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International Journal of Energetic Materials and Chemical Propulsion
ESCI SJR: 0.149 SNIP: 0.16 CiteScore™: 0.29

ISSN Print: 2150-766X
ISSN Online: 2150-7678

International Journal of Energetic Materials and Chemical Propulsion

DOI: 10.1615/IntJEnergeticMaterialsChemProp.2014005400
pages 319-337

EVALUATING AND TESTING BIOFUELS TO MEET COLD START AND ALTITUDE RELIGHT REQUIREMENTS

Joel Jean
Department of Mechanical Engineering, Universite Laval, 1065, Avenue de la Medicine, Quebec, QC G1V0A6 Canada
Alain Fossi
Department of Mechanical Engineering, Universite Laval, 1065, Avenue de la Medicine, Quebec, QC G1V0A6 Canada
Alain de Champlain
Combustion Laboratory, Mechanical Engineering Department, Laval University, Quebec, QC, Canada G1V0A6
Bernard Paquet
Combustion Laboratory, Mechanical Engineering Department, Laval University, Quebec, QC, Canada G1V0A6

ABSTRACT

Cold start and altitude relight pose special challenges to the gas turbine combustion system in the operating envelope when using biofuel with different properties. To ensure proper ignition characteristics, the properties for different biofuel blends are compared to Jet A-1 fuel. This investigation reviews proper engine operability and finds the minimum fuel-to-air ratio for these conditions. Also, some features of the combustor aerodynamics are accounted for by considering various differential pressures across the combustor. The relevant variables to simulate altitude relight and cold start are pressure and temperature since they are critical factors to consider for successful ignition. Another significant parameter to consider is the amount of spark energy to ensure ignition of a sufficiently rich mixture. Light-up at altitude is critical because there is a limited window of opportunity. Therefore, a significantly higher fuel-to-air ratio region obtained by delivering enough fuel vapors locally will greatly assist thee ventual start or restart of the engine. The altitude relight facility at Universite Lavalis capable of generating conditions for cold start down to −50° C and relight up to an altitude of 15,240 m (50,000 ft or 50 kft). This rig represents an economical way to simulate these altitude conditions with the use of a steam ejector that can cover a wide pressure range and Mach number. As demonstrated with test results and properties for the various biofuel/Jet A-1 blends, significant improvements were noted for a number of these drop-in biofuel blends because of their higher reactivity as reflected in their higher content of long-chain paraffins.