Hydrogen as an energy carrier is critical for building a zero-carbon emission society. Solid oxide electrolysis cell (SOEC) is a feasible technology for hydrogen production with a high efficiency. Currently, the durability of SOEC systems still needs to be improved and technical issues need to be overcome. Reducing the working temperature is helpful for the lifetime. A good cell design to avoid delamination is also very important. In this study, the performance of a metal-supported intermediate-temperature SOEC is estimated using gadolinium doped ceria Gd_0.1Ce_0.9O_2-δ (GDC) as the main electrolyte. First, a mathematical model is setup for the metal-supported SOEC. The effects of the porosity and tortuosity of the electrodes are analyzed. Subsequently, the influences of the working temperature, pressure, and steam concentration are estimated. Finally, the partial oxygen pressure inside the multi-layer electrolyte is determined and the risk of delamination is discussed. The results indicate that increasing the operation temperature can decrease the activation, concentration, and ohmic overpotentials simultaneously while increasing the pressure also can enhance the performance. Compared with the conventional design of Ceres Power, the new design using 10Sc1CeSZ as the barrier layer can increase the partial oxygen pressure of the GDC layer close to the cathode such that decomposition of GDC is avoided. Meanwhile, the partial oxygen pressure inside the multi-layer electrolyte close to the anode declines and the risk of delamination is reduced. Hence, the new design of the SOEC is beneficial for the durability of metal-supported SOEC.

A dual loop organic Rankine cycle (DORC) system is designed to recover waste heat from a heavy-duty compressed natural gas engine (CNGE), and the performance of the DORC–CNGE combined system is simulated and discussed. The DORC system includes high-temperature (HT) and low-temperature (LT) cycles. The HT cycle recovers energy from the exhaust gas emitted by the engine, whereas the LT cycle recovers energy from intake air, engine coolant, and the HT cycle working fluid in the preheater. The mathematical model of the system is established based on the first and second laws of thermodynamics. The characteristics of waste heat energy from the CNGE are calculated according to engine test data under various operating conditions. Moreover, the performance of the DORC–CNGE combined system is simulated and analyzed using R245fa as the working fluid. Results show that the maximum net power output and the maximum thermal efficiency of the DORC system are 29.37 kW and 10.81%, respectively, under the rated power output condition of the engine. Compared with the original CNG engine, the maximum power output increase ratio and the maximum brake specific fuel consumption improvement ratio are 33.73% and 25%, respectively, in the DORC–CNGE combined system.