Pengaruh Lingkungan Terhadap Efisiensi Inhibisi Asam Askorbat (Vitamin C) Pada Laju Korosi Tembaga

Corrosion rate can be reduced by adding inhibitor and inhibition efficiency is a measure if its ability to suppress corrosion. The result of the immersion tests show that the inhibition efficiencies are different on each environment. Addition of 50 ppm of ascorbic acid results in the highest efficiency for NaC1 and CaCO3 environment while for Ca SO4 environment needs 100 ppm

Studi Perbandingan Kinerja Anoda Korban Paduan Aluminium Dengan Paduan Seng Dalam Lingkungan Air Laut

There are two kinds of sacrificial anodes available to protect steel structure in the marine environment; they are zinc and aluminum alloy. This research studies their performance by conducting galvanic corrosion test in the substitute ocean water. The performance evaluated covers potential of protection, galvanic current, capacity and efficiency, the rate of anode consumption, the induction time, and their corrosion form. The result shows that aluminum alloy has galvanic current and anode capacity higher than the zinc alloy. It is also found that this alloy gives the higher efficiency and shows the lower anode consumption rate than the zinc alloy. From the macro photographs, it is found that these two alloys corrode locally by pitting formation

Studi Pengaruh Magnetic Arc Blow Pada Hasil Las TIG Baja AISI 1021

Discontinuities and size of the weld deposit are affected by many factors. Magnetic arc blow is one of the factors that one may not be aware of. Magnetic arc blow was studied in this research with the ground position and welding current were varied. The discontinuities and size of the weld deposit were observed and measured by taking specimens of the carbon steel of AISI 1021 welded by TIG welding process using argon as protective gas. Macro photographs and data of the size of the weld deposit show magnetic arc blow has strong influence on the size of the weld on the first cut section. This specimen was welded by using 200 Ampere with the ground placed in the starting point of the welding process. Undercut and incomplete penetration are commonly found as discontinuities in all cut sections of the specimens. While porosities occur mainly in the first section with high current. It 's believed that these discontinuities occur due to the lack of shielding by the protective gas caused by very strong arc blow around the melt. Tungsten inclusions are also the common discontinuities to take place, they are found more when welding using high current (200 A). Their occurrence is because of the melting of the tip of the tungsten electrode caused by the high heat input.. At the end of the weld, crater and spatter are always found. Backward arc blow are very strong at the end of the process that arises these defects

Airflow Characteristics Investigation of a Diesel Engine for Different Helical Port Openings and Engine Speeds

Intake airflow characteristics are essential for the performance of diesel engines. However, previous investigations of these airflow characteristics were mostly performed on two-valve engines despite the difference between the airflow of two-valve and four-valve engines. Therefore, in this study, particle image velocimetry (PIV) investigations were performed on a four-valve diesel engine. The investigations were conducted under different engine speeds and helical port openings using a swirl control valve (SCV). The results suggest that the position of the swirl center does not significantly shift with different engine speeds and helical port openings, as the dynamics of the flow remained closely similar. The trends of the airflow characteristics can be best observed during the compression stroke. A higher engine speed increases the angular velocity of the engine more compared to the increase of the airflow velocity and results in a lower swirl ratio of the flow. On the other hand, a higher engine speed leads to a higher mean velocity and the variation of velocity results in a larger turbulence intensity of the flow. Increasing the helical port opening brings a reduction in the swirl ratio and turbulence intensity as more airflow from the helical port disturbs the airflow from the tangential port

Effects of extraction methods on the fuel characteristics and diesel engine performances of jatropha curcas biodiesel

The development of high-quality biodiesel fuel has become more relevant due to the limited reserve and environmental effects of fossil fuel. In this study, oils derived from Jatropha curcas seeds through two extraction methods (soxhlet and cold-press) were compared. The fuel characteristics investigation suggested that methyl ester derived from oil extracted with the soxhlet method has lower viscosity, higher calculated cetane index, and slightly higher sulphur content. Comparison on the fuel characteristics with biodiesel standards showed that the methyl esters still had substantial amount of methanol and water due to low temperature during transesterification. The oils were also compared for their engine performances in a diesel engine under engine rotation of 1800 to 3000 RPM by blending derived methyl ester with pure petro-diesel to create B20 biodiesel. On average, B20 from soxhlet extraction has 3.86% higher power output, 3.55% higher torque, 3.4% higher BMEP, and 5.89% lower BSFC compared to cold-press. The extraction method affects the fuel characteristics of the methyl ester and the engine performances of the B20 biodiesel