4. Diesel (TDI) engine

#### 4.1. Crank angle advance injection timing

The effect of injection timing of all the test fuels (B0, B5, B10, and B20) is indicated in Figure 1. The engine operating speeds selected for testing were 1500 rpm and 3000 rpm. When the operating speed was high the fuel was injected earlier than when the speed was reduced to allow for the correct retention time for the fuel to burn adequately. Running on partial load in n-Butanol-Diesel (D2) Blend Fired in a Turbo-Charged Compression Ignition Engine: Performance and Combustion… http://dx.doi.org/10.5772/intechopen.72879 41

Figure 1. Effect of test fuels on injection timing.

terms of brake-mean effective pressure (BMEP), or when the engine was running at low speed, the engine's start of injection (SOI) timing was retarded by the EDC in order to meet the engine's operating conditions.

#### 4.2. Manifold boost (air) pressure

Typical fuel consumption and fuel air ratios are given in Table 1 and operating conditions in

DF B05 B10 B20

(A) At 1500 rpm 5.47 5.47 5.43 5.63 (B) At 1500 rpm 3.0 3.06 3.12 3.12 (B) At 3000 rpm 7.13 7.34 7.56 7.62

(A) At 1500 rpm 1.4 1.42 1.5 1.52 (B) At 1500 rpm 1.72 1.82 1.92 1.92 (B) At 3000 rpm 2.37 2.73 2.42 2.79

(A) At 1500 rpm 235 231 237 248 (B) At 1500 rpm 252.9 258.02 263.09 263.08 (B) At 3000 rpm 249.4 256.75 264.4 266.54

Table 1. Typical fuel consumption, λ, BSFC with DF and blends at 1500 and 3000 rpm; A = 100%, and B = 75% load [21].

MAP (bar)

Torque (Nm) Speed (rpm) Exhaust temperature (C) \*

184.6 3004 562 0.82 136.4 3004 473 0.71 92 3002 419 0.56 45 3000 333 0.38 168.9 3504 584 0.79 187.8 2505 519 0.84 153.7 1502 532 0.35

The effect of injection timing of all the test fuels (B0, B5, B10, and B20) is indicated in Figure 1. The engine operating speeds selected for testing were 1500 rpm and 3000 rpm. When the operating speed was high the fuel was injected earlier than when the speed was reduced to allow for the correct retention time for the fuel to burn adequately. Running on partial load in

Table 2.

\*

Fuel cons. (kg/h)

40 Improvement Trends for Internal Combustion Engines

λ ()

BSFC (g/kWh)

4. Diesel (TDI) engine

4.1. Crank angle advance injection timing

Ambient air temperature 20C, intake air temperature 25C.

Manifold (boost) air pressure (above atmospheric pressure).

Table 2. Operating conditions of engine for fuel D2 [21].

Figure 2a and b depict the effect of the blends on manifold boost (air) pressure at 1500 rpm and 3000 rpm, respectively. The increasing boost (air) pressure (above atmospheric of 1 bar) level with BMEP is a measure that helps to improve the brake thermal efficiency (BTE) as the fuel-air ratio is reduced.

Figure 2. Manifold boost (air) pressure (MAP) vs. BMEP (a) at 1500 rpm (b) at 3000 rpm.

#### 4.3. Torque, power, and EGT

The derated power and torque indicated in Figure 3 is attributed to the fixed algorithm and set points in the EDC unit, which reads diesel as the reference fuel as programmed if not modified. In this case, the EDC was not calibrated for the n-butanol/diesel blends. When the diesel fuel was changed to n-butanol/diesel blend, the lower heating value due to the blend triggered the EDC to increase the mass flow of fuel to compensate for the drop in energy delivered; the heating value of n-butanol is lower than that of diesel fuel. This is achieved by altering the fuelcontrol ring position of the control system. However, the EDC set point for DF which controls the amount of diesel that can be delivered at different loads was fixed. Therefore, the mass flow of the blend could not be increased above this point. This explains the lowered power and torque output when using n-butanol/DF as shown in Figure 3.

The effect of exhaust gas temperature (EGT) on BMEP is indicated in Figure 4a and b. The trend shows an increase of EGT with BMEP for all the test fuels: DF, B5, B10, and B20. The

higher heat of evaporation of the blends than DF resulted in evaporative cooling which lowers EGT. Furthermore, the increasing higher molecular oxygen content of the blends than DF is also a contributing factor in lowering EGT by reducing the energy content of the fuel. The irregularity for B10 at 25% and 50% load at 3000 rpm could be due to unstable combustion,

Figure 5. (a) Indicated pressure (ip) and HRR at 2500 rpm source [21]; (b) indicated pressure and HRR at 3000 rpm source

n-Butanol-Diesel (D2) Blend Fired in a Turbo-Charged Compression Ignition Engine: Performance and Combustion…

http://dx.doi.org/10.5772/intechopen.72879

43

which is also evident in the high standard of deviation for B10% in Figure 6.

Figure 6. Standard deviation of indicated pressure [21].

[21]; (c) indicated pressure and HRR at 3500 rpm source [21].

Figure 3. Effects of blends on torque, brake power vs. speed [21].

Figure 4. EGT vs. BMEP (a) at 1500 rpm and (b) at 3000 rpm [21].

n-Butanol-Diesel (D2) Blend Fired in a Turbo-Charged Compression Ignition Engine: Performance and Combustion… http://dx.doi.org/10.5772/intechopen.72879 43

Figure 5. (a) Indicated pressure (ip) and HRR at 2500 rpm source [21]; (b) indicated pressure and HRR at 3000 rpm source [21]; (c) indicated pressure and HRR at 3500 rpm source [21].

higher heat of evaporation of the blends than DF resulted in evaporative cooling which lowers EGT. Furthermore, the increasing higher molecular oxygen content of the blends than DF is also a contributing factor in lowering EGT by reducing the energy content of the fuel. The irregularity for B10 at 25% and 50% load at 3000 rpm could be due to unstable combustion, which is also evident in the high standard of deviation for B10% in Figure 6.

Figure 6. Standard deviation of indicated pressure [21].

4.3. Torque, power, and EGT

42 Improvement Trends for Internal Combustion Engines

The derated power and torque indicated in Figure 3 is attributed to the fixed algorithm and set points in the EDC unit, which reads diesel as the reference fuel as programmed if not modified. In this case, the EDC was not calibrated for the n-butanol/diesel blends. When the diesel fuel was changed to n-butanol/diesel blend, the lower heating value due to the blend triggered the EDC to increase the mass flow of fuel to compensate for the drop in energy delivered; the heating value of n-butanol is lower than that of diesel fuel. This is achieved by altering the fuelcontrol ring position of the control system. However, the EDC set point for DF which controls the amount of diesel that can be delivered at different loads was fixed. Therefore, the mass flow of the blend could not be increased above this point. This explains the lowered power and

The effect of exhaust gas temperature (EGT) on BMEP is indicated in Figure 4a and b. The trend shows an increase of EGT with BMEP for all the test fuels: DF, B5, B10, and B20. The

torque output when using n-butanol/DF as shown in Figure 3.

Figure 3. Effects of blends on torque, brake power vs. speed [21].

Figure 4. EGT vs. BMEP (a) at 1500 rpm and (b) at 3000 rpm [21].
