Wu-Yang Sean

In this study, a battery management system (BMS) is developed for reused lithium-ion battery (RLIB). Additional enhancing functions of battery management are established, i.e., estimation of life-sensitized parameters and life extension. Life-sensitizing parameters mainly include open-circuit voltage (OCV) and internal resistances (IRs). They are sensitized parameters individually relative to state of charge (SOC) and state of health (SOH). For estimating these two parameters, an adaptive control scheme is implemented in BMS. This online adaptive control approach has been extensively applied to nonlinear systems with uncertainties. In two experiments, OCV and IRs of reused battery packs are accurately extracted from working voltage and discharge current. An offline numerical model using a schematic method is applied to verify the applicability and efficiency of this proposed online scheme. Furthermore, a solution of actively extending life by using an ultracapacitor to share peak power of RLIB through adjusting duty ratio is also proposed. It is shown that this enhancing battery management for RLIB can properly estimate OCV and IRs, and actively extend the life of the RLIB in two experiments.

Among various carbon capture and storage technologies to mitigate global warming and ocean acidification due to greenhouse gases, ocean geological storage is considered the most feasible for Korea due to insufficient inland space to store CO₂. However, the risk of CO₂ leakage and the behavior and environmental effects of the leaked CO₂ need to be assessed for its successful implementation. Therefore, the behavior of CO₂ bubbles/droplets dissolving into the surrounding seawater and the diffusion of dissolved CO₂ by ocean flows should be accurately predicted. However, finding corresponding research has been difficult in Korea. Herein, the behavior and convection-diffusion of CO₂ that was assumed to have leaked from the seafloor near the southeastern coast of Korea were numerically predicted using a multi-scale ocean model for the first time. In the simulation region, one of the pilot projects of CO₂ ocean geological storage had started but has been temporarily halted. In the ocean model, hydrostatic approximation and the Eulerian–Lagrangian two-phase model were applied for meso- and small-scale regions, respectively. Parameters for the simulations were the leakage rate and the initial diameter of CO₂. Results revealed that all leaked and rising CO₂ bubbles were dissolved into the seawater before reaching the free surface; further, the change in the partial pressure of CO₂ did not exceed 500 ppm during 30 days of leakage for all cases.

For reusing automotive lithium-ion battery, an in-house battery management system is developed. To overcome the issues of life cycle and capacity of reused battery, an online function of estimating battery’s internal resistance and open-circuit voltage based on adaptive control theory are applied for monitoring life cycle and remained capacity of battery pack simultaneously. Furthermore, ultracapacitor is integrated in management system for sharing peak current to prolong life span of reused battery pack. The discharging ratio of ultracapacitor is adjusted manually under Pulse-Width-Modulation signal in battery management system. In case study in 52V LiMnNiCoO₂ platform, results of estimated open-circuit voltage and internal resistances converge into stable values within 600(s). These two parameters provide precise estimation for electrical capacity and life cycle. It also shows constrained voltage drop both in the cases of 25% to 75% of ultracapacitors discharging ratio compared with single battery. Consequently, the Life-cycle detection and extending functions integrated in battery management system as a total solution for reused battery are established and verified.

For stabilizing renewable energies and shaving peak power at noon, both the energy consumption and potential renewable energies in Dihua waste water treatment plant (WWTP) in Taiwan are analyzed. Under the consideration of environment, cost, and performance, automotive reused lithium-ion battery (RLIB) is employed. Two typical automotive lithium-ion batteries are used in this study after the selection of suitable battery cells. In particular, one simple, converterless energy management system (EMS) is developed and integrated in new RLIB packs. The control strategy between RLIB and an additional physical battery is adjusted by simulation. An online estimation of RLIB’s internal resistance and open-circuit voltage monitoring scheme is applied in EMS to ensure the safety of RLIB. The bench test and rough economical estimation reveal that EMS shows great potential in elongating life cycle and possibly benefits from feed-in tariff and peak shift of electricity charges.

To ensure electrical safety in electric vehicles equipped with a high‐voltage battery pack, an insulation monitoring circuit is indispensible to continuously monitor the insulation resistance during charging or driving. Existing methods such as to inject specific signals into the monitoring circuit and earth help to extract the resistance value from the voltage waveform. However, parasitic or stray capacitances in the monitoring circuit, which might introduce higher‐order dynamics into the waveform are ignored. Or to avoid estimation error, the insulation resistance must be known in advance to carry out parameter calibration. In this work, one parasitic capacitance is applied in the circuit model and employ a new adaptive algorithm based on Lyapunov stability to estimate the insulation resistance. This new online monitoring method and circuit are verified through simulation and experimentation, respectively. The results demonstrate that the proposed method can quickly react and track variations of insulation resistance on both positive and negative DC lines. © 2017 American Institute of Chemical Engineers Environ Prog, 36: 1882–1887, 2017

Dissociation processes of CO₂ hydrate under water flow conditions were investigated by experimental measurements and numerical calculation. Dissociation experiments were carried out with a CO₂ hydrate ball (diameter 10 mm) mounted in a flow cell, and the overall dissociation rate of CO₂ hydrate without bubble formation was measured under various conditions of temperature, pressure, and water flow rate. A linear phenomenological rate equation in the form of the product of the dissociation rate constant and the molar Gibbs free energy difference, between the hydrate phase and the ambient aqueous phase, was derived by considering the Gibbs free energy difference as the driving force for the dissociation. The molar Gibbs free energy difference was expressed by the logarithm of the ratio of the concentration of CO₂ dissolved in water at the hydrate surface to the solubility of CO₂ in the aqueous solution in equilibrium with the hydrate. The dissociation rate constant was determined from the experimental results of the overall dissociation rate combined with the numerical simulation results of the concentration profile of CO₂ constructed by the computational fluid dynamics (CFD) method. The obtained dissociation rate constant at the same pressure was found to be dependent on the temperature with the apparent activation energy of 97.51 kJ/mol. A general form with product of the dissociation rate constant times driving force is proposed to calculate the dissociation rate of CO₂ hydrate in the water. © 2014 Society of Chemical Industry and John Wiley & Sons, Ltd