Search results for " conversion"
showing 10 items of 447 documents
Reverse electrodialysis heat engine with multi-effect distillation: Exergy analysis and perspectives
2019
Abstract The increasing worldwide energy demand is rising the interest on alternative power production technologies based on renewable and emission-free energy sources. In this regard, the closed-loop reverse electrodialysis heat engine is a promising technology with the potential to convert low-grade heat into electric power. The reverse electrodialysis technology has been under investigation in the last years to explore the real potentials for energy generation from natural and artificial solutions, and recent works have been addressing also the potential of its coupling with regeneration strategies, looking at medium and large energy supply purposes. In this work, for the first time, a c…
Performance Analysis of a RED-MED Salinity Gradient Heat Engine
2018
A performance analysis of a salinity gradient heat engine (SGP-HE) is presented for the conversion of low temperature heat into power via a closed-loop Reverse Electrodialysis (RED) coupled with Multi-Effect Distillation (MED). Mathematical models for the RED and MED systems have been purposely developed in order to investigate the performance of both processes and have been then coupled to analyze the efficiency of the overall integrated system. The influence of the main operating conditions (i.e., solutions concentration and velocity) has been quantified, looking at the power density and conversion efficiency of the RED unit, MED Specific Thermal Consumption (STC) and at the overall syste…
Exothermic adsorption of chromate by goethite
2020
Abstract Goethite is a common Fe oxyhydroxide coating soil particle surfaces, which has a high Cr(VI) adsorption capacity under acidic pH conditions. Batch equilibrium adsorption experiments with chromate concentrations of 0.1, 0.2, and 0.3 mM were performed using solutions with ionic strengths of 0.1, 0.05, and 0.01 M and pH values of 3–11 and at four temperatures between 10 and 75 °C. The results of these experiments show that the amount of chromate adsorbed decreases as the pH increases towards the zero-point-of-surface-charge of goethite (pHPZC 9.1), which is typical for anions. The chromate adsorption efficiency also depends on the ionic strength of the solution. The amount of chromate…
Generation of Design Principles as Knowledge Conversion - Elucidating Dynamics
2021
In this paper we apply the perspective of knowledge conversion with recent identified core elements for developing design principles to elucidate the dynamics of design principles. In the paper, the elements of influence, actors, and formulation are integrated in a knowledge conversion process of socialization, externalization, combination, and internalization – through which tacit knowledge is made explicit, shared, and turned into action. We exemplify this process with three empirical cases using action design research (ADR) to develop IT artifacts and generate design principles. Our paper shows the dynamics across a process of generating design principles. Viewing the generation of desig…
Controlled solution-based fabrication of perovskite thin films directly on conductive substrate
2021
Abstract Organometallic perovskites are one of the most investigated materials for high-efficiency thin-film devices to convert solar energy and supply energy. In particular, methylammonium lead iodide has been used to realize thin-film perovskite solar cells, achieving an efficiency higher than 20%. Different fabrication procedures based on the spin-coating technique have been proposed, which do not ensure homogenous morphologies. In this work, we present a scalable process to fabricate methylammonium lead iodide thin films directly on conductive substrates, consisting of electrodeposition and two subsequent chemical conversions. A thorough investigation of the morphological, structural an…
Phenothiazine-based dyes for efficient dye-sensitized solar cells
2016
As an emerging photovoltaic technology, dye-sensitized solar cells (DSSCs) have attracted a great deal of academic and industrial interest due to their reasonably high power conversion efficiency, low material cost and facile fabrication process. Metal-free organic dyes, as one of the key components of DSSCs, play a pivotal role in light harvesting and electron injection. Among the various species of organic dyes, easily tunable 10H-phenothiazine-based dyes hold a large proportion. The electron-rich nitrogen and sulfur atoms render 10H-phenothiazine a stronger donor character than other amines, even better than triphenylamine, tetrahydroquinoline, carbazole and iminodibenzyl. On the other h…
Advances in Perovskite Solar Cells.
2015
Organolead halide perovskite materials possess a combination of remarkable optoelectronic properties, such as steep optical absorption edge and high absorption coefficients, long charge carrier diffusion lengths and lifetimes. Taken together with the ability for low temperature preparation, also from solution, perovskite-based devices, especially photovoltaic (PV) cells have been studied intensively, with remarkable progress in performance, over the past few years. The combination of high efficiency, low cost and additional (non-PV) applications provides great potential for commercialization. Performance and applications of perovskite solar cells often correlate with their device structures…
Concepts for medium-high to high temperature thermoelectric heat-to-electricity conversion: a review of selected materials and basic considerations o…
2015
Within the last decade, novel materials concepts and nanotechnology have resulted in a great increase of the conversion efficiency of thermoelectric materials. Despite this, a mass market for thermoelectric heat-to-electricity conversion is yet to be opened up. One reason for this is that the transfer of the lab records into fabrication techniques which enable thermoelectric generator modules is very challenging. By closing the gap between record lab values and modules, broad industrial applications may become feasible. In this review, we compare three classes of materials, all designed for medium-high to high temperature applications in the field of waste heat recovery: skutterudites, half…
Fede/fiducia, razionalità, conversione
2021
A partire da confronto tra alcuni passi dei Vangeli e testi di Wittgenstein e Kuhn, il saggio ragiona sulla su alcune questioni teoriche che ruotano attorno al tema della credenza e del cambiamento di credenza, a partire da una nozione molto densa del lessico greco antico, quella di pistis, che tra i suoi significati ha anche quelli di fede e fiducia. In particolare, si cerca di fare emergere come la dicotomia classica tra due tipi di pistis (da intendere qui genericamente come “credenza”), una pistis filosofico-scientifica razionale e una pistis religiosa irrazionale – distinzione che rimanda all’ancor più classica dicotomia “razionale” vs “irrazionale” – sia non soltanto difficile da sost…
Corporate Investment, Debt and Liquidity Choices in the Light of Financial Constraints and Hedging Needs
2015
We examine firms' simultaneous choice of investment, debt financing and liquidity in a large sample of US corporates between 1980 and 2014. We partition the sample according to the firms' financial constraints and their needs to hedge against future shortfalls in operating income. In contrast to earlier work, our joint estimation approach shows that cash flows affect the corporate decisions of unconstrained firms more strongly than those of constrained firms. Investment-cash flow sensitivities are particularly intense for unconstrained firms with high hedging needs. Investment opportunities (as proxied by Q), however, play a larger role for constrained firms with the effects being strongest…