Hydrogen Research Institute Research Articles

Online identification of semi-empirical model parameters for PEMFCs

In this paper, a semi-empirical model has been proposed for online identification in order to improve the performances of Fuel Cell Vehicles (FCV). The Adaptive Recursive Least Square (ARLS) method has been considered to update the semi-empirical model parameters online to cope with Fuel Cell System (FCS) parameter variations. After introducing a literature review of the semi-empirical model for online identification to show its importance. A Matlab/Simulink model has been designed to define the initial parameters of the ARLS algorithm for the online identification in real time. Then, an experimental test bench has been performed to verify the ARLS algorithm in real time on a Proton Exchange Membrane Fuel Cell (PEMFC). In order to simplify the semi-empirical model, an extensive ANalysis Of VAriance (ANOVA) technique has been used to evaluate the impact of each model parameter. It has been confirmed that the ARLS algorithm is suitable to take into account the operating parameters that changes the PEMFC performance. The simulation using ANOVA results has shown that a parameter with relative low impact (mass transport) is very relevant for the energy management. Therefore, the proposed study can be used for the control and energy management of the Hydrogen Research Institute FCV taking into account the influence of operating conditions.

Finite element simulation for charge–discharge cycle of cryo-adsorptive hydrogen storage on activated carbon

Due to the advantages of high hydrogen storage capacity, low cost of production, and long life cycle, activated carbon used for adsorption hydrogen storage has become a research focus in recent years. Cryo-adsorption of hydrogen on activated carbon is presently promising because it reaches a reasonable gravimetric density of more than 10 wt% and a volumetric density of 41 kg/m3. This paper builds a mathematical model based on a set of partial differential equations (PDEs) controlling the balances or conservations of mass, momentum and energy in the tank and simulates the charge–discharge cycle of cryo-adsorptive hydrogen storage on activated carbon, which is implemented in the finite element analysis software COMSOL Multiphysics™. A modified Dubinin-Astakhov (D-A) model is used to express the relationship between hydrogen adsorption density and the pressure and the temperature in the tank. The constant isosteric heat of adsorption is modified by variational isosteric heat of adsorption based on the Dubinin-Astakhov isotherm of adsorption. The stainless steel container packed with activated carbon is cooled by liquid nitrogen at 80 K. As the liquid nitrogen is evaporated slowly in the whole experiment process, in order to simulate the realistic environment we use a dynamic boundary condition in the model. To monitor the variations of pressure, temperature and adsorption density in the tank, we choose eight monitoring points along axial and radial directions of the hydrogen storage tank. The simulated results are compared with experimental data obtained at the Hydrogen Research Institute of the University of Quebec at Trois-Rivieres. A good agreement between the experiments and simulations has been achieved.

Finite element model for charge and discharge cycle of activated carbon hydrogen storage

One of the main challenges to introduce hydrogen on the energy market is to improve on-board hydrogen storage and develop more efficient distribution technologies to increase the amount of stored gas while lowering the storage pressure. The physisorption of hydrogen on activated carbons (AC) is being investigated as a possible route for hydrogen storage. The objective of this work is to study the performance of adsorption-based hydrogen storage units from a "systems" point of view. A realistic two-dimensional axisymmetric geometric model which couples mass, momentum and energy balances is established based on the thermodynamic conservation laws using finite element method as implemented in COMSOL Multiphysics™. We consider the charging and discharging of the storage unit at a rated pressure of 9 MPa, and at an initial temperature of 302 K. The results are compared with experimental data obtained at the Hydrogen Research Institute of the University of Quebec at Trois-Rivieres. The storage tank is cooled by ice water. Research results show that both the simulated variations of pressure and temperatures during charge and discharge processes are in good agreement with the experimental data. The temperatures in the central region of tank are higher than those at the entrance and near the wall at the end of charge time while they are lower than those at the entrance and near the wall at the end of discharge time. The velocities are largest at the entrance, and decrease gradually along the axis of the tank. Owing to thermal effects, the larger flow rates result in less amount of adsorption in the condition of the same charging pressure. Hence measures of increasing heat transfer should be adopted, such as increasing the thermal conductivity of the storage bed. From the point of view of storage capacity, it is therefore possible to realize rapid hydrogenation, which is conducive to the use of such systems for on-board hydrogen storage based on activated carbon adsorption.

Islanding Detection Method for a Hybrid Renewable Energy System

The Hydrogen Research Institute (HRI) developed a hybrid renewable energy power system that uses a wind turbine, a photovoltaic array and a fuel cell. In order to fulfill utility requirements , an islanding protection device is being developed. This paper presents the passive (Under/Over Voltage, Under/Over Frequency) and active (Sandia Frequency Shift and Sandia Voltage Shift) protection methods that were chosen to be added to the system. Those four methods were combined in an innovative way in order to benefit from the strengths of each of them. This way, the islanding protection will be more efficient and the non detection zone will be reduced. This paper also presents a Matlab/Simulink model of the protection device and the simulation results that were obtained using different critical operating conditions for which the clearing times can surpass those defined by the Canadian standard C22.2 No 107.1-01. This standard is similar to the IEEE 1547 standard with a few differences. Finally, the paper presents the experimental results for a grid-connected inverter, designed by the HRI, which uses the islanding protection method presented above.

04/02455 Can photovoltaic technologies help attain sustainable rural development in Bangladesh?: Biswas, W. K. et al. Energy Policy, 2004, 32, (10), 1199–1207

The Hydrogen Research Institute (HRI) has developed a stand-alone renewable energy (RE) system based on energy storage in the form of hydrogen. When the input devices (wind generator and photovoltaic array) produce more energy than is required by the load, the excess energy is converted by an electrolyzer to electrolytic hydrogen, which is then stored after stages of compression, purification and filtration. Conversely, during a time of input energy deficit, this process is reversed and the hydrogen produced earlier is reconverted to electrical energy through a fuel cell. The oxygen which has been produced by the electrolyzer during the hydrogen production is also stored at high pressure, after having gone through a purification and drying process. This stored oxygen can be re-utilized as oxidant in place of compressed air in the fuel cell. The modifications of the electrolyzer for oxygen storage and re-utilization of it as oxidant for the fuel cell are presented. Furthermore, the HRI has designed and developed the control system with power conditioning devices for effective energy management and automatic operation of the RE system. The experimental results show that a reliable autonomous RE system can be realized for such seasonal energy sources, using stored hydrogen as the long-term energy buffer, and that utilizing the electrolyzer oxygen by-product as oxidant in the fuel cell increases system performance significantly.

Performance of a Stand-Alone Renewable Energy System Based on Energy Storage as Hydrogen

Electrolytic hydrogen offers a promising alternative for long-term energy storage of renewable energy (RE). A stand-alone RE system based on energy storage as hydrogen has been developed and installed at the Hydrogen Research Institute, and successfully tested for autonomous operation with developed control system and power conditioning devices. The excess energy produced, with respect to the load requirement, has been sent to the electrolyzer for hydrogen production. When energy produced from the RE sources became insufficient, with respect to the load requirement, the stored hydrogen was fed to a fuel cell to produce electricity. The RE system components have substantially different voltage-current characteristics and they are integrated through power conditioning devices on a dc bus for autonomous operation by using a developed control system. The developed control system has been successfully tested for autonomous operation and energy management of the system. The experimental results clearly indicate that a stand-alone RE system based on hydrogen production is safe and reliable.

Electrolytic hydrogen based renewable energy system with oxygen recovery and re-utilization

The Hydrogen Research Institute (HRI) has developed a stand-alone renewable energy (RE) system based on energy storage in the form of hydrogen. When the input devices (wind generator and photovoltaic array) produce more energy than is required by the load, the excess energy is converted by an electrolyzer to electrolytic hydrogen, which is then stored after stages of compression, purification and filtration. Conversely, during a time of input energy deficit, this process is reversed and the hydrogen produced earlier is reconverted to electrical energy through a fuel cell. The oxygen which has been produced by the electrolyzer during the hydrogen production is also stored at high pressure, after having gone through a purification and drying process. This stored oxygen can be re-utilized as oxidant in place of compressed air in the fuel cell. The modifications of the electrolyzer for oxygen storage and re-utilization of it as oxidant for the fuel cell are presented. Furthermore, the HRI has designed and developed the control system with power conditioning devices for effective energy management and automatic operation of the RE system. The experimental results show that a reliable autonomous RE system can be realized for such seasonal energy sources, using stored hydrogen as the long-term energy buffer, and that utilizing the electrolyzer oxygen by-product as oxidant in the fuel cell increases system performance significantly.