Search results for "Vapo"

Novel solutions for closed-loop Reverse Electrodialysis: thermodynamic characterisation and perspective analysis

2019

Abstract Closed-loop Reverse Electrodialysis is a novel technology to directly convert low-grade heat into electricity. It consists of a reverse electrodialysis (RED) unit where electricity is produced exploiting the salinity gradient between two salt-water solutions, coupled with a regeneration unit where waste-heat is used to treat the solutions exiting from the RED unit and restore their initial composition. One of the most important advantages of closed-loop systems compared to the open systems is the possibility to select ad-hoc salt solutions to achieve high efficiencies. Therefore, the properties of the salt solutions are essential to assess the performance of the energy generation a…

Isobaric vapor–liquid equilibrium for binary mixtures of 2-methylpentane+ethanol and +2-methyl-2-propanol

1999

Abstract Vapor–liquid equilibrium (VLE) data for the binary systems, 2-methylpentane+ethanol and 2-methylpentane+2-methyl-2-propanol (TBA), are reported at 101.3 kPa, including pure component vapor pressures. The systems deviate remarkably from ideal behaviour presenting one positive azeotrope. The activity coefficients and boiling points of the solutions were correlated with its composition by Wilson, UNIQUAC, NRTL, and Wisniak–Tamir equations.

Isobaric vapor-liquid equilibria and densities for the system methyl 1,1-dimethylethyl ether+2-propanol

2002

Vapor-liquid equilibrium data at 50, 75 and 94 kPa have been determined for the binary system methyl 1,1-dimethylethyl ether + 2-propanol, in the temperature range 308-344 K. The measurements were made in an equilibrium still with circulation of both the vapor and liquid phases. Excess volumes have been also determined from density measurements using a vibrating tube densimeter at 298.15 K. The system exhibits positive deviation from ideal behavior and does not present azeotropy within the range of pressures studied. The excess volume of the system is negative over the whole mole fraction range. The activity coefficients and boiling points of the solutions were well correlated with the mole…

Vapor–liquid equilibria in the systems 3-methylpentane+methyl 1,1-dimethylethyl ether and 3-methylpentane+methyl 1,1-dimethylpropyl ether at 101.3 kPa

1999

Abstract Pure-component vapor pressure of 3-methylpentane and vapor–liquid equilibrium (VLE) for the binary systems of 3-methylpentane with methyl 1,1-dimethylethyl ether (MTBE) and with methyl 1,1-dimethylpropyl ether (TAME) at 101.3 kPa have been measured. Both systems exhibit small positive deviations from ideality. They can be described as regular solutions and do not present azeotrope. The activity coefficients and boiling points of the solutions were correlated with its composition by Wilson, UNIQUAC, NRTL, and Wisniak–Tamir equations.

Vapor−Liquid Equilibria for the Binary Systems tert-Butyl Alcohol + Toluene, + Isooctane, and + Methylcyclohexane at 101.3 kPa

1998

Vapor-liquid equilibria were measured for binary systems of tert-butyl alcohol with toluene, isooctane, and methylcyclohexane at 101.3 kPa using a recirculating still. Experimental values of the vapor pressure of non-oxygenated pure components have been obtained. The accuracy of experimental measurements was ±0.01 K in temperature, ±0.01 kPa in pressure, and ±0.001 in mole fractions. The results are thermodynamically consistent according to the point-to-point consistency test. The data were correlated with five liquid-phase activity coefficients models (Margules, Van Laar, Wilson, NRTL, UNIQUAC).

Evapotranspiration from an Olive Orchard using Remote Sensing-Based Dual Crop Coefficient Approach

2013

A remote sensing-based approach to estimate actual evapotranspiration (ET) was tested in an area covered by olive trees and characterized by Mediterranean climate. The methodology is a modified version of the standard FAO-56 dual crop coefficient procedure, in which the crop potential transpiration, T p, is obtained by directly applying the Penman-Monteith (PM) equation with actual canopy characteristics (i.e., leaf area index, albedo and canopy height) derived from optical remote sensing data. Due to the minimum requirement of in-situ ancillary inputs, the methodology is suitable also for applications on large areas where the use of tabled crop coefficient values become problematic, due to…

Daily evapotranspiration assessment by means of residual surface energy balance modeling: A critical analysis under a wide range of water availability

2012

Summary An operational use of the actual evapotranspiration assessed by remote sensing approaches requires the integration of instantaneous fluxes to daily values. This is commonly achieved under the hypotheses of daytime self-preservation of evaporative fraction and negligible daily ground heat flux. The aim of this study is to evaluate the effect of these assumptions on estimate daily evapotranspiration over a full phenological cycle, including phases characterized by significant changes both in net radiation and vegetation cover. To assess the reliability of these hypotheses, the observations made by a flux tower, installed within a homogeneous field of cereal located in the valley part …

The impact of in-canopy wind profile formulations on heat flux estimation in an open orchard using the remote sensing-based two-source model

2010

Abstract. For open orchard and vineyard canopies containing significant fractions of exposed soil (>50%), typical of Mediterranean agricultural regions, the energy balance of the vegetation elements is strongly influenced by heat exchange with the bare soil/substrate. For these agricultural systems a "two-source" approach, where radiation and turbulent exchange between the soil and canopy elements are explicitly modelled, appears to be the only suitable methodology for reliably assessing energy fluxes. In strongly clumped canopies, the effective wind speed profile inside and below the canopy layer can strongly influence the partitioning of energy fluxes between the soil and vegetation co…

Actual evapotranspiration assessment in a sparse tall Mediterranean crops

2010

Comparing actual evapotranspiration and plant water potential on a vineyard

2011

Agricultural water requirement in arid and semi-arid environments represents an important fraction of the total water consumption, suggesting the need of appropriate water management practices to sparingly use the resource. Furthermore the quality and quantity of some crops products, such as grape, is improved under a controlled amount of water stress. The latter is related, on a side to actual evapotranspiration (ET) through water demand, on the other side to plant water content through leaf water potential. Residual energy balance approaches based on remote sensing allow to estimate the spatial distribution of daily actual ET at plant scale, representing an useful tool to detect its spati…