## 7 Driving Cycles Testing  
The complete development and simulation of the ORC system model provided useful data regarding the efficiency and fuel consumption of the new, improved powertrain. This fact enables a comparison to be made between the initial engine setup and the new, improved one. The best way to compare these two powertrains is to assign them to a conventional lightweight vehicle and test them for various driving cycles. In this way the percentage difference between these two powertrains can be obtained, showing how much difference the ORC system produced. The fuel consumption benefit was the main target of this assessment, but emissions were also computed, and the major concern of this study remains the minimization of the fuel consumption of a lightweight passenger vehicle with the use of an ORC WHR recovery system. \begin{table}
\begin{tabular}{l c c c c c c} \hline \hline  & \multicolumn{6}{c}{**ORC’s Main Components**} \\ \cline{2-7}
**Design Parameters** & **Evaporator** & **Evaporator** & **Condenser** & **Condenser** & **Turbine** & **Pump** \\  & **(Slave)** & **(Master)** & **(Slave)** & **(Master)** & **(Master)** & **Expander** & **Pump** \\ \hline Average Inlet Pressure (bar) & 1.00102 & 24.9 & 2.15 & 3.28 & 24.3 & 2.6 \\ Average Outlet Pressure (bar) & 1 & 24.3 & 2 & 2.6 & 3.28 & 24.9 \\ Average Pressure Drop (bar) & 0.0010197 & 0.631 & 0.148264 & 0.674932 & - & - \\ Average Inlet Temperature (K) & 973.1 & 315.8 & 296.1 & 405.1 & 445.2 & 314.1 \\ Average Outlet Temperature (K) & 450.7 & 445.2 & 302.6 & 314.1 & 405.263 & 315.8 \\ Average Mass Flow Rate (g/s) & 140 & 269.2 & 3394.6 & 269.3 & 0.269 & 0.269 \\ Combined Energy Rate out of Fluid (\(\lambda\)W) & 78.7 & -78.7 & -73.2 & 73.2 & - & - \\ Average Speed (ppm) & - & - & - & - & 1350 & 2000 \\ Average Map Pressure Ratio & - & - & - & - & 7.37 & - \\ Average Efficiency (\(\%\)) & - & - & - & - & 51.61 & 61.42 \\ Average Power (\(\%\)W) & - & - & - & - & 5.3 & 0.75 \\ Average Pressure Rise (bar) & - & - & - & - & - & 22.3 \\ Heat Exchange Volume (L) & 11.75 & 3.33 & 6.5 & 5.65 & - & - \\ Heat Exchanger Reference Length (m) & 0.007 & 0.007 & 0.003 & 0.003 & - & - \\ Heat Exchanger Heat Transfer Area (m\({}^{2}\)) & 1.87 & 1.87 & 9.33 & 9.33 & - & - \\ Heat Exchanger Flow Area (m\({}^{2}\)) & 0.0138 & 0.0038 & 0.02 & 0.02 & - & - \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Organic Rankine cycle component design parameters using R245 fa refrigerant. Figure 4: Schematic view of the engine system model in GT-Power: (**a**) organic Rankine cycle system sub-model; and (**b**) complete model used for driving cycle testing. With the use of three typical driving cycles, the fuel consumption of the initial powertrain and the powertrain with the ORC system was measured to define the extent that the ORC system benefits the vehicle. The driving cycles include:  
* NEDC (New European Driving Cycle, EU)
* FTP-75 (Federal Test Procedure, US)
* US06 (a more realistic, aggressive supplement to FTP-75)  
All of these driving cycles represent different driving scenarios, different durations, and average speeds. In this way, the comparison between the two powertrains (the original standalone hybrid and the hybrid powertrain equipped with the ORC WHR system) is fair and also shows where space for improvement exists if the ORC system is to be implemented in a HEV vehicle. When the developed ORC system is assigned to a HEV vehicle, different hybrid driving modes can be selected for further improved fuel economy in each driving cycle, regardless of the configuration of the HEV vehicle (series, parallel, or complex). These tests were run in GT-Power, where a virtual vehicle was modeled with an average weight of 1500 kg and several parameters set to simulate the driving scenarios. The library of the software includes all of the selected driving cycles, which ensures the precision and consistency of the results.