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Title: Physical properties of bio-diesel & Implications for use of bio-diesel in diesel engines

Abstract

In this study we identify components of a typical biodiesel fuel and estimate both their individual and mixed thermo-physical and transport properties. We then use the estimated mixture properties in computational simulations to gauge the extent to which combustion is modified when biodiesel is substituted for conventional diesel fuel. Our simulation studies included both regular diesel combustion (DI) and premixed charge compression ignition (PCCI). Preliminary results indicate that biodiesel ignition is significantly delayed due to slower liquid evaporation, with the effects being more pronounced for DI than PCCI. The lower vapor pressure and higher liquid heat capacity of biodiesel are two key contributors to this slower rate of evaporation. Other physical properties are more similar between the two fuels, and their impacts are not clearly evident in the present study. Future studies of diesel combustion sensitivity to both physical and chemical properties of biodiesel are suggested.

Authors:
 [1];  [1];  [1];  [1];  [1]
  1. ORNL
Publication Date:
Research Org.:
Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Fuels, Engines and Emissions Research Center (FEERC); National Transportation Research Center
Sponsoring Org.:
USDOE Laboratory Directed Research and Development (LDRD) Program
OSTI Identifier:
974208
DOE Contract Number:
DE-AC05-00OR22725
Resource Type:
Conference
Resource Relation:
Conference: SAE 2007 Powertrain & Fluid Systems Conference, Chicago, IL, USA, 20071029, 20071101
Country of Publication:
United States
Language:
English
Subject:
33 ADVANCED PROPULSION SYSTEMS; CHEMICAL PROPERTIES; COMBUSTION; COMPRESSION; DIESEL ENGINES; DIESEL FUELS; EVAPORATION; IGNITION; MIXTURES; PHYSICAL PROPERTIES; SENSITIVITY; SIMULATION; SPECIFIC HEAT; TRANSPORT; VAPOR PRESSURE

Citation Formats

Chakravarthy, Veerathu K, McFarlane, Joanna, Daw, C Stuart, Ra, Youngchul, and Griffin, Jelani K. Physical properties of bio-diesel & Implications for use of bio-diesel in diesel engines. United States: N. p., 2008. Web.
Chakravarthy, Veerathu K, McFarlane, Joanna, Daw, C Stuart, Ra, Youngchul, & Griffin, Jelani K. Physical properties of bio-diesel & Implications for use of bio-diesel in diesel engines. United States.
Chakravarthy, Veerathu K, McFarlane, Joanna, Daw, C Stuart, Ra, Youngchul, and Griffin, Jelani K. Tue . "Physical properties of bio-diesel & Implications for use of bio-diesel in diesel engines". United States. doi:.
@article{osti_974208,
title = {Physical properties of bio-diesel & Implications for use of bio-diesel in diesel engines},
author = {Chakravarthy, Veerathu K and McFarlane, Joanna and Daw, C Stuart and Ra, Youngchul and Griffin, Jelani K},
abstractNote = {In this study we identify components of a typical biodiesel fuel and estimate both their individual and mixed thermo-physical and transport properties. We then use the estimated mixture properties in computational simulations to gauge the extent to which combustion is modified when biodiesel is substituted for conventional diesel fuel. Our simulation studies included both regular diesel combustion (DI) and premixed charge compression ignition (PCCI). Preliminary results indicate that biodiesel ignition is significantly delayed due to slower liquid evaporation, with the effects being more pronounced for DI than PCCI. The lower vapor pressure and higher liquid heat capacity of biodiesel are two key contributors to this slower rate of evaporation. Other physical properties are more similar between the two fuels, and their impacts are not clearly evident in the present study. Future studies of diesel combustion sensitivity to both physical and chemical properties of biodiesel are suggested.},
doi = {},
journal = {},
number = ,
volume = ,
place = {United States},
year = {Tue Jan 01 00:00:00 EST 2008},
month = {Tue Jan 01 00:00:00 EST 2008}
}

Conference:
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  • In this study we identify components of a typical biodiesel fuel and estimate both their individual and mixed thermo-physical and transport properties. We then use the estimated mixture properties in computational simulations to gauge the extent to which combustion is modified when biodiesel is substituted for conventional diesel fuel. Our simulation studies included both regular diesel combustion (DI) and premixed charge compression ignition (PCCI). Preliminary results indicate that biodiesel ignition is significantly delayed due to slower liquid evaporation, with the effects being more pronounced for DI than PCCI. The lower vapor pressure and higher liquid heat capacity of biodiesel aremore » two key contributors to this slower rate of evaporation. Other physical properties are more similar between the two fuels, and their impacts are not clearly evident in the present study. Future studies of diesel combustion sensitivity to both physical and chemical properties of biodiesel are suggested.« less
  • The CRC Fuels for Advanced Combustion Engines working group has worked to identify a matrix of research diesel fuels for use in advanced combustion research applications. Nine fuels were specified and formulated to investigate the effects of cetane number aromatic content and 90% distillation fraction. Standard ASTM analyses were performed on the fuels as well as GC/MS and /u1H//u1/u3C NMR analyses and thermodynamic characterizations. Details of the actual results of the fuel formulations compared with the design values are presented, as well as results from standard analyses, such as heating value, viscosity and density. Cetane number characterizations were accomplished bymore » using both the engine method and the Ignition Quality Tester (IQT/sT) apparatus.« less
  • A computational study is performed to investigate the effects of physical property on diesel engine combustion characteristics using bio-diesel fuels. Properties of typical bio-diesel fuels that were either calculated or measured are used in the study and the simulation results are compared with those of conventional diesel fuels. Sensitivity of the computational results to individual physical properties is also investigated, and the results can provide information for desirable characteristics of the blended fuels. The properties considered in this study include liquid density, vapor pressure, surface tension, liquid viscosity, liquid thermal conductivity, liquid specific heat, latent heat, vapor specific heat, vapormore » diffusion coefficient, vapor viscosity and vapor thermal conductivity. The results show significant effects of the fuel physical properties on ignition delay and burning rates at various engine operating conditions. It is seen that there is no single physical property that dominates differences of ignition delay between diesel and bio-diesel fuels. However, among the 11 properties considered in the study, the simulation results were found to be most sensitive to the liquid fuel density, vapor pressure and surface tension through their effects on the mixture preparation processes.« less
  • A biorefinery, considered a chemical process plant under the Clean Air Act permitting program, could be classified as a major or minor source based on the size of the facility and magnitude of regulated pollutants emitted. Our previous analysis indicates that a biorefinery using fast pyrolysis conversion process to produce finished gasoline and diesel blendstocks with a capacity of processing 2,000 dry metric tons of biomass per day would likely be classified as a major source because several regulated pollutants (such as particulate matter, sulfur dioxide, nitrogen oxide) are estimated to exceed the 100 tons per year (tpy) major sourcemore » threshold, applicable to chemical process plants. Being subject to a major source classification could pose additional challenges associated with obtaining an air permit in a timely manner before the biorefinery can start its construction. Recent developments propose an alternative approach to utilize bio-oil produced via the fast pyrolysis conversion process by shipping it to an existing petroleum refinery, where the raw bio-oil can be blended with petroleum-based feedstocks (e.g., vacuum gas oil) to produce gasoline and diesel blendstocks with renewable content. Without having to hydro-treat raw bio-oil, a biorefinery is likely to reduce its potential-to-emit to below the 100 tpy major source threshold, and therefore expedite its permitting process. We compare the PTE estimates for the two biorefinery designs with and without hydrotreating of bio-oils and examine the air permitting implications on potential air permit classification and discuss the best available control technology requirements for the major source biorefinery utilizing hydrotreating operation. Our analysis is expected to provide useful information to new biofuel project developers to identify opportunities to overcome challenges associated with air permitting.« less
  • This paper presents the main results of an experimental research on the use of alcohols and in particular methanol, as integrative fuels of gas-oil for 4 stroke Diesel engines. A comparison has been made between performances and contribution to air pollution of a typical engine for medium and heavy truck, operating with binary gas-oil-methanol and gas-oil-ethanol mixtures both in the supercharged and in the aspirated type. More over tests have been made on ternary mixtures obtained by adding variable quantities of additive. During the tests, the engine regulations have not been changed: in particular the advance of injection has beenmore » kept constant in order to point out the different response and therefore the adaptability of a serial engine to fuel variations. By using methanol, decreases in power and increases in specific consumption are in line with the reduction in the heat value of the fuel mixture; such variations are more remarkable at higher r.p.m. and, in any case, in aspirated engine than in the supercharged type. By increasing methanol content it is remarkable the reduction in nitrogen oxides, due to the cooling caused by high vaporization heat of methanol mixtures. The addition of an additive improves combustion conditions, hence the grade of smoke decreases.« less