Abstract

Solid electric heat storage technology is an important part of energy conversion and utilization technology, which plays a key role in wind power, clean heating and flexible peak regulation of coal-fired units. The development of solid electric heat storage technology has a great significance to improve the utilization efficiency of renewable energy, enhance the peaking capacity of thermal power generation and relieve the grid dispatching pressure. In this paper, the development status, application, development trend, advantages and disadvantages of solid heat storage technology are summarized.

Abstract

In this paper, the influence of co-firing natural gas and biogas on part-load performance of a natural gas combined cycle (NGCC) plant is investigated from thermodynamics perspective. Simulations of the plant, of which design fuel is natural gas, are developed. Performance of the plant fueled by natural gas is determined as a benchmark. Part-load performance of the plant running with different mixtures of natural gas and biogas is calculated and compared with the benchmark. Results show that co-firing mixed fuel leads a reduction in energy utilization efficiency at low gas turbine load, and leads an increase at high gas turbine load. When the gas turbine is fueled by mixed fuel, exergy efficiency decreases at every condition, and the most reduction is around 6% from benchmark. It is not efficient to use biogas at low power load from both energy and exergy efficiency perspectives for the plant in this study.

Abstract

This paper studies the control strategy for adaptive cruise control (ACC) system on pure electric vehicle (PEV) in the car-following process. The hierarchical control structure is adopted for the ACC system, and the structure contains upper controller and lower controller. In the upper controller, multiple objectives including the safety, tracking, comfort and energy consumption are optimized in a model predictive control (MPC) framework. In the lower controller, the energy is recovered during braking. So the energy economy is improved by reducing energy consumption and increasing energy recovery. The proposed ACC control strategy is evaluated in simulation. The simulation results show that safety and tracking are guaranteed, and the comfort and energy economy are improved significantly.

Abstract

This paper proposes a novel load forecasting algorithm aiming at improving the accuracy of prediction near the holiday. The improvement can be divided into two aspects: during the holiday, and a period after the holiday. Trend-Bias Prediction (TBP) algorithm is applied for predicting the load during the holiday, while Virtual Load Replacement (VLR) algorithm is used after a period of the holiday. The data in this experiment is from an industrial part in China. Comparing with the benchmark, both proposed TBP and VLR are efficient and have better performances.

Abstract

Natural refrigerants such as carbon dioxide (R744), ammonia (R717) or propane (R290) have been considered as promising candidates for the next generation in order to make the friendly environment refrigeration systems. This study investigates the two-phase flow heat transfer coefficient and pressure drop of ammonia and propane during the evaporation inside a minichannel multiport tubes. The tube has a hydraulic diameter of 0.83 mm. The length of test section is 200 mm. The experimental data were conducted at saturation temperatures of 6 °C, the heat flux from 3 to 12 kW/m2, the mass flux varied from 50 to 150 kg/m2s and the quality up to a unit. The effects of mass flux, heat flux and vapor quality on heat transfer coefficient and pressure drop are analyzed. Also, the heat transfer coefficient data were compared with various correlations in the literature.

Abstract

A two-stage program for the integrated energy system (IES) based on Optimistic and Pessimistic criterion is presented in this paper, considering the uncertainty of energy price. Then, based on the framework of the energy hub in IES, the model of energy management is well formulated to minimize the total cost according to the Optimistic and Pessimistic criterion. Furthermore, the proposed model is solved by Aimms solver. Finally, a case study based on Optimistic and Pessimistic criterion is employed to examine the characteristic of the proposed model for the decisionmaker.

Abstract

Wind power output shows obvious fluctuations characteristics, and direct grid-connection will bring great challenges to the safe and stable operation of power system. This paper adopts the dual-battery energy storage operation mode which performs chargedischarge tasks separately based on the consideration of the effect of discharge depth and frequent chargedischarge conversion on battery life and energy utilization. In addition, this paper proposes chargedischarge operational stability index for characterizing the operation of DBESS, according to the real-time operating conditions of the energy storage system and wind power fluctuations. In order to solve the extreme operation problems caused by the unbalance of charge and discharge energy during the long-term operation of the dual-battery energy storage system, this paper uses the two proposed indicators as input, and presents a control strategy to adaptively fine-tune the first-order low-pass filtering time constant. Purpose of the above work is to change the battery throughput power in real time and optimize the state of charge of the two battery packs. The effectiveness of the proposed control strategy is verified from two aspects: optimization control effect on SOC and power fluctuations smoothing effect using MATLAB/Simulink software.

Abstract

With heat pump (HP) heating getting popular in China, a control strategy for air source heat pump-low temperature hot water floor radiant heating system (AHPFHS) is required to reduce the operating cost of the it. Model of household AHPFHS was established based on the characteristics of the equipment. The forecast data from weather stations was utilized to build the residential building thermal load model based on the heat balance equation. A rolling optimization control method was proposed. Considering thermal comfort of the customers, the indoor temperature set-point was scheduled for the lowest operating cost of the AHPFHS. A typical case was built to validate the feasibility of the proposed method. Numerical studies show that the proposed control method is able to effectively reduce the operating cost of the system.

Abstract

The Chinese government has promised to cut carbon dioxide emission per unit gross domestic product by 60 to 65 percent by 2030, compared with the 2005 level. Moreover, it’s highly outlined that the comprehensive utilization of coal resources is a crucial way to reach this goal in the latest energy development plans. Accordingly, we conducted a life cycle comparison assessment of a coal-based polygeneration system and separate production systems. The polygeneration system can generate electricity, gasoline, diesel, liquefied natural gas (LNG), sulfur, benzene, hydrogen, carbon monoxide and ammonia sulfate simultaneously. Moreover, some representative separate production systems have been carefully selected for the comparison study. The life cycle results indicate that the current polygeneration system can reduce global warming potential (GWP) by 26.5 percent, acidification potential (AP) by 53.1 percent, eutrophication potential (EP) by 53.7 percent, photochemical ozone creation potential (POCP) by 49.1 percent, and ozone depletion potential (ODP) by 20.4 percent, respectively, compared with representative separate production processes. As a result, this study may also demonstrate the potential advantages to develop coal-based polygeneration systems in China.

Abstract

Recovering water from exhaust could solve the water-shortage problem for some power plants, and it is conductive to the spread of pollutants in the lower atmosphere. Transport membrane condenser (TMC) is a novel device used to recover water from exhaust. In the past, most researchers used mesoporous membrane to manufacture TMC, and the experiments were conducted using the artificial flue gas. In this paper, macroporousTMC and microporous-TMC are proposed and designed. The water recovery performance of both kinds of TMCs are compared experimentally under real flue gas environment. According to the experimental results, the water recovery performance of macroporous-TMC is better than that of microporous-TMC. Furthermore, the effect of Re number of flue gas and cooling water on the water recovery performance are analyzed.