**4.4.3 Testing of producer gas in an internal combustion engine-generator**

Table 11 shows the results of testing of producer gas in the internal combustion enginegenerator with the electrical loads of 18, 24, 30 and 36 kW. At the beginning, only diesel fuel was used as fuel in order to examine the diesel consumption rate. Later, the experiments of using dual fuel, in this case: diesel fuel and producer gas, were carried out.


Table 11. Results for testing of producer gas in the internal combustion engine-generator

It can be noticed that the producer gas consumption increases with increasing electrical load until the electrical load of 30 kW and for the higher electrical load, the producer gas consumption decreases. It means the producer gas can replace diesel fuel successfully if the electrical load is increased but at the higher electrical load, the producer gas cannot further replace diesel fuel due to the low heating value of producer gas which is not sufficient to sustain the higher load. The maximum diesel replacing rate of 83.69 % is taken place at the electrical load of 24 kW, by which the engine efficiency is accounted to be 24.72 %. At this point, the overall efficiency for power generation from pelletizing PEFB via gasification process is calculated to be 16.36 %.

#### **4.5 Conclusion**

146 Renewable Energy – Trends and Applications

Table 10 shows the overall results for pelletized PEFB at different air flow rates, in term of

90 111.40 45.08 5.49±0.10 70.47 100 129.44 61.57 6.99±0.29 76.34 105 176.73 74.82 6.50±0.15 79.73 110 182.19 80.58 5.64±0.23 66.21 120 191.76 88.09 5.18±0.40 58.55 Table 10. Overall results for pelletized PEFB at different air flow rates in prototype gasifer From Table 10, the maximum heating value of 6.99±0.29 MJ/Nm3 is observed at the air flow rate of 100 Nm3/hr which correspondances to the cold gas efficiency of 76.34 %. From the observation during the experiments, although at the air flow rate of 100 or 105 Nm3/hr the heating value of producer gas and the cold gas efficiency reach the maximum value, the producer gas was unstable and non-continuously formed. Instead, at the air flow rate of 110 Nm3/hr, the producer gas was continuously and uniformly generated. Therefore, for testing of using producer gas as fuel in the internal combustion engine-generator, the air flow rate

Lower heating value (MJ/Nm3)

Cold gas efficiency (%)

Engine efficiency (%)

Fuel consumption rate (kg/hr)

producer gas yield, fuel consumption rate and cold gas efficiency.

of 110 Nm3/hr is selected as optimum operating condition.

**4.4.3 Testing of producer gas in an internal combustion engine-generator** 

using dual fuel, in this case: diesel fuel and producer gas, were carried out.

Diesel fuel Dual fuel

Producer gas consumption (Nm3/hr)

Table 11 shows the results of testing of producer gas in the internal combustion enginegenerator with the electrical loads of 18, 24, 30 and 36 kW. At the beginning, only diesel fuel was used as fuel in order to examine the diesel consumption rate. Later, the experiments of

> Diesel consumption (kg/hr)

18 5.41 37.63 2.49 53.97 20.01 24 6.44 53.60 1.05 83.69 24.72 30 7.78 53.60 2.19 71.85 26.96 36 9.12 39.91 4.32 52.63 30.95 Table 11. Results for testing of producer gas in the internal combustion engine-generator

It can be noticed that the producer gas consumption increases with increasing electrical load until the electrical load of 30 kW and for the higher electrical load, the producer gas consumption decreases. It means the producer gas can replace diesel fuel successfully if the electrical load is increased but at the higher electrical load, the producer gas cannot further replace diesel fuel due to the low heating value of producer gas which is not sufficient to sustain the higher load. The maximum diesel replacing rate of 83.69 % is taken place at the electrical load of 24 kW, by which the engine efficiency is accounted to be 24.72 %. At this

Diesel replacing rate (%-wt.)

Producer gas yield (Nm3/hr)

**4.4.2 Overall results** 

Air flow rate (Nm3/hr)

Load (kW)

Diesel consumption (kg/hr)

From the experiments in a prototype downdraft gasifier, it can be concluded that the producer gas obtained from pelletized PEFB can be used as a substitute fuel to conventional diesel fuel. The optimum air flow rate for gasification process is 110 Nm3/hr, by which the producer gas was continuously and uniformly generated. The producer gas contains 23.74 % wt. CO, 15.48 % wt. H2, 2.97 % wt. CH4 and 10.01 % wt. CO2. The heating value is 5.64±0.23 MJ/Nm3 and the cold gas efficiency is 66.21 %. After using this producer gas in an internal combustion engine-generator, it can be found that the diesel fuel consumption can be reduced by more than 80 % at the electrical load of about half-load (24 kW) and the overall efficiency of 16.36 % can be achieved at this load.
