Slavery and the Revival of Anti-slavery Activism

This chapter sets out the volumes critical approach to the dominant discourse on modern slavery and its impulse to question the assumptions and the politics behind that discourse. It explores the limits of the modern slavery rhetoric for understanding the complicated logics of agency, freedom and belonging, and of past, present and future, for those who are constituted as slaves. Document type: Part of book or chapter of boo

Development of an in-service snowmobile emission test procedure for the SAE clean snowmobile challenge

As concerns over air pollution continue to increase, all vehicles are subject to greater scrutiny for their emissions levels. Snowmobiles and other off-road recreational vehicles are now required to meet emissions regulations enacted by the United States Environmental Protection Agency (EPA). Currently these vehicles are certified using a stationary test procedure with the engine operating attached to a dynamometer and following a five-mode test cycle. The five modes range from idle to wide open throttle and are chosen to represent the typical operation regime of a vehicle. In addition, the EPA five-mode stationary emissions test has been traditionally used for scoring competition snowmobiles at the SAE Clean Snowmobile Challenge (CSC). For the 2009 CSC, in-service emission testing was added to the competition to score the teams on actual, in-use emissions during operation of their competition snowmobile operated on a controlled test course. The testing was done using a Semtech-DS mobile emissions analyzer that was installed in an enclosed sleigh and pulled behind the snowmobile. This paper discusses the development of the in-service test procedure that was used to score the competition snowmobiles during the 2009 CSC and presents preliminary data collected during this development. The results from the In-Service Emission Event at the 2009 CSC are also presented and discussed along with the results from the stationary, five-mode emissions test. Future development plans for in-service emission measurements include improving accuracy and incorporating real-time fuel flow measurement to permit truly dynamic vehicle operation during emissions sampling

Review of waste heat recovery mechanisms for internal combustion engines

The demand for more fuel efficient vehicles has been growing steadily and will only continue to increase given the volatility in the commodities market for petroleum resources. The internal combustion engine utilizes approximately one third of the chemical energy released during combustion. The remaining two-thirds are rejected from the engine via the cooling and exhaust systems. Significant improvements in fuel conversion efficiency are possible through the capture and conversion of these waste energy streams. Promising waste heat recovery techniques include turbocharging, turbo compounding, Rankine engine compounding, and thermoelectric generators. These techniques have shown increases in engine thermal efficiencies that range from 2% to 20%, depending on system design, quality of energy recovery, component efficiency, and implementation. The purpose of this paper is to provide a broad review of the advancements in the waste heat recovery methods; thermoelectric generators and Rankine cycles for electricity generation, which have occurred over the past 10 years as these two techniques have been at the forefront of current research for their untapped potential. The various mechanisms and techniques, including thermodynamic analysis, employed in the design of a waste heat recovery system are discussed. Copyright © 2010 by ASME

Review of waste heat recovery mechanisms for internal combustion engines

The demand for more fuel efficient vehicles has been growing steadily and will only continue to increase given the volatility in the commodities market for petroleum resources. The internal combustion (IC) engine utilizes approximately one third of the chemical energy released during combustion. The remaining two-thirds are rejected from the engine via the cooling and exhaust systems. Significant improvements in fuel conversion efficiency are possible through the capture and conversion of these waste energy streams. Promising waste heat recovery (WHR) techniques include turbocharging, turbo compounding, Rankine engine compounding, and thermoelectric (TE) generators. These techniques have shown increases in engine thermal efficiencies that range from 2% to 20%, depending on system design, quality of energy recovery, component efficiency, and implementation. The purpose of this paper is to provide a broad review of the advancements in the waste heat recovery methods; thermoelectric generators (TEG) and Rankine cycles for electricity generation, which have occurred over the past 10 yr as these two techniques have been at the forefront of current research for their untapped potential. The various mechanisms and techniques, including thermodynamic analysis, employed in the design of a waste heat recovery system are discussed. © 2014 by ASME

Determination of heat transfer augmentation due to fuel spray impingement in a high-speed diesel engine

As the incentive to produce cleaner and more efficient engines increases, diesel engines will become a primary, worldwide solution. Producing diesel engines with higher efficiency and lower emissions requires a fundamental understanding of the interaction of the injected fuel with air as well as with the surfaces inside the combustion chamber. One aspect of this interaction is spray impingement on the piston surface. Impingement on the piston can lead to decreased combustion efficiency, higher emissions, and piston damage due to thermal loading. Modern high-speed diesel engines utilize high pressure common-rail direct-injection systems to primarily improve efficiency and reduce emissions. However, the high injection pressures of these systems increase the likelihood that the injected fuel will impinge on the surface of the piston. This research focuses on identifying impingement in a high-speed direct-injection diesel engine as well as characterizing its effects on heat transfer to the surface of a piston. This is achieved by measuring the instantaneous surface temperature of one of the pistons in the engine using eight, fast-response surface thermocouples and a wireless microwave telemetry system for data transfer. By reorienting the fuel injector, and therefore repositioning the fuel spray plumes in the combustion chamber, the effects of the fuel spray impingement on the heat transfer to the surface of the piston have been identified at various locations on the piston. The extent to which the spray plume augments the heat transfer was quantified by calculating the instantaneous surface heat flux with the injector (i.e. spray plumes) in various positions. The minimum heat flux occurred between spray plumes where no impingement signature was found. The maximum heat flux occurred when the spray plume was impinging directly upon the thermocouples on the piston bowl lip. The difference in surface heat flux was determined to vary by a factor of three, between the two injector locations

Nucleate boiling identification and utilization for improved internal combustion engine efficiency

Internal combustion engines continue to become more compact and require greater heat rejection capacity. This demands research in cooling technologies and investigation into the limitations of current forced convection based cooling methods. A promising solution is the cooling strategy optimized with nucleate boiling to help meet these efficiency and emission requirements. Nucleate boiling results in an increased heat transfer coefficient, potentially an order of magnitude greater than forced convection, thereby providing improved cooling of an engine. This allows reduced coolant flow rates, increased efficiency, and reduced engine warm-up time. A study was conducted to characterize nucleate boiling occurring in the cooling passages of an IC engine cylinder head in a computational as well as experimental domain. The simulation was conducted to understand the physics of boiling occurring in an engine cooling passage and provide support for a potential boiling detection method. The computational fluid dynamics (CFD) simulation was performed for a simplified, two dimensional domain that resembled an engine cooling passage. The simulation results were followed by investigations of a pressure-based detection technique which was proven to be an effective method to detect boiling. An experimental test rig was used which consisted of a single combustion chamber section from a 5.4L V8 cylinder head. Water was used as the coolant. Results demonstrate the phase change physics involved in the boiling in an engine cooling passage, pressure variations in the coolant, heat flux data associated with the onset of nucleate boiling, and a comparison with existing boiling curves for water. Results of the simulation and experimental setup indicated that the change in energy and accompanying increase in pressure values can be related to bubble dynamics and thus provides a potential method to accurately detect nucleate boiling occurrence in an engine cooling system. Copyright © 2010 by ASME

Experimental study of spark plasma stretching and combustion variations analysis using flame luminosity images from an optically accessible internal combustion engine

Understanding the behavior of spark plasma and flame initiation in internal combustion engines leads to improvement in fuel economy and exhaust emissions. This paper experimentally investigated spark plasma stretching and cycle-to-cycle variations under various engine speed, load, and air–fuel mixtures using natural luminosity images. Natural luminosity images of combustion in an IC engine provide information about the flame speed, rate of energy release, and combustion stability. Binarization of the intensity images has been a desirable method for detecting flame front and studying flame propagation in combustors. However, binarization can cause a loss of information in the images. To study spark plasma stretching, the location of maximum intensity was tracked and compared to the trajectory of the flame centroid in binarized images as a representative for bulk flow motion. Analysis showed comparable trends between the trajectories of the flame centroid and spark stretching. From three air–fuel mixtures, the spark plasma for the lean mixture appeared to be more sensitive to the stretching. In addition, this research investigated combustion variations using two-dimensional (2D) intensity images and compared the results to coefficient of variation (COV) of indicated mean effective pressure (IMEP) computed from in-cylinder pressure data. The results revealed a good correlation between the variations of the luminosity field during the main phase of combustion and the COV of IMEP. However, during the ignition and very early flame kernel formation, utilizing the luminosity field was more powerful than in-cylinder pressure-related parameters to capture combustion variations

Development of a turbulent burning velocity model based on flame stretch concept for SI engines

According to the US Energy Information Administration, fossil fuels will remain the main source of energy for transportation over the next decades and thus the combustion of these fuels remains an important concern. This research studied the flame propagation under engine in-cylinder conditions and developed a correlation for turbulent burning velocity based on the global flame stretch concept. To study the impact of engine operation on flame stretch, two speeds, two loads, and three fuel-air mixtures were investigated. The flame front was determined by processing images of the flame natural luminosity. A turbulent burning velocity model was developed using dimensional analysis. The model showed that the turbulent burning velocity decreased due to flame stretching. Higher engine speeds increased the turbulent burning velocity by increasing the turbulent intensity, yet a tradeoff between the flame stretch and the turbulent burning velocity due to higher engine speed was observed. In cases where the flame distortion was very high, the flame stretch may cancel out any benefits of a large enflamed area. Incorporating the flame stretch into the burning velocity model and coupling the developed model with GT-Power simulation software revealed that the stretch may result in a 35% reduction in turbulent burning velocity