Advanced Materials Research Vols. 953-954

Abstract: The absorption thermal energy storage (TES) system stores the energy in the form of potential energy of solution and is a promising technology for efficient energy transformation process. The performance of the absorption refrigeration system with integral storage for cooling applications using LiBr-H₂O as working pair under the condition without crystallization was analyzed on the basis of the first law of thermodynamics. Simulation was employed to determine the coefficient of performance (COP) and energy storage density (ESD) of the absorption TES system under different conditions such as the absorption temperature and storage temperature. The results show that the COP of the system is 0.7453 and ESD is 169.853 MJ/m³ under typical operation conditions in summer. A low absorption temperature yields both a higher COP and ESD. The solution heat exchanger could improve the COP of the system while has no effect on ESD. Results also showed that system has a good advantage when compared to other storage methods since it is do no need thermal insulation. The absorption TES may be considered as one of the promising thermal energy storage methods.

Abstract: There is a great demand on promotion of heat utilization below 373 K to establish highly-efficient energy system, because such heat is enormously unused and discharged from every process. Towards this demand, we have focused on chemical heat storage due to its high heat storage density. In this study, the promising inorganic hydrates were investigated for low-temperature heat storage with the differential scanning calorimetry. Consequently, it is found that lithium hydroxide monohydrate dehydrates at 337 K with endothermic heat of 1,440 kJ/kg-LiOH・H₂O. Due to its high storage density and the simplicity of dehydration reaction, LiOH/LiOH・H₂O reaction was chose as the most promising reaction for chemical heat storage below 373 K. From the chemical equilibrium calculation, this reaction system is found to be more suitable for chemical heat storage than chemical heat pump. Fundamental study of dehydration behavior of LiOH・H₂O was also performed with a thermogravimetric analyzer, and the apparent activation energy of dehydration of LiOH・H₂O was determined to be 51.7 kJ/mol in the conversion ranges of 0.4-0.7.

Abstract: With the rapid development of renewable energy technologies, wind power is playing a more and more important role. However the volatility and uncertainty of wind power has brought the grid great adverse effect and limited the range of application. In this paper, we come up with solutions of wind power integration problems according to the different energy storage capacity, charge discharge cycle characteristics. By combining wind power and energy storage technology, we can improve the efficiency and the range of utilization of wind power.

Abstract: Due to the large number of distributed power supply random connected to power grid, it has severely influenced on power quality of the grid. In the storage battery directly on the basis of the DC bus, adopting the method of hybrid energy storage system makes a research on the output characteristics of photovoltaic array and the charging and discharging of battery and super capacitor. Research results show that the hybrid energy storage system can take advantage of the DC/DC converter to coordinate photovoltaic array, energy storage unit and the energy flows among load, also that the stability of DC bus voltage can be ensured by the system switch from the different work patterns.

Abstract: This paper makes an introduction of the working principle and the technical and economic benefits of the combined ground-source heat pump and water energy storage system. And then according to the characteristic of this system itself and its mode of operation, we can point out that the energy storage rate, the local policy of electricity price and the strategy of operation are the main factors which influent the economic characteristics of the system. Using the initial investment and the operation cost of the system as the economy evaluation index, we respectively analyze the influence of the above factors on the index. And wish the results of the analysis can provide reference on the design of this new type air-conditioning system.

Abstract: In allusion to nonlinear characteristic of power lithium-ion battery, presented a method for identifying of power lithium-ion battery based on Laplace transform. First, analyzed the characteristics of the equivalent circuit model of power lithium-ion battery, determined the model of second-order RC equivalent circuit; Second, established equation of second-order RC equivalent circuit and conducted a Laplace transform; Third,using the massive data of charge-discharge test,model parameters was identified by least-squares method; Simulation results show that the method can effectively identify the equivalent model parameters, and model parameters small error.

Abstract: Li-ion battery formation is to get a good performance of charging and discharging through a certain way. When the internal energy of the battery is discharging, it’s usually using resistance to consume energy. Owing to the present technical level and energy wasting of battery formation, a novel high-efficiency formation system was presented for Li-ion battery. The scheme is that its energy is feedback to grid through a bi-directional DC/DC converter topology and PWM Rectifier. In addition, this system uses CAN bus to communicate so to connect the whole system.

Abstract: The consistency tests of power Li-ion batteries were researched about open circuit voltage at 20°C, 40°C and 65°C environment temperatures. The results showed that the poor consistency could affect the safety performance of the batteries. That the higher the environment temperature is, the worse the batteries consistency is. The hidden safety trouble caused by consistency could be eliminated by some methods such as selecting the cell or monitoring circuit.

Abstract: Accurate battery state of charge is the prerequisite and precondition for optimal control of hybrid vehicles. This article will be based on the established dynamic model of battery, estimate the battery state of charge in real time. Firstly, analysis the application limitations of Kalman filtering algorithm estimates battery state of charge. Secondly, for some uncertain parameters contained in the model of battery system, paper proposes a parameter line identification extended Kalman filter algorithm to estimate the battery state of charge. Finally, experimental verification algorithm dynamic conditions in the battery state of charge estimation accuracy and effectiveness.

Abstract: Accurate estimation of battery state of charge (SOC) is important to ensure operation of electric vehicle. Since a nonlinear feature exists in battery system and extended kalman filter algorithm performs well in solving nonlinear problems, the paper proposes an EKF-based method for estimating SOC. In order to obtain the accurate estimation of SOC, this paper is based on composite battery model that is a combination of three battery models. The parameters are identified using the least square method. Then a state equation and an output equation are identified. All experimental data are collected from operating EV in Beijing. The results of the experiment show  that the relative error of estimation of state of charge is reasonable, which proves this method has good estimation performance.