Compression ignition engines are required to operate over a wide temperature range and still maintain their high thermal efficiency. This requires the fuel injection system of the engine to operate at optimum conditions. It is known that fuel properties play important role in determining characteristics of fuel sprays which, in turn, influence mixing process. One of the fuel properties of interest is the fuel compressibility. Experiments were conducted to measure compressibility of diesel and methanol fuels by the P-V-T method. Fuel temperatures were varied from about -32C to +25C and fuel pressures were raised to as high as 110 MPa.
The results show the compressibility of both the fuels to decrease as the fuel temperature was lowered at a constant fuel pressure. The relationship for both the fuels was almost linear over the temperature range investigated in this study. For the same fuel pressure and temperature, compressibility of methanol was higher than the corresponding value for diesel fuel. For a given fuel temperature compressibility decreased rapidly with an increase in fuel pressure. The experimental results are used to derive correlations between the fuel compressibility, pressure and temperature. The relations are useful in designing fuel injection systems of compression ignition engines.