Добірка наукової літератури з теми "Engine insulation"

Cooling heat loss is one of the most dominant losses among the various engine losses to be reduced. Although many attempts to reduce it by insulating the combustion chamber wall have been carried out, most of them have not been successful. Charge air heating by the constantly high temperature insulating wall is a significant issue, because it deteriorates charging efficiency, increases the emissions of soot and NOx in diesel engines, and promotes the knock occurrence tendency in gasoline engines. A new concept heat insulation methodology which can reduce cooling heat loss without heating the charging air has been developed. Surface temperature of insulation coating on the combustion chamber wall changes rapidly, according to the quickly changing in-cylinder gas temperature in each engine stroke. During the compression and expansion stroke, the surface temperature of the insulation coating goes up rapidly, and consequently, the heat transfer becomes lower by the reduced temperature difference between the surface and the gas. During the intake stroke, the surface temperature goes down rapidly, and it prevents intake air heating from the wall. To realize the above-mentioned functionality, a thin coating layer with low thermal conductivity and low heat capacity was developed. It was applied on the pistons of diesel engines, and showed improvement in thermal efficiency. It also showed a reduction of unburnt fuel emission in low temperature engine starting condition. The energy balance analysis showed reduction of cooling heat loss and, on the contrary, increase in the brake power and the exhaust loss.

The heat of vehicle engine emission is still can be used in order to efficiency effort and thermal polution preventive activity. This research is aimed to get the effect of the insulator coating pattern on the header on the motorcycle exhaust temperature. The reserach is done for Honda Scoopy motorcycle with engine rotation vary as 1000, 1500 and 2000 rpm. Isolator insulation vary for insulation pattern as 0, 1 and 2 cm in distance. The temperatures of exhaust are measured in 4 points measurement with K type thermocouple. The result shows that insulator coating pattern affects the temperature of the exhaust gas heat dissipation exhaust pipe (header) motorcycle exhaust. Keywords: header, exhaust, isolator insulation, heat

The low-heat-rejection (LHR) diesel promises decreased engine fuel consumption by eliminating the traditional liquid cooling system and converting energy normally lost to the coolant into useful shaft work instead. However, most of the cooling energy thus conserved is transferred into the exhaust stream rather than augmenting crankshaft output directly, so exhaust-energy recovery is necessary to realize the full potential of the LHR engine. The higher combustion temperature of the LHR diesel favors increased emission of NOx, with published results on hydrocarbon and particulate emissions showing mixed results. The cylinder insulation used to effect low heat rejection influences convective heat loss only, and in a manner still somewhat controversial. The cyclic aspect of convective heat loss, and radiation from incandescent soot particles, also deserve attention. The temperatures resulting from insulating the cylinder of the LHR diesel require advancements in lubrication. The engine designer must learn to deal with the probabilistic nature of failure in brittle ceramics needed for engine construction. Whether ceramic monoliths or coatings are more appropriate for cylinder insulation remains unsettled. These challenges confronting the LHR diesel are reviewed.

At present, fuel efficiency improvement technologies for example weight, engine efficiency improvement, design modification, and eco-friendly car are being proceed due to the tightened international regulations. Therefore, production of eco-friendly cars specially electric car has increased. Due to that, the main noise source has changed from engine to motor noise and road noise as it has been changed from engine cars that have led engine technology to eco-friendly cars. As the noise source has changed, it is necessary to manufacture sound absorption/insulation structure for the noise characteristics generated by electric vehicles. In this work, the elastomer sheet was applied to the Dash outer as automotive terior parts for reducing engine noise. We applied the elastomer sheets for generation Dash outer layers (nonwooven/PU foam/nonwooven) to improve sound insulation properties. The elastomer sheet showed surface wetting between PU foam and elastomer sheets by optical microscopy. The acoustic properties were measured by APAMAT-II and BUCK tests.

This research is a development of previous research, where in the previous research, a design innovation was carried out on an alpha-type stirling engine by making the phase angle to 180o, with the aim of reducing the effect when the cold cylinder is compressed, because the phase angle currently used is (90o) with disadvantages, namely the cold cylinder is perpendicular to the top, so that the compression process against gravity. But in previous studies, the generator pipe was too long, causing a lot of energy or heat loss (heat loss) so that the compression speed was small. So that in the research, innovated and analyzed the pipe insulation of alpha-type stirling engine generators, alpha-type stirling engines, 180o phase angle. The research method used is to use the thermodynamic approach with Schmidt theory and the theory of the ideal cycle stirling engine. while the simulation is done using the Ideal Stirling Cycle Calculator. Results investigated shows that providing insulation on the generator pipes of an alpha-type stirling engine for an alpha-type stirling engine with a 180o phase angle is proven to reduce a lot of energy or heat loss (heat loss) due to too long generator pipes, with a heat loss value ratio of 226.66 W for the pipe. generator that uses insulation whose value is smaller than the value of the heat loss when the generator pipe without using isocation is 1,584.12 W.

Clean and highly efficient internal combustion engines will still be necessary in the future to meet the ambitious CO2 emissions reduction targets set for light-duty vehicles. The maximal efficiency of stoichiometric Spark-Ignited (SI) gasoline engines has been steadily increasing in recent years but remains limited by the important relative share of cooling losses. Low heat rejection engines using ceramic barrier coatings have been presented in the past but smart insulation coatings are gaining a renewed interest as a more promising way to further increase the engine maximal thermal efficiency. This article is highlighting some important effects of smart insulation coatings developed for lean-burn spark-ignited gasoline engines. Five different coatings with low heat conductivity and capacity are applied on aluminum engine parts with the atmospheric plasma spray technique and are tested with two different engines. The laser induced phosphorescence technique is firstly used in an optical single cylinder engine to quantify the thermal performance of these coatings in terms of temperature swing during combustion. A maximal increase in the piston surface temperature of around 100 °C is measured at low load, confirming thus the expected impact of the low heat conductivity and capacity, and suggesting thus a positive impact on fuel consumption. Thanks to the tests performed with a similar metal single cylinder engine, it is shown that the unburned hydrocarbon emissions can significantly increase by up to 25% if the open porosity on top of the coating is not properly sealed, while the surface roughness has no impact on these emissions. When applied on both the piston and the cylinder head, the optimized coating displays some distinct effects on the maximal heat release rate and NOx emissions, indicating that the thermal environment inside the combustion chamber is modified during combustion. Thanks to the temperature swing between cold and hot engine phases the volumetric efficiency can also be kept constant. However, no increase in efficiency can be measured with this optimized coating which suggests that the heat balance is not affected only by the reduction in the temperature differential between the walls and the gas.

Using a cooling system in water transport is considered the most effective way to increase the energy efficiency of a vessel. Currently, closed-loop cooling systems and frequency-controlled drives of seawater electric pumps are actively used. An option of improving the energy efficiency of cooling systems with mounted seawater pumps is being studied. The hydraulic scheme of the unit with an energy-efficient ship engine cooling system is presented. To study ways to reduce mechanical losses in the drive of auxiliary mechanisms of a marine engine, the laboratory “Marine Diesels” of Astrakhan State Technical University developed a test bench for the Iveco 8041I06 engine. The engine cooling system does not have a thermostat to control the thermal state; instead of a thermostat on the engine, an electronically controlled variator is installed between the engine power take-off shaft and the VKS 1/16 pump. At a constant engine speed, the variator allows changing the pump speed, supply of sea water through the heat exchanger and regulating the thermal state of the engine. It has been found that during engine tests it is necessary to maintain the temperature of the outboard water constant. A description is given of the use of tanks with thermal insulation at the stand to reduce heat exchange with the environment. Variants of types of containers and materials for insulation are considered. To prepare water of the required temperature a chiller is connected to the cooling system at the experimental stand. The calculation of thermal insulation and comparison of the result with a real test is given. On the stands for testing diesel engines the change in the thermal state of the engine is carried out only by changing the load on the engine. On the developed stand, the thermal state can also be changed, including by controlling the seawater temperature, which expands its capabilities for modeling real processes.

Abstract The use of Atmospheric Plasma Spraying (APS) and yttria stabilized zirconia (YSZ) nanostructured coatings has been applied to the bond layer of NiCrAlY coated engine cylinder heads, pistons, and valve substrates. Thermal barrier coatings (TBCs) have been utilized to increase the engine performance in the design of combustion chamber components for internal combustion engines. ASTM-C-633-01 standard has been employed to conduct the bonding strength testing. It was also considered and directed to estimate the coating’s thermal performance by evaluating its insulation value and conducting a thermal insulation durability assessment. Field emission scanning electron microscope (FESEM) and X-ray diffraction (XRD) were used to look at the nano powders and coatings’ microstructures and phase compositions. In YSZ, it was discovered that the topcoat of samples had a tri-modal pattern of nano sized particles engaged by the powder, micro-columnar grains generated from the re-solidification of the molten part of the powder, and almost equiaxed grains, which were a unique construction feature. The results demonstrated the creation of nano zones in one of three nanostructured coating zones and improved the top coating properties, including bonding strength and thermal insulation capacity. The high temperature of the diesel engine caused fatigue failure in the intake and exhaust valves.

Taking into account the oil resources depletion the requirements to fuel consumption of internal combustion engines are now increasing as well as to their reliability and durability. With the continual increase in the number of internal combustion engines in operation, along with the problem of parts of the cylinder piston group wearing out has caused exhaust from such engines to be one of the main source of harmful pollutant emissions in cities. Therefore, environmental requirements have in turn increased dramatically. The engine resource and its efficiency largely depend on the process of fuel combustion in the combustion chamber. Experimental studies aimed to improve the working process on diesel engines by piston insulation have shown an effective decrease in fuel consumption by reducing heat loss and more complete fuel combustion. When oxide ceramic coatings were used on the piston and cylinder head, the maximum power increased and the specific fuel consumption decreased. However ceramic coatings are not widely used due to their peeling. We have developed a technology for the galvanic plasma treatment of pistons, which made it possible to obtain on the pistons surface made of aluminum alloys a ceramic corundum layer with high adhesion to the base metal that does not peel and has electret properties. In 1993, pistons with a corundum surface layer were installed in a shunting diesel locomotive and life-time running tests were conducted. Such pistons increased wear resistance, reduced the wear of cylinder liners, increased the strength of the annular jumpers, and were not prone to burnouts and scuffing. They provided an increase in the resource of the cylinder-piston group of the diesel engine by more than 125 thousand engine hours. The paper provides an analysis of the effect of corundum pistons thermal insulation on significant increasing the, engine power and fuel consumption reduction. Basing on experimental bench studies of a gasoline engine, a tractor diesel engine and long-term operational life tests of diesel engines, an attempt had been made to explain the reasons for the improvement in the engines’ efficiency.

Diesel exhaust aftertreatment systems are required for meeting China StageIV emission regulations. This paper addresses an aftertreatment system designed to meet the China StageIV emission standards for nonroad vehicle markets. It presents a comprehensive experimental research work on aftertreatment skin temperature and the radiated impact on its neighboring parts in a nonroad vehicle powered by a middle range diesel engine under aftertreatment inlet/outlet with insulation and without insulation with multiple experimental conditions, as well as validating the emission results with these two different aftertreatment configurations. According to the experimental results, it can be observed that the aftertreatment inlet/outlet with insulation and without insulation using a Diesel Oxidant Catalyst (DOC) + Diesel Particle Filter (DPF) + Selective Catalytic Reduction (SCR) scheme could both meet China StageIV emission regulations and the whole vehicle arrangement. The connection pipe is generally short between the aftertreatment and the engine turbo charger on nonroad application vehicles, which results in the exhaust gas temperature of the internal aftertreatment at each point being similar, with variation within ±2% for the aftertreatment inlet/outlet with insulation compared to the aftertreatment inlet/outlet without insulation. The aftertreatment skin temperature differences under these two configurations occur on the inlet module and outlet module, and the skin temperatures of other aftertreatment modules are little impacted. These experimental results also validate the radiation model. All aftertreatment skin temperatures are measured with different experimental conditions. In future, if considering integrating other parts like sensors on the surface of the aftertreatment, the configuration with insulation is recommended. As per the experimental results, the maximum inlet skin temperature can lower nearly 50% with insulation and the maximum outlet temperature could lower about 28% compared to the configuration without inlet/outlet insulation. If taking cost into consideration, the configuration without insulation is suggested. This research also introduces alternative solutions for different concerns for real applications. The methodology provides effective guidance and reference for future aftertreatment insulation considerations for inlet modules and outlet modules on real applications.

Describing planned acoustic design by single number ratings yields a weak link to the subjective event, especially when the single number ratings are interpreted by others than experienced acousticians. When developing infrastructure, tools for decision making needs to address visual and aural perception. Visual perception can be addressed using game engines and this has enabled the establishment of tools for visualizations of planned constructions in virtual reality. Audio engines accounting for sound propagation in the game engine environment are steadily developing and have recently been made available. The aim of this project is to simulate airborne sound insulation by extending the support of recently developed audio engines directed towards virtual reality applications. The case studied was airborne sound insulation between two adjacent rooms in a building, the sound transmitted to the receiving room through the building structure resulting from sound pressure exciting the structural elements in the adjacent source room into vibration. The receiving room composed modelled space in the game engine Unreal Engine and Steam Audio was the considered audio engine. Sound transmission was modelled by filtering based on calculations of transmission loss via direct and flanking paths using the model included in the standard EN 12354-1. It was verified that the filtering technique for modelling sound transmission reproduced attenuations in correspondence with the predicted transmission loss. Methodology was established to quantify the quality of the audio engine room acoustics simulations. A room acoustics simulation was evaluated by comparing the reverberation time derived from simulation with theoretical predictions and the simulated reverberation time showed fair agreement with Eyring’s formula above its frequency threshold. The quality of the simulation of airborne sound insulation was evaluated relating the sound field in simulation to insulation classification by the standardized level difference. The spectrum of the simulated standardized level difference was compared with the corresponding sound transmission calculation for a modelled scenario. The simulated data displayed noticeable deviations from the transmission calculation, caused by the audio engine room acoustics simulation. However, the simulated data exhibited cancellation of favourable and unfavourable deviations from the transmission calculation resulting in a mean difference across the spectrum below the just noticeable difference of about 1 dB. Single number ratings was compared and the simulated single number rating was within the standard deviation of how the transmission model calculates predictions for a corresponding practical scenario measured in situ. Thus, the simulated data shows potential and comparisons between simulated data, established room acoustics simulation software and in situ measurements should further be made to deduce whether the deviations entails defects in the airborne sound insulation prediction or is an error imposed by the audio engine room acoustics simulation.

In-cylinder thermal barrier materials have been thoroughly investigated for their potential improvements in thermal efficiency in reciprocating internal combustion engines. These materials show improvements both directly in indicated work and indirectly through reduced demand on the cooling system. Many experimental and analytical sources have shown reductions in heat losses to the combustion chamber walls, but converting the additional thermal energy to indicated work has proven more difficult. Gains in indicated work over the expansion stroke could be made, but these were negated by increased compression work and reduced volumetric efficiency due to charge heating. Typically, the only improvements in brake work would come from the pumping loop in turbocharged engines, or from additional exhaust energy extraction through turbine-compounding devices. The concept of inter-cycle wall-temperature-swing holds promise to reap the benefits of insulation during combustion and expansion, while not suffering the penalties incurred with hotter walls during intake and compression. The combination of low volumetric heat capacity and low thermal conductivity would allow the combustion chamber surface temperature to quickly respond to the gas temperature throughout combustion. Surface temperatures are capable of rising in response to the spike in heat flux, thereby minimizing the temperature difference between the gas and wall early in the expansion stroke when the greatest conversion of thermal energy to mechanical work is possible. The combination of low heat capacity and thermal conductivity is essential in allowing this temperature increase during combustion, and in enabling the surface to cool during expansion and exhaust to avoid harmfully affecting engine volumetric efficiency during the intake stroke and minimizing compression work performed on the next stroke. In this thesis, thermal and thermodynamic models are constructed in an attempt to predict the effects of material properties in the walls, and to characterize the effects of heat transfer at different portions of the cycle on indicated work, volumetric efficiency, exhaust energy and gas temperatures of a reciprocating internal combustion engine. The expected impact on combustion knock in spark-ignited engines was also considered, as this combustion mode was the basis for the experimental engine testing performed. Conventional insulating materials were evaluated to benchmark the current state-of-the-art, and to gain experience in the analysis of materials with temperature-swing capability. Unfortunately, the effects of permeable porosity within the conventional coating on heat losses, fuel absorption and compression ratio tended to mask the effects of temperature swing. The individual impact of each of these loss mechanisms on engine performance was analyzed, and the experience helped to further refine the necessary traits of a successful temperature-swing material Finally, from the learnings of this analysis phase, a novel material was created and applied to the piston surface, intake valve faces, and exhaust valve faces. Engine data was taken with these coated components and compared to an un-coated baseline. While some of the test pieces physically survived the testing, analysis of the data suggests that they were not fully sealed and suffered from the same permeability losses that affected the conventional insulation. Further development is necessary to arrive at a robust, effective solution for minimizing heat transfer through wall temperature swing in reciprocating internal combustion engines. The success of temperature-swing thermal barrier materials requires very low thermal conductivity, heat capacity, and appropriate insulation thickness, as well as resilient sealing of any porous volume within the coating to avoid additional heat and fuel energy losses throughout the cycle.
Los materiales aislantes han sido investigados a fondo por sus posibles mejoras en la eficiencia térmica de los motores de combustión interna alternativos. Estas mejoras se ven reflejadas tanto directamente en el trabajo indicado como indirectamente a través de la reducción del sistema de refrigeración del propio motor. Diferentes estudios, tanto experimentales como analíticos, han mostrado la reducción en la transferencia de calor a través de las paredes de la cámara de combustión mediante la utilización de estos materiales. Sin embargo, demostrar la conversión de la energía térmica adicional en trabajo indicado ha resultado más difícil. En ciertos estudios se pudieron obtener mejoras en el trabajo indicado durante la carrera de expansión, pero éstas fueron reducidas debido a un menor rendimiento volumétrico debido al calentamiento de la carga durante el proceso de admisión y un mayor trabajo en la carrera de compresión. Típicamente, las únicas mejoras en el trabajo al freno provendrían de la reducción de pérdidas por bombeo en los motores turboalimentados, o de la extracción de la energía adicional de los gases de escape a través de turbinas. El concepto de los materiales con oscilación de la temperatura durante el ciclo motor intenta aprovechar los beneficios del aislamiento durante los procesos de combustión y expansión, mitigando las perdidas por el incremento de la temperatura de las paredes durante la admisión y la compresión. La combinación de baja capacidad calorífica y baja conductividad térmica permitiría que la temperatura de la superficie de la cámara de combustión respondiera rápidamente a la temperatura del gas durante el proceso de combustión. Las temperaturas de la superficie son capaces de aumentar en respuesta al pico de flujo de calor, minimizando así la diferencia de temperatura entre el gas y la pared en la carrera de expansión cuando es posible la mayor conversión de energía térmica en trabajo mecánico. La combinación de baja capacidad calorífica y conductividad térmica es también esencial para permitir este aumento de temperatura durante la combustión y para permitir que la superficie se enfríe durante la expansión y el escape para no perjudicar así el rendimiento volumétrico del motor durante la carrera de admisión y minimizar el trabajo de compresión realizado en el siguiente ciclo. En esta tesis se han desarrollado modelos térmicos y termodinámicos para predecir los efectos de las propiedades de los materiales en las paredes y caracterizar los efectos de la transferencia de calor en diferentes partes del ciclo sobre el trabajo indicado, el rendimiento volumétrico, la energía en los gases de escape y las temperaturas del gas para un motor de combustión interna alternativo. También se ha evaluado el impacto del uso de estos materiales en el knock en motores de combustión de encendido provocado, ya que los estudios experimentales de esta tesis se realizaron en un motor de estas características. Durante la investigación se evaluaron materiales aislantes convencionales para comprender el estado actual de esta técnica y para adquirir también experiencia en el análisis de materiales aislantes con oscilación de temperatura. Desafortunadamente, los efectos de la permeabilidad a través de la porosidad del material en los recubrimientos convencionales, la absorción de combustible y la relación de compresión tendieron a ocultar los efectos de la oscilación de la temperatura y la reducción de la transferencia de calor a través de las paredes. Así pues, se analizó el impacto individual de cada uno de estos mecanismos y su influencia en el rendimiento del motor para así definir un nuevo material con las características necesarias que mejorasen el aislante con de oscilación de temperatura. Finalmente, a partir de los estudios de esta fase de análisis, se creó un nuevo material y se aplicó a la superficie del pistón y a la supe
Els materials aïllants han estat investigats a fons per les seves possibles millores en l'eficiència tèrmica en el motors de combustió interna alternatius. Aquestes millores es veuen reflectides tant directament en el treball indicat com indirectament a través de la reducció del sistema de refrigeració del propi motor. Diferents estudis, tant experimentals com analítics, han mostrat la reducció en la transferència de calor a través de les parets de la cambra de combustió mitjançant la utilització d'aquests materials. No obstant això, demostrar la conversió de l'energia tèrmica addicional en treball indicat ha resultat més difícil. En certs estudis es van poder obtenir millores en el treball indicat durant la carrera d'expansió, però aquestes van ser reduïdes a causa d'un menor rendiment volumètric causat de l'escalfament de la càrrega durant el procés d'admissió i un major treball en la carrera de compressió. Típicament, les úniques millores en el treball al fre provindrien de la reducció de pèrdues per bombeig en els motors turbo alimentats, o de l'extracció addicional de l'energia dels gasos d'escapament a través de turbines. El concepte dels materials amb oscil·lació de la temperatura durant el cicle motor intenta aprofitar els beneficis de l'aïllament durant els processos de combustió i expansió, mitigant les perdudes per l'increment de la temperatura de les parets durant l'admissió i la compressió. La combinació de baixa capacitat calorífica i baixa conductivitat tèrmica permetria que la temperatura de la superfície de la cambra de combustió respongués ràpidament a la temperatura del gas durant el procés de combustió. Les temperatures de la superfície són capaços d'augmentar en resposta al flux de calor, minimitzant així la diferència de temperatura entre el gas i la paret en la carrera d'expansió quan és possible la major conversió d'energia tèrmica en treball mecànic. La combinació de baixa capacitat calorífica i conductivitat tèrmica és també essencial per permetre aquest augment de temperatura durant la combustió i el refredament de la superfície durant l'expansió i l'escapament per no perjudicar així el rendiment volumètric del motor durant la carrera d'admissió i minimitzar el treball de compressió realitzat en el següent cicle. En aquesta tesi s'han desenvolupat models tèrmics i termodinàmics per predir els efectes de les propietats dels materials en les parets i caracteritzar els efectes de la transferència de calor en diferents parts del cicle sobre el treball indicat, el rendiment volumètric, l'energia en els gasos d'escapament i les temperatures del gas per un motor de combustió interna alternatiu. També s'ha avaluat l'impacte d'aquests materials en el knock en motors de combustió d'encesa provocada, ja que les proves experimentals d'aquesta tesi es van realitzar en un motor d'aquestes característiques. Durant la investigació es van avaluar materials aïllants convencionals per comprendre l'estat actual d'aquesta tècnica i per adquirir també experiència en l'anàlisi de materials aïllants amb oscil·lació de temperatura. Desafortunadament, els efectes de la permeabilitat a través de la porositat del material en el recobriment convencional, l'absorció de combustible i la relació de compressió van tendir a ocultar els efectes de l'oscil·lació de la temperatura i la reducció de la transferència de calor a través de les parets. Així doncs, es va analitzar l'impacte individual de cada un d'aquests mecanismes i la seva influència en el rendiment del motor per així definir un nou material amb les característiques necessàries que milloressin el aïllant d'oscil·lació de temperatura. Finalment, a partir dels estudis d'aquesta fase d'anàlisi, es va crear un nou material i es va aplicar a la superfície del pistó i a la superfície interna de les vàlvules d'admissió i d'escapament. Les dades de motor es van prendre a
Andruskiewicz, PP. (2017). ANALYTICAL AND EXPERIMENTAL INVESTIGATION OF TEMPERATURE-SWING INSULATION ON ENGINE PERFORMANCE [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/90467
TESIS

This master thesis project was performed in collaboration with Scania CV AB, Engine Materials group. The purpose with the project was to investigate different ceramic TBC (Thermal Barrier Coating) thermal insulation properties inside the combustion chamber. Experimental testing was performed with a Single-Cylinder engine with TBC deposited on selected components. A dummy-valve was developed and manufactured specifically for this test in order to enable a water cooling system and to ease the testing procedure. The dummy-valve consists of a headlock, socket, valve poppet and valve shaft. Additionally, a copper ring is mounted between the cylinder head and the valve poppet to seal the system from combustion gases. Thermocouples attached to the modified valve poppet and valve shaft measured the temperature during engine test to calculate the heat flux. The TBCs consisted of three different materials: 7-8% yttrium-stabilized zirconia (8YSZ), gadolinium zirconia and lanthanum zirconia. The 8YSZ TBC was tested as standard, but also with microstructural modifications. Modifications such as pre-induced segmented cracks, nanostructured zones and sealed porosity were used. The results indicated that the heat flux of 8YSZ-standard, 8YSZ-nano and 8YSZ-segmented cracks was in level with the steel reference. In the case of 8YSZ-sealed porosity the heat flux was measured higher than the steel reference. Since 8YSZ-standard and 8YSZ-sealed porosity are deposited with the same powder it is believed that the high heat flux is caused by radiative heat transfer. The remaining samples have had some microstructural changes during engine testing. 8YSZ-nano had undergone sintering and its nanostructured zones became fewer and almost gone after engine testing leading to less heat barrier in the top coat of the TBC. However, for 8YSZ-segmented cracks and gadolinium zirconia lower heat flux was measured due to the appearance of horizontal cracks. These cracks are believed to act as internal barriers as they are orientated perpendicular to the heat flow. During long-time (5 hour) engine tests the 8YSZ-standard exhibited the same phenomena: a decrease in heat flux due to propagation of horizontal cracks. One-dimensional heat flux was not achieved and the main reason for that was caused by heating and cooling of the shafts outer surface. However, the dummy-valve system has proven to be a quick, easy and stable to perform tests with a Single-Cylinder engine. Both water-cooling and long-time engine tests were conducted with minor issues. The dummy-valve has been further developed for future tests. Changes to the valve shaft are the most remarkable: smaller diameter to reduce heat transfer and smaller pockets to ensure better thermocouple positioning. Another issue was gas leakage from the combustion chamber through the copper ring and valve poppet joint. The copper ring will be designed with a 1 mm thick track to improve sealing, hence better attachment to the valve poppet.

[ES] Las nuevas regulaciones en materia de emisiones de efecto invernadero y calidad del aire han conducido la evolución tecnológica de los motores de combustión interna durante los últimos años. Las mejoras en el proceso de la combustión, la sobrealimentación, la gestión térmica, los sistemas de post tratamiento y técnicas como la recirculación de gases de escape, han permitido que los motores de combustión interna de hoy en día sean cada vez más limpios. La adopción en Europa del nuevo ciclo de homologación WLTP, que considera un ciclo de conducción más realista que su predecesor el NEDC, así como la necesidad de evaluar las emisiones contaminantes en diferentes escenarios de temperatura ambiente y de altitud, suponen un desafío para los fabricantes a la hora de diseñar y optimizar sus motores. En este contexto, el modelado unidimensional del motor ofrece la posibilidad de desarrollar y probar diferentes soluciones con la suficiente precisión,a la vez que permite agilizar el proceso de diseño del motor y reducir los costes de éste. El objetivo de esta tesis es el de desarrollar un modelo completo de motor virtual que permita simular condiciones transitorias de régimen de giro y grado de carga, así como diferentes condiciones ambientales de presión y temperatura. Con este modelo de motor se pretende predecir las principales variables termo-fluidodinámicas en diferentes puntos del motor y las emisiones contaminantes liberadas en el escape. Por otra parte, el arranque en frío y el funcionamiento a bajas temperaturas están asociados a un mayor consumo, mayores emisiones de hidrocarburos (HC) y monóxido de carbono (CO), así como mayores emisiones de óxidos de nitrógeno (NOx) debido a la desactivación de los sistemas de recirculación de gases de escape. Para paliar estos efectos adversos, una opción es lograr que el sistema de postratamiento alcance su temperatura de activación lo más pronto posible. En este trabajo se aborda este objetivo mediante dos soluciones. Por un lado, se ha explorado la posibilidad de elevar la temperatura de los gases en el escape mediante un sistema de distribución variable. Con este método se pueden reducir las emisiones de CO y HC en torno a un 40-50 % y las emisiones de NOx hasta un 15 % durante la primera fase del ciclo WLTC, a costa de una penalización en el consumo de combustible. Por otro lado, también se ha estudiado la posibilidad de aislar térmicamente el sistema de escape. En este caso, es posible reducir las emisiones de CO y HC en torno a un 30 % sin mejorar las de NOx.
[CA] Les noves regulacions en matèria d'emissions d'efecte d'hivernacle i qualitat de l'aire han conduït la evolució tecnològica dels motors de combustió interna durant els darrers anys. Les millores en el procés de la combustió, la sobrealimentació, la gestió tèrmica, els sistemes de postractament i tècniques com la recirculació de gasos d'escapament, han permès que els motors de combustió interna d'avui dia siguen cada vegada més nets. L'adopció a Europa del nou cicle d'homologació WLTP, que considera un cicle de conducció més realista que el seu predecessor el NEDC, així com la necessitat d'avaluar les emissions de gasos contaminants en diferents escenaris de temperatura ambient i humitat, suposen un repte per als fabricants a l'hora de dissenyar i optimitzar els seus motors. En aquest context, el modelatge unidimensional del motor ofereix la possibilitat de desenvolupar i provar diferents solucions amb la suficient precisió, al mateix temps que agilitza el procés de disseny del motor i reduïx els costos derivats d'aquest. L'objectiu d'aquesta tesi és el de desenvolupar un model complete de motor virtual que permeta simular condicions transitòries de règim de gir i grau de càrrega, així com diferents condicions ambientals de pressió i temperatura. Amb aquest model de motor es pretén predir les principals variables termo-fluidodinàmiques en diferents punts del motor i les emissions contaminants alliberades en l'escapament. Per altra banda, l'arrancada en fred i el funcionament a baixes temperatures están associats a un major consum, majors emissions d'hidrocarburs (HC) i monòxid de carboni (CO), així com majors emissions d'òxids de nitrògen (NOx) degudes a la desactivació dels sistemes de recirculació de gasos d'escapament. Per a pal·liar aquestos efectes indesitjats, una opció és aconseguir que el sistema de postractament arribe a la seua temperatura d'activació el més prompte possible. En aquest treball, aquest objectiu s'aborda mitjançant dues solucions. Per una banda, s'ha investigat la possibilitat d'augmentar la temperatura dels gasos en l'escapament per mitjà d'un sistema de distribució variable. Amb aquest mètode s'ha aconseguit reduïr les emissions de CO i HC al voltant d'un 40-50 % i les emissions de NOx fins a un 15 % durant la primera fase del cicle WLTC, acosta d'una penalització en el consum de combustible. Per altra banda, també s'ha estudiat la possibilitat d'aïllar tèrmicament el sistema d'escapament. En aquest cas, és possible reduir les emissions de CO i HC vora un 30 % sense millorar les de NOx .
[EN] The new regulations regarding greenhouse emissions and air quality have led the technological progress of the internal combustion engines during the recent years. Improvements in the combustion process, turbocharging, thermal management, after-treatment systems and techniques such as the exhaust gases recirculation, have resulted in cleaner internal combustion engines. The adoption of the new type approval test in Europe, so-called WLTP, which represents a more realistic driving cycle than its forerunner the NEDC, as well as the need to evaluate pollutant emissions at different conditions of ambient temperature and altitude, represent a challenge for manufacturers when it comes to design and optimise their engines. In this context, one-dimensional engine models offer the possibility to develop and test different solutions with enough accuracy, while hastening the engine design process and reducing its costs. The main objective of this thesis is to develop a complete virtual engine model able to simulate transient conditions of engine speed and load, as well as different ambient conditions of pressure and temperature. The engine model is used to predict the main thermo-and fluid dynamic variables at different engine locations and the tailpipe pollutant emissions. Furthermore, engine cold start and its operation at low temperature is associated to a greater fuel consumption, hydrocarbon (HC) and carbon monoxide (CO) emissions; as well as more nitrogen oxide (NOx) emissions due to the deactivation of the exhaust gases recirculation systems. A solution to mitigate these negative effects is to heat up the after-treatment system so as to achieve its activation temperature as soon as possible. In the work presented, this goal is addressed through two different standpoints. On the one hand, variable valve timing systems have been studied as a way to increase the exhaust gases temperature. With this option it is possible to reduce CO and HC emissions by 40-50 % and NOx emissions by 15 % during the first stage of the WLTC cycle, at the expense of a penalty in the fuel consumption. On the other hand, the thermal insulation of the exhaust system has also been studied with the same objective. In this case, it is possible to reduce CO and HC emissions by 30 %, while not improving NOx ones.
The author wishes to acknowledge the financial support received through the FPI S2 2018 1048 grant of Programa de Apoyo para la Investigación y Desarrollo (PAID) of Universitat Politècnica de València.
Auñón García, Á. (2021). Development and validation of a virtual engine model for simulating standard testing cycles [Tesis doctoral]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/168906
TESIS

One of the most important challenges for the next generation of aircraft propulsion systems is an engine more efficient, with less pollutants emission and so definitely more sustainable. To reach this goal a lot of new technical solutions must be exhibit in order to optimize the main engine parts, but the attention should also be focused on how the different engine components work, due to the thermal loads they undergo during the different phases of the flight. Typical examples of the effects that the thermal loads produce are the gaps among the different components, producing unavoidable leakages, due to their differential thermal expansion. Actually in the Low Pressure Turbines (LPT) one of the countermeasures applied to control and to minimize these gaps consists in blowing into the stator cavities some relatively cold air bled from one of the compressor stages. This technique, even if effective for the turbine thermal control, results in supplementary fuel consumption. In this research a first attempt to reduce the required cooling air, by introducing insulating materials in the proper LPT cavities, is shown. The preliminary numerical analyses performed to point out and compare suitable configurations are here presented. The configuration, identified as the most performing, has been used to forecast the insulation technology effectiveness. The obtained numerical results evaluated both in terms of temperature decreasing of the Casing plate and of Cooling air reduction, are reported. The technological solution, numerically pointed out, has been experimentally validated by means of the available testing facility, whose Test Article reproduces, properly scaled, one stage of a modern LPT. After the experimental campaign, the experimental data and the ones obtained by running the numerical model have been compared in order to evaluate the final model accuracy. Finally, a thermal insulating selection has been performed to overcome the limits that the tested technology has exhibited. The studied alternative solutions and the obtained results are here reported and compared with the ones obtained with the technology previously implemented.

AbstractUnderstanding the relationship between frequency f [Hz] and wavelength λ [m] is fundamental for a professional EMC design engineer. This chapter introduces the term wavelength λ and explains how the wavelength of an electromagnetic wave depends on the cable insulation or PCB material.

AbstractWhen you think about aviation noise, you might imagine an airplane taking off. When you think about decreasing aviation noise, the first thing that usually comes up in one’s mind are the new silent plane engines. This makes perfect sense, but it does not fully grasp the issue of aviation noise. The ANIMA project is based on a holistic approach to aviation noise, as it focuses on non-acoustical factors as well. Annoyance, as perceived by local communities surrounding airports, also depends on non-acoustical factors, which can be situational (time of the day, day of the week, activity performed while exposed to noise) and personal (sensitivity to noise, attitudes, noise insulation).

An inventor—any creative person—knows to look under the surface of what things seem to be, to learn what they are. I have been able to find only one constant in the creative mind. It is that surprise is the hidden face of the coin of invention. In their operetta Pinafore, Gilbert and Sullivan warn us: . . . Things are seldom what they seem, Skim milk masquerades as cream; Highlows pass as patent leathers; Jackdaws strut in peacock’s feathers. . . . For example, an engineer designing a highway system wants to include crossroads between the major arteries. Common sense says that crossroads will increase driver options and speed traffic. Only very keen insight, or a complex computer analysis, reveals that crossroads tend to make matters worse. They often create localized traffic jams where none would otherwise occur. We are caught off guard when common sense fails us. Yet it is clear we would live in a deadly dull world if common sense alone were sufficient to lead us through all the mazes around us. If what we learn is no more than what we expect to learn, then we have learned nothing at all. Sooner or later, every student of heat flow is startled to find out that insulation on a small pipe can sometimes increase heat loss. Common sense is the center of gravity we return to after our flights of fancy. But it is the delicious surprise—the idea that precedes expectation—that makes science, technology, and invention such a delight. A wonderful old expression calls creativity “a fine madness,” and it is. Invention lies outside the common ways and means. If it is sane to respond predictably to reality, then invention surely is madness. A well-known riddle shows us something of the way that madness works. You are asked to connect nine dots, in a square array, with four straight lines. Each line has to continue from the end of the last line. The problem seems to have no solution.

Fibers are everywhere around us. They are essential parts of the human body, our hair, for example; the threads in our clothing, natural or synthetic; the insulation in our houses. Natural fibers have been useful to humans for more than ten thousand years. They were mixed with clay before firing to strengthen and reinforce pottery vessels, making them more durable. Textiles that combined the fibers of flax and asbestos were known in ancient times for their seemingly magical resistance to fire and decay. It was industrialization, however, that caused a dramatic increase in the use of natural inorganic or mineral fibers. By the late nineteenth century asbestos had become an important commodity with a variety of commercial applications. It served as insulation to control heat generated by engines and, because of its incombustibility, as a fire retardant in its more recent general use as building insulation. Asbestos fibers are found worldwide in many products: as reinforcement in cement water pipes and the inert and durable mesh material used in filtration processes of chemicals and petroleum, for example. However, asbestos is not the only inorganic fiber in use today. Synthetic inorganic fibers abound. Glass fibers have replaced copper wire in some intercontinental telephone cables. Fiberglas (a trade name) has become the insulation material of choice in construction. Carbon and graphite fiber composites are favored materials for tennis racket frames and golf clubs. Fibrous inorganic materials have become commonplace in our everyday lives. As the use of inorganic fibers increased, there were some indications that fibers might be hazardous to our health. Since the first century A.D. it was suspected that asbestos might be the cause of illness among those who mined and processed the material. Asbestosis, a debilitating and sometimes fatal lung disorder, was documented and described in the nineteenth century. Within the last 25 years, lung cancer and mesothelioma have also been linked to asbestos exposure among construction and textile workers, as well as others exposed to dusts containing asbestos fibers. Although the etiology and specific mechanisms that give rise to these two cancers are not yet understood, concern for the health of exposed workers led the governments of the United States and other countries to specify the maximum allowable concentrations of asbestos in the ambient air of the workplace.

Abstract This chapter examines Thoreau’s experiences on Mt. Katahdin, vis-à-vis exposure science and wilderness therapy. A close reading of Thoreau’s account suggests the experience had a profound effect on him, emotionally and philosophically, an effect that is relevant to environmental exposure and eco-vulnerability in the contexts of the COVID-19 pandemic and climate change. Thoreau’s experience on that mountain presented to him an aspect of wilderness antithetical to the romantic, transcendentalist notions he previously held and ultimately led to more nuanced, therapeutic depictions found in works like “Walking” and Walden. That such a reconciliation was possible for Thoreau suggests a privileged insulation from trauma not afforded to many. It also indicates the value of both philosophical contemplation and wilderness therapy to promote psychological resilience and adaptability. The author argues philosophers should begin to engage conceptually and normatively with exposure, vulnerability, and resilience.

Abstract For turbocharged diesel engine systems, emission reduction is the most significant challenge that manufacturers should overcome. In response to the emission reduction challenge most turbocharged diesel engine systems have adopted complex exhaust aftertreatment systems. Due to the current stringent emission regulation, exhaust aftertreatment system nowadays needs to discover new methods to increase its efficiency of pollution conversion. Increasing the inlet temperature of aftertreatment systems can help reduce the light-off time. Whilst most methods to do this involve increases in fuel consumption (retarded injection, engine throttling), insulating the turbocharger turbine to reduce heat loss does not have this drawback. This paper presents a simulation and experimental study the performance of a turbocharger with inner insulated turbine housing, compared with the standard turbocharger (same turbine wheel without inner insulation). Both turbochargers were tested on an engine gas stand test rig with a 2.2L prototype engine acting as an exhaust gas generator. In a steady state condition, the insulated turbocharger can achieve 5 to 14K higher turbine outlet temperature depending on the engine speed and load conditions. Three types of transient tests were implemented to investigate turbocharger turbine heat transfer performance. The test plan was designed to the engine warm up, step load transient, WLTC cycle and simplified RDE cycle. In the engine warm up test result, the temperature drops between the turbine inlet and outlet was reduced by 4K with the insulated turbine housing. In the results of step load transient test, the turbine with insulated turbine housing was observed to get only 4K temperature benefit but with 2kRPM higher turbocharger speed under the same turbocharger inlet and outlet boundary conditions. In the WLTC cycle test result, turbocharger average speed was increased by 0.8kRPM due to the increased enthalpy of the turbine with insulation, the turbine outlet temperature has an average 1.7K improvement. The experimental results were used to parameterise a simple, 1D, lumped capacitance model which could predict similar aerodynamic behaviour of the two turbines (turbine housing insulated and non-insulated). However, current model has less accuracy in highly transient process as the heat transfer coefficients are unchangeable in each process. The turbine outlet temperature got at most 10K error for the turbine with non-insulated housing and 13K error for the insulated one. The model was shown to over-estimate the benefits of the inner insulation for 1K in turbine outlet temperature.

Abstract Widely studied in the 1980s, the insulation of pistons in engines aimed at reducing the heat losses and thus increasing the indicated efficiency. However, those studies stopped in the beginning of the 1990s due to NOx emission legislation, and also due to acceptable oil prices. Nowadays, with the improvement of exhaust after treatment systems (Diesel Particulate Filter, Selective Catalytic Reduction, and Diesel Oxidation Catalyst) and engine technologies (Exhaust Gas Recirculation), there are more trade-offs for NOx reduction. Besides, the fast rise of the oil prices tends to come back to insulation technologies in order to save fuel. This paper deals with the realization of a 1 mm thick plasma sprayed thermal barrier coating with a graded transition between the topcoat and the bondcoat on top of a serial piston for heavy-duty truck engines (11L displacement – Exhaust Gas recirculation – Single Stage Turbocharger with Variable Geometry Turbine and intercooler). The effects of the insulated pistons on the engine performance are also discussed.

Misalignment couplings for ship drive lines are installed between engine and gear or between gear and waterjet and transmit torque from one shaft to another while accommodating misalignment between the two shafts. The development process, the analysis and the in-service-experience of a new membrane type flexible coupling entirely made of advanced composite material are presented in this paper. The concept of this new coupling promises low mass, high misalignment capacity and good sound insulation compared to conventional couplings.