*3.2. Variable Load*

The profile chosen for the variable load is of the scale up and down type with the following constant levels within 4 s: 0.75 *Pload(AV)*, 1.25 *Pload(AV)*, and *Pload(AV)*. Thus, the average value (AV) of the variable load profile is *Pload(AV)* = (0.75 *Pload(AV)*·4 s + 1.25 *Pload(AV)*·4 s + *Pload(AV)*·4 s)/12 s, where *Pload(AV)* is mentioned in the first column of Tables 5–7. The second column of the Tables 5–7 mentions the hydrogen consumption during the variable load cycle for the sFF strategy (*FuelT*0).


**Table 5.** Fuel economy for *kfuel* = 0 and different *Pload(AV)*.


**Table 6.** Fuel economy for *kfuel* = 25 and different *Pload(AV)*.

**Table 7.** Fuel economy for *kfuel* = 50 and different *Pload(AV)*.


The fuel economy ΔFuelTk= FuelTk− FuelT0 for each RTOk strategy (k = 1 ÷ 7) compared to commercial strategy, such as the sFF strategy is listed in Tables 4–6 for *kfuel* =0, *kfuel* = 25, and *kfuel* = 50.

The fuel economy (ΔFuel) mentioned in Tables 4–6 for all RTOk strategy (k = 1 ÷ 7) are presented in Figures 5–7 for *kfuel* = 0, *kfuel* = 25, and *kfuel* = 50, using *Pload(AV)* as variable.

ΔΔΔΔΔΔΔ

ΔΔΔΔΔΔΔ

**Figure 5.** Fuel saving for *kfuel* = 0 and different *Pload(AV)*.

**Figure 6.** Fuel saving for *kfuel* = 25 and different *Pload(AV)*.

**Figure 7.** Fuel saving for *kfuel* = 50 and different *Pload(AV)*.

Analysis of the Figures 5–7 highlights the same best four strategies for the load profile with *Pload(AV)* > 5 kW (as in case of *Pload* > 5 kW). This validates the results obtained for constant load.

Besides the strategies RTO5 and RTO3, it also appears that the RTO4 strategy cannot be used for *Pload(AV)* ≤ 5 kW due to low performance compared to strategy RTO6 for variable load. So, the SW strategies that remain to be tested, compared to strategy RTO6 (which still ensure fuel saving for different *Pload*(*AV*)) are as follows:

• SW1 strategy, which will use the strategies RTO6 and RTO5 for *Pload* ≤ 5 kW and *Pload*> 5 kW, respectively;

• SW3 strategy, which will use the strategies RTO6 and RTO3 for *Pload* ≤ 5 kW and *Pload*> 5 kW, respectively;

These results validate the aforementioned conclusions for constant load.
