Search results for "Osmotic"
showing 10 items of 156 documents
Towards the first proof of the concept of a Reverse ElectroDialysis - Membrane Distillation Heat Engine
2019
Abstract The coupling of Reverse Electrodialysis with Membrane Distillation is a promising option for the conversion of waste heat into electricity. This study evaluates the performances of the integrated system under different operating conditions, employing validated model and correlations. This work provides a detailed description of the behaviour of a real RED-MD heat engine and indicates the set of inlet concentrations, velocities and equipment size which returns the highest cycle exergy efficiency. These operating conditions were selected for the pilot plant developed within the EU-funded project RED Heat to Power. For the first time, a perspective analysis was also included, consider…
Regeneration units for thermolytic salts applications in water & power production: State of the art, experimental and modelling assessment
2021
Abstract Thermolytic solutions are often proposed as high salinity or “draw” stream to generate a chemical potential driving force in Salinity Gradient Power (SGP) and Forward Osmosis (FO) technologies. Depleted “draw” solutions exiting the process can be regenerated by a thermal process powered at very-low grade heat, which is able to decompose the salt into gaseous ammonia and carbon dioxide, which can be stripped and then reabsorbed in the draw solution, restoring its initial concentration. In this work, two different experimental prototypes for the regeneration of ammonium bicarbonate aqueous solution were designed, built and tested. The effect of several operating parameters on the reg…
Osmotic stress affects the stability of freeze-dried Lactobacillus buchneri R1102 as a result of intracellular betaine accumulation and membrane char…
2014
Aims To help cells to better resist the stressful conditions associated with the freeze-drying process during starter production, we investigated the effect of various osmotic conditions on growth, survival and acidification activity of Lactobacillus buchneri R1102, after freeze-drying and during storage for 3 months at 25°C. Methods and Results High survival rates during freeze-drying, but not during storage, were obtained when 0·1 mol l−1 KCl was added at the beginning of fermentation, without any change in membrane properties and betaine accumulation. This condition made it possible to maintain a high acidification rate throughout the process. In contrast, the addition of 0·6 mol l−1 KCl…
Reservoir characteristics of Mainz pouch studied in animal model
1993
In a canine model of the Mainz pouch, intracavitary pressure and compliance were measured during instillation of isosmotic and hyperosmotic (900 mmol/kg water) solutions of saline. Wall properties of small- and large-bowel segments of the pouch were assessed individually by sonomicrometry. Intraluminal pressures increased more steeply during filling with hyperosmotic solution, resulting in reduced distensibility of small- and large-bowel segments. Additionally, instillation of the hyperosmotic solution resulted in increased amplitudes and frequency of intracavitary pressure waves. The results indicate that this was the result of a combination of intensified bowel contractions and an increas…
Thermodynamic studies of octyltrimethylammonium chloride in water
1992
Densities, heat capacities, enthalpies of dilution at 298 K and osmotic coefficients at 310 K of octyltrimethylammonium chloride were measured as functions of concentration. From the experimental data, the partial molar volumes, heat capacities, relative enthalpies, nonideal free energies and entropies at 298 K were derived as functions of concentration. A comparison between the above data and those of dodecyltrimethylammonium chloride reported in the literature shows that the increase of the alkyl chain length shifts the apparent molar volumevs. concentration curves towards greater values and the heat capacity, relative enthalpy and free energyvs. concentration curves towards smaller value…
Thermodynamic properties of some N-alkyl-N-methylpiperidinium chlorides and N-alkylpiperidine hydrochlorides in water
1993
Densities and heat capacities at 25[degrees]C were measured for N-octyl-, N-decyl- and N-dodecyl-N-methylpiperidinium chlorides and for N-octyl- and N-dodecylpiperidine hydrochlorides in water as functions of concentration. Enthalpies of dilution at 25[degrees]C and osmotic coefficients at 37[degrees]C of the N-methyl-N-alkylpiperidinium chlorides were also measured as functions of concentration. The partial molar volumes, heat capacities, relative enthalpies, nonideal Gibbs energies and entropies at 25[degrees]C were derived as functions of the surfactant concentration. By increasing the alkyl chain length of the surfactant, both the apparent molar volume vs. concentration curves are shift…
Salt extraction regeneration technologies
2022
Abstract A salinity gradient power heat engine is a novel sustainable technology for the conversion of low-grade waste heat (T This chapter presents an overview of the main regeneration technologies based on the “salt extraction strategy” reported in the literature. A salt extraction regeneration unit takes advantage of the property of specific chemical compounds to shift from a soluble form to separable species in solution allowing the salt transfer between the exhausted solutions and aiding their regeneration. The regeneration processes reported here are classified into (i) switchable solubility salts and (ii) thermolytic salts. The first class includes compounds characterized by thermal…
Excess free energy, enthalpy and entropy of surfactant-surfactant mixed micelle formation
1996
Enthalpies of dilution and osmotic coefficients of sodium decylsulfate (NaDeS)-dodecyldimethylamine oxide (DDAO) mixtures in water were determined at 298 and 310 K, respectively. From the enthalpies of dilution, the apparent and then the partial molar relative enthalpies of the surfactant mixtures were calculated. From the osmotic coefficients, calculated at 298 K, the non-ideal free energies were derived. The latter were combined with the partial molar relative enthalpies to obtain the non-ideal entropies. From the apparent molar properties, using a previously reported approach, the excess thermodynamic properties for the surfactant-surfactant mixed micelle formation in water were evaluate…
Zur kinetik des einstellvorganges im osmometer. IV. Bestimmung des zahlenmittels des molekulargewichts bei unfraktionierten polymeren1
1962
Der durch teilweise Permeation bedingte Fehler des gemessenen osmotischen Druckes eines unfraktionierten Polymeren kann berechnet werden, wenn die fur das Permeationsverhalten masgebenden Konstanten der Membran und die molekulare Verteilungsfunktion des Polymeren bekannt sind. Unter diesen Voraussetzungen wird unter Verwendung fruher abgeleiteter Beziehungen1 der durch Gl. (1) definierte Fehlbetrag Δt berechnet. Ist die spezielle Verteilungsfunktion nicht bekannt, so kann der Fehlbetrag fur ein bestimmtes Polymeres abgeschatzt werden, wenn auser einer osmotischen Mesreihe eine Bestimmung des Gewichtsmittels des Molekulargewichts Mw (bzw. Pw) vorliegt. Voraussetzung der Rechnung ist die Kenn…
N,N,N-Alkyloctyldimethylammonium Chlorides in Water: A Thermodynamic Investigation
1993
Abstract Specific conductivities, densities, heat capacities and enthalpies of dilution at 298 K and osmotic coefficients at 310 K were measured for N,N,N -octylbutyldimethylammonium, N,N,N -octylpentyldimethylammonium, and N,N -dioctyldimethylammonium chlorides in water as functions of concentration. From the specific conductivity data, the CMC and the degree of the counterion dissociation have been calculated. It is shown that additional CH 2 groups in the variable alkyl chain affect both CMC and β less than they do in the single chain surfactants. The partial molar volumes, heat capacities, relative enthalpies, nonideal free energies, and entropies at 298 K were derived as functions of t…