Investigation of the High-Pressure-Dual-Fuel (HPDF) combustion process of natural gas on a fully optically accessible research engine

Prager

et al. 2021

Further improvement of hydrogen combustion in port fuel injection engines is limited by backfire. To overcome this drawback of hydrogen port fuel injection engines it is essential to locate and understand the reasons for the inflammation of a backfiring cycle. To contribute to this understanding a minimal invasive lateral optical access was developed for a medium speed large bore engine. The access uses a UV enhanced endoscope to investigate the OH radical’s natural chemiluminescence to locate the inflammation of a backfiring cycle in the combustion chamber. The investigations are carried out at high engine load. The optical investigations were based on a thermodynamic screening. This included the variation of the start of the hydrogen port fuel injection and the engine’s backpressure. These experiments prove the influence of exhaust backpressure and the start of injection on the probability of backfire. As higher backpressure leads to an increased probability of backfire, the SoI strategy has also a decisive influence. An optimum start of injection timing with less backfire under high backpressure was experimentally determined at 300°CA with respect to 720°CA as FTDC. The conducted optical investigations show that backfire starts by ignition by hot residual gasses during the first cycle located under the exhaust valves. Furthermore, the results show ongoing combustion in the intake manifold leading to serious damage of the engine if not prohibited.

Section: Methodsmentioning

confidence: 99%

Optical screening investigations of backfire in a large bore medium speed hydrogen engine

Eicheldinger

Prager

et al. 2021

“…LaVision’s high-efficiency endoscope with a field of view of ∼25° enhanced for the ultraviolet spectral range of 280–350 nm was installed for the test setup. A beam splitter similar to Gleis et al 52 makes it possible to simultaneously record the visible range of the combustion (cf. Figure 5) and the ultraviolet spectral range, especially the chemiluminescence of the OH-radical comparable to Di Iorio et al, 23 Catapano et al, 33,34 Di Iorio et al 38,48 The visible path is recorded by a color imaging Phantom v2012 high-speed camera equipped with a Wallimex f# 2.8, f100 objective.…”

Section: Test Bench Designmentioning

confidence: 99%

Optical and thermodynamic investigations of a methane and hydrogen blend fueled large bore engine

Eicheldinger

Prager

et al. 2022

The following paper presents thermodynamic and optical investigations of the natural flame and OH radical chemiluminescence of a hydrogen enriched methane combustion compared to natural gas combustion. The engine under investigation is a port-fueled unscavenged prechamber 4.8 L single cylinder large bore engine. The blends under consideration are 2%V, 5%V,10%V, and 40%V of hydrogen expected to be blended within existing natural gas grids in a short and mid-term timeline in order to store green energy from solar and wind. These fuel blends could be used for stabilization of the energy supply by reconverting the renewable fuel CH4/H2 in combined heat and power plants. As expected, admixture of hydrogen extends the ignition limits of the fuel mixture toward lean ranges up to an air-fuel equivalence ratio of almost 2. No negative effect on combustion is observed up to an admixture of 40%V hydrogen. At 40%V hydrogen, abnormal combustion like backfire occurs at an air-fuel equivalence ratio of 1.5. The higher mixtures exhibit increased nitrogen oxide emissions due to higher combustion chamber temperatures, while methane slip and CO emissions are reduced due to more complete combustion. The optical investigation of the natural flame and OH radical chemiluminescence are in good agreement with the thermodynamic results verifying the more intense combustion of the fuel blends by means of the chemiluminescence intensity. Further, lube oil combustion and a continuing luminescence after the thermodynamic end of combustion are observed.

“…The used numerical model is validated using data from the optical accessible single cylinder test engine described in Gleis et al 13 and Frankl and Gleis. 15 Developed for methane-diesel dual fuel it is extended for the fuel combinations hydrogen/diesel and ammonia/diesel in this work.…”

Section: Methodsmentioning

confidence: 99%

“…The compression end pressure for the numerical study is 90 bar. This is, because the study was performed before the experimental data was gained, and therefore based on the experiments published in Gleis et al 13 and Frankl and Gleis. 15 The first hydrogen HPDF simulation was made in order to find out, if an engine process with hydrogen in HPFD combustion would be safe.…”

Section: Numerical Study Of Hydrogen and Ammonia Hpdfmentioning

confidence: 99%

“…11,12 This injector has been used experimentally for the above mentioned methane-diesel and methanol-diesel dual fuel combustion in a full optical accessible internal combustion engine in previous works. 13,14 From the experiments a numerical CFD-model was developed and validated. 15,16 A derived model is used in this study to investigate the substitution of methane through hydrogen or ammonia in order to find out whether these fuels are suitable for HPDF-engines.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Investigation of ammonia and hydrogen as CO2-free fuels for heavy duty engines using a high pressure dual fuel combustion process

Frankl

Gleis

et al. 2020

Self Cite

This work is a numerical study of the use of ammonia and hydrogen in a high-pressure-dual-fuel (HPDF) combustion. The main fuels (hydrogen and ammonia) are direct injected and ignited by a small amount of direct injected pilot fuel. The fuels are injected using a dual fuel injector from Woodward L’Orange, which can induce two fuels independently at high pressures up to 1800 bar for the pilot fuel and maximum 500 bar for the main. The numerical CFD-model gets validated for of hydrogen-HPDF with experimental data. Due to safety issues at the test rig it was not possible to use ammonia in the experiments, so it is modelled using the numerical model. It is assumed that the CFD-model also gives qualitative correct results for the use of ammonia as main fuel, so a parameter study of ammonia-HPDF is made. The results for the hydrogen-HPDF show, that hydrogen can be used in the engine without any further modifications. The combustion is very stable, and the hydrogen ignites almost immediately when it enters the combustion chamber. The results of the ammonia combustion indicate, that the HPDF combustion mode can handle ammonia effectively. It seems beneficial to inject the ammonia at higher pressures than hydrogen. Also pre-heating the ammonia can increase the combustion efficiency.