The hybridization of fuel cells (FC) and battery in electric vehicles necessitates designing an energy management system (EMS) for optimal energy use of the two power sources. The EMS represents a high‐level controller (HLC) calculating the optimal power split between the two power sources, using a prediction model for the vehicle's electric load over a planned journey trajectory. However, the instantaneous actual power demand of the vehicle is likely to deviate from the prediction due to varying traffic circumstances. This power offset needs to be compensated for whilst the optimality is still considered. A control approach is proposed here that converts the optimal power split into a dimensionless power split ratio (PSR). This ratio is passed to a low‐level controller (LLC) to be implemented as a set‐point. The LLC is responsible for simultaneously controlling the power of the FC and the battery using solely one control element, which is the DC‐DC boost converter. The PSR will be maintained whatever the actual power demand of the vehicle is. This approach will result in a fully controlled optimal power utilization, so that the high efficiency of the battery and the extended range enabled by the FC system are used to best effect.

Solid oxide fuel cells (SOFC) generate electricity with high quality waste heat which if harnessed and used as energy source for vapour absorption refrigeration systems (VARS) will address the emission issues related to refrigerated transport infrastructure. The temperature range of the heat source required at the desorber of the VARS is between 120 and 200oC, while SOFCs cathode exhaust heat temperatures are 600oC and above. Therefore, an internally finned double pipe heat exchanger (DPHX) was development mathematically in this study with thermal oil as the coupling fluid and validated experimentally for indirect couplingof the SOFC cathode exhaust heat with the VARS.The experimental setup mimics a 5 kWe SOFC stack. Results showed that 1.84 kW of heat was recovered at a cathode exhaust flow rate of 24.64 L s-1 resulting in a heat exchanger effectiveness of 12.22 % and overall heat transfer coefficient of 60.15 W m-2 K-1. The recovered 1.84 kW of heat are able to power a single effect VARS on board a small refrigerated truck to supply 1 kW of cooling load. Results also revealed an exchanger effectiveness and overall heat transfer coefficient increase by 70.2 and 19.4 %, respectively, at a reduced exhaust flow rate of 7.347 L s-1. Further improvement of 81.1 and 39.22 %, respectively, of exchanger effectiveness and overall heat transfer coefficient was achieved at 4.653 L s-1exhaust flow rate.

Green hydrogen can be produced by integrating water electrolyzers to renewable energy sources. The integration confronts the problem of renewable power volatility that requires advanced control strategies. There are three main electrolyzer control approaches, which are: battery hysteresis cycle, model‐based scheduling, and frequency response. These approaches do not fully solve the problem of electrolyzer operation under power fluctuating conditions. This study introduces a novel integration and control approach for water electrolyzers based on model predictive control algorithm. The algorithm controls electrolyzer load so that steering the system into a breakeven energy balance across the main DC busbar that links generation and demand sides. However, the energy balance is subject to power conditioning losses and capacity constraints of electrolyzer. The novel approach uses simplified prediction models for the generation and demand and introduces a compensator for model uncertainty based on a novel role to the battery as a sensor of energy imbalance. The approach is tested on a 5 kW polymer electrolyte membrane electrolyzer and showed that fully automated energy balancing is achievable for grid connected and stand‐alone systems. Also, the electrolyzer can operate at partial capacity with improved efficiency and hydrogen yield, and it is applicable to any mix of renewables.

In this report, a 5 kW PEFC system running on dry hydrogen with an appropriately sized Balance of Plant (BoP) was used to conduct experimental studies and analyses of gas supply subsystems. The improper rating and use of BoP components has been found to increase parasitic loads, which consequently has a direct effect on the polymer electrolyte fuel cell (PEFC) system efficiency. Therefore, the minimisation of parasitic loads while maintaining desired performance is crucial. Nevertheless, little has been found in the literature regarding experimental work on large stacks and BoP, with the majority of papers concentrating on modelling. A particular interest of our study was the anode side of the fuel cell. Additionally the rationale behind the use of hydrogen anode recirculation was scrutinised, and a novel anode purging strategy was developed and implemented. Through experimental modelling, the use of cathode air blower was minimised since it was found to be the biggest contributor to the parasitic loads.