Zahrul Fuadi

Formation of Carbon-Based Tribofilm Under Palm Methyl Ester

The popularity of biodiesel is continuously increasing nowadays because of fossil fuel’s shortage and environment concerns. Biodiesel is renewable, carbon neutral, and, most importantly, usable in diesel engines without modification. Particularly, the biodiesel from palm oil, palm methyl ester (PME), has become the main source of the world’s biodiesel due to its availability. One of the main concerns in biodiesel fuel usage is its ability to lubricate the mechanical components of the fuel system such as injection pump and nozzle sprayer since those parts are mainly lubricated by the fuel. In this research, an investigation has been conducted to analyze the characteristic of a tribofilm (boundary film) produced by friction of self-mated stainless steel at boundary lubrication condition using palm methyl ester as the lubricant. The friction tests were conducted using a ball on disk tribometer. The results show that excessive wear of the material was prevented; thanks to the tribofilm formed on the contact interface. The analysis shows that the tribofilm has a unique characteristic indicated by the presence of D-band’s peak but the absence of G-band’s peak in its Raman spectra. It seems that the carbon-based tribofilm was formed on the solid surface as a result of carbon decomposition from the palm methyl ester assisted by the tribo-chemical reaction. Although its real structure is still not clear, the tribofilm has an excellent ability to protect the material from severe friction and wear.

Analysis of wind energy potential for agriculture pump in mountain area Aceh Besar

In this study, the potential of wind power for agricultural pump driver in Saree mountainous area of Aceh Besar is analyzed. It is found that the average usable wind speed is 6.41 m/s, which is potential to produce 893.96 Watt of electricity with the wind turbine rotor diameter of 3 m. This energy can be used to drive up to 614 Watt of water pump with static head of 20 m to irrigate 19 hectare of land, 7 hours a day. HOMER analysis indicated the lowest simulated NPC value of USD 10.028 with CoE of USD 0.717 kWh. It is also indicated that the wind has potential to produce 3452 kWh/year with lifetime of 15 years.

Stiffness Effect on Low-Frequency Stick-Slip Motion Generated on a Simple Caliper-Slider Experimental Model

This paper discusses the occurrence and non occurrence of low-frequency stick-slip motion on a simple caliper-slider experimental model. The analysis focused on the relationship between stiffness, i.e. contact stiffness and structure’s stiffness, and the generation of stick-slip motion. The occurrence of stick-slip motion is determined by analyzing the frequency characteristic of resulted vibration acceleration at the beginning of sliding which is resulted from a simultaneous application of force in tangential direction and slow release of force in normal direction. The results show that the occurrence and non occurrence of stick-slip motion can be classified into three regions according to the parameter of stiffness ratio, i.e. non occurrence region, mixed region, and occurrence region. The stiffness ratio Sr, the ratio of contact stiffness Kc to structure’s stiffness Ks, of 40 is found to be critical for the low-frequency stick-slip generation in this experimental model.

Wear Characteristic of Stainless Steel 304 Sliding against Cast Iron under Lubrication Environment of Palm Biodiesel Fuel

The used of palm-biodiesel fuel in automotive industry is increasing rapidly nowadays. Among the reasons are high efficiency modern fuel injection system of diesel engines and the shortage of petroleum diesel fuel from fossil resources. Among the parts affected by the fuel switch are fuel pumps components, including the fuel injection needle. Those components, working under the lubrication environment of the fuel, have to be prevented from excessive wear to maintain their high performances. This paper discussed the wear characteristics of stainless steel 304 sliding against cast iron under the lubrication environment of palm-biodiesel fuel with the concentration of 7.5% palm methyl ester in the petroleum diesel fuel. The material pair is chosen because of their widely used as mechanical components. The tests were conducted using a ball on disk tribometer. The results show that wear of the stainless steel ball is smaller in the environment with the presence of palm methyl ester content in the diesel fuel compared to that in the environment without the presence of the palm methyl ester content. The results suggested that palm-biodiesel fuel is favorable in decreasing the wear of the material.