition process of household heating sources towards zero-emission. One of the key technologies to improve the efficiency of heat pump systems utilizing natural working fluids is application of the two-phase ejector, which is able to recover part of the expansion losses. The comparative experimental analysis of a novel ejector-based air-source R290 heat pump was performed. The two-phase bypass ejector was installed in a R290 heat pump unit and a number of modifications were introduced to the baseline system. The adaptions included implementation of the internal heat exchanger, increasing the superheat at the compressor suction port, and a liquid separator for handling the two-phase flow at the ejector outlet. The performance evaluation of the system was based on COP and system heating capacity. The comparative analysis with the R290 heat pump utilizing standard expansion valve and two-phase ejector was carried out for typical operating conditions for its domestic application during heating seasons. The system working with an ejector as a throttling device allowed for up to 25% of COP improvement over the system utilizing an expansion valve. Additionally, the ejector implementation resulted in decreased pressure ratio of the compressor, which increased the system heating capacity by up to 10%
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