This paper presents speed of sound measurements on pentafluoroethane (R125) in the vapor phase. T... more This paper presents speed of sound measurements on pentafluoroethane (R125) in the vapor phase. The measurements were performed in a stainless steel spherical resonator of ∼900cm3 at temperatures in the range 260–360K and pressures up to 500kPa. Acoustic virial coefficients and ideal gas heat capacities are deduced directly from the data. The whole set of speed of sound measurements and
The present work focuses both on biomass energy conversion by means of gasification and pyrolysis... more The present work focuses both on biomass energy conversion by means of gasification and pyrolysis, and on the tar bioremediation. In the first part a mathematical model, based on Gibbs free energy minimization, has been used to simulate the thermochemical processes and to characterize the producer gas from various feedstocks. Different process configurations have been taken into account by varying a set of parameters (such as equivalent ratio, steam to carbon ratio, temperature, feedstock water content and biomass ultimate analysis). The most efficient gasification/pyrolysis configuration has been assessed trough an overall energy balance carried out at the plant scale. For this purpose, three plant layouts have been modeled to compare different pathways suitable to generate syngas; in particular the gasifier has been coupled with an IC engine, a gas turbine and a CCGT (combined cycle gas turbine). The second part of this work is focused on the research of the bacterial species invo...
This document has been made available through Purdue e-Pubs, a service of the Purdue University L... more This document has been made available through Purdue e-Pubs, a service of the Purdue University Libraries. Please contact epubs@purdue.edu for additional information. Complete proceedings may be acquired in print and on CD-ROM directly from the Ray W. Herrick Laboratories at
The Corresponding States (CS) density models for mixture proposed here, one for saturated and one... more The Corresponding States (CS) density models for mixture proposed here, one for saturated and one for compressed liquid, are analytically similar to the pure fluid liquid density exposed in the former paper, but now with critical constants and 8,, replacing wm , as from the mixing rules. The mixing rules present two adjustable interaction coefficients for each binary pair, but they are set to unity making the two models completely predictive: both in fact do not preliminarily require any density data for the mixture of interest. To improve the prediction accuracy a correlative mode is here proposed in which the om parameter is substituted with a 8,, (x) function which parameters are regressed from saturated liquid data, when available, for the binary mixture of interest. The two models are validated with mixtures experimental data for the families of alkanes and hydrofluoroalkanes (HFC) and the prediction accuracy obtained is significatively better with respect to the existing predi...
Within this work, a very simple but yet fully effective and cheap online measuring system has bee... more Within this work, a very simple but yet fully effective and cheap online measuring system has been tested and evaluated. The analytic method is based on the optical absorption principle. The syngas produced from a lab scale fluidized bed gasifier and post-processed in a methanation reactor has been continuously online monitored and analyzed into an optical measurement cell. In this cell, called TOM (Tar Online Measuring), a UV light stream is produced employing LEDs operating at different wavelengths and transmitted to a spectrometer, positioned on the other side of the cell, by passing through the gas stream. The presence of tar in the gas stream causes a variation of the light transmittance that is recorded from the spectrometer. At the selected UV-wavelengths, only the electronic transitions from energetic levels n to p* and n to s* are allowed. In plain words, the permanent gas components result transparent unlike tars. The tar concentration is proportional to the light transmittance, or rather to the absorption. Two different experimental approaches have been applied in order to calculate the tar concentration from the light absorption data. The analytic method fulfills its purpose, especially if the tar composition is totally or partially known. In any case, the TOM can be suitable in order to detect tar concentration exceedings, for instance in a feedback sensor. The apparatus itself is finally absolutely cheap.
In these last years, in the context of thermochemical conversion processes, the mild thermal proc... more In these last years, in the context of thermochemical conversion processes, the mild thermal process known also as "torrefaction" has emerged as particularly strategic in view of enhancing the entire biomass chain exploitation value. In particular the kinetic studies of this process has become important in supporting the design procedure expected to widespread the industrial applications linked to torrefaction. The aim of this study consists in proposing a kinetic model for torrefaction of lignocellulosic materials based on a combination of the three independent reactions set up to describe the thermal degradation of each of the constituent fibres: hemicelluloses, cellulose and lignin. This approach is based on the hypothesis proposed by Shafizadeh and McGinnis that assumed that the three fibres, during thermal degradation, present the behaviour they have when they are treated separately. By utilizing the thermogravimetric data (TGA) of the single fibers, in this work it is demonstrated that it is possible to set up a kinetic model for the thermal degradation of different biomasses that presents an enhanced predictive character. Within the torrefaction temperature conditions, usually in the range of 475K – 590K, the maximum deviation errors is nearby 4% while AAD to 1%.
The paper presents a new formulation for the viscosity surface of the refrigerant R152a. This is ... more The paper presents a new formulation for the viscosity surface of the refrigerant R152a. This is a multiparameter viscosity equation ( ) T , ρ η η = obtained from an optimization technique of the functional form based only on the available experimental data. The equation is valid for temperatures from 240 to 440 K and pressures up to 20 MPa. Two lines of viscosity minima have been observed and they have been analytically defined. Comparisons with the data are given to establish the accuracy of the viscosity values calculated using this equation. The obtained results are very satisfactory with an average absolute deviation of 0.27 % for the selected 264 primary data points and this is a significant improvement with respect to a corresponding equation in the literature. A high accuracy equation of state for the fluid is in the same time required in order to convert the experimental variables ( ) T , P into the independent variables of the viscosity equation, ( ) T , ρ .
This paper presents speed of sound measurements on pentafluoroethane (R125) in the vapor phase. T... more This paper presents speed of sound measurements on pentafluoroethane (R125) in the vapor phase. The measurements were performed in a stainless steel spherical resonator of ∼900cm3 at temperatures in the range 260–360K and pressures up to 500kPa. Acoustic virial coefficients and ideal gas heat capacities are deduced directly from the data. The whole set of speed of sound measurements and
The present work focuses both on biomass energy conversion by means of gasification and pyrolysis... more The present work focuses both on biomass energy conversion by means of gasification and pyrolysis, and on the tar bioremediation. In the first part a mathematical model, based on Gibbs free energy minimization, has been used to simulate the thermochemical processes and to characterize the producer gas from various feedstocks. Different process configurations have been taken into account by varying a set of parameters (such as equivalent ratio, steam to carbon ratio, temperature, feedstock water content and biomass ultimate analysis). The most efficient gasification/pyrolysis configuration has been assessed trough an overall energy balance carried out at the plant scale. For this purpose, three plant layouts have been modeled to compare different pathways suitable to generate syngas; in particular the gasifier has been coupled with an IC engine, a gas turbine and a CCGT (combined cycle gas turbine). The second part of this work is focused on the research of the bacterial species invo...
This document has been made available through Purdue e-Pubs, a service of the Purdue University L... more This document has been made available through Purdue e-Pubs, a service of the Purdue University Libraries. Please contact epubs@purdue.edu for additional information. Complete proceedings may be acquired in print and on CD-ROM directly from the Ray W. Herrick Laboratories at
The Corresponding States (CS) density models for mixture proposed here, one for saturated and one... more The Corresponding States (CS) density models for mixture proposed here, one for saturated and one for compressed liquid, are analytically similar to the pure fluid liquid density exposed in the former paper, but now with critical constants and 8,, replacing wm , as from the mixing rules. The mixing rules present two adjustable interaction coefficients for each binary pair, but they are set to unity making the two models completely predictive: both in fact do not preliminarily require any density data for the mixture of interest. To improve the prediction accuracy a correlative mode is here proposed in which the om parameter is substituted with a 8,, (x) function which parameters are regressed from saturated liquid data, when available, for the binary mixture of interest. The two models are validated with mixtures experimental data for the families of alkanes and hydrofluoroalkanes (HFC) and the prediction accuracy obtained is significatively better with respect to the existing predi...
Within this work, a very simple but yet fully effective and cheap online measuring system has bee... more Within this work, a very simple but yet fully effective and cheap online measuring system has been tested and evaluated. The analytic method is based on the optical absorption principle. The syngas produced from a lab scale fluidized bed gasifier and post-processed in a methanation reactor has been continuously online monitored and analyzed into an optical measurement cell. In this cell, called TOM (Tar Online Measuring), a UV light stream is produced employing LEDs operating at different wavelengths and transmitted to a spectrometer, positioned on the other side of the cell, by passing through the gas stream. The presence of tar in the gas stream causes a variation of the light transmittance that is recorded from the spectrometer. At the selected UV-wavelengths, only the electronic transitions from energetic levels n to p* and n to s* are allowed. In plain words, the permanent gas components result transparent unlike tars. The tar concentration is proportional to the light transmittance, or rather to the absorption. Two different experimental approaches have been applied in order to calculate the tar concentration from the light absorption data. The analytic method fulfills its purpose, especially if the tar composition is totally or partially known. In any case, the TOM can be suitable in order to detect tar concentration exceedings, for instance in a feedback sensor. The apparatus itself is finally absolutely cheap.
In these last years, in the context of thermochemical conversion processes, the mild thermal proc... more In these last years, in the context of thermochemical conversion processes, the mild thermal process known also as "torrefaction" has emerged as particularly strategic in view of enhancing the entire biomass chain exploitation value. In particular the kinetic studies of this process has become important in supporting the design procedure expected to widespread the industrial applications linked to torrefaction. The aim of this study consists in proposing a kinetic model for torrefaction of lignocellulosic materials based on a combination of the three independent reactions set up to describe the thermal degradation of each of the constituent fibres: hemicelluloses, cellulose and lignin. This approach is based on the hypothesis proposed by Shafizadeh and McGinnis that assumed that the three fibres, during thermal degradation, present the behaviour they have when they are treated separately. By utilizing the thermogravimetric data (TGA) of the single fibers, in this work it is demonstrated that it is possible to set up a kinetic model for the thermal degradation of different biomasses that presents an enhanced predictive character. Within the torrefaction temperature conditions, usually in the range of 475K – 590K, the maximum deviation errors is nearby 4% while AAD to 1%.
The paper presents a new formulation for the viscosity surface of the refrigerant R152a. This is ... more The paper presents a new formulation for the viscosity surface of the refrigerant R152a. This is a multiparameter viscosity equation ( ) T , ρ η η = obtained from an optimization technique of the functional form based only on the available experimental data. The equation is valid for temperatures from 240 to 440 K and pressures up to 20 MPa. Two lines of viscosity minima have been observed and they have been analytically defined. Comparisons with the data are given to establish the accuracy of the viscosity values calculated using this equation. The obtained results are very satisfactory with an average absolute deviation of 0.27 % for the selected 264 primary data points and this is a significant improvement with respect to a corresponding equation in the literature. A high accuracy equation of state for the fluid is in the same time required in order to convert the experimental variables ( ) T , P into the independent variables of the viscosity equation, ( ) T , ρ .
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