M. Yusuf Khan

Bio: M. Yusuf Khan is an academic researcher from University of California, Riverside. The author has contributed to research in topics: Propulsion & Diesel particulate filter. The author has an hindex of 7, co-authored 13 publications receiving 203 citations. Previous affiliations of M. Yusuf Khan include Community emergency response team.

Benefits of Two Mitigation Strategies for Container Vessels: Cleaner Engines and Cleaner Fuels

Abstract: Emissions from ocean-going vessels (OGVs) are a significant health concern for people near port communities. This paper reports the emission benefits for two mitigation strategies, cleaner engines and cleaner fuels, for a 2010 container vessel. In-use emissions were measured following International Organization for Standardization (ISO) protocols. The overall in-use nitrogen oxide (NOx) emission factor was 16.1 ± 0.1 gkW–1 h–1, lower than the Tier 1 certification (17 gkW–1 h–1) and significantly lower than the benchmark value of 18.7 gkW–1 h–1 commonly used for estimating emission inventories. The in-use particulate matter (PM2.5) emission was 1.42 ± 0.04 gkW–1 h–1 for heavy fuel oil (HFO) containing 2.51 wt % sulfur. Unimodal (∼30 nm) and bimodal (∼35 nm; ∼75 nm) particle number size distributions (NSDs) were observed when the vessel operated on marine gas oil (MGO) and HFO, respectively. First-time emission measurements during fuel switching (required 24 nautical miles from coastline) showed that concen...

Greenhouse gas and criteria emission benefits through reduction of vessel speed at sea.

Abstract: Reducing emissions from ocean-going vessels (OGVs) as they sail near populated areas is a widely recognized goal, and Vessel Speed Reduction (VSR) is one of several strategies that is being adopted by regulators and port authorities. The goal of this research was to measure the emission benefits associated with greenhouse gas and criteria pollutants by operating OGVs at reduced speed. Emissions were measured from one Panamax and one post-Panamax class container vessels as their vessel speed was reduced from cruise to 15 knots or below. VSR to 12 knots yielded carbon dioxide (CO(2)) and nitrogen oxides (NO(x)) emissions reductions (in kg/nautical mile (kg/nmi)) of approximately 61% and 56%, respectively, as compared to vessel cruise speed. The mass emission rate (kg/nmi) of PM(2.5) was reduced by 69% with VSR to 12 knots alone and by ~97% when coupled with the use of the marine gas oil (MGO) with 0.00065% sulfur content. Emissions data from vessels while operating at sea are scarce and measurements from this research demonstrated that tidal current is a significant parameter affecting emission factors (EFs) at lower engine loads. Emissions factors at ≤20% loads calculated by methodology adopted by regulatory agencies were found to underestimate PM(2.5) and NO(x) by 72% and 51%, respectively, when compared to EFs measured in this study. Total pollutant emitted (TPE) in the emission control area (ECA) was calculated, and emission benefits were estimated as the VSR zone increased from 24 to 200 nmi. TPE(CO2) and TPE(PM2.5) estimated for large container vessels showed benefits for CO(2) (2-26%) and PM(2.5) (4-57%) on reducing speeds from 15 to 12 knots, whereas TPE(CO2) and TPE(PM2.5) for small and medium container vessels were similar at 15 and 12 knots.

Measuring in-use ship emissions with international and U.S. federal methods

Abstract: Regulatory agencies have shifted their emphasis from measuring emissions during certification cycles to measuring emissions during actual use. Emission measurements in this research were made from two different large ships at sea to compare the Simplified Measurement Method (SMM) compliant with the International Maritime Organization (IMO) NOx Technical Code to the Portable Emission Measurement Systems (PEMS) compliant with the U.S. Environmental Protection Agency (EPA) 40 Code of Federal Regulations (CFR) Part 1065 for on-road emission testing. Emissions of nitrogen oxides (NOx), carbon dioxide (CO2), and carbon monoxide (CO) were measured at load points specified by the International Organization for Standardization (ISO) to compare the two measurement methods. The average percentage errors calculated for PEMS measurements were 6.5%, 0.6%, and 357% for NOx , CO2, and CO, respectively. The NOx percentage error of 6.5% corresponds to a 0.22 to 1.11 g/kW-hr error in moving from Tier III (3.4 g/kW-hr) to Ti...

Ultrafine Particles in the Urban Air: To the Respiratory Tract-And beyond? Is the Central Nervous System Yet Another Target for Ultrafine Particles? (Editorial)

Abstract: fine particle hypothesis stating that ambient ultrafine particles (UFP; < 0.1 μm in aerodynamic diameter) may cause adverse health effects at the first Colloquium for Particulate Air Pollution and Human Mortality and Morbidity in Irvine, California, it was met with friendly skepticism as well as out-right dismissal. Arguments were that UFP are very short-lived and disappear through heterogeneous and homogeneous aggregation within seconds or minutes and therefore are toxicologically irrelevant. These arguments did not recognize that UFP are continuously generated or that ambient UFP contribute very little, if any, mass to ambient PM10 (particles < 10 μm in aerodynamic diameter) or PM2.5 (particles < 2.5 μm in aerodynamic diameter). Indeed, the mass distribution of a typical urban aerosol among the different particle sizes may support this point (Figure 1). This attitude of skepticism has changed considerably. Research teams across the world are working now on UFP, forming multidisciplinary alliances between atmospheric scientists, engineers, epidemiologists, clinicians, and toxicologists. They investigate UFP sources, generation, physicochemical characteristics, behavior in ambient air, and potential effects and underlying mechanisms following their inhalation. Still, sound skepticism lingers, as demonstrated by the title of a presentation at the 2002 meeting of the Health Effects Institute: “Nanoparticles: Are They Real?” Obviously, there is no question that UFP are real, but it is also clear that we still do not know enough about them, despite significant progress in our understanding since 1994. Atmospheric UFP derived from gas-to-particle conversions have many sources, natural and anthropogenic, the latter being mostly derived from internal combustion processes. Diesel fuel, gasoline, and even compressed natural gas—considered to be “clean”—powered engines all emit high numbers of UFP. If these anthropogenic UFP cause significant health effects, is the conversion of dieselpowered buses to compressed natural gas—as practiced now in several cities—really a good idea? We should be more cautious about introducing technologies based on the assumption that they result in cleaner air with fewer and less toxic contaminants. The experience with methyl tert-butyl ether as a fuel additive should serve as a reminder of the potential unintended health and environmental consequences of altering fuels and resulting emissions on a large scale without an adequate understanding of toxicity. Since vehicular emissions are regulated by mass output, modern technologies for internal combustion engines favor the generation and formation of UFP because they contribute minimally to the mass output of fine particles (Figure 1). It should come as no surprise that “clean” engines are built to conform to present standards of mass output, despite emitting high numbers of UFP. A standard based on particle number would be more appropriate to reduce UFP emissions. A standard based on particle surface area—as is also proposed—may not be helpful to control UFP because fine particles comprise most of the total particle surface area (Figure 1). In recent measurements made during road-chase studies in Minnesota, UFP concentrations were as high as 1 × 107 particles/cm3 (Kittelson et al. 2001). A short distance from the highways, these high UFP concentrations are lower, but individuals in automobiles on the highways are directly exposed to the high concentrations. Moreover, these UFP are freshly generated, and if results of earlier toxicologic studies with UFP generated from thermodegradation products of polymers are an indication of a general principle of UFP toxicity, freshness and proximity to the source are key requirements for inducing acute adverse effects of UFP. Do UFP emitted from internal combustion engines cause adverse health effects? We still need to know more, but results from our controlled clinical and animal studies using ultrafine elemental carbon particles permit some preliminary conclusions: The high deposition of inhaled UFP (0.007–0.1 μm) in the human respiratory tract as predicted by ICRP (1994) could be confirmed; moreover, deposition was even higher during exercise and in asthmatics. Unlike larger fine particles, UFP seem to escape phagocytosis by alveolar macrophages and are translocated to extrapulmonary organs, as was determined in rodents using ultrafine 13C particles, although such translocation was only minimal with ultrafine iridium particles. Cardiovascular effects in humans and animals and mild pulmonary inflammation in animals were also found following ultrafine carbon particle exposures. Although health effects data and understanding of mechanisms are still limited, there are intriguing data from other disciplines, in particular the field of drug delivery: Intravenously administered UFP were found to cross the blood–brain barrier (Kreuter, 2001), and a transport function of caveolae for macromolecules with molecular radii of several

Effects of alternative fuels on the combustion characteristics and emission products from diesel engines: A review

Abstract: Diesel engines are the main source of rapidly-growing energy consumption worldwide. Diesel consumption is responsible for serious air pollution, which includes nitrogen oxides (NOx), hydrocarbon (HC), carbon monoxide (CO) emissions and some particulate matter (PM) discharged from the combustion chamber. In the past few decades, alternative fuels, such as alcohol, biodiesel, natural gas, and Di Methyl Ether (DME), have been used in diesel engines to reduce energy costs and environmental pollution. As a result of alternative fuels directives, an increasing number of diesel engines have adapted dual fuel blends, and an enormous amount of research is focused on new and inadequately studied combustion and emission profiles. Compared to conventional diesel fuel, the application of dual fuels would add new parameters to combustion and emission profiles for diesel vehicles worldwide. This review aims to reveal (1) Known and anticipated combustion characteristics and emissions products from dual fuels. (2) Toxic properties and the expected influence on engine performance. (3) Identifying promising alternative fuels for emissions control in compression combustion engines. The results presented herein will show a significant reduction of regular gas and PM emissions by the use of alcohol/diesel dual fuel, while unregulated emissions such as methanol, ethanol, acetaldehyde, formaldehyde, ketone, have increased compared to those from diesel fuel. PM emissions decreased significantly with the increase of alternative fuels, such as alcohols, natural gas, biodiesel and DME, while regular gaseous emissions varied depending on the type alternative fuel and the engine conditions. As one new and cleaner substitute for diesel engines, DME operation has a longer injection delay, lower maximum cylinder pressure, a lower ratio of pressure rise, and shorter ignition delay in comparison with diesel operation--the opposite of alcohol/diesel and dual fuels. This review evaluates the effects of some alternative fuels (alcohol, biodiesel, natural gas and Di Methyl Ether (DME)) on combustion characteristics and emission products from diesel engines to meet future emission regulations using alternative fuel.