Optimization of combined Brayton-Rankine cycle with respect to the total thermal efficiency

In this paper combined Brayton–Rankine cycle was mathematically simulated. In the Matlab program package an adequate numerical procedure has been developed to determine the maximum thermal efficiency of the combined cycle limited by the temperature of exhaust gases at the entrance of the gas turbine and the temperature of the condensation of water vapour in the steam condenser. Furthermore, additional limitations were introduced: the exhaust gases temperatures at the exit of the gas turbine and dryness fraction at the exit of the steam turbine. Impact of adiabatic flame temperature, temperature difference of the working fluid (water) and the exhaust gases at the pinch point and dryness fraction on change of the overall thermal efficiency of the combined cycle was examined. It was concluded that adiabatic flame temperature has the most impact for the selected intervals of the observed values

Optimization of Combined Brayton-Rankine Cycle With Respect to the Total Thermal Efficiency

In this paper combined Brayton–Rankine cycle was mathematically simulated. In the Matlab program package an adequate numerical procedure has been developed to determine the maximum thermal efficiency of the combined cycle limited by the temperature of exhaust gases at the entrance of the gas turbine and the temperature of the condensation of water vapour in the steam condenser. Furthermore, additional limitations were introduced: the exhaust gases temperatures at the exit of the gas turbine and dryness fraction at the exit of the steam turbine. Impact of adiabatic flame temperature, temperature difference of the working fluid (water) and the exhaust gases at the pinch point and dryness fraction on change of the overall thermal efficiency of the combined cycle was examined. It was concluded that adiabatic flame temperature has the most impact for the selected intervals of the observed values

Entropy Analysis of Complete Condensation of Saturated Steam on a Vertical Wall Using Nusselt Velocity and Temperature Profile in a Condensate Layer

In this paper an analytical model for calculation of entropy production for Nusselt model of condensation of pure substance vapour is given. Model development starts from basic two-dimensional integral equation for entropy production and describes film condensation on a vertical wall. Model covers entropy production, which is a result of two-dimensional heat transfer in a condensate layer, existence of velocity gradient and condensate layer viscosity. Entropy contribution of each of the members is explicitly derived in a closed form and the results of calculation are shown in the appropriate diagrams. Diagrams present film condensation of dry saturated water steam and dry saturated ammonia steam, both with saturation temperature of 100 °C with surface wall temperature of 98.5 °C. Obtained equations and presentation of the related results have shown that dominant entropy production is directly connected only with heat conduction in y-axis direction, where y-axis corresponds with thickness of condensate layer

Local Entropy Production of the Parallel Flow and Counterflow Heat Exchanger

The paper gives an analytical dimensionless analysis of the local entropy generation and its ratio with the local exchanged heat flow rate for parallel flow and counterflow heat exchangers. The end (side) of the heat exchanger, which is the inlet of the weaker stream, is, among other, proven to be relevant variable for those local values. Elaborated algorithm provides explicit connection between entropy generation and ratio of entropy generation to local exchanged heat flow rate in dependence on the relevant dimensionless variables A/A0, π2=kA0/C1, π3=C1/C2 and πT =T1\u27/T2\u27. Value π2 vary between 1.0 and 4.0, value π3 amounts 0.0; 0.5 and 1.0, while 0.5 and 2.0 were taken for value πT. From obtained general equations for parallel flow and counterflow heat exchanger special cases for observed values were extracted, considering the cases where one of the streams condenses or evaporates. Given algorithm, aside the local amounts of the observed values, also gives overall amounts of the mentioned values. The results are presented by appropriate diagrams and additionally interpreted

Exergy Analysis of an Air Conditioning Process

The exergy analysis of an air conditioning process in wintertime is presented in this paper. This process consists of mixing outdoor air with conditioned air, heating, humidifying, and reheating the air mixture. The air is heated in the heat exchangers by warm water at a temperature of 80/60 °C and humidified by spraying water at a temperature of 12 °C. The ratio of the mass flow rates of outdoor and conditioned air is varied, and it is upon this variable that the exergy analysis is performed. The five cases are analyzed with different outdoor air temperature values. It is shown that the heat transfer rate in the heat exchangers is the smallest at the ratio of mass flow rates of outdoor and conditioned air g1 = 0.45. The greatest exergy destruction is apparent in the heat exchangers, and the maximum exergy efficiency of the whole process ɛex = 0.71 is achieved at the ratio g1 = 0.45. According to the exergy criterion, this air conditioning is a relatively efficient process

Swiss Product Management 2013/14 : Von den Besten lernen

StudieIm Rahmen der Studie wurden 389 Entscheidungsträger zu ihrem Rollenverständnis, ihren Herausforderungen und den relevanten Trends im Product Management befragt. Das diesjährige Motto der Studie lautet "Von den Besten lernen" – es stellt sich die Frage: Was machen erfolgreiche Product Manager besser als ihre weniger erfolgreichen Kollegen

Swiss Marketing Leadership Studie 2016 : digitale Transformation im Marketing

Die meisten Schweizer Unternehmen haben verstanden, dass die Digitale Transformation das Marketing grundlegend verändert. Doch vielerorts fehlt es an strategischer Verankerung, Systematik und Ressourcen. Das Institut für Marketing Management der ZHAW School of Management hat am 8. September im Rahmen des Swiss CRM Forum seine diesjährige Swiss Marketing Leadership Studie vorgestellt. Die Befragung von 646 Schweizer Unternehmen zeigt, dass hierzulande ein grundlegendes Verständnis für die Veränderungen im Marketing vorhanden ist, welche die Digitale Transformation mit sich bringt. Allerdings befinden sich viele Unternehmen noch am Anfang des Transformationsprozesses. Auch nicht alle Unternehmen sehen die Entwicklung vornehmlich als Chance. Bisweilen fürchtet man eine Bedrohung des Status quo. Insgesamt zeigt sich, dass hierzulande noch viele Herausforderungen zu meistern sind, will man weiterhin im internationalen Wettbewerb mithalten können.­­ Kundenbeziehungsmanagement als Treiber: Bei B2C-Unternehmen geniesst die Digitale Transformation einen signifikant höheren Stellenwert als im B2B-Bereich. Insbesondere das Kundenbeziehungsmanagement gilt vielerorts als Katalysator der Entwicklung. Weniger ausgeprägt ist das Verständnis für den Wandel hingegen im Produktmanagement, wo entsprechende Methoden und Tools noch eine untergeordnete Rolle spielen. Zudem zeigt sich, dass kaum ein Unternehmen bisher ein ganzheitliches, toolbasiertes Product-Lifecycle-Management betreibt. Fachleute verzweifelt gesucht: Gemäss Studie planen Schweizer Unternehmen mehr denn je, in das Kundenbeziehungsmanagement zu investieren. Allerdings zeigen sich dabei grosse Unterschiede: Je reifer das Unternehmen bezüglich Digitalisierung, desto grösser die Bereitschaft für Investitionen. Ausserdem gibt es grosse branchenspezifische Unterschiede. Trotz teilweise reger Aktivität fehlt es jedoch an strategischer Verankerung, Systematik und vor allem Ressourcen. Entsprechende Budgets sind zwar vielerorts vorhanden, doch die Rekrutierung geeigneter Mitarbeitenden stellt eine grosse Herausforderung dar. Die Studie wurde in Zusammenarbeit mit zahlreichen Partnern aus der Privatwirtschaft realisiert

The current benefit of genome sequencing compared to exome sequencing in patients with developmental or epileptic encephalopathies

Background: As the technology of next generation sequencing rapidly develops and costs are constantly reduced, the clinical availability of whole genome sequencing (WGS) increases. Thereby, it remains unclear what exact advantage WGS offers in comparison to whole exome sequencing (WES) for the diagnosis of genetic diseases using current technologies. Methods: Trio-WGS was conducted for 20 patients with developmental or epileptic encephalopathies who remained undiagnosed after WES and chromosomal microarray analysis. Results: A diagnosis was reached for four patients (20%). However, retrospectively all pathogenic variants could have been detected in a WES analysis conducted with today's methods and knowledge. Conclusion: The additional diagnostic yield of WGS versus WES is currently largely explained by new scientific insights and the general technological progress. Nevertheless, it is noteworthy that whole genome sequencing has greater potential for the analysis of small copy number and copy number neutral variants not seen with WES as well as variants in noncoding regions, especially as potentially more knowledge of the function of noncoding regions arises. We, therefore, conclude that even though today the added value of WGS versus WES seems to be limited, it may increase substantially in the future

Pathogenic SCN2A variants cause early-stage dysfunction in patient-derived neurons

Pathogenic heterozygous variants in SCN2A, which encodes the neuronal sodium channel NaV1.2, cause different types of epilepsy or intellectual disability (ID)/autism without seizures. Previous studies using mouse models or heterologous systems suggest that NaV1.2 channel gain-of-function typically causes epilepsy, whereas loss-of-function leads to ID/autism. How altered channel biophysics translate into patient neurons remains unknown. Here, we investigated iPSC-derived early-stage cortical neurons from ID patients harboring diverse pathogenic SCN2A variants [p.(Leu611Valfs*35); p.(Arg937Cys); p.(Trp1716*)], and compared them to neurons from an epileptic encephalopathy patient [p.(Glu1803Gly)] and controls. ID neurons consistently expressed lower NaV1.2 protein levels. In neurons with the frameshift variant, NaV1.2 mRNA and protein levels were reduced by ~ 50%, suggesting nonsense-mediated decay and haploinsufficiency. In other ID neurons, only protein levels were reduced implying NaV1.2 instability. Electrophysiological analysis revealed decreased sodium current density and impaired action potential (AP) firing in ID neurons, consistent with reduced NaV1.2 levels. By contrast, epilepsy neurons displayed no change in NaV1.2 levels or sodium current density, but impaired sodium channel inactivation. Single-cell transcriptomics identified dysregulation of distinct molecular pathways including inhibition of oxidative phosphorylation in neurons with SCN2A haploinsufficiency, and activation of calcium signaling and neurotransmission in epilepsy neurons. Together, our patient iPSC-derived neurons reveal characteristic sodium channel dysfunction consistent with biophysical changes previously observed in heterologous systems. Additionally, our model links the channel dysfunction in ID to reduced NaV1.2 levels and uncovers impaired AP firing in early-stage neurons. The altered molecular pathways may reflect a homeostatic response to NaV1.2 dysfunction and can guide further investigations