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The use of biofuel is essential for the reduction of greenhouse gas emission. This study highlights the use of biodiesel as a means of reducing greenhouse gas emission from the diesel engine of heavy-duty vehicles. Biodiesel is fatty acid methyl ester (FAME) obtained through ester exchange reaction by adding methanol to oil, such as rapeseed oil, soybean oil, palm oil, etc. The CO2 emission from combustion of biodiesel is defined to be equivalent to the CO2 volume absorbed by its raw materials or plants in their course of growth. On the other hand, however, operation of diesel engine with biodiesel is known to increase the NOx emission when compared with that with conventional diesel fuel. Then suppressing this NOx increase is regarded as a critical issue. This paper consists of two parts: comprehending the factors of NOx emission increase and improving this emission performance in a diesel engine fuelled with biodiesel.

The use of biofuel is essential for the reduction of greenhouse gas emission. This paper highlights the use of biodiesel as a means of reducing greenhouse gas emission from the diesel engine of heavy-duty vehicles. Biodiesel is fatty acid methyl ester (FAME) obtained through ester exchange reaction by adding methanol to oil, such as rapeseed oil, soybean oil, palm oil, etc. The CO₂ emission from combustion of biodiesel is defined to be equivalent to the CO₂ volume absorbed by its raw materials or plants in their course of growth. On the other hand, however, biodiesel is known to increase the NOx emission when compared with operating with conventional diesel fuel, then suppressing this increase is regarded as a critical issue. This study is intended to identify the fuel properties of biodiesel free from increase in the NOx emission.

A monolithic aluminum block using a newly developed Al-20%Si alloy was made by a vacuum die-casting process. The bore surface design was a sleeveless type with uniformly dispersed primary-Si crystals around 20μm. The die-casting technology consists of a highly airtight die with two series of evacuation systems. The vacuum level in the die cavity was determined to be as low as 5kPa. The gas content of the block was found to be as low as 5cc/100g Al, which has enabled T6 heat treatment. The die cavity temperature was carefully controlled to generate a fine dispersion of primary-Si crystals. The engine testing has proved that the bore wall temperature is 30 K lower than that of the aluminum block enclosing a press-fitted cast iron liner. The superior cooling performance has decreased the oil consumption value to one half that of the aluminum block enclosing a cast iron liner.