Article
Thermodynamics
Yunren Sui, Wei Wu
Summary: Absorption technologies using CO2/ionic liquid mixtures have great potential in utilizing renewable energy and waste heat. Through screening and optimization, the study identifies the optimal ILs and CO2/IL mixture for a transcritical CO2/IL absorption heat pump, leading to improved cycle performance.
Article
Thermodynamics
Cong You, Benoit Michel, Remi Revellin
Summary: The study utilized two 1-D homogeneous equilibrium models to analyze the ejector expansion transcritical CO2 heat pump cycle, showing that the compressor's isentropic efficiency has a greater impact on system performance. The models exhibited deviations in predicting certain parameters, which can be minimized through data post-processing methods for calibration.
APPLIED THERMAL ENGINEERING
(2022)
Article
Green & Sustainable Science & Technology
Fatih Yilmaz, Murat Ozturk, Resat Selbas
Summary: Renewable energy-based multigeneration plants have the potential to address environmental issues and achieve a carbon-free future. This research focuses on designing and examining a combined cycle powered by solar energy for multigeneration, including power, hydrogen, ammonia, and freshwater generation. A comprehensive analysis is conducted to evaluate the performance and carbon dioxide emission reduction of the plant. The findings indicate high net power and hydrogen production capacities, along with freshwater and ammonia production rates.
SUSTAINABLE ENERGY TECHNOLOGIES AND ASSESSMENTS
(2022)
Article
Thermodynamics
Feng Zhang, Bingjie Chen, Gaoliang Liao, Jiaqiang E
Summary: Exploiting waste heat from the engine is crucial for alleviating the current energy and environmental crises. The use of CO2-based power cycles is seen as a competitive and promising system for recovering engine waste heat due to its efficiency and environmentally friendly nature. However, there is still room for improvement in the thermodynamic and economic performance of CO2-based power cycles. To address this, two novel CO2-based power cycles are proposed and analyzed using mathematical models developed in MATLAB. The results show significant improvements in power output and cost reduction compared to traditional systems. Exergy analysis reveals the areas with the highest exergy destruction in the proposed systems.
APPLIED THERMAL ENGINEERING
(2022)
Article
Construction & Building Technology
Xu Peng, Jintao Xie, Xinxin Liu, Guanghui Wang, Dingbiao Wang, Yushen Yang
Summary: The experimental results showed that the heating capacity and discharge temperature of the refrigerant of the vapor injection cycle were better than that of the single-stage cycle under the same condition. The coefficient of performance of the vapor injection cycle was higher, indicating a wider range of applications in cold conditions.
ENERGY AND BUILDINGS
(2021)
Article
Construction & Building Technology
Enrico Sisti, Antonio Rossetti, Silvia Minetto, Sergio Marinetti, Giacomo Tosato, Alessandro Beghi, Mirco Rampazzo
Summary: Modelling and simulation tools are essential for tackling the complexity of industrial applications and accelerating the innovation process by exploring and utilizing efficient, reliable, and sustainable solutions. This paper presents a dynamic model of a chiller system using carbon dioxide as a refrigerant, which is validated against experimental data and can be used to evaluate different control strategies. The results highlight the potential benefits of integrating the model into Computer-aided Control System Design (CACSD) software tools.
ENERGY AND BUILDINGS
(2023)
Article
Thermodynamics
Ahmed Okasha, Norbert Mueller, Kalyanmoy Deb
Summary: This paper investigates the transcritical CO2 heat pump cycle as a bi-objective optimization problem, optimizing the gas cooler pressure for maximum COP and cooling or heating capacity. The Non-Dominated Sorting Genetic Algorithm is employed to generate the best non-dominated solutions, including the Pareto Front. A control methodology is proposed to set optimization parameters based on preferences for maximum capacity, COP, or a trade-off point. The proposed approach can be applied offline or integrated with online optimization methods for enhanced capabilities and accuracy.
Article
Thermodynamics
Harrison M. Skye, Wei Wu
Summary: The study tested a prototype CO2 ground-source heat pump, providing experimental data under different conditions. The COP of the CO2 ground-source heat pump was 4.14 under standard conditions and 4.92 under part-load conditions. Additional results showed that compressor efficiency and heat exchanger have impacts on performance under different antifreeze liquid temperatures.
INTERNATIONAL JOURNAL OF REFRIGERATION
(2021)
Article
Energy & Fuels
Dazhang Yang, Yang Li, Jing Xie, Jinfeng Wang
Summary: A novel transcritical carbon dioxide two-stage compression/ejector refrigeration system for low-temperature cold storage is proposed in this study. The exergy destruction characteristics inside the system are evaluated using a combination of conventional and advanced exergy methods. The results indicate that the high-pressure compressor has the maximum potential for optimization, while the high-pressure and low-pressure expansion valves have the lowest priority for optimization. The system has a COP of 0.42 under actual operating conditions and 0.62 under unavoidable operating conditions. The efficiencies of the ejector and compressors, as well as the discharge and intermediate pressures, greatly influence the exergetic performance of the system.
Article
Thermodynamics
Bo Li, Shun-sen Wang
Summary: A hybrid cascade carbon dioxide cycle (HCCC) is proposed to recover waste heat. Compared with the traditional series cascade carbon dioxide cycle (SCCC), the HCCC shows higher system performance and better thermal performance.
Article
Green & Sustainable Science & Technology
Helio A. G. Diniz, Tiago F. Paulino, Juan J. G. Pabon, Antonio A. T. Maia, Raphael N. Oliveira
Summary: This paper presents a distributed mathematical model for a carbon dioxide direct expansion solar-assisted heat pump used to heat bath water. The model was validated using experimental data and revealed important findings, such as a reduction in water mass flow rate resulting in an increase in water outlet temperature.
Article
Thermodynamics
Ahmed Mansour, Junior Lagrandeur, Sebastien Poncet
Summary: A new real gas model is developed to accurately estimate the cold and hot exit temperatures of a vortex tube. The model shows improved predictions for high cold mass fractions and enhances the results for working fluids such as R134a and carbon dioxide. Under transcritical conditions, the vortex tube demonstrates significantly higher cooling and heating powers along with notable increase in exergy efficiency.
INTERNATIONAL JOURNAL OF THERMAL SCIENCES
(2022)
Article
Thermodynamics
Bo Li, Shun-sen Wang
Summary: This paper proposes a cascade transcritical carbon dioxide cycle to utilize waste heat from a gas turbine and the cold energy of liquefied natural gas (LNG). Detailed models and simulation results are analyzed from the perspectives of thermodynamics and economics. The optimization results show that the maximum exergy efficiency of the proposed cascade transcritical CO2 cycle is 49.24%.
APPLIED THERMAL ENGINEERING
(2022)
Article
Thermodynamics
Feng Zhang, Junbin Zhou, Gaoliang Liao, E. Jiaqiang, Mingye You, Chenxu Yang
Summary: Waste heat recovery is an efficient way to reduce fuel consumption and carbon dioxide emissions. In shipboards, recovering gas turbine exhaust can provide power and cooling. Combined cooling and power systems (CCPs) integrating sCO2 power cycle with tCO2 refrigeration cycle are considered competitive and promising. This study proposes a novel CCP based on two traditional CCPs and analyzes its performance through parametric analyses, optimizations, and exergy analyses. The results show that the proposed system can significantly improve net power output while maintaining comparable refrigeration capacity and total product unit cost, and reduce exergy destructions compared to traditional systems.
APPLIED THERMAL ENGINEERING
(2023)
Article
Thermodynamics
Laura Nebot-Andres, Manuel Gesu Del Duca, Ciro Aprea, Andrej Zerovnik, Jaka Tusek, Rodrigo Llopis, Angelo Maiorino
Summary: Subcooling methods for transcritical CO2 plants are being studied to improve performance in hot climates. Magnetic refrigeration devices can achieve high Coefficient of Performance values and can be applied as a CO2 subcooling method. This study presents the coupling of vapour compression and magnetocaloric refrigeration technologies, and evaluates the magnetic refrigeration system as a subcooling method for transcritical CO2 cycles. The results show that the existing prototype of magnetic refrigeration system can enhance the overall Coefficient of Performance of transcritical CO2 cycle by up to 9%.
ENERGY CONVERSION AND MANAGEMENT
(2022)
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.