Figure 4 - uploaded by Carlos Alberto Romero
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Heat rejected to coolant calculated after measuring coolant flow through the engine and inlet and outlet coolant temperatures. The trace of the fuel equivalent energy and mean block temperature has been also plotted.
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In the present work, an automotive Diesel engine has been experimentally tested under a New European Driving Cycle (NEDC) with the aim of getting experimental plots of time dependent partitioning of energy injected during the warm-up process. An additional objective of this work is to assess the energy recovery capacity installed in the engine, i.e...
Contexts in source publication
Context 1
... temperatures and flows were measured during engine testing at different points of the engine, the passenger heater, and the EGR cooler, as Figure 2 shows. Figure 4 shows the evolution of mean block, inlet and outlet coolant temperatures through the engine block. The knowledge of coolant temperatures and the coolant flow allowed to calculate, by using expression (2), the heat carried off with the coolant mass, as it passes through the engine water jacket under the warm-up operating conditions. ...
Context 2
... knowledge of coolant temperatures and the coolant flow allowed to calculate, by using expression (2), the heat carried off with the coolant mass, as it passes through the engine water jacket under the warm-up operating conditions. The plot of these heat losses is presented in figure 4, where for comparison purposes the fuel equivalent energy rate has been also reproduced. The trends in both plots are very similar, suggesting some kind of linear relationship between them. ...
Context 3
... the time passes the share of the energy transferred to the ambience increases, reaching an important value. An estimation of the energy transferred to the surrounding air at the end of the last ECE part of the driving cycle entails 1.8 kW, calculated with the experimental external block temperature (Figure 4), an average ambient temperature of 24 °C, and an average convection coefficient between the engine block and the air of 35 W/(m 2 K). This heat corresponds to a 12% of the input energy, giving an idea of its importance. ...
Context 4
... the exchange of heat in the radiator takes place only after the temperature imposed by the thermostat valve characteristics is reached, which is achieved in the engine tested after approximately 720 seconds of running operation, as follows from Figure 4. After this time the thermostat valve starts to regulate the coolant flow diverting part of the coolant through engine radiator. ...
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The research paper mainly deals with waste heat recovery from internal combustion engines (ICE) using the organic Rankine cycle (ORC) and Thermoelectric generator (TEG). Simultaneously recovering the wasted heat of both exhaust gases and coolant, a novel configuration named two-stage is proposed. Then a comprehensive thermo-economic analysis and op...
Citations
... Nevertheless, these experiments are not appropriate for examining two factors of the number and distribution pattern of the TEMs that influence ATEG electrical output power because they cannot accurately and rapidly obtain temperatures on the hot and cold sides of each TEM. Romero et al. [396] analyzed the impact of different engine efficiency factors throughout engine start-up and warm-up in various sections of the New European Driving certification cycle, focusing on the engine's operation in transient conditions. Tao et al. [393] and Wang et al. [394] indicated that the total power output increases rapidly due to increases in the number of TEMs. ...
Improving thermal efficiency and reducing carbon emissions are the permanent themes for internal combustion (IC) engines. In the past decades, various advanced strategies have been proposed to achieve higher efficiency and cleaner combustion with the increasingly stringent fuel economy and emission regulations. This article reviews the recent progress in the improvement of thermal efficiency of IC engines and provides a comprehensive summary of the latest research on thermal efficiency from aspects of thermodynamic cycles, gas exchange systems, advanced combustion strategies, and thermal and energy management. Meanwhile, the remaining challenges in different modules are also discussed. It shows that with the development of advanced technologies, it is highly positive to achieve 55% and even over 60% in effective thermal efficiency for IC engines. However, different technologies such as hybrid thermal cycles, variable intake systems, extreme condition combustion (manifesting low temperature, high pressure, and lean burning), and effective thermal and energy management are suggested to be closely integrated into the whole powertrains with highly developed electrification and intelligence.
... Engines are optimized for maximum efficiency, so less waste heat is available to heat up powertrain and cabin. [3], [4] analyzed that during the first minute of a Diesel engine cold start, about two-third of the fuel energy is used for heating up the engine. This issue gains importance under low-load operating conditions. ...
... With a similar approach but focused on the operation of the engine in transitory conditions, Romero et al. [2] studied the effect of different parameters on engine efficiency during engine start-up and warm-up in different parts of the New European Driving Cycle certification cycle. ...
The best possible thermal and mechanical energy management is necessary to have more efficient and less pollutant means of transport. This can be accomplished recovering part of the energy lost through exhaust systems in internal combustion engines. One of the devices able to recover this waste thermal energy is a thermoelectric generator. Plenty of works about their design have already been presented but their effects on the energy fluxes of the engine, which are crucial to the future thermal management of vehicles with thermoelectric generators, have not yet been studied in a comprehensive manner. A thorough and novel experimental analysis of the behavior of the main energy fluxes in a diesel engine with a thermoelectric generator was accomplished, an approach not already followed in previous literature. Due to their higher air-to-fuel ratio, in diesel engines is more difficult to recover exhaust energy. Furthermore, this study was conducted in the most adverse for energy recovery but most used part of the engine map, i.e. common driving conditions, and not only at high loads. Conditions in which thermoelectric generators could be more beneficial and less harmful to the efficiency of the engine were identified. It was found that thermoelectric generators can improve the global efficiency of internal combustion engines despite the low efficiency of current thermoelectric materials.
... In fact, there is a lack of works dealing with the GEB in transient operation and only a limited number can be found in the literature. 21 As an example, Romero et al. 21 performed the thermal balance of a diesel engine under transient conditions, exploring the instantaneous energy split during real driving conditions, with the objective of showing the dynamics of energy split, and providing an estimate of the energy losses averaged along the cycle. ...
... In fact, there is a lack of works dealing with the GEB in transient operation and only a limited number can be found in the literature. 21 As an example, Romero et al. 21 performed the thermal balance of a diesel engine under transient conditions, exploring the instantaneous energy split during real driving conditions, with the objective of showing the dynamics of energy split, and providing an estimate of the energy losses averaged along the cycle. ...
In recent years, the interests on transient operation and real driving emissions have increased because of the global concern about environmental pollution that has led to new emissions regulation and new standard testing cycles. In this framework, it is mandatory to focus the engines research on the transient operation, where a Virtual Engine has been used to perform the global energy balance of a 1.6-L diesel engine during a World harmonized Light vehicles Test Cycle. Thus, the energy repartition of the chemical energy has been described with warmed engine and cold start conditions, analyzing in detail the mechanisms affecting the engine consumption. The first analysis focuses on the “delay” effect affecting the instantaneous energy balance due to the time lag between the in-cylinder processes and pipes: as a main conclusion, it is obtained that it leads to an apparent unbalance than can reach more than 10% of the cumulated fuel energy at the beginning of the cycle, becoming later negligible. Energy split analysis in cold starting World harmonized Light vehicles Test Cycle shows that in this condition the energy accumulation in the block is a key term at the beginning (about 50%) that diminishes its weight until about 10% at the end of the cycle. In warmed conditions, energy accumulation is negligible, but the heat transfer to coolant and oil are higher than in cold starting conditions (21% vs 28%). The lower values of the mean brake efficiency at the beginning of the World harmonized Light vehicles Test Cycle (only about 20%) is affected, especially in cold starting, by the higher mechanical losses due to the higher oil viscosity and the heat rejection from the gases. The friction plays an important role only during the first half of the cycle, with a percentage of about 65% of the total mechanical losses and 10% of the total fuel energy at the end of the World harmonized Light vehicles Test Cycle. However, at the end of the cycle, it does not affect dramatically the mean brake efficiency which is about 31% both in cold starting and warmed World harmonized Light vehicles Test Cycle.
... Fuel conversion efficiency is one of the most key evaluation factors involved with the ICE [4][5][6]. In order to enhance the fuel conversion efficiency or effective thermal efficiency, researchers have already conducted heat balance or energy balance on ICE for understanding the distribution of energy based on the first law of thermodynamics [7,8]. Thus, it is of most significant to evaluate the fraction of each term where losses occur in engines. ...
Improving the performance and reducing emissions in a Diesel engine is the single most objective in current research. Various methods of approach have been studied and presented in literature. A novel but not so pursued study is on the performance of a rotating diesel injector. To date, there has been very little study by implementing a rotating injector. Studies have shown an improvement on the performance of an engine, but with a complicated external rotating mechanism. In the present research, a novel self-rotating fuel injector is designed and developed that is expected to improve the performance without the need for a complicated rotating mechanism. The design procedure, CFD simulation along with 3- D printing of a prototype is presented. Numerical modelling and simulation are performed to study the combustion characteristics of the rotating injector viz-a-viz a standard static injector. Comparison based on heat release, efficiency, and emissions are presented. While the proposed 9-hole injector had slight loss in thermal efficiency, the modified 5-hole had a slight increase in thermal efficiency when compared to the static baseline readings. The NOx reduced by 13% and CO increased by 14% compared baseline emissions for the 5-hole version.
... A critical target for thermal management is warm-up shortening, which allows the engine to reach nominal temperatures earlier. This leads to less HC and CO emissions [11], lower friction, reduced heat loss [12] and faster catalyst light-off [13]. Means of hasting warm-up are: coolant path optimization [14], exhaust heat recovery [15], immersion heaters, thermal mass reduction, thermal energy storage and improvement of heat transfer between oil and coolant [16]. ...
... La mayoría de los motores de encendido provocado durante el calentamiento tras su puesta en marcha y también mientras funcionan en vacío, operan con mezclas ricas en combustible, por lo que la combustión es incompleta y son elevadas las emisiones de monóxido de carbono (CO) y de hidrocarburos sin quemar (HC) [20]. De ahí que, en la búsqueda de reducir las emisiones contaminantes, se busque reducir el tiempo de calentamiento de los motores, mediante diferentes estrategias en el sistema de gestión térmica de los motores y mediante las investigaciones en materiales para las partes, ante todo las que conforman la cámara de combustión [21][22][23][24][25]. La sensibilidad del motor a la composición del combustible depende también de su tiempo de operación en servicio: los depósitos acumulados en la cámara de combustión durante la operación de los motores, resultado de la acumulación de carbón, reducen la disipación de calor (los depósitos llegan a tener capacidad aislante cercana a la de algunos cerámicos como el óxido de zirconio) [16][17][18]; el desgaste del motor se refleja en el tiempo en la reducción de su relación de compresión efectiva. ...
... Por tanto, estas pérdidas son particularmente elevadas a temperatura ambiente durante los primeros minutos después del arranque en frío del motor hasta que éste alcanza su estado térmico óptimo (temperatura del aceite cercana a 90 ºC). En general, el calentamiento del motor es un período de sobreconsumo significativo de combustible [23,24,29]. ...
En este trabajo se presenta la evaluación de los efectos causados por variaciones de la relación de compresión, el material de la culata y la composición del combustible sobre la velocidad del motor, el consumo de combustible, el tiempo de calentamiento y las emisiones de un motor de encendido por chispa enfriado por aire, bajo una metodología de diseño de experimentos. El objetivo del trabajo ha sido determinar la sensibilidad de las respuestas del motor operando en vacío, así como la combinación óptima entre los parámetros mencionados. De los tres factores evaluados bajo los límites de las pruebas realizadas, la relación de compresión es el factor que ha ejercido la mayor influencia sobre el desempeño del motor bajo el régimen de marcha en vacío. Las temperaturas de estado estacionario del motor bajan con el aumento de la relación de compresión, con la mayor conductividad del material y con el mayor contenido de etanol.
... Researchers have studied the effect on pollutant emissions and engine performance in cold driving cycles [6]. Currently, the U.S Environmental Protection Agency includes a cold cycle of FTP-75 as an optional driving cycle carried out at -7 ºC. ...
... [5] Where , , are the outlet coolant TFE temperature, inlet coolant TFE temperature and inlet gas temperature respectively. Equation 6 shows the cooling performance of the TFE when LP EGR is enabled. [6] Where, , , are the inlet gas temperature, outlet gas temperature and inlet coolant TFE temperature respectively. ...
... Equation 6 shows the cooling performance of the TFE when LP EGR is enabled. [6] Where, , , are the inlet gas temperature, outlet gas temperature and inlet coolant TFE temperature respectively. Equation 7 shows the WCAC effectiveness when the heat recovery system is running. ...
Further reduction of pollutant emissions and fuel consumption is one of the major challenges that automotive engineers currently have to overcome. Low ambient temperature testing for diesel engines will be mandatory in the near future, making cold engine start and warm up analysis important topics for researchers. In order to improve the engine operation under those critical conditions, different systems have been proposed in recent years. Previous studies have shown that heating the intake air is one of the most effective solutions to boost engine performance during warm up. In this paper a novel exhaust heat recovery system combined with a Water cooled Charge Air Cooler is presented. A gas/liquid heat exchanger, the Twin Function Exchanger, fulfilling two different functions is firstly used to recover energy from the exhaust side transferring it to the intake, and later as low pressure EGR cooler. Moreover, a complete thermal management strategy to control the intake air temperature has been put in place in order to optimize the engine behavior to be as close as possible as running conditions at 20°C. Experiments were carried out in transient load conditions of NEDC and WLTC cycles with a 2.0 liter turbocharged diesel engine, installed in a climatic test cell. Using this new system, intake air temperature was increased improving the combustion process during the engine warm up at-7°C. Important benefits on HC and CO were obtained in both cycles
... Researchers have study the effect on pollutant emissions and engine performance in cold driving cycles [8]. Currently, the U.S Environmental Protection Agency includes a cold cycle of FTP-75 as an optional driving cycle carried out at -7 ºC. ...
In this paper, an experimental facility is implemented with the aim of improving the performance of internal combustion engines working at low ambient temperatures. Pollutant emissions and fuel consumption are one of the major issues that automotive engineers have to face. Cold engine start and warming up analysis have become important topics for researches. In this work, an exhaust heat recovery system for a diesel engine has been proposed as a solution to cold operation negative effects. The energy obtained from the exhaust gases was used to increase the intake air temperature. The experiments were carried out in transient load conditions at three different levels of ambient temperature (up to −7 °C). Exhaust heat recovery was combined with different strategies of exhaust gas recirculation. Intake air heating results with the heat recovery system show a reduction of 65% in unburned hydrocarbons, 40% in carbon monoxide and 10% in fuel use compared to standard air–air intercooler.
... Singh et al. [10] and Donn et al. [11] studied the effect of different running parameters, such as cooling water temperature, injection strategy, and EGR rate on the engine energy balance. Romero et al. [12] proposed an energy balance calculation method direct at NEDC driving cycles and analyzed the energy balance during the warming-up process. Rabeau and Magand [13] built a thermal balance model on AMEsim platform, and gave some suggestions on improving thermal efficiency basing on the simulation results. ...
This paper presented the analytical results for the energy balance of a diesel methanol dual-fuel (DMDF)
engine. A methanol injection system was fixed on a diesel engine and let the engine to alternate to run in
either the pure diesel (D) mode or DMDF mode. Primary application of the thermal balance analysis was to
investigate the cause of methanol replacement ratio SR changing with engine loads. Calculations were
conducted within the control volume by comparing each of the energy terms. The results show that the
reduction in cooling loss in DMDF mode is the dominant factor for low SR at high loads. While, a substantial
increase in incomplete combustion loss in DMDF mode is the most important reason for high SR at low
loads. Another application of the thermal balance analysis was to research the cooling loss in DMDF mode
which implied unique characteristics. Therefore, the changing methanol replacement rate SP experiments
were carried out in various engine loads, giving the results that the cooling loss in DMDF mode is always
lower than that in D mode, and it goes even lower as SP rises. Finally, the effect of methanol temperature on
SR was also investigated from the thermal balance point of view. The results reveal that the incomplete
combustion loss decreasing in higher methanol temperature conditions will lead to a certain extent of
SR drop. All these results are related to the energy flow distribution within the engine.
