Determination and evaluation of biogas and methane productions of vegetable and fruit wastes with Hohenheim Batch Test method

Nowadays,biogas technology applications are gradually increasing worldwide due to the economic and environmental benefits.Many researches and studies related to the determination of the biogas potential of organic waste materials have been carried out in the recent years.Studies to determine the specific methane potential of organic waste materials have a great importance for both design and economical operation of the biogas plants.Energy potential that will be recovered from organic wastes is substantial in Turkey.Thanks to biogas plants gathering vegetable-fruit wastes and other organic wastes are planned to produce significant amount of renewable energy in Turkish markets.Owing to the use of organic wastes,the disposal of waste as well as energy production,soil,water and air pollution in terms of environmental protection are also minimized.On the other hand,the organic wastes produced from plants can also be utilized as fertilizer in vegetable production.In this study,the cumulative biogas and methane production of vegetable and fruit wastes were experimentally determined with HBT(Hohenheim Batch Test)method.Biogas and methane yields of vegetable and fruit wastes were found as 0.54-0.73 Nm^(3)/(kg ODM)and 0.29-0.37 Nm^(3)/(kg ODM),respectively.The highest value of the cumulative specific methane production was tomato wastes(0.37 Nm^(3)/(kg ODM)),and the lowest value was lettuce wastes(0.29 Nm^(3)/(kg ODM)),as well.The average cumulative specific methane production values of mixed vegetable and fruit wastes are determined as 0.34 Nm^(3)/(kg ODM).

Spline regression modelling of PTO performance of tractor fuelled with different biodiesels

The objective of this study was to investigate the possibility of fitting spline regression models for power take-off(PTO)performance characteristics of an agricultural tractor tested with four different fuels,including diesel fuel(B0)and three biodiesel blends made of canola oil(B10:10%biodiesel+90%petro-diesel blend;B20:20%biodiesel+90%petro-diesel blend;B30:30%biodiesel+90%petro-diesel blend).The performance characteristics evaluated were PTO power,engine torque,engine fuel consumption,and specific fuel consumption.Due to sharp slopes in measured quantities around the nominal engine speed(2200 r/min),compared to the standard regression method,the spline regression models suited well to the experimental data with coefficient of determination R2=0.99 for PTO power and engine torque.R2 varied between 0.97 and 0.99 for fuel consumption and 0.91 and 0.95 for specific fuel consumption.The weaker correlation found for specific fuel consumption could be attributed to profound fluctuations in measured data causing atypical pattern in the corresponding graphs around the nominal engine speed.It was concluded that splines were useful to accurately predict the measured PTO power and engine torque.Neither standard methods nor splines were sufficient to obtain very good regression models for specific fuel consumption.