Article
Energy & Fuels
Xinwei Wang, Donglin Liu, Tanxiao Zhu, Tiejun Zhu, Fengming Li, Dong Wang, Zhengda Yang, Riyi Lin
Summary: This study improves the downhole coaxial open-loop heat collector by using a slotted liner to create a free open space for better heat exchange. Field tests in a geothermal well in Shengli Oilfield, Dongying, China, show that the improved heat output is greater than that of traditional downhole heat exchangers. After 15 days of continuous operation, the heat output stabilizes at 200 kW with a water outlet temperature of 34.6 degrees Celsius.
PETROLEUM SCIENCE AND TECHNOLOGY
(2023)
Article
Thermodynamics
Hongmei Yin, Chaofan Song, Ling Ma, Liuhua Gao, Xuan Yang, Wenjia Li, Jun Zhao
Summary: Geothermal energy is crucial for energy transformation, but reinjection difficulty and heat extraction efficiency need to be addressed urgently. A new leaky downhole coaxial open loop geothermal system shows promising results with heat output up to 930 kW, 3.5 times higher than traditional casing. An analytical and numerical simulation model was established to study heat extraction performance and optimize design parameters such as aquitard thickness and permeability ratio.
APPLIED THERMAL ENGINEERING
(2021)
Article
Green & Sustainable Science & Technology
Gaosheng Wang, Xianzhi Song, Yu Shi, Ruiyue Yang, Feixue Yulong, Rui Zheng, Jiacheng Li
Summary: The novel multilateral-well coaxial closed-loop geothermal system (CCGS) provides a solution to the high-cost fracturing and environmental issues by closed-loop circulation, and significantly increases heat production through lateral wellbores. A new 3D transient model is established and validated with experimental data.
Article
Thermodynamics
Gaosheng Wang, Xianzhi Song, Chao Yu, Yu Shi, Guofeng Song, Fuqiang Xu, Jiayan Ji, Zihao Song
Summary: This study proposes a novel hydrothermal open-loop geothermal system and establishes a numerical model to analyze its performance. The results indicate that the novel system has significant advantages in the exploitation of multi-layer reservoirs and can improve energy efficiency.
Article
Thermodynamics
Gaosheng Wang, Xianzhi Song, Guofeng Song, Yu Shi, Chao Yu, Fuqiang Xu, Jiayan Ji, Zihao Song
Summary: This study focuses on developing a geothermal system using a horizontal-well to exploit deep hydrothermal resources, considering the complex convection process in the reservoir. The results show that forced convection can greatly enhance heat transfer, emphasizing the importance of factors such as horizontal length, permeability, and reverse circulation in improving heat extraction. Compared to vertical well systems, horizontal-well systems can fully extract heat stored in the reservoir, providing valuable insights for scientific research and engineering applications.
INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER
(2021)
Article
Green & Sustainable Science & Technology
Nanzhe Wang, Haibin Chang, Xiang-Zhao Kong, Dongxiao Zhang
Summary: To maximize the economic benefits of geothermal energy production, this research proposes a closed-loop optimization framework for well control optimization of geothermal reservoirs using deep learning surrogates. The framework combines a convolutional neural network and long short-term memory recurrent network to extract spatial information and approximate sequence-to-sequence mapping. The trained model can predict production responses for cases with different permeability fields and well control sequences. The framework also incorporates production optimization and data assimilation alternately to achieve real-time well control optimization and estimate reservoir properties while considering geologic uncertainty.
Article
Thermodynamics
Feng Gu, Youwu Li, Dazhen Tang, Ying Gao, Yue Zhang, Peng Yang, Hao Ye
Summary: This paper presents a horizontal-well deep borehole closed-loop heat exchanger (DBHE) and investigates its temperature characteristics, system efficiency, and key factors by comparing with vertical wells. The study results provide important guidance for the design and retrofitting of DBHEs.
APPLIED THERMAL ENGINEERING
(2022)
Article
Thermodynamics
Yuancheng Lou, Guokun Liu, Alessandro Romagnoli, Dongxu Ji
Summary: This study proposes a novel combined system of Organic Rankine cycle (ORC) and thermoelectric generators (TEG) to boost geothermal power generation. The system utilizes a coaxial casing geothermal well with a thermoelectric generator layer. The integrated simulation model for both underground and aboveground power generation has been verified with experiments, showing a significant improvement in power output, heat extraction, and overall efficiency compared to a standalone ORC system.
APPLIED THERMAL ENGINEERING
(2023)
Article
Green & Sustainable Science & Technology
Sajjan Pokhrel, Agus P. Sasmito, Atsushi Sainoki, Toshiyuki Tosha, Tatsuya Tanaka, Chiaki Nagai, Seyed Ali Ghoreishi-Madiseh
Summary: This study investigates a 500 m deep coaxial borehole heat exchanger system for geothermal power generation through experimental and computational analyses. The numerical model accurately predicts the underground temperature distribution and the output power of the geothermal system. A parametric study shows that the total thermal energy generated by the geothermal system can reach up to 194 MWh, and after extraction is terminated, the ground temperature can recover to around 86% of the initial temperature within 456 hours.
Article
Energy & Fuels
Dong Xiao, Chun Cai, Haijun Tang, Li Li, Yifan Hu, Jianhong Liu, Ruitao Yang
Summary: Hot dry rocks (HDRs) have significant potential for geothermal development, and a downhole coaxial heat exchanger geothermal system (DCHEGS) with a horizontal well is an effective method. Economic evaluation model showed that the project can only be profitable within a specific range of horizontal section length, providing theoretical support for practical design and operation.
INTERNATIONAL JOURNAL OF ENERGY RESEARCH
(2022)
Article
Green & Sustainable Science & Technology
Yongqiang Luo, Guozhi Xu, Nan Cheng
Summary: The study proposed a novel stratified segmented finite line source method (SS-FLS) for simulating the temperature field of deep borehole heat exchangers, which was validated and found to be accurate and robust through comparisons with actual engineering project data. Additionally, the study investigated the effects of stratification on soil and fluid temperature fields.
Article
Energy & Fuels
Kunqing Jiang, Xianbiao Bu
Summary: Traditional deep borehole heat exchangers are limited by the low thermal conductivity of rocks, while a study found that the single-well enhanced geothermal system significantly improves performance in convective heat exchange, indicating promising prospects for its widespread application.
Article
Green & Sustainable Science & Technology
Ji Li, Wei Xu, Jianfeng Li, Shuai Huang, Zhao Li, Biao Qiao, Chun Yang, Deyu Sun, Guangqiu Zhang
Summary: Middle and deep geothermal resources are abundant and advantageous, but there is a lack of theoretical model for deep ground heat exchangers. This study establishes a heat extraction model for a coaxial deep borehole heat exchanger and verifies it through numerical simulation, providing important guidance for research in this field.
Review
Energy & Fuels
Haohua Chen, Ingrid Tomac
Summary: This review paper summarizes recent developments in geothermal exploitation using coaxial deep borehole heat exchangers (DBHE). The paper discusses field tests, analytical and semi-analytical approaches, and numerical simulations. Future work should focus on long-term performance, effects of groundwater flow, technology for larger diameter boreholes, new materials for insulated inner pipe, treatment of fluid and different working fluids, and economic analysis. Analytical methods and numerical simulations should consider the dependence of fluid and formation properties on pressure and temperature. Optimizing borehole properties and pump parameters, using an insulated inner pipe, and modeling an intermittent working pattern could improve the performance of DBHE.
GEOMECHANICS AND GEOPHYSICS FOR GEO-ENERGY AND GEO-RESOURCES
(2023)
Article
Thermodynamics
Ke Chen, Jinping Zhang, Xiangjun Kong, Jia Zheng, Juan Li, Lijuan Yuan, Aihua Liu, Qiulan Zhang
Summary: In this study, a comprehensive numerical model is established to investigate the performance sustainability of medium deep borehole heat exchanger systems. The model considers factors such as layered strata, groundwater flow, thermophysical properties, and geothermal gradient. The results show that after 20 years of continuous operation, the outlet temperature of the system decreases by 0.48 degrees C (3.1%) and the heat transfer impact scope is within 20 m around the borehole. This study provides valuable insights for the long-term operation of medium deep borehole heat exchanger systems.
APPLIED THERMAL ENGINEERING
(2023)
Article
Energy & Fuels
Shitong Fang, Houfan Du, Tao Yan, Keyu Chen, Zhiyuan Li, Xiaoqing Ma, Zhihui Lai, Shengxi Zhou
Summary: This paper proposes a new type of nonlinear VIV energy harvester (ANVEH) that compensates for the decrease in peak energy output at low wind speeds by introducing an auxiliary structure. Theoretical and experimental results show that ANVEH performs better than traditional nonlinear VIV energy harvesters under various system parameter variations.
Article
Energy & Fuels
Wei Jiang, Shuo Zhang, Teng Wang, Yufei Zhang, Aimin Sha, Jingjing Xiao, Dongdong Yuan
Summary: A standardized method was developed to evaluate the availability of solar energy resources in road areas, which combined the Analytic Hierarchy Process (AHP) and the Geographic Information System (GIS). By analyzing critical factors and using a multi-indicator evaluation method, the method accurately evaluated the utilization of solar energy resources and guided the optimal location selection for road photovoltaic (PV) projects. The results provided guidance for the application of road PV projects and site selection for route corridors worldwide, promoting the integration of transportation and energy.
Article
Energy & Fuels
Chang Liu, Jacob A. Wrubel, Elliot Padgett, Guido Bender
Summary: The study investigates the effects of coating defects on the performance of the anode porous transport layer (PTL) in water electrolyzers. The results show that an increasing fraction of uncoated regions on the PTL leads to decreased cell performance, with continuous uncoated regions having a more severe impact compared to multiple thin uncoated strips.
Article
Energy & Fuels
Marcos Tostado-Veliz, Xiaolong Jin, Rohit Bhakar, Francisco Jurado
Summary: In this paper, a coordinated charging price mechanism for clusters of parking lots is proposed. The research shows that enabling vehicle-to-grid characteristics can bring significant economic benefits for users and the cluster coordinator, and vehicle-to-grid impacts noticeably on the risk-averse character of the uncertainty-aware strategies. The developed pricing mechanism can reduce the cost for users, avoiding to directly translate the energy cost to charging points.
Article
Energy & Fuels
Duan Kang
Summary: Building an energy superpower is a key strategy for China and a long-term goal for other countries. This study proposes an evaluation system and index for measuring energy superpower, and finds that China has significantly improved its ranking over the past 21 years, surpassing other countries.
Article
Energy & Fuels
Fucheng Deng, Yifei Wang, Xiaosen Li, Gang Li, Yi Wang, Bin Huang
Summary: This study investigated the synergistic blockage mechanism of sand and hydrate in gravel filling layer and the evolution of permeability in the layer. Experimental models and modified permeability models were established to analyze the effects of sand particles and hydrate formation on permeability. The study provided valuable insights for the safe and efficient exploitation of hydrate reservoirs.
Article
Energy & Fuels
Hao Wang, Xiwen Chen, Natan Vital, Edward Duffy, Abolfazl Razi
Summary: This study proposes a HVAC energy optimization model based on deep reinforcement learning algorithm. It achieves 37% energy savings and ensures thermal comfort for open office buildings. The model has a low complexity, uses a few controllable factors, and has a short training time with good generalizability.
Article
Energy & Fuels
Moyue Cong, Yongzhuo Gao, Weidong Wang, Long He, Xiwang Mao, Yi Long, Wei Dong
Summary: This study introduces a multi-strategy ultra-wideband energy harvesting device that achieves high power output without the need for external power input. By utilizing asymmetry, stagger array, magnetic coupling, and nonlinearity strategies, the device maintains a stable output voltage and high power density output at non-resonant frequencies. Temperature and humidity monitoring are performed using Bluetooth sensors to adaptively assess the device.
Article
Energy & Fuels
Tianshu Dong, Xiudong Duan, Yuanyuan Huang, Danji Huang, Yingdong Luo, Ziyu Liu, Xiaomeng Ai, Jiakun Fang, Chaolong Song
Summary: Electrochemical water splitting is crucial for hydrogen production, and improving the hydrogen separation rate from the electrode is essential for enhancing water electrolyzer performance. However, issues such as air bubble adhesion to the electrode plate hinder the process. Therefore, a methodology to investigate the two-phase flow within the electrolyzer is in high demand. This study proposes using a microfluidic system as a simulator for the electrolyzer and optimizing the two-phase flow by manipulating the micro-structure of the flow.
Article
Energy & Fuels
Shuo Han, Yifan Yuan, Mengjiao He, Ziwen Zhao, Beibei Xu, Diyi Chen, Jakub Jurasz
Summary: Giving full play to the flexibility of hydropower and integrating more variable renewable energy is of great significance for accelerating the transformation of China's power energy system. This study proposes a novel day-ahead scheduling model that considers the flexibility limited by irregular vibration zones (VZs) and the probability of flexibility shortage in a hydropower-variable renewable energy hybrid generation system. The model is applied to a real hydropower station and effectively improves the flexibility supply capacity of hydropower, especially during heavy load demand in flood season.
Article
Energy & Fuels
Zhen Wang, Kangqi Fan, Shizhong Zhao, Shuxin Wu, Xuan Zhang, Kangjia Zhai, Zhiqi Li, Hua He
Summary: This study developed a high-performance rotary energy harvester (AI-REH) inspired by archery, which efficiently accumulates and releases ultralow-frequency vibration energy. By utilizing a magnetic coupling strategy and an accumulator spring, the AI-REH achieves significantly accelerated rotor speeds and enhanced electric outputs.
Article
Energy & Fuels
Yi Yang, Qianyi Xing, Kang Wang, Caihong Li, Jianzhou Wang, Xiaojia Huang
Summary: In this study, a novel hybrid Quantile Regression (QR) model is proposed for Probabilistic Load Forecasting (PLF). The model integrates causal dilated convolution, residual connection, and Bidirectional Long Short-Term Memory (BiLSTM) for multi-scale feature extraction. In addition, a Combined Probabilistic Load Forecasting System (CPLFS) is proposed to overcome the inherent flaws of relying on a single model. Simulation results show that the hybrid QR outperforms traditional models and CPLFS exceeds the best benchmarks in terms of prediction accuracy and stability.
Article
Energy & Fuels
Wen-Jiang Zou, Young-Bae Kim, Seunghun Jung
Summary: This paper proposes a dynamic prediction model for capacity fade in vanadium redox flow batteries (VRFBs). The model accurately predicts changes in electrolyte volume and capacity fade, enhancing the competitiveness of VRFBs in energy storage applications.
Article
Energy & Fuels
Yuechao Ma, Shengtie Wang, Guangchen Liu, Guizhen Tian, Jianwei Zhang, Ruiming Liu
Summary: This paper focuses on the balance of state of charge (SOC) among multiple battery energy storage units (MBESUs) and bus voltage balance in an islanded bipolar DC microgrid. A SOC automatic balancing strategy is proposed considering the energy flow relationship and utilizing the adaptive virtual resistance algorithm. The simulation results demonstrate the effectiveness of the proposed strategy in achieving SOC balancing and decreasing bus voltage unbalance.
Article
Energy & Fuels
Raad Z. Homod, Basil Sh. Munahi, Hayder Ibrahim Mohammed, Musatafa Abbas Abbood Albadr, Aissa Abderrahmane, Jasim M. Mahdi, Mohamed Bechir Ben Hamida, Bilal Naji Alhasnawi, A. S. Albahri, Hussein Togun, Umar F. Alqsair, Zaher Mundher Yaseen
Summary: In this study, the control problem of the multiple-boiler system (MBS) is formulated as a dynamic Markov decision process and a deep clustering reinforcement learning approach is applied to obtain the optimal control policy. The proposed strategy, based on bang-bang action, shows superior response and achieves more than 32% energy saving compared to conventional fixed parameter controllers under dynamic indoor/outdoor actual conditions.