Interfacing Models for Thermal Separation Processes with Fluid Property Data from External Sources

So far, when modelling processes that demand for multi-phase and multi-component fluid property data, the user has to implement the required media models in the Modelica language as these types of fluids are not supported by Modelica.Media. This paper presents a first approach on how to implement fluid property data in process models of an existing library from external sources and highlights which problems have to be overcome. Furthermore, it provides recommendations for the design of an efficient and user-friendly interface to external media packages

Requirements Engineering für Communities of Practice: Aufbau der ReqMan Community

Eine der Herausforderungen des Requirements Engineering (RE) ist, dass bei der Entwicklung eines Software-Systems sowohl die technischen Einzelheiten als auch der Kontext des Einsatzes berücksichtigt werden müssen. Wie schon andere Autoren bemerkt haben, ist RE ein sozio-technisches Unterfangen. Bei der Entwicklung von Desktop-Software zum Beispiel ist zu berücksichtigen, wie der einzelne Benutzer die Anwendung einsetzen wird. Im Bereich Computer Supported Cooperative Work (CSCW) ist der Einsatzkontext komplizierter, da Kommunikation und Interaktion zwischen Benutzern ebenfalls berücksichtigt werden müssen. Bei der Entwicklung einer Community of Practice (CoP) muss der Kontext noch weiter ausgedehnt werden, da Dinge wie Kooperation, Gruppenbildung bzw. Bildung von Netzwerken, Lernen etc. auch in die Anforderungen einfließen

Die Ökostromlücke, ihre Strommarkteffekte und wie sie gestopft werden kann

DIE ÖKOSTROMLÜCKE, IHRE STROMMARKTEFFEKTE UND WIE SIE GESTOPFT WERDEN KANN Die Ökostromlücke, ihre Strommarkteffekte und wie sie gestopft werden kann / Lenck, Thorsten (Rights reserved) ( -

Volatile emissions of scented Alstroemeria genotypes are dominated by terpenes, and a myrcene synthase gene is highly expressed in scented Alstroemeria flowers

Native to South America, Alstroemeria flowers are known for their colourful tepals, and Alstroemeria hybrids are an important cut flower. However, in common with many commercial cut flowers, virtually all the commercial Alstroemeria hybrids are not scented. The cultivar ‘Sweet Laura’ is one of very few scented commercial Alstroemeria hybrids. Characterization of the volatile emission profile of these cut flowers revealed three major terpene compounds: (E)-caryophyllene, humulene (also known as α-caryophyllene), an ocimene-like compound, and several minor peaks, one of which was identified as myrcene. The profile is completely different from that of the parental scented species A. caryophyllaea. Volatile emission peaked at anthesis in both scented genotypes, coincident in cv. ‘Sweet Laura’ with the maximal expression of a putative terpene synthase gene AlstroTPS. This gene was preferentially expressed in floral tissues of both cv. ‘Sweet Laura’ and A. caryophyllaea. Characterization of the AlstroTPS gene structure from cv. ‘Sweet Laura’ placed it as a member of the class III terpene synthases, and the predicted 567 amino acid sequence placed it into the subfamily TPS-b. The conserved sequences R28(R)X8W and D321DXXD are the putative Mg2+-binding sites, and in vitro assay of AlstroTPS expressed in Escherichia coli revealed that the encoded enzyme possesses myrcene synthase activity, consistent with a role for AlstroTPS in scent production in Alstroemeria cv. ‘Sweet Laura’ flowers

Efficiency Improvement in Precombustion CO2 Removal Units With a Waste–Heat Recovery ORC Power Plant

This paper presents an analysis about recovering low-grade thermal energy from a precombustion CO2 capture process as part of an integrated gasification combined cycle (IGCC) power plant by means of organic rankine cycle (ORC) turbogenerators. The distinguishing feature of this system is the thermal energy source that is a syngas-water mixture, which is cooled from a temperature of approximately 140 °C, and partly condenses due to the heat transfer to the ORC primary heat exchanger. This study explores various types of ORC power systems for this application. The performance of commercially available ORC units is used as a benchmark and compared to the performance of two types of tailor-designed ORC power plants. The working fluid has a major influence on system performance and other technical and economic factors. The effect of selecting a fluid from the hydrocarbon and refrigerant families are therefore investigated, targeting the maximum net power output. In addition to pure fluids, two-component mixtures are also considered. The use of mixtures as working fluids in subcritical heat-recovery ORC systems allows for a better match of the temperature profiles in the primary heat exchanger and the condenser due to the temperature glide associated with phase-transition, leading to lower irreversibilities within the heat exchanging equipment. In order to further improve the thermal coupling between the cooling heat source and the heating of the working fluid, the supercritical cycle configuration is also studied. The performance of the three categories of systems, depending on working fluid and cycle configuration, i.e., systems based on (i) commercially available units, (ii) tailor-designed subcritical cycle, (iii) tailor-designed supercritical cycle, are analyzed in terms of net power output, second law efficiency, and component-based exergy efficiencies. The analysis shows that an improvement of 38.0% in terms of net power output compared to the benchmark system can be achieved by an optimized supercritical ORC power plant using an R134a/R236fa mixture as the working fluid. It is estimated that the total power consumption of the considered exemplary CO2 capture plant can be reduced by approximately 10% with the optimal ORC system. In this study, particular attention is focused on the semi-empirical optimization approach, in order to avoid unnecessary computations, and general guidelines are provided.</jats:p