Letter pubs.acs.org/journal/estlcu
Lubricating Oil as a Major Constituent of Ship Exhaust Particles Philipp Eichler,† Markus Müller,† Carolina Rohmann,† Benjamin Stengel,‡ Jürgen Orasche,§ Ralf Zimmermann,§,∥ and Armin Wisthaler*,†,⊥ †
Institute for Ion Physics and Applied Physics, University of Innsbruck, Innsbruck 6020, Austria Chair of Piston Machines and Internal Combustion Engines, University of Rostock, Rostock 18059, Germany § Joint Mass Spectrometry Centre, CMA-Comprehensive Molecular Analytics, Helmholtz Zentrum München, Neuherberg 85764, Germany ∥ Joint Mass Spectrometry Centre, Chair of Analytical Chemistry, Institute of Chemistry, University of Rostock, Rostock 18059, Germany ⊥ Department of Chemistry, University of Oslo, Oslo 0315, Norway ‡
S Supporting Information *
ABSTRACT: A proton-transfer-reaction time-of-flight mass spectrometer combined with the novel CHARON (“chemical analysis of aerosol online”) aerosol inlet was used for characterization of submicrometer particulate organic matter in ship engine exhaust. Particles were sampled from diluted and cooled exhaust of a marine test bench engine that was operated on residual heavy fuel oil (HFO) and low-sulfur distillate marine gas oil (MGO), respectively. In both fuel operation modes, exhaust particle mass spectra were dominated by polycycloalkanes in the C20-to-C39 range, which are typical main constituents of lubricating oils. Exhaust particle mass spectra were closely reproduced when the engine’s lubricant oil was directly measured in aerosolized form. We report emission profiles of lubricant oil hydrocarbons as a function of their volatility and as a function of their carbon atom number. Total emissions of lubricant oil amounted to 183 and 74 mg kW−1 h−1 for HFO and MGO combustion, respectively. These values resemble typical oil loss rates of marine four-stroke trunk piston engines in which most of the lubricant is known to be lost through the combustion chamber and the tailpipe. We conclude that marine trunk piston engines are generally prone to high emissions of particles mainly composed of unburned lubricating oil.
1. INTRODUCTION
engine and demonstrate that the organic fraction in ship exhaust particles is primarily composed of lubricating oil.
Ship exhaust particles pose a health risk to the population living in harbor cities and along coastlines with heavy ship traffic.1 Over the open sea, ship exhaust particles induce and alter the formation of marine clouds, which in turn affect the Earth’s radiative balance.2 A detailed understanding of the underlying biological, chemical, and physical processes can be developed only if the chemical composition of the particles is quantitatively known. Ships are typically powered by diesel engines, which are known for their high emissions (hundreds of milligrams per kilowatt hour) of particulate organic matter (POM).3−10 For nonmarine diesel engines, it has been extensively documented that lubrication oil is an important parent material of emitted POM.11−15 For marine diesel engines, this has been shown in only a few technical conference papers.16,17 The organic composition of ship exhaust particles is hitherto largely (>97.5% of total organic mass) unknown.9 We have recently succeeded in using proton-transfer-reaction time-of-flight mass spectrometry (PTR-ToF-MS) for online organic analysis of submicrometer POM.18 In this letter, we will present the results from emission measurements of a ship diesel © 2017 American Chemical Society
2. EXPERIMENTAL SECTION 2.1. Engine and Engine Operation Fluids. A onecylinder, four-stroke, trunk piston engine (SKL 1 VDS 18/15, VEB Elbe-Werk Roßlau) with common rail injection was used for the experiments. The test bench engine was run under stable conditions (50% load, 40 kW, 1500 rpm, λ = 4.3 for lowNOx combustion) for several hours before the experiments were started. The test bench did not include an exhaust treatment system, and the crankcase was not ventilated into the exhaust. We used two types of fuel, heavy fuel oil (HFO, ISO-F RMG 380) and marine gas oil (MGO, ISO-F DMA), with sulfur contents of 2.33 and 0.08% (w/w), respectively. HFO is a residual oil from crude oil refining primarily composed of high-molecular weight hydrocarbons (C20−C45). MGO is a Received: Revised: Accepted: Published: 54
December 30, 2016 January 18, 2017 January 18, 2017 January 18, 2017 DOI: 10.1021/acs.estlett.6b00488 Environ. Sci. Technol. Lett. 2017, 4, 54−58
Letter
Environmental Science & Technology Letters complex mixture of middle distillate hydrocarbons (C10−C28). The engine was run on a lubricating oil for marine diesel engines (Gulfmar Select Plus 430, Golf Oil Nederland B.V., Den Helder, The Netherlands) of viscosity grade SAE 40. The Safety Data Sheet describes the lubricating oil as a mixture of mineral base oils (mostly C20−C50,
