Selection and evaluation of degradation intensity indicators of gas combustion engine oil

J. Pošta, B. Peterka, Z. Aleš, J. Pavlů* and M. Pexa

Faculty of Engineering, Czech University of Life Sciences Prague, Kamycka 129, CZ16521 Prague 6, Czech Republic
*Correspondence: jindrichpavlu@seznam.cz

Abstract:

The paper is focused on the analysis of data obtained during the operation of gas combustion engines running on biogas. The observed engines were running continuously in cogeneration units of biogas plants. The long-term operational monitoring of engines operating on biogas was carried out using tribotechnical diagnostics methods focused on oil properties. Each of individual indicators was determined in obtained time series. As critical indicators oils were identified oxidation, sulfation, nitration and total acid number. The prerequisite for correct selection of the oil change interval is knowledge on evolution of critical indicators over time. In the reference case, oil oxidation was identified as critical indicator. This knowledge allows to optimize intervals of oil sampling and oil change interval on the basis of time series evaluation.

Key words:

Stability of rapeseed oil with horseradish Amorica rusticana L. and lovage Levisticum officinale L. extracts under medium temperature accelerated storage conditions

L. Tomsone* and Z. Krūma

Latvia University of Agriculture, Faculty of Food Technology, Department of Food Technology, Liela iela 2, LV-3001, Jelgava, Latvia *Correspondence: lolita.tomsone@llu.lv

Abstract:

This study examined the antioxidant activity of horseradish leaves and lovage leaves and stems extracts added to crude rapeseed oil, under medium temperature accelerated storage conditions. To evaluate efficiency of plant extracts they were added to oil in different concentrations (0.25, 0.5, 1.0 and 1.5%). As a control rapeseed oil without extracts where analysed. For comparison 0.01% butylatedhydroxytoluene (BHT) were added to oil. Efficiency of extracts in oil where tested at +60 ± 1°C in the dark for 22 days. For all samples peroxide value, acid value and 2,2-diphenyl-1-picrylhydrozyl (DPPH˙) activity were determined. In all steps of the experiments for samples with extract peroxide value was significantly (P < 0.05) lower comparing to the control. The control sample without extract reached 15meq O2 kg-1 oil (maximal allowed value in Latvian legislation) in 3 days. The best results showed the horseradish leaves extract (1%) and the lovage leave extract (1.5%) reaching this value in 8.3 days and 7 days, respectively. DPPH˙ activity of the oil was compared after 3 days (when blank sample reached maximal allowed a peroxide value) and it shown that for all samples it was higher compared to the control sample. The highest activity showed the samples with horseradish leave extracts. A acid value in oil samples changed slightly. Lovage leave as stem and horseradish leave extracts could be successfully used for retarding of oxidation of rapeseed oil and in further experiments their activity in meat products will be tested.

Key words:

extract, horseradish, lovage, oxidation., rapeseed oil