2
Bulk modulus - N/mm
1400
1200
1000
800
600
400
200
0
–20
p = 300 bar
p = 200 bar
p = 100 bar
p = 10 bar
0
2 0
4 0
6 0
8 0
Temperature - °C
171
Dimethyl Ether
the volumetric heating value in Table 6.1. The viscosity of DME is very low,
and special attention needs to be paid to leakage. In addition to low viscosity,
DME has low lubricity (Sivebaek and Sorenson 2000) and is prone to accelerated wear in diesel engine pumping systems. The ignition temperature
is much lower than that of gasoline, and comparable to that of good diesel
fuels. Consequently, DME is exceptionally well suited to combustion in a diesel engine. The high vapor pressure aids evaporation, the fuel-bound oxygen
reduces smoke, and the low ignition temperature provides rapid ignition
and smooth combustion. It is these properties that first aroused attention to
DME as an alternative fuel (Fleisch et al. 1995). Later in the development of
DME as a fuel, additional applications have come into focus.
In connection with use in a diesel engine, a property of interest is the compressibility of DME, which is more compressible than diesel fuel. It has been
shown that this increases the magnitude of pressure pulsations in injections,
which must be taken into account to prevent improper fuel injection (Sorenson,
Glensvig, and Abata 1998). A second element is that due to higher compressibility than diesel fuel, DME will increase the amount of energy needed to
raise the pressure, and thereby increases fuel heating in an injection system.
This is important in the modern common rail injection system, where the
fuel is pumped to a high pressure in a recirculating system, and special fuel
cooling arrangements may be needed. DME’s high vapor pressure reduces
the required injection pressures, alleviating this point somewhat, but fuel
cooling may still be needed. Figure 6.3 shows the compressibility in terms of
the bulk modulus of DME as a function of temperature and pressure.
The compressibility is given in terms of the bulk modulus,
dp
K = −
,
dv ⋅ρ
Figure 6.3
The bulk modulus of DME as a function of temperature and pressure.
Bulk modulus - N/mm
1400
1200
1000
800
600
400
200
0
–20
p = 300 bar
p = 200 bar
p = 100 bar
p = 10 bar
0
2 0
4 0
6 0
8 0
Temperature - °C
171
Dimethyl Ether
the volumetric heating value in Table 6.1. The viscosity of DME is very low,
and special attention needs to be paid to leakage. In addition to low viscosity,
DME has low lubricity (Sivebaek and Sorenson 2000) and is prone to accelerated wear in diesel engine pumping systems. The ignition temperature
is much lower than that of gasoline, and comparable to that of good diesel
fuels. Consequently, DME is exceptionally well suited to combustion in a diesel engine. The high vapor pressure aids evaporation, the fuel-bound oxygen
reduces smoke, and the low ignition temperature provides rapid ignition
and smooth combustion. It is these properties that first aroused attention to
DME as an alternative fuel (Fleisch et al. 1995). Later in the development of
DME as a fuel, additional applications have come into focus.
In connection with use in a diesel engine, a property of interest is the compressibility of DME, which is more compressible than diesel fuel. It has been
shown that this increases the magnitude of pressure pulsations in injections,
which must be taken into account to prevent improper fuel injection (Sorenson,
Glensvig, and Abata 1998). A second element is that due to higher compressibility than diesel fuel, DME will increase the amount of energy needed to
raise the pressure, and thereby increases fuel heating in an injection system.
This is important in the modern common rail injection system, where the
fuel is pumped to a high pressure in a recirculating system, and special fuel
cooling arrangements may be needed. DME’s high vapor pressure reduces
the required injection pressures, alleviating this point somewhat, but fuel
cooling may still be needed. Figure 6.3 shows the compressibility in terms of
the bulk modulus of DME as a function of temperature and pressure.
The compressibility is given in terms of the bulk modulus,
dp
K = −
,
dv ⋅ρ
Figure 6.3
The bulk modulus of DME as a function of temperature and pressure.