A New Tool to Perform Global Energy Balances in DI Diesel Engines 2014-01-0665

[EN] The generalization of exhaust aftertreatment systems along with the growing awareness about climate change is leading to an increasing importance of the efficiency over other criteria during the design of reciprocating engines. Using experimental and theoretical tools to perform detailed global energy balance (GEB) of the engine is a key issue for assessing the potential of different strategies to reduce consumption. With the objective of improving the analysis of GEB, this paper describes a tool that allows calculating the detailed internal repartition of the fuel energy in DI Diesel engines. Starting from the instantaneous in-cylinder pressure, the tool is able to describe the different energy paths thanks to different submodels for all the relevant subsystems. Hence, the heat transfer from gases to engine walls is obtained with specific convective and radiative models in the chamber and ports; the repartition of the heat flux throughout the engine metal elements towards the oil and coolant is estimated with a lumped capacitance model; finally, the ancillary systems and friction losses are obtained through specific semiempirical submodels. The validation of the tool is performed in a 4- cylinder DI Diesel engine instrumented to perform detailed experimental GEB. Finally, a simple analysis of combined internal and external analysis in the complete engine map shows the effect of operating conditions on each energy term. Thus it is demonstrated the utility of the proposed tool, that complements the experimental heat flow measurements in Diesel engine researches oriented to the reduction of energy consumption.The support of the Universitat Politècnica de València (PAID06-09) and Generalitat Valenciana (GV/2010/045) is greatly acknowledged.Payri González, F.; Olmeda González, PC.; Martín Díaz, J.; Carreño, R. (2014). A New Tool to Perform Global Energy Balances in DI Diesel Engines 2014-01-0665. SAE International Journal of Engines. 7(1):1-17. doi:10.4271/2014-01-0665S1177

Dynamic Identification of thermodynamic parameters for Turbocharger Compressor Models

A novel experimental procedure is presented which allows simultaneous identification of heat and work transfer parameters for turbocharger compressor models. The method introduces a thermally transient condition and uses temperature measurements to extract the adiabatic efficiency and internal convective heat transfer coefficient simultaneously, thus capturing the aerodynamic and thermal performance. The procedure has been implemented both in simulation and experimentally on a typical turbocharger gas stand facility. Under ideal conditions, the new identification predicted adiabatic efficiency to within 1% point1 and heat transfer coefficient to within 1%. A sensitivity study subsequently showed that the method is particularly sensitive to the assumptions of heat transfer distribution pre- and postcompression. If 20% of the internal area of the compressor housing is exposed to the low pressure intake gas, and this is not correctly assumed in the identification process, errors of 7–15% points were observed for compressor efficiency. This distribution in heat transfer also affected the accuracy of heat transfer coefficient which increased to 20%. Thermocouple sensors affect the transient temperature measurements and in order to maintain efficiency errors below 1%, probes with diameter of less than 1.5 mm should be used. Experimentally, the method was shown to reduce the adiabatic efficiency error at 90 krpm and 110 krpm compared to industry-standard approach from 6% to 3%. However at low speeds, where temperature differences during the identi- fication are small, the method showed much larger errors.The authors would like to acknowledge the staff at CMT Motores Termicos at the Universitat Politecnica de Valencia for their assistance in undertaking the experimental aspects of this work and funding from the Powertrain and Vehicle Research Centre at the University of Bath.Burke, R.; Olmeda González, PC.; Serrano Cruz, JR. (2015). Dynamic Identification of Thermodynamic Parameters for Turbocharger Compressor Models. Journal of Engineering for Gas Turbines and Power. 137(10):1-10. doi:10.1115/1.4030092S11013710Chesse, P., Chalet, D., & Tauzia, X. (2011). Impact of the Heat Transfer on the Performance Calculations of Automotive Turbocharger Compressor. Oil & Gas Science and Technology – Revue d’IFP Energies nouvelles, 66(5), 791-800. doi:10.2516/ogst/2011129Cormerais, M., Hetet, J.-F., Chesse, P., and Maiboom, A., 2006, “Heat Transfers Characterisations in a Turbocharger: Experiments and Correlations,” ASME Paper No. ICES2006-1324. 10.1115/ICES2006-1324Shaaban, S., 2006, “Experimental Investigation and Extended Simulation of Turbocharger Non-Adiabatic Performance,” Ph.D. thesis, Fachbereich Maschinenbau, Universität Hannover, Hannover, Germany.Baines, N., Wygant, K. D., & Dris, A. (2010). The Analysis of Heat Transfer in Automotive Turbochargers. Journal of Engineering for Gas Turbines and Power, 132(4). doi:10.1115/1.3204586Serrano, J., Olmeda, P., Arnau, F., Reyes-Belmonte, M., & Lefebvre, A. (2013). Importance of Heat Transfer Phenomena in Small Turbochargers for Passenger Car Applications. SAE International Journal of Engines, 6(2), 716-728. doi:10.4271/2013-01-0576Burke, R. D., 2013, “Analysis and Modelling of the Dynamic Behavior of Automotive Turbochargers,” ASME Paper No. ICEF2013-19120.10.1115/ICEF2013-19120Serrano, J. R., Olmeda, P., Páez, A., & Vidal, F. (2010). An experimental procedure to determine heat transfer properties of turbochargers. Measurement Science and Technology, 21(3), 035109. doi:10.1088/0957-0233/21/3/035109Bohn, D., Heuer, T., & Kusterer, K. (2005). Conjugate Flow and Heat Transfer Investigation of a Turbo Charger. Journal of Engineering for Gas Turbines and Power, 127(3), 663-669. doi:10.1115/1.1839919Burke, R. D., Copeland, C. D., and Duda, T., 2014, “Investigation Into the Assumptions for Lumped Capacitance Modelling of Turbocharger Heat Transfer,” 6th International Conference on Simulation and Testing, Berlin, May 15–16

A new methodology for uncertainties characterization in combustion diagnosis and thermodynamic modelling

Combustion diagnosis based on in-cylinder pressure signals as well as 0D thermodynamic modelling, are widely used to study and optimize the combustion in reciprocating engines. Both approaches share some uncertainties regarding the sub-models and the experimental installation that, for the sake of accuracy, must be reduced as much as possible in order to obtain reliable results. A methodology, based on the sensitivity effect of such uncertainties on heat release and simulated pressure, is proposed to adjust their values. The methodology is capable of identifying the separate influence of each parameter and to provide a set of values thanks to the Multi-Variable linear regression (MLR) in motoring conditions. The method is flexible enough to deal with different number of uncertainties and can be applied to different engines and thermodynamic models. The final results of the adjustment are validated in combustion conditions, showing an improvement of the apparent combustion efficiency of about 7% with respect to the reference values.The support of the Generalitat Valenciana (BEST/2010/145) is greatly acknowledged.Benajes Calvo, JV.; Olmeda González, PC.; Martín Díaz, J.; Carreño Arango, R. (2014). A new methodology for uncertainties characterization in combustion diagnosis and thermodynamic modelling. Applied Thermal Engineering. 71(1):389-399. https://doi.org/10.1016/j.applthermaleng.2014.07.010S38939971

Monitoring and analysing oil condition to generate maintenance savings: a case study in a CNG engine powered urban transport fleet

The authors from Universitat Politecnica de Valencia wish to thank Spanish Grant TRA2008-06508 from Ministerio de Ciencia e Innovacion - Direccion General de Investigacion for supporting this work. Mr Gomez thanks the UPV for his grant 2011-S2-5003 in the frame of the PAID programme.Tormos Martínez, BV.; Olmeda González, PC.; Gomez Estrada, YA.; Galar, D. (2013). Monitoring and analysing oil condition to generate maintenance savings: a case study in a CNG engine powered urban transport fleet. Insight - Non-Destructive Testing & Condition Monitoring. 55(2):84-87. https://doi.org/10.1784/insi.2012.55.2.84S848755

Equivalent circuit definition and calendar aging analysis of commercial Li(NixMnyCoz)O2/graphite pouch cells

Aging-induced degradation of commercial Li-ion pouch cells with lithium nickel-manganese‑cobalt-oxide-based cathodes and graphite anodes is studied at various operating conditions (temperature and voltage) by galvanostatic measurements and in situ electrochemical impedance spectroscopy (EIS). A detailed equivalent electrical circuit model, capable to fit the measured EIS spectra, is developed and validated. The work also confirms the capacity fade dependence of the calendar-aged cells on stress factors such as temperature and state-of-charge. The retained capacity is found to decrease linearly with t0.5. However, it stands out that the degradation registered for cells held at 95% state-of-charge is lower than that for those at 70% and for the cases when temperatures are between 25 °C and 37.5 °C, which is a not very common singularity. A high performing calendar aging model is introduced accordingly. Both the electrical circuit model defined and the accurate calendar aging model developed provide useful tools for battery management systems in order to monitor and control both the state-of-health and the state-of-charge of these commercial cells

Influence of the intraday electricity market structure on the degradation of Li-ion batteries used to firm PV production

This article considers the introduction of Li-ion batteries in photovoltaic power plants to firm their energy production and analyzes the dependence of their degradation on the structure of the electricity market where the power production is traded. The operation of the batteries is decided as a result of successive optimization problems that benefit from the use of deep-learning-based irradiance forecasting tools with low prediction error, which allows the batteries to keep a small size. In addition, state-of-the-art battery aging models are handled to derive a realistic lifetime prognosis. The simulation results obtained by using real data from three European locations, which have different irradiance patterns and market structures, show how the proposed control strategy makes it possible to decouple the saturation rate of the batteries from the climatic conditions of the plant location. Furthermore, regarding the market structure, the results show that the shorter the energy block and the closer the lead time, the lower is the degradation of the batteries.Funding for open access charge: CRUE-Universitat Jaume

Importance of Heat Transfer Phenomena in Small Turbochargers for Passenger Car Applications

[EN] Nowadays turbocharging the internal combustion engine has become a key point in the reduction on pollutant emissions and the improvement on engine performance. The matching between the turbocharger and the engine is vital due to the highly unsteady flow the turbocharger works with. In the present paper the importance of the heat transfer phenomena inside small automotive turbochargers will be analyzed. This phenomenon will be studied from the point of view of both the turbine and the compressor in one-dimensional modelling. The goodness of the model will be demonstrated predicting turbine and compressor outlet temperatures. An accurate prediction of these parameters will be key designing the intercooler and the after treatment devices. A series of tests in a gas stand with steady and pulsating hot flow in the turbine side will be modeled to show the good agreement in turbocharger enthalpies prediction.This paper is partially supported by the Universitat Politècnica de València PAID-06-11 2034.Serrano Cruz, JR.; Olmeda González, PC.; Arnau Martínez, FJ.; Reyes Belmonte, MA.; Lefebvre, A. (2013). Importance of Heat Transfer Phenomena in Small Turbochargers for Passenger Car Applications. SAE International Journal of Engines. 6(2):1-13. doi:10.4271/2013-01-0576S1136

Modelling of Turbocharger heat transfer under stationary and transient conditions

A lumped capacity heat transfer model has been developed and compared tomeasurements from a turbocharger operating on a 2.2L Diesel engine under steadyand transient conditions ranging from 1000-3000rpm and 2-17bar BMEP. Themodel parameters have been estimated based on similar devices and this studyquantifies the errors associated with this approach. Turbine outlet gas temperatureprediction was improved with RMSE reduced from 29.5oC to 13oC. A sensitivitystudy showed the parameters of the heat transfer model influence gastemperatures by only ±4oC but housing temperatures by up to 80oC. Transientsimulations showed how errors in the thermal capacitance also lead to errors. Thisstudy shows the importance of undertaking a full thermal characterisation and theneed for accurate adiabatic maps in turbocharger simulations

Importance of Mechanical Losses Modeling in the Performance Prediction of Radial Turbochargers under Pulsating Flow Conditions

This work presents a study to characterize and quantify the mechanical losses in small automotive turbocharging systems. An experimental methodology to obtain the losses in the power transmission between the turbine and the compressor is presented. The experimental methodology is used during a measurement campaign of three different automotive turbochargers for petrol and diesel engines with displacements ranging from 1.2 l to 2.0 l and the results are presented. With this experimental data, a fast computational model is fitted and used to predict the behaviour of mechanical losses during stationary and pulsating flow conditions, showing good agreement with the experimental results. During pulsating flow conditions, the delay between compressor and turbine makes the mechanical efficiency to fluctuate. These fluctuations are shown to be critical in order to predict the turbocharger behaviour.Serrano Cruz, JR.; Olmeda González, PC.; Tiseira Izaguirre, AO.; García-Cuevas González, LM.; Lefebvre, A. (2013). Importance of Mechanical Losses Modeling in the Performance Prediction of Radial Turbochargers under Pulsating Flow Conditions. SAE International Journal of Engines. 6(2):1-10. doi:10.4271/2013-01-0577S1106