Air Charging System Research Articles

Potential of Hydrogen Internal Combustion Engine for the Decarbonised Passenger Vehicle

CO2 regulations are becoming very stringent due to the goal of reducing greenhouse gases and achieving carbon neutrality. It has already become a common situation that electric vehicles are emerging as eco-friendly power systems rather than vehicles equipped with conventional internal combustion engines and their share in the market is increasing. However, even with an internal combustion engine, CO2 can be drastically reduced if a carbon-free fuel such as hydrogen is used. Raw nitrogen oxides (NOx) emissions can be overcome to a certain level through ultra-lean burn operation, but in order to balance the amount of hydrogen and air in the limited space of the combustion chamber, a drop in the engine’s maximum output should be accepted. Hyundai Motor Company (HMC) also previously developed an engine using hydrogen fuel (), but was unable to progress to mass production. Since then, hybrid technology has become popular, and with the development of hydrogen injection devices, an era has arrived where mass production becomes a possibility. For this reason, studies on internal combustion engines using hydrogen fuel based on existing spark ignition or compression ignition engines are rapidly increasing. In this study, a hydrogen fuel engine was designed and manufactured based on the mass produced gasoline spark ignition engine. CO2 level was confirmed from initial performance evaluation, and it was found that raw NOx levels and maximum power were in a trade-off relationship with each other under the same air-charging system application. In addition, the method to improve maximum engine torque was verified while maintaining the raw NOx level, and the maximum engine power improvement level was confirmed when raw NOx emissions were allowed to increase. Thereby the potential of the carbon-neutral internal combustion engine has been demonstrated.

A New Simulation-Based Methodology to Improve Medium-Speed Diesel Engines BSFC/NOx Tradeoff With an Optimized Air Charging System

Abstract This paper aims at introducing an original, simulation based, methodology to optimize air charging system of a medium speed engine in order to improve fuel consumption/NOx tradeoff, over a given load profile. A preliminary study is performed on an engine originally equipped with fixed geometry turbocharger (TC) matched at full load. It shows that improving the TC efficiency has a positive impact at matching point but an adverse effect at lower loads. Therefore, matching the TC at part load is more promising when the whole engine operating range is considered. However, this requires using a relief system to avoid unacceptable peak firing pressure (PFP) at full load, and may alter regulated NOx emission. A new, original methodology is then proposed. Using an advanced existing algorithm, it allows for simultaneous optimization of injection timing, main TC matching and relief system design. The objective is to minimize fuel consumption averaged over several operating points (corresponding to actual load profile). At the same time, NOx emission, evaluated on regulatory cycle, is kept below a given limit and others reliability constrains are fulfilled. The methodology is assessed with several case studies: • First, various relief systems (blow-off valve, waste gate (WG) and parallel sequential turbocharger (PTC)) are compared on a given load profile. • Then, the dimensioning of a TC + WG system is performed for two different load profiles. In both cases, the proposed methodology leads to a charging system design customized for a given user profile, which enables a significant fuel consumption reduction.

Surge Limit Prediction for Automotive Air-Charged Systems

Compressor surge has been investigated and predicted since the early days of turbomachinery research. Experimental testing of turbomachinery applications is still needed to determine whether stable compressor operation is possible in the expected application regime. Measuring compressor maps and operating ranges on hot gas test stands is common. The test benches are designed and optimized to ensure ideal inflow and outflow conditions as well as low measurement uncertainty. Compressor maps are used to match turbocharger and application. However, a shift in surge limit, caused by the piping system or application, can only be adequately addressed with full engine tests. Ideal measurements use the corresponding piston engine in the charged-air system. This can only take place in the development process, when surge detection is unfavorable from an economic perspective. The surge model for turbochargers presented here is an extension of the Greitzer’s surge model, which considers the effect of inlet throttling. Application components, such as air filters, pipe elbows and flow straighteners, reduce pressure in front of the compressor and flow conditions might differ from those in laboratory testing. Experimental results gathered from the hot gas test stand at TU Darmstadt indicate strong variation in surge limit, influenced by inlet throttling. An extension to the surge model is developed to explain the observed phenomena. The model was validated using extensive experimental variations and matches the experienced surge limit shift. Additional measurements with a piston engine downstream of the turbocharger demonstrated the validity of the surge model. The results also show that surge is a system-dependent phenomenon, influenced by compressor aerodynamics and boundary conditions.

Assessing the reproducibility of high definition urethral pressure profilometry and its correlation with an air-charged system.

Recently, a new urodynamic method for the assessment of stress urinary incontinence called high definition urethral pressure profilometry (HD-UPP) has been introduced. This method combines a novel microtip catheter with advanced signal processing to enable spatial data location and the reconstruction of a pressure image inside the urethra. In order to assess the reproducibility of HD-UPP data, we statistically evaluate HD-UPP datasets and compare them to data from a double balloon air-charged system. Both catheters are used on sedated female minipigs. Data from the microtip catheter are processed through a signal reconstruction algorithm, urodynamic features are extracted, and compared to the air-charged system. Reproducibility of HD-UPP data is assessed by statistically evaluating consecutive, intra-individual datasets. HD-UPP delivers results in agreement with previous comparisons of microtip and air-charged systems. The average deviation of two consecutive, intra-individual pressure images is very low at 7 cm H2 O. HD-UPP provides physicians with detailed information on the pressure distribution inside the urethra. Through comparison with an air-charged catheter, it is shown that HD-UPP delivers results in agreement with previous studies on the comparison of microtip and air-charged catheters. It provides excellent reproducibility, as the difference between sequentially measured profiles from the same minipig is significantly lower than the one between profiles from different minipigs.

Deep recycling heat from exhaust gases and compressed air of modern low speed engine

The energy flows in the propulsion plant with low-speed engine MAN 14S90ME–C9.2–TII are considered. It is noted that only one quarter of the energy released by combustion of fuel in the engine cylinder is transformed in propeller thrust. The amount of heat from the charge air slightly exceeds the amount of heat from exhaust gases when the engine’s load is 90% and under ISO conditions. The thermal scheme of exhaust heat recovery and air charging system at reasonable for marine conditions cooling depth has been presented and analyzed. Operating parameters of the system are shown in the diagram «Temperature — Heat». In the diagram «enthalpy — entropy» there has been considered a steam expansion process occurring in the turbine with two transitional supplies of superheated steam. It is indicated that all primary superheat pressure is needed to avoid excessive humidity of steam at the end of the expansion process.

High definition urethral pressure profilometry: Evaluating a novel microtip catheter.

Urethral pressure profilometry (UPP) is used in the diagnosis of stress urinary incontinence (SUI). SUI is a significant medical, social, and economic problem, affecting about 12.5% of the population. A novel microtip catheter was developed for UPP featuring an inclination sensor and higher angular resolution compared to systems in clinical use today. Therewith, the location of each measured pressure sample can be determined and the spatial pressure distribution inside the urethra reconstructed. In order to assess the performance and plausibility of data from the microtip catheter, we compare it to data from a double balloon air charged system. Both catheters are used on sedated female minipigs. Data from the microtip catheter are processed through a signal reconstruction algorithm, plotted and compared against data from the air-charged catheter. The microtip catheter delivers results in agreement with previous comparisons of microtip and air-charged systems. It additionally provides a new level of detail in the reconstructed UPPs which may lead to new insights into the sphincter mechanism of minipigs. The ability of air-charged catheters to measure pressure circumferentially is widely considered a main advantage over microtip catheters. However, directional pressure readings can provide additional information on angular fluctuations in the urethral pressure distribution. It is shown that the novel microtip catheter in combination with a signal reconstruction algorithm delivers plausible data. It offers the opportunity to evaluate urethral structures, especially the sphincter, in context of the correct location within the anatomical location of the pelvic floor. Neurourol. Urodynam. 35:888-894, 2016. © 2015 Wiley Periodicals, Inc.

Steady-state emulation of a diesel engine air charging system through real-time turbocharger modelling

Engine downsizing is an important route to meeting tightening emission regulations and improving engine efficiency. However, when a new air charging system such as a turbocharger is selected to enable downsizing of an internal-combustion engine for increased specific power and efficiency, extensive resource-intensive optimization procedures are currently required. In this paper, a method of emulating an engine charge system is developed on the basis of a charge air-handling unit and a real-time turbocharger model comprising map based compressor and turbine models with improved data density and range via numerical and analytical approaches. Variables such as the boost pressure, back pressure, turbocharger speed and the mass flow rate of air are used to compare the response of the charge system emulation with the real turbocharger. The emulation method achieves considerable accuracy when compared with the real turbocharger hardware. This approach will enable future engine developments to be assessed prior to the prototype hardware phase, resulting in significantly lower costs and shorter time frames for the development process.

Performance Simulation of Sequentially Turbocharged Marine Diesel Engines With Applications to Compressor Surge

This paper presents the SELENDIA code designed for the simulation of marine diesel engines. Various measured and simulated results are compared for the performance of a sequentially turbocharged marine diesel engine during a switch from one to two turbochargers. The results show a good agreement between measured and simulated data. Surge loops that are experimentally observed in case of an anomaly are analyzed using simulated results. Finally, the predictive capabilities of the simulation code are utilized to investigate the influence of the inlet manifold volume on the engine and air charging system performance with a special focus on compressor surge. [S0742-4795(00)01104-2]

Numerical Simulation of CAES Champagne Effect. 2nd Report. Preliminary Calculation for Plant Design.

Evaluation of champagne effect is indispensable for successful commercialization of a compressed air energy storage (CAES) system which is one of the most promising candidates of energy storage system. In the present study, we examined optimum design of the CAES system through numerical calculations of the champagne effect based on a two-fluid model. As a result, the following conclusions were obtained. (1) Charging rate of air into a lower reservoir should be gradually changed during startup and shutdown periods to avoid pressure oscillation in the lower reservoir. (2) If the water level in the lower reservoir is too low when the charging is finished, the inertial force makes the water level enter into the U-bend, which also induces the pressure oscillation in the lower reservoir. (3) If appropriate procedures are adopted during the startup and shutdown period of air charging system, the water level in the lower reservoir does not enter into the U-bend. The construction cost can hence be reduced by shortening the U-bend.

A Study on Surging Phenomena in Diesel Engine Air-Charging System

Pulsating air flow in a diesel engine air-charging system caused by the opening and closing of the scavenging ports produces surging phenomena which are considerably different in their characteristics from those observed in the ordinary, steady flow blower system. By substituting a simple model for the engine air-charging system, the authors analyzed the surging phenomena through theoretical calculations and determined the effects of each model element on the surging. A series of experiments were then made to verify the validity of the analytical calculation method adopted. A good agreement was observed between the results of calculations and experiments, and it was found that a simplified theoretical calculation neglecting the influence of the pressure waves in the air duct of the air-charging system could serve as an effective means to deal with the surging phenomena where the air duct was comparatively short in length as that of the diesel engine.