Fabio Polonara

Development and optimization of a method for analyzing biodiesel mixtures with non-aqueous reversed phase liquid chromatography.

Biodiesel (a mixture of fatty acid esters) is normally analyzed using gas chromatography/flame ionization detection, as specified by the ASTM D6584 and EN14105 standards. This paper proposes a binary gradient method for analyzing biodiesel mixtures using non-aqueous reverse phase HPLC with a UV detector capable of overcoming the drawbacks of the gas chromatographic technique normally used. The new analytical method was developed by means of a statistical sensitivity analysis applied to the main parameters influencing the recording, using the full factorial design method combined with the Yates algorithm and the steepest ascent optimization procedure. The present study shows the influence of the main biodiesel mixture separation analysis parameters. The resulting tool proved valid for analyzing not only biodiesel but also any traces of unreacted oil.

Assessment of the impact of local energy policies in reducing greenhouse gas emissions.

The present work investigates the potential energy savings coming from a careful and detailed local energy policy. The paper analyzes and assesses from technical, economic and environmental viewpoints different initiatives in the energy sector aimed at increasing energy efficiency in end-uses and reducing overall carbon emissions. The results are based on energy planning for five Italian urban areas sized at about fifty thousand inhabitants. The analysis has been developed with the aim of reaching generally applicable criteria suitable for evaluating the local energy policy contribution to the greenhouse gas (GHG) emissions reduction. Several initiatives for the private and public sectors have been considered, such as: (i) the introduction of combined heat and power generation based on useful thermal demand, suitable for the industry and service sectors (swimming pools, large distribution organizations); (ii) generation of electricity from renewables (solar energy, biomass); (iii) thermal insulation of private and public buildings, such as schools; (iv) introduction of micro-combined heat and power generation in the residential sector. For each solution the primary energy reduction and the consequent reduction in GHG emissions have been evaluated and a feasibility analysis has been developed in order to assess the profitability of the investment. Great attention has been paid to the public sector, which has an important role in providing leadership and driving changes in other sectors; furthermore, a rational use of energy combined with the exploitation of country-based incentives is able to reduce the public administrative expenditure. The results show that local energy policy can give an important contribution to gas emission reduction targets, and underline the fundamental role of public sector initiatives.

CO2 + R23 Binary System: Virial Coefficients Derived from Burnett Measurements

Burnett PVT measurements were performed on trifluoromethane (R23) and mixtures of R23 with carbon dioxide (CO2). The Burnett apparatus was calibrated using helium. Fourteen expansions were performed for 5 isotherms and in a pressure range from 130 kPa to 6 MPa for R23. Second and third virial coefficients were derived from the collected data and compared with literature values; good agreement was found between them. PVTx measurements for the binary CO2+R23 system were carried out for five isotherms (303, 313, 323, 333, and 343 K). In all, 18 runs were performed in a pressure range from 150 kPa to 5.9 MPa. The composition of the mixtures was measured with a gas chromatograph after it had been calibrated using samples prepared gravimetrically. Second and third virial coefficients for the system were derived, together with the second and third cross virial coefficients, from experimental results using virial coefficients for CO2 from previous measurements (for the same sample as used in the present study). Samples for composition measurements were collected during the first Burnett expansion. Second virial coefficients for the system showed positive deviations from ideal values, while the third virials were negative. No previous experimental results were found for the PVTx properties of this binary system.

A prediction method for thermal conductivity of alternative refrigerants in the liquid phase

A prediction method for the thermal conductivity of halocarbon refrigerants in the saturated liquid state in the reduced temperature range 0.3 to well above 0.9 is presented in this paper. The aim of the method is to present a very simple calculation of the transport property useful for engineering purposes. The method determines thermal conductivity as a sole function of the reduced temperature and requires the knowledge of a parameter dependent upon easily available physical constants characteristic of each compound. The method is validated against experimental data available in the literature, giving average absolute deviations which are usually less than 5%, with maximum absolute deviations generally less than 10%. An extension of the method to estimate thermal conductivity of binary mixtures is also presented, along with a comparison with the few experimental data available in the literature.

The feasibility of liquefied biomethane as alternative fuel: a comparison between European and Chinese markets

ABSTRACT Natural gas is considered the alternative fuel that, in the short-medium term, can best substitute conventional fuels, in order to reduce their environmental impact. The purpose of this paper is to outline the feasibility of liquefied natural gas (LNG), especially from biogas (LBG), as vehicle fuel in Europe and in China. Firstly, the analysis presents the difficulty of methane supply in some regions and the need for feasible ways of producing LNG. For this purpose, biogas recovery and its upgrade are presented as an interesting source to produce such alternative vehicle fuel, being also a renewable source with a reduced environmental impact. Secondly, an economic analysis is performed for a specific European country (Italy): it takes into account technical aspects, costs, the foreseen market price for the new fuel and the necessary incentive policy. The latter aspect has been revealed to cover a major role for the feasibility of such projects.

A relationship between dynamic viscosity and reduced temperature of refrigerant fluids and their mixtures in the liquid phase

Abstract A prediction method relating dynamic viscosity with reduced temperature is proposed in this paper for pure and mixed refrigerant fluids in the liquid state along the saturation line. The validity of the method is checked by comparison with dynamic viscosity data available in literature. Comparison results are reported for many halocarbon refrigerants and for bis(difluoromethyl)ether (RE134) as well. Some experimental data for azeotropic and non-azeotropic binary mixtures have also been compared with the dynamic viscosity predicted with the present method and a simple mixing rule. The results of the comparisons give average absolute deviations and maximum absolute deviations compatible with engineering applications.

Thermophysical properties of greenhouse gases thermal conductivity and dynamic viscosity as function of temperature and pressure

Modelling the atmosphere and its flows requires the knowledge of the physical and chemical properties of its components. In this work thermal conductivity and dynamic viscosity as function of temperature and inside well stated pressure constraints are evaluated for the major greenhouse gases as methane, carbon dioxide, nitric oxide and nitrogen dioxide and for the normal air. A general review of the existing experimental data is presented, together with a critical analysis of their precision and accuracy. Correlation and prediction methods are proposed to allow the estimation of thermal conductivity and dynamic viscosity when experimental values are not available.

Double Green Process: a low environmental impact method for recycling of CdTe, a-Si and CIS/CIGS thin-film photovoltaic modules

Abstract On the basis of the method for managing the end of life of CdTe photovoltaic panels previously proposed by the authors, a new method for the recycling of all types of thin-film panels (CdTe, a-Si and CIS/CIGS) has been developed and optimised under a research project founded by Enel Foundation and CRUI Foundation. The DGP process has been developed through a feasibility study carried out from three points of view: technical, environmental and economic. The process is composed by two sub-processes matched to each other, one suitable for CdTe panels (named DGPa) and the other one for a-Si and CIS/CIGS panels (DGPb). The Double Green Panel process is based mainly on mechanical treatments with a minimum use of chemicals and it is characterised by a greater level of automation and a high flexibility in production capacity. The potential environmental impacts of various configurations of the DGP process have been extensively analysed with LCA tool in order to develop an environmentally friendly process. The economic feasibility has been assessed through the Discounted Cash Flow Analysis (DCFA) method. The revenues associated to the recovery of valuable and common materials and the recycling costs have been taken into account.

Modelling the pressurization induced by solar radiation on above ground installations of LPG pipeline systems

Pipelining Liquefied Petroleum Gas (LPG) is a mode of LPG transportation more environmentally-friendly than others due to the lower energy consumption and exhaust emissions. Worldwide, there are over 20000 kilometers of LPG pipelines. There are a number of codes that industry follows for the design, fabrication, construction and operation of liquid LPG pipelines. However, no standards exist to modelling particular critical phenomena which can occur on these lines due to external environmental conditions like the solar radiation pressurization. In fact, the solar radiation can expose above ground pipeline sections at pressure values above the maximum Design Pressure with resulting risks and problems. The present work presents an innovative practice suitable for the Oil & Gas industry to modelling the pressurization induced by the solar radiation on above ground LPG pipeline sections with the application to a real case.

Biogas purification and liquefaction by means of a cryogenic upgrading process

Transport sector represents one of the main responsible for greenhouse gas (GHG) emissions and natural gas (NG) could efficiently reduce them, especially in its liquid form (LNG) suitable for heavy-duty vehicles. Nevertheless, in certain regions, LNG is difficult to supply and biogas is actually used as feedstock gas. However, due to its high CO2 content, biogas needs to be purified. At present, several upgrading technologies are existing but since the final scope is the LNG production, cryogenic upgrading technology looks very promising. However, this technology is still in a developing phase. This study proposes a cryogenic upgrading process in which CO2 is removed and biomethane is liquefied (LBG) at the same time. Moreover, specific energy consumption is optimized by means of HYSYS simulation and a rough economical analysis is also performed to evaluate its attractiveness. As a result, cryogenic upgrading technology represents an interesting option for LBG production.