Publications
69 results found
Song J, Li X, Ren X, et al., 2020, Supercritical CO2-cycle configurations for internal combustion engine waste-heat recovery: A comparative techno-economic investigation, 33rd International Conference on Efficiency, Cost, Optimization, Simulation and Environmental Impact of Energy Systems (ECOS 2020), Publisher: ECOS
Supercritical-CO2(S-CO2) cycle systems have appeared as an attractive option for waste-heat recovery from internal combustion engines(ICEs) thanks to the advantages offered by CO2as a working fluid, which is nontoxic and non-flammable, and does not suffer decomposition at high temperatures. Since the high density of CO2in the supercritical region enables compact component design, various S-CO2cycle systemconfigurations have been presented involving different layouts and combinations of heat exchangers with which to enhance heat recovery from both engine exhaust gases and jacket waterstreams. Despite the thermodynamicperformance improvement offered by more complex configurations, the additional heat exchangers bring extra costs and therefore key thermo-economic decisions need to be considered carefully during the design and development of suchsystems. This paper seeks to conduct both thermodynamic and economic (cost) assessments of a variety of S-CO2cycle system configurationsin ICE waste-heat recovery applications, with results indicating that in some cases a significant thermodynamic performance improvement can compensate the extra costs associated with a morecomplex system structure. The comparison results across a range ofICEs can also be a valuable guide for the early-stage S-CO2cycle system design in ICE waste-heat recovery andother similar applications.
Song J, Loo P, Teo J, et al., 2020, Thermo-economic optimization of Organic Rankine Cycle (ORC) systems for geothermal power generation: A comparative study of system configurations, Frontiers in Energy Research, Vol: 8, ISSN: 2296-598X
The suitability of organic Rankine cycle (ORC) technology for the conversion of low- and medium-grade heat sources to useful power has established this as a promising option in geothermal power-generation applications. Despite extensive research in this field, most of which has focused on parametric analyses and thermodynamic performance evaluations, there is still a lack of understanding concerning the comparative performance of different plant configurations from both thermodynamic and economic perspectives. This study seeks to investigate the thermo-economic performance of subcritical and transcritical geothermal ORC power-plants, while considering a range of working fluids and the use of superheating and/or recuperation. A specific case study based on the exploitation of a medium-temperature geothermal heat source (180 °C, 40 kg/s) is conducted. Multi-objective optimization is performed to maximize the power/exergy efficiency (i.e., resource use) and to minimize the payback period. Different optimized configurations are compared and the influence on system performance of superheating, recuperation, and subcritical vs. transcritical operation are evaluated. The results reveal that superheating is preferable for working fluids with low critical temperatures, but hinders the performance of fluids whose critical temperature is higher. Recuperation is not attractive under most operating conditions, since the thermodynamic performance improvement and cooling water saving cannot compensate the cost associated with the installation of the additional heat exchanger. Finally, transcritical ORC systems are favored thanks to the better thermal match between the heat source and the working fluid in these configurations. A more generalized geothermal heat source is then considered to explore the optimal configuration over a range of heat sources, which indicates that non-recuperated transcritical-cycle systems with working fluids whose critical temperature is close to the
Zhou A, Li X-S, Ren X-D, et al., 2020, Thermodynamic and economic analysis of a supercritical carbon dioxide (S-CO<sub>2</sub>) recompression cycle with the radial-inflow turbine efficiency prediction, ENERGY, Vol: 191, ISSN: 0360-5442
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- Citations: 13
Wang Y, Song J, Oyewunmi OA, et al., 2020, Integrated optimisation of organic Rankine cycle systems considering dynamic responses, Pages: 577-588
The organic Rankine cycle (ORC) has emerged as a promising and attractive technology for power generation from low- and medium-temperature heat sources. While a considerable amount of research effort has been devoted to the optimisation of ORC system under steady operating conditions, dynamic responses to various fluctuations in the heat source conditions are generally ignored; such transients in the heat source, however, may lead to safety issues and significant performance losses. In this paper, an optimisation method integrated with system dynamic responses is proposed to achieve optimal operating parameters for ORC systems. This method is implemented to obtain the best thermodynamic performance, as well as a secure and safe operation of the ORC system, and to maintain the working fluid in a saturated or superheated state during the expansion process. The effects of different design constraints (i.e., evaporation pressure, condensation pressure, pinch-point temperature differences, and degree of superheat) on the system's dynamic response are investigated, in order to choose appropriate design constraints corresponding to different heat-source variations. Thermodynamic optimisation is implemented for an ORC system exploiting a heat source with different condition variations, and results of the system's dynamic responses are compared with those obtained without such considerations. It is found that the dynamic responses of ORC systems to heat-source fluctuations need to be carefully considered in the design stage of such systems, in order to ensure safe and efficient operation.
Song J, Li X, Ren X, et al., 2020, Thermodynamic and economic investigations of transcritical CO2-cycle systems with integrated radial-inflow turbine performance predictions, Applied Thermal Engineering, Vol: 165, ISSN: 1359-4311
Transcritical CO2 (TCO2) cycle systems have emerged as a promising power-generation technology in certain applications. In conventional TCO2-cycle system analyses reported in the literature, the turbine efficiency, which strongly determines the overall system performance, is generally assumed to be constant. This may lead to suboptimal designs and optimization results. In order to improve the accuracy and reliability of such system analyses and offer insight into how knowledge of these systems from earlier analyses can be interpreted, this paper presents a comprehensive model that couples TCO2-cycle calculations with preliminary turbine design based on the mean-line method. Turbine design parameters are optimized simultaneously to achieve the highest turbine efficiency, which replaces the constant turbine efficiency used in cycle calculations. A case study of heat recovery from an internal combustion engine (ICE) using a TCO2-cycle system with a radial-inflow turbine is then considered, with results revealing that the turbine efficiency is influenced by the system’s operating conditions, which in turn has a significant effect on system performance in both thermodynamic and economic terms. A more generalized heat source is then considered to explore more broadly the role of the turbine in determining TCO2-cycle power-system performance. The more detailed turbine-design modelling approach allows errors of the order of up to 10-20% in various predictions to be avoided for steady-state calculations, and potentially of an even greater magnitude at off-design operation. The model allows quick preliminary designs of radial-inflow turbines and reasonable turbine performance predictions under various operating conditions, and can be a useful tool for more accurate and reliable thermo-economic studies of TCO2-cycle systems.
Wang T, Yang F, Pan C, et al., 2019, Spectral-Efficient Hybrid Dimming Scheme for Indoor Visible Light Communication: A Subcarrier Index Modulation Based Approach, JOURNAL OF LIGHTWAVE TECHNOLOGY, Vol: 37, Pages: 5756-5765, ISSN: 0733-8724
Li X, Song J, Yu G, et al., 2019, Organic Rankine cycle systems for engine waste-heat recovery: Heat exchanger design in space-constrained applications, Energy Conversion and Management, Vol: 199, ISSN: 0196-8904
Organic Rankine cycle (ORC) systems are a promising solution for improving internal combustion engine efficiencies, however, conflicts between the pressure drops in the heat exchangers, overall thermodynamic performance and economic viability are acute in this space-constrained application. This paper focuses on the interaction of the heat exchanger pressure drop (HEPD) and the thermo-economic performance of ORC systems in engine waste-heat recovery applications. An iterative procedure is included in the thermo-economic analysis of such systems that quantifies the HEPD in each case, and uses this information to revise the cycle and to resize the components until convergence. The newly proposed approach is compared with conventional methods in which the heat exchangers are sized after thermodynamic cycle modelling and the pressure drops through them are ignored, in order to understand and quantify the effects of the HEPD on ORC system design and working fluid selection. Results demonstrate that neglecting the HEPD leads to significant overestimations of both the thermodynamic and the economic performance of ORC systems, which for some indicators can be as high as >80% in some cases, and that this can be effectively avoided with the improved approach that accounts for the HEPD. In such space-limited applications, the heat exchangers can be designed with a smaller cross-section in order to achieve a better compromise between packaging volume, heat transfer and ORC net power output. Furthermore, we identify differences in working fluid selection that arise from the fact that different working fluids give rise to different levels of HEPD. The optimized thermo-economic approach proposed here improves the accuracy and reliability of conventional early-stage engineering design and assessments, which can be extended to other similar thermal systems (i.e., CO2 cycle, Brayton cycle, etc.) that involve heat exchangers integration in similar applications.
Zhang H, Ding W, Yang F, et al., 2019, Resource Allocation in Heterogeneous Network With Visible Light Communication and D2D: A Hierarchical Game Approach, IEEE TRANSACTIONS ON COMMUNICATIONS, Vol: 67, Pages: 7616-7628, ISSN: 0090-6778
Xiao L, Sheng G, Liu S, et al., 2019, Deep Reinforcement Learning-Enabled Secure Visible Light Communication Against Eavesdropping, IEEE TRANSACTIONS ON COMMUNICATIONS, Vol: 67, Pages: 6994-7005, ISSN: 0090-6778
Huang L, Zhang Y, Li Q, et al., 2019, Task-scheduling scheme based on greedy algorithm in integrated radar and communication systems, JOURNAL OF ENGINEERING-JOE, Vol: 2019, Pages: 5864-5867
Wang J, He L, Song J, 2019, Towards Higher Spectral Efficiency: Spatial Path Index Modulation Improves Millimeter-Wave Hybrid Beamforming, IEEE JOURNAL OF SELECTED TOPICS IN SIGNAL PROCESSING, Vol: 13, Pages: 1348-1359, ISSN: 1932-4553
Song J, Simpson M, Wang K, et al., 2019, Thermodynamic assessment of combined supercritical CO2 (SCO2) and organic Rankine cycle (ORC) systems for concentrated solar power, International Conference on Applied Energy 2019
Concentrated solar power (CSP) systems are acknowledged as a promising technology for solar energy utilisation. Supercritical CO2 (SCO2) cycle systems have emerged as an attractive option for power generation in CSP applications due to the favourable properties of CO2 as a working fluid. In order to further improve the overall performance of such systems, organic Rankine cycle (ORC) systems can be used in bottoming-cycle configuration to recover the residual heat. This paper presents a thermodynamic performance assessment of a combined SCO2/ORC system in a CSP application using parabolic-trough collectors. The parametric analysis indicates that the heat transfer fluid (HTF) temperature at the inlet of the cold tank, and the corresponding HTF mass flow rate, have a significant influence on the overall system performance. The results suggest that the combined system can offer significant thermodynamic advantages at progressively lower temperatures. Annual simulations for a case study in Seville (Spain) show that, based on an installation area of 10,000 m2, the proposed combined cycle system could deliver an annual net electricity output of 2,680 MWh when the HTF temperature at the cold tank inlet is set to 250 °C, which is 3% higher than that of a stand-alone CO2 cycle system under the same conditions. Taking the size of the thermal storage tanks into consideration, a lower HTF temperature at the cold tank inlet and a lower mass flow rate would be desirable, and the combined system offers up to 66% more power than the stand-alone version when the HTF inlet temperature is 100 °C.
Unamba CK, Sapin P, Li X, et al., 2019, Operational optimisation of a non-recuperative 1-kWe organic Rankine cycle engine prototype, Applied Sciences, Vol: 9, Pages: 3024-3024, ISSN: 2076-3417
Several heat-to-power conversion technologies are being proposed as suitable for waste-heat recovery (WHR) applications, including thermoelectric generators, hot-air (e.g., Ericsson or Stirling) engines and vapour-cycle engines such as steam or organic Rankine cycle (ORC) power systems. The latter technology has demonstrated the highest efficiencies at small and intermediate scales and low to medium heat-source temperatures and is considered a suitable option for WHR in relevant applications. However, ORC systems experience variations in performance at part-load or off-design conditions, which need to be predicted accurately by empirical or physics-based models if one is to assess accurately the techno-economic potential of such ORC-WHR solutions. This paper presents results from an experimental investigation of the part-load performance of a 1-kWe ORC engine, operated with R245fa as a working fluid, with the aim of producing high-fidelity steady-state and transient data relating to the operational performance of this system. The experimental apparatus is composed of a rotary-vane pump, brazed-plate evaporator and condenser units and a scroll expander magnetically coupled to a generator with an adjustable resistive load. An electric heater is used to provide a hot oil-stream to the evaporator, supplied at three different temperatures in the current study: 100, 120 and 140 ∘ C. The optimal operating conditions, that is, pump speed and expander load, are determined at various heat-source conditions, thus resulting in a total of 124 steady-state data points used to analyse the part-load performance of the engine. A maximum thermal efficiency of 4.2 ± 0.1% is reported for a heat-source temperature of 120 ∘ C, while a maximum net power output of 508 ± 2 W is obtained for a heat-source temperature at 140 ∘ C. For a 100- ∘ C heat source, a maximum exergy efficiency of 18.7 ± 0.3% is achieved. A detailed exergy analysis all
Li X, Song J, Simpson M, et al., 2019, THERMO-ECONOMIC COMPARISON OF ORGANIC RANKINE AND CO2 CYCLE SYSTEMS FOR LOW-TO-MEDIUM TEMPERATURE APPLICATIONS, 5th International Seminar on ORC Power Systems
Zhou AZ, Song J, Ren XD, et al., 2019, The Study and Analysis of Supercritical Carbon Dioxide Brayton Cycle and Its Radial Inflow Turbine, Kung Cheng Je Wu Li Hsueh Pao/Journal of Engineering Thermophysics, Vol: 40, Pages: 1233-1239, ISSN: 0253-231X
The thermodynamic parameters of supercritical carbon dioxide (S-CO2) are preliminarily designed in this study and the output power is about 1.5 MW. The design of a radial inflow turbine, one of the core components of the S-CO2 cycle, is accomplished. Numerical simulation and study of off-design performance are also conducted. The simulation results show that the overall flow parameters including mass flow rate and efficiency achieves the design goals, and the calculation values are in good agreement with design values trend. The prediction results of off-design performance are consistent with the simulation ones.
Xia L, Li X, Song J, et al., 2019, Design and Analysis of S-CO<sub>2</sub> Cycle and Radial Turbine for SOFC Vehicle Waste-Heat Recovery, JOURNAL OF THERMAL SCIENCE, Vol: 28, Pages: 559-570, ISSN: 1003-2169
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- Citations: 12
Unamba C, Li X, Song J, et al., 2019, Off-design performance of a 1-kWe organic Rankine cycle (ORC) system, 32nd International Conference on Efficiency, Costs, Optimization, Simulation and Environmental Impact of Energy Systems (ECOS 2019), Publisher: ECOS
Several heat-to-power conversion technologies are being proposed as suitable for waste heat recovery (WHR) applications, including thermoelectric generators, hot-air (e.g., Ericsson or Stirling) engines, and vapour-cycle engines such as steam or organic Rankine cycle (ORC) power systems. The latter has demonstrated the highest efficiencies at low and intermediate scales and heat-source temperatures. However, ORC systems suffer a deterioration in performance at part-load or off-design conditions, and the high global warming potential (GWP) or flammability of common working fluids is an increasing concern. This paper presents the experimental investigation of a 1-kWe ORC test facility under time-varying heat-source conditions. It aims to compare the part-load performance of various architectures with different working fluids, namely: (i) R245fa, which is widely used in ORC systems, and (ii) low-GWP HFOs. The experimental apparatus is composed of a rotary-vane pump, brazed-plate evaporators and condensers, and a scroll expander with an adjustable load. An electric heater is used to provide a hot oil stream at three different temperatures: 80, 100 and 120 °C. The optimal operating conditions, i.e., pump speed and expander load, are determined for each architecture at various heat-source conditions. A maximum thermal efficiency of 2.8% is reported for a heat-source temperature of 100 °C, while a maximum net power output of 430 W is obtained for a heat source at 120 °C. An exergy analysis allows us to quantify the contribution of each component to the overall exergy destruction. The share of the evaporator, condenser and expander units remain major for all three heat-source conditions, while the exergy destroyed in the pump is negligible in comparison (below 4%).
Song J, An W, Wu Y, et al., 2018, Neutronics and Thermal Hydraulics Analysis of a Conceptual Ultra-High Temperature MHD Cermet Fuel Core for Nuclear Electric Propulsion, FRONTIERS IN ENERGY RESEARCH, Vol: 6, ISSN: 2296-598X
Song J, Li X-S, Ren X-D, et al., 2018, Performance improvement of a preheating supercritical CO<sub>2</sub> (S-CO<sub>2</sub>) cycle based system for engine waste heat recovery, ENERGY CONVERSION AND MANAGEMENT, Vol: 161, Pages: 225-233, ISSN: 0196-8904
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- Citations: 82
Song J, Ren X-D, Li X-S, et al., 2018, One-dimensional model analysis and performance assessment of Tesla turbine, APPLIED THERMAL ENGINEERING, Vol: 134, Pages: 546-554, ISSN: 1359-4311
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- Citations: 28
Zhou A, Song J, Li X, et al., 2018, Aerodynamic design and numerical analysis of a radial inflow turbine for the supercritical carbon dioxide Brayton cycle, APPLIED THERMAL ENGINEERING, Vol: 132, Pages: 245-255, ISSN: 1359-4311
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- Citations: 41
Song J, Li X-S, Ren X-D, et al., 2018, Performance analysis and parametric optimization of supercritical carbon dioxide (S-CO<sub>2</sub>) cycle with bottoming Organic Rankine Cycle (ORC), ENERGY, Vol: 143, Pages: 406-416, ISSN: 0360-5442
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- Citations: 92
Song J, Ren XD, Gu CW, 2018, Investigation of engine waste heat recovery using supercritical CO<inf>2</inf> (S-CO<inf>2</inf>) cycle system
Primary energy consumption of diesel engines is increasingrapidly and strict emission standards are introduced by thegovernment. Interests in engine waste heat recovery have beenrenewed to alleviate the energy shortage and emission issues.Supercritical CO2 (S-CO2) cycle has emerged as a promisingmethod considering its compact structure and system safety levelin addition to the environmental friendly characteristics. Thispaper explores the potential of using S-CO2 cycle system forengine waste heat recovery. Both heat load from the lowtemperature jacket cooling water and the high temperatureengine exhaust gas are intended to be recovered. In the originalsystem, the jacket cooling water is used to preheat the S-CO2working fluid and the engine exhaust gas is utilized in thepreheater. As an optimized scheme, system with two preheatersis presented. The engine exhaust gas is further cooled in a hightemperature preheater after the jacket cooling water in the lowtemperature preheater. The available heat load from these twoheat sources can be entirely recovered. However, the increasingpreheating temperature suppresses the regeneration effect. Aregeneration branch is then added in the system. Part of the SCO2 working fluid from the compressor goes into a lowtemperature regenerator and then converges with the other partfrom the two preheats. A deeper utilization of the regenerationheat load is achieved and performance enhancement of the SCO2 cycle system is expected. The maximum net power outputof the system with regeneration branch reaches 82.8 kW, whichresults in an 8.5% increment on the engine power output.
Ye F, Li Y, Zhang Y, et al., 2018, Comparative Analyses Between Two Techniques To Understand Metal-Induced Recombination Losses In Industrial N-Type Bifacial PERT Solar Cells, 12th International Photovoltaic Power Generation and Smart Energy Conference and Exhibition (SNEC), Publisher: ELSEVIER SCIENCE BV, Pages: 15-20, ISSN: 1876-6102
Song J, Ren XD, Gu CW, 2017, Performance Analysis of Dual-loop Heat Recovery System, Kung Cheng Je Wu Li Hsueh Pao/Journal of Engineering Thermophysics, Vol: 38, Pages: 1491-1495, ISSN: 0253-231X
A dual-loop system is designed to recover the waste heat of a diesel engine in this paper. The high-temperature (HT) loop utilizes the heat load of the engine exhaust gas, and the low-temperature (LT) loop uses the heat load of the jacket cooling water and the residual heat of the HT loop sequentially. These two loops are coupled via a shared heat exchanger. Water is selected as the working fluid for the HT loop while organic fluids are used in the LT loop. The influence of the HT loop parameters on the performance of the LT loop is evaluated. The simulation results reveal that under different operating conditions of the HT loop, the pinch point of the LT loop occurs at different locations and therefore, results in different evaporation temperatures and other thermal parameters. The maximum net power output of the dual-loop ORC system reaches 115.1 kW, which leads to an increase of 11.6% on the original power output of the diesel engine.
Song J, Gu C-W, Li X-S, 2017, Performance estimation of Tesla turbine applied in small scale Organic Rankine Cycle (ORC) system, APPLIED THERMAL ENGINEERING, Vol: 110, Pages: 318-326, ISSN: 1359-4311
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- Citations: 45
Song J, Gu C-W, 2017, 1-D MODEL ANALYSIS OF TESLA TURBINE FOR SMALL SCALE ORGANIC RANKINE CYCLE (ORC) SYSTEM, ASME Turbine Technical Conference and Exposition (Turbo Expo), Publisher: AMER SOC MECHANICAL ENGINEERS
Song J, Gu C-W, Ren X, 2016, Influence of the radial-inflow turbine efficiency prediction on the design and analysis of the Organic Rankine Cycle (ORC) system, ENERGY CONVERSION AND MANAGEMENT, Vol: 123, Pages: 308-316, ISSN: 0196-8904
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- Citations: 72
Song J, Gu C-W, Ren X, 2016, Parametric design and off-design analysis of organic Rankine cycle (ORC) system, ENERGY CONVERSION AND MANAGEMENT, Vol: 112, Pages: 157-165, ISSN: 0196-8904
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- Citations: 78
Song J, Gu CW, 2016, Thermodynamic analysis of organic rankine cycle (ORC) systems based on turbine performance prediction
Energy shortage and environmental deterioration are two crucial issues that the developing world must face. As a promising solution, the conversion of low grade energies is attracting more and more attention. Among all of the existing technologies, Organic Rankine Cycle (ORC) has been proven to be an effective method to utilize the low grade energies. Thermodynamic analysis is important for working fluid selection and system parameter determination in the ORC system. In conventional studies, the efficiency of the organic turbine is fixed at a constant value. However, the turbine efficiency is evidently related to the working fluid property and system operating condition. Thus, the constant turbine efficiency is unreasonable and may lead to sub-optimal thermal results. To enhance the reliability and accuracy of ORC system analysis, the one-dimensional analysis model is used to predict the turbine performance in this paper. The calculated onedimensional turbine efficiency replaces the constant efficiency in the system analysis. The influence of the working fluid property and system operating condition on the turbine performance is evaluated. Thermal performances of the ORC systems with the one-dimensional turbine efficiency and the constant turbine efficiency are simulated and compared. The results reveal that the turbine efficiency plays a significant role in working fluid selection and system parameter determination for the ORC system.
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