This study aims to reveal the performance and exhaust emissions of a spark ignition (SI) engine fueled by a gasoline-bioethanol mixture. The main performance characteristics of the SI engine tested are torque, power output; thermal efficiency, brake specific fuel consumption, and brake mean effective pressure. Meanwhile, the exhaust emissions seen are carbon monoxide and hydrocarbons. The test is carried out by comparing the performance of the SI engine under standard conditions without modification with gasoline fuel, with the SI engine with modification with 85% bioethanol fuel. The mass flow of fuel is regulated by modifying the carburetor choke at 3/4 and 7/8. The results show that although slightly lower than gasoline, in general, it can be seen that bioethanol can improve SI engine performance and produce environmentally friendly exhaust emissions.

In previous studies, the initial process of burning briquettes still takes a long time, i.e. app 15-20 minutes. In normal briquette burning, a flame comes out from the briquette hole surface. The purpose of this research is to find a solution to accelerate the burning process and then the solution to use this process easily. The main objective of this research is to examine the amount of heat generated from the briquettes burning process with the number of holes as much as 10, 12, and 14, and to measure the time of initial briquette burning until the first time the flame came out on the briquettes surface. The basic ingredients of briquettes used in this study were sago waste. The tools used are a moisture meter to measure the water content, an infrared thermometer, a temperature measuring instrument, a Stopwatch to measure time, a digital anemometer to measure the airflow speed. From this study, the results obtained indicate that the combustion process in a forced air convection conditions, resulting in the rate of heat transfer as follows: a). For using the 10 holes briquettes, the heat transfer rate is about 8.51 watts, b). In the burning of 12 holes briquettes, the resulting heat transfer rate is about 16.57 watts, c). While on the 14 holes briquettes burning, the rate of heat transfer is about 20.43 watts. When heat energy is applied to boil 5 liters of water, with a 10-hole briquette, the water boils within 23.54 minutes. When using 12 holes briquettes, the water boils in 21.31 minutes, and in the use of 14 holes briquettes, the water boils in 20.21 minutes. It is concluded that the shortest time to boil 5 liters of water is when using briquettes with 14 holes, which boils in 23.34 minutes. These results indicate that forced convection can speed up the briquette burning process and produce a fairly high temperature.

This study examines the Ignition characteristics of blended fuel droplets with crude coconut oil and rhodium liquid as a liquid metal catalyst. The ignition behavior was observed by igniting the oil droplet on a junction of a thermocouple, and the droplet evolution recorded with the high-speed camera. The results show that the addition of a liquid metal catalyst successfully reduces the molecular mass of the triglyceride and weakens the bonding force between the carbon chain, and therefore the viscosity and flash point decreases. Moreover, the addition of liquid metal catalysts increased the reactivity of fuel molecules such as C-H, C-C, C = C, and C-O. Changes in the physical properties of the fuel, the geometry of the carbon chain, and molecular mass ease the absorption of heat by the fuel droplet, thereby increasing fuel ignition performances.

For now, energy sources uses are still dominated by fossil fuels, whose availability is limited and continues to decline. Therefore, new alternative energy is needed to reduce dependence on fossil fuels. Crude vegetable oil is one alternative energy source that can be utilized as a substitute for fossil fuels because vegetable oil has a composition almost similar to fossil fuel. Crude coconut oil is an alternative to biodiesel to reduce dependency on fossil fuels. The combustion reaction of crude coconut oil is tricky because it has bonds saturated chain, so a substance is needed to weaken the carbon chain to increase the burning rate. The burning rate of coconut oil droplets has been investigated experimentally by adding clove oil and eucalyptus oil bio-additives. Tests were carried out with single droplets suspended on a thermocouple at atmospheric pressure and room temperature and ignited with a hot wire. The addition of clove oil and eucalyptus oil as bio-additives in crude coconut oil was 100 ppm and 300 ppm, respectively. The suspended droplet combustion method was chosen to increase the contact area between the air and fuel so that the reactivity of the fuel molecules increases. The results showed that the eugenol compounds in clove oil and cineol compounds in eucalyptus oil were both aromatic and had an unsymmetrical carbon chain geometry structure. Therefore, this factor has the potential to accelerate the occurrence of effective collisions between fuel molecules; thus, the fuel is flammable, as evidenced by the increased burning rate. Moreover, from the observations, it was found that the highest burning rate was achieved in both bio-additives with a concentration of 300 ppm

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