Wyniki wyszukiwania - BazTech

1

Thermodynamic analysis of combustion events in the natural gas fuelled SI engine with VVT

Szwaja M., Mazuro P., Szwaja S.

Journal of KONES

|

2018

|

Vol. 25, No. 4

421--427

EN

The main aim of the research was to investigate influence of overlap of the natural gas fuelled spark ignited engine on the following parameters: Indicated Mean Effective Pressure (IMEP), heat rate release including combustion phases (ignition lag, main combustion phase). The content of the study includes results from processing in-cylinder pressure measurements, heat release rate analysis, combustion phases, and finally the conclusions. The tests were carried out on the test bed including the single cylinder research engine with a displacement volume of 550 cm3. The engine was equipped with independent cam phasors for both intake and exhaust valves, but for this investigation, the exhaust valve timing was fixed (the exhaust cam centre line was fixed at -95 crank angle (CA) deg before Top Dead Centre) and intake valve timing was changed (the intake cam centre line was varied from 90 to 150 CA deg after Top Dead Centre). The overlap was changed in the range from 85 to 25 CA deg. 8 tests series were performed, each singular series consisted of 300 consecutive engine combustion cycles. As observed, by varying the valve overlap it contributes to significant change in the peak combustion pressure, peak of heat release rate, and combustion phases. Summing up, variable valve timing affects compression and expansion strokes by changing polytropic indexes due to various amounts of exhaust residuals trapped in the cylinder. It affects not only engine volumetric efficiency but also the heat release rate and IMEP, so it does engine performance. Thus, variable valve timing can be considered as valuable tool that can be applied to the natural gas fuelled internal combustion engine.

2

Phase constitution of an LaFe11.0Co0.8(Si0.4Al0.6)1.2 alloy investigated by Mössbauer spectroscopy

Gębara P., Pawlik P., Wysłocki J. J., Szwaja M.

Nukleonika

|

2013

|

Vol. 58, No. 1

113-116

EN

In the present work the phase constitution and magnetic ordering of the magnetocaloric LaFe11.0Co0.8(Si0.4Al0.6)1.2 alloy in the as-cast state and after annealing at 1323 K for 1 h (in case of ribbons) and 49 days (in case of bulk) were studied. For bulk and ribbon samples in as-cast state three crystalline phases were identified: dominant ferromagnetic alfa-Fe, minor ferromagnetic La(Fe,Co)Si and traces of paramagnetic La(Fe,Si)13 phase. Appropriate heat treatment resulted in the evolution of phase constitution of the alloy, where two crystalline phases were developed: the dominant paramagnetic La(Fe,Si)13 phase and a minor fraction of the ferromagnetic alfa-Fe for both bulk and ribbon samples.

3

Characterization of phase constitution and magnetic properties of the hard magnetic nanocrystalline Nd9.5Fe63.65B21.85Nb5 alloy ribbons

Szwaja M., Pawlik K., Wysłocki J. J., Pawlik P., Gębara P.

Nukleonika

|

2013

|

Vol. 58, No. 1

159-163

EN

In order to investigate the phase constitution of the nanocrystalline Nd9.5Fe63.65B21.85Nb5 alloy ribbons in the as-cast state and after short-time annealing Mossbauer study has been carried out. In as-cast state, ribbon samples were not fully amorphous but revealed soft magnetic properties. X-ray diffraction analysis showed the presence of hard magnetic Nd2Fe14B, metastable Nd2Fe23B3 and paramagnetic Nd1+epsilonFe4B4 phases in annealed samples. Mossbauer spectroscopy was used to determine the fractions of constituent phases formed during annealing of ribbons. Magnetic measurements were made with a vibrating sample magnetometer (VSM) and have shown that with increasing annealing temperature the remanence polarization Jr and maximum energy product (BH)max values were increasing.

4

Magnetic properties of the nanocrystalline Nd9.6Fe64.32Nb4B22.08 alloy ribbons

Szwaja M., Pawlik P., Wysłocki J. J., Gębara P.

Archives of Metallurgy and Materials

|

2012

|

Vol. 57, iss. 1

233-236

EN

Studies of magnetic properties and phase constitution of nanocrystalline Nd9.6Fe64.32Nb4B22.08 alloy ribbon samples are presented. In as-cast state, ribbon samples were fully amorphous and soft magnetic. Subsequent annealing resulted in an evolution of the phase constitution together with change of their magnetic properties. The main phase observed in the material is Nd2Fe14B hard magnetic phase.

PL

W pracy badano własności magnetyczne oraz skład fazowy taśm wytworzonych ze stopu Nd9,6Fe64,32Nb4B22,08. Taśma w stanie po odlaniu ma amorficzną budowę i wykazuje miękkie właściwości magnetyczne. Wygrzewanie taśm powoduje zmiany składu fazowego wraz ze zmianą ich właściwości magnetycznych. Podstawową fazą obserwowaną w badanym materiale jest faza magnetycznie twarda Nd2Fe14B.