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Energy system models are advancing rapidly. However, it is not clear whether models are becoming better, in the sense that they address the questions that decision-makers need to be answered to make well-informed decisions. Therefore, we investigate the gap between model improvements relevant from the perspective of modellers compared to what users of model results think models should address. Thus, we ask: What are the differences between energy model improvements as perceived by modellers, and the actual needs of users of model results? To answer this question, we conducted a literature review, 32 interviews, and an online survey. Our results show that user needs and ongoing improvements of energy system models align to a large degree so that future models are indeed likely to be better than current models. We also find mismatches between the needs of modellers and users, especially in the modelling of social, behavioural and political aspects, the trade-off between model complexity and understandability, and the ways that model results should be communicated. Our findings suggest that a better understanding of user needs and closer cooperation between modellers and users is imperative to truly improve models and unlock their full potential to support the transition towards climate neutrality in Europe.

sCO2 power cycle is the most investigated and most promising technology for replacing conventional steam cycle in CSP plants. Nevertheless, the efficiency of sCO2 power cycle is strongly penalized by high ambient temperatures which are typical of favourable CSP locations. This paper focuses on a new working fluid for power cycles which consists of CO2 blended with C6F6. The addition of C6F6 increases the fluid critical temperature allowing for a condensing cycle for ambient temperatures up to 45 °C. The calculated gross mechanical efficiency of the innovative cycle is around 42% when adopting a typical Peng Robinson equation of state with van der Waals mixing rules for a maximum operating temperature of 550 °C and a minimum cycle temperature of 51 °C. This performance varies just of ±0.1% if the prediction of the binary interaction parameter of the Peng Robinson is over- or under-estimated by 50%, but more significantly if other equations of states are adopted (up to 1% points). Moreover, a detailed analysis on the operating conditions of the cycle components highlighted that components design is affected by the adopted EoS. A sensitivity analysis is then performed to identify where the largest differences in predicting the efficiency of the cycle occur.

In the energy renovation process, usually, buildings are upgraded to become energy-neutral annually with installed photovoltaic systems and heat pumps. However, the energy self-sufficiency of these buildings is surprisingly low. Therefore, the rapid deployment of heat pump based heating systems creates a shift of natural-gas consumption from the previously consumed building side (boilers) towards the electricity production side (power-plants). Fortunately, the development of information and communication technology enables access to consumption/generation data of building-related energy systems. Thus, there is an opportunity to strategically use this data and improve energy self-sufficiency and accommodate heat pump based heating systems. In this study, the improvement of self-sufficiency is discussed using a renovated neighborhood. The presented method incorporates a smart-grid application with a data-driven clustering, prediction, and an energy management strategy. First, clustering of similar demand-profiled dwellings with the k-means algorithm, and demand-prediction using the random-forest technique was performed. Afterwards, electric energy storage was introduced and multi-objective optimization reducing annualized costs and carbon emissions have been performed. For the carbon-dioxide optimal case, when aimed at the entire neighborhood, an annual self-sufficiency increment of more than 25% can be achieved, while four months out of the twelve being 100% energy self-sufficient.

Aqueous MEA-based CO2 capture is one of main technologies for CO2 capture. However, there are various different sources of flue gases from different industries which have different flow conditions. In particular the CO2 content is very important and it will have a critical impact on the associated design of CO2 capture processes. In this study a superstructure optimization methodology is applied to ranges of different flue gases found in non-power industries such as cement, steel and refinery plants. Optimization of both operating conditions and structural modifications reveals the optimal configurations of equipment for the different industrial sources of CO2. A case study is given to address how energy consumption and process design of MEA-based CO2 capture systems is influenced by CO2 concentration in the feed gas. It is shown that flue gas splitting is the most significant and useful process modification for all the different flue gases tested in particular for low CO2 content flue gases. At higher CO2 contents the optimal designs are shown to require a combination of process modifications to give an even greater reduction of energy requirements.

The thermal decomposition of oxygen-containing functional groups produces CO, CO2 and active sites that accelerate coal spontaneous combustion. Study on this process is of great significance for research on the mechanism of coal spontaneous combustion. In this paper, research was made on the dependency relationship between gas production and time under the condition of different coal samples, particle sizes and pyrolysis temperatures. Results reveal that the time-dependent generation rate of active sites follows an exponential compound function P = A + B e - t/ K 1 + C e - t/ K 2 during isothermal pyrolysis of coal. Besides, infrared spectrum experiments were also carried out to study changes in oxygen-containing functional groups of raw coal, pyrolyzed coal and room temperature oxidized coal after pyrolysis. The results prove that when coal reaches a certain temperature, oxygen-containing functional groups will adsorb heat and undergo decomposition to produce active sites and a few gas products. Then, active sites are oxidized, generating oxygen-containing functional groups and releasing both massive heat and gas products. Therefore, the whole reaction is a continuous cyclic process where combined effects of the two reactions cause rapid accumulation of heat, which triggers uncontrollable coal spontaneous combustion. The results from this research will be helpful to inhibit the occurrence of coal spontaneous combustion by reducing the generation and oxidation of active sites.

Integrated gasification combined cycle (IGCC) power plant with dual-stage Selexol™ for carbon capture is compared to pressure swing adsorption (PSA)-based warm gas CO2 capture. Capture with Selexol™ was limited to 83.4% due to high syngas CH4 content while the efficiency was 31.11% HHV resulting in a 1st year cost of electricity (COE) of 148.6 $/MWh. Carbon capture can be increased to 88.6% and efficiency to 33.76% HHV with warm gas CO2 removal. When holding the same carbon capture level as the Selexol™ case, efficiency is increased to 34.20% HHV and after further optimization of the water gas shift (WGS) reactors to 35.63% HHV leading to a lower COE of 127.2 $/MWh. Reaction kinetic models are developed and applied for optimization of WGS reactors to convert syngas CO to CO2. Cost for warm gas carbon capture reduced to 47.5 $/tonne from 66.0 $/tonne for IGCC without carbon capture while CO2 avoided cost reduced from 89.4 $/tonne to 54.3 $/tonne. Carbon capture cost dropped from 88.0 $/tonne to 72.7 $/tonne while the CO2 avoided cost decreased from 112.2 $/tonne to 78.3 $/tonne over supercritical boiler plant without carbon capture. Furthermore, warm gas cleanup lowered the specific net water withdrawal/usage by 13.4%.

This study aims at analyzing dynamic behavior for the full operation cycle considering various alternatives and constraints related to small-scale and seaborne environment for a BOG re-liquefaction process in LNG-fueled ships, leading to significant enhancement of its operability. The design framework includes steady-state modeling, dynamic modeling and control system, with which system-wide dynamic characteristics are readily investigated and operating guidelines for achieving optimal process operations are obtained. Equipment sizing with the appropriate choice of design parameters is made such that the dynamic model developed in this study simulates non-steady-state characteristics in a realistic manner. 8 different process control schemes are proposed, and their technical gains as well as dynamic characteristics are investigated in details. The control algorithms are assessed through controllability analysis, including open loop test, open loop disturbance test and dynamic response against disturbances. For improving process efficiency, operation procedure for shut-down and start-up is designed with constraints imposed such as rotating speed variation and inert material filling for the effective and practically-adequate control for a refrigeration cycle, with which feasible heat transfer can be readily maintained. The case study presented fully demonstrates the validity and applicability of the control system proposed in this study.

This paper proposes a combined cooling, heating and power (CCHP), and multi-effect desalination system to supply cooling, heating, power and freshwater. The proposed system mainly includes a gas turbine (GT), a multi-effect desalination unit with a thermal vapor compressor (MED-TVC), an organic Rankine cycle (ORC) integrated with a steam ejector refrigerator (SER), and heat exchangers. The mathematical model is developed to thermodynamically conduct energy-exergy analysis, and a parametric study is performed to explore the effects of key design parameters such as air compressor pressure ratio, inlet air temperature of air compressor, pinch point temperature difference of waste heat boiler, motive steam pressure of MED-TVC unit, TVC compression ratio and working medium flow rate of ORC on the system performance. The proposed system can provide power, heating, cooling and freshwater at loads of 31.25 MW, 1.108 MW, 4.203 MW and 85.89 kg/s under the design conditions. The electrical, the exergy, and the overall energy efficiencies of the present system are 36.44%, 41.26% and 46.70%, respectively. The results indicate that the power output of GT can be increased by precooling the inlet air of air compressor, and the integration of GT with MED-TVC unit, ORC and heat exchangers can efficiently recover the waste heat from exhaust gas based on the principle of “energy cascade utilization”. In addition, the largest exergy destruction occurs in the combustion chamber followed by regenerator 1 and the MED-TVC unit.

The excellent fuel economy of power-split hybrid electric bus has facilitated its extensive promotion for applications. However, a conventional rule-based energy management strategy for this bus involves large numbers of calibration, which considerably increases the application cost. To solve this problem, this study proposes an optimal rule design method that combines fixed thresholds with local working probability. This method effectively extracts control rules to obtain near-optimal result of global optimization and reduce calibration workload. In addition, a charge-sustaining strategy based on a linear quadratic regulator is designed to ensure the robustness of the energy management strategy based on rule design methodology. Finally, a simulation and hardware-in-loop (HIL) test are conducted on the Chinese city bus cycle. In comparison with the compared to rule-based engine optimal control, the proposed local probability-based instantaneous optimal control strategy is closer to the global optimization results, with oil savings of 10.6%. The comparison of the results between HIL and offline simulations show that they are largely coincident. Therefore, the proposed rule design methodology can serve as a theoretical reference for extraction rules in engineering practices.

The interaction between solar chimney and wind were investigated numerically and theoretically. A higher wind velocity does not represent a better performance, which depends on wind angle (α), which is the angle between wind direction and outward normal of the wall with the window. A windward situation (0°≤α

The impacts of climate change, largely fuelled by the consumption of fossil fuels and an unhealthy consuming lifestyle, are encouraging a wide and far ranging adoption of renewable energy sources. This is critical, and well received, for countries who are on the frontline of climate change, in particular Small Island Developing States (SIDS) and those with fragile, unique and complex natural ecosystems. While there has been research on the importance of renewable energy and on the increasing of its efficiency for bettering its adoption and resulting economic gain, there is however little literature on the design and its implementation in respect to the rich and fragile biodiversity of areas; which contribute greatly to local ecosystems, and even to liveability dimensions of fauna, flora as well as humans, regions and cities. To ensure optimal energy generation while preserving fragile ecosystems, a method for numerical Genetic Algorithm (GA) is proposed for wind farming optimization to determine both the sitting of wind turbines and the Levelised Cost of Energy (LCOE). Optimal sites were identified in the small island of Mauritius and the model was applied on a complex terrain around an airport to identify optimal sites for the sitting of wind turbines while analysing the energy offset in terms of demand and supply of the area to encourage decentralised and more stable energy networks. Based on a set of parameters including local regulations and guidelines, 3 scenarios with a layout of 12, 24 and 36 wind farming sitting arrangements were proposed with a minimal impact on the fauna and flora; including the pathways of migratory birds. This paper is aimed at energy, urban planners and policy makers looking at sustainable energy planning.

A water-cooled, stove-powered thermoelectric generator was designed and tested to provide electricity in off-grid areas and under emergency conditions. An Ω-shaped heat collector, which facilitates the compact incorporation of 20 thermoelectric modules and works under the radiation heat transfer mode, was proposed. A power load test was performed and compared with previous studies, thereby indicating that a standardization is required for future studies. Different aspects for evaluating the performance of a stove-powered thermoelectric generator were discussed, and appropriate parameters to qualify a stove-powered thermoelectric generator were suggested. Thermoelectric efficiency was measured and compared with a theoretical prediction. A simplified theoretical model, which was verified with experimental data, was developed to explore the temperature distribution inside the thermoelectric module and the power generation performance of the entire stove-powered thermoelectric generator. Special efforts were exerted to reveal the influences of thermal grease, ceramic substrate, and thermal contact on the effective temperature difference.

Thermally-driven sorption chillers offer a sustainable alternative to compression chillers. However, the expected benefits of sorption chillers are often not realised in practice due to high electricity consumption of auxiliaries, such as pumps and fans. To obtain an overall optimal full sorption chiller system, we propose a method for integrated optimisation of design and control. The proposed method applies dynamic optimisation to identify optimal control for each investigated system design. Thus, each design is evaluated under optimal control regarding a problem-specific objective, such as electrical efficiency or total costs. We illustrate the method for a case study of a solar-thermally-driven adsorption chiller system. The results are compared to an established design method and nominal control: optimising for electricity demand allows to increase the electrical energy efficiency ratio (EER) by one order of magnitude. When optimising for total costs, optimal control increases the energy efficiency by a factor 4 and decreases the total costs by 28% to 0.13 EUR/kWh. Moving to a cost-optimal design further increases the energy efficiency by 50% to 16.2 and reduces the total costs by another 8%. Thus, the proposed method allows for efficient integrated design and control of full sorption chiller systems.

A novel multi-form thermochemical energy storage method is proposed for high energy-density thermal energy storage based on multi-step sorption processes. The proposed multi-form thermochemical energy storage combines the physisorption energy storage of a porous matrix, the chemisorption energy storage of a salt hydrate, and the absorption energy storage of the salt solution. High-performance composite sorbent of MgCl2@zeolite was prepared to demonstrate the feasibility of the proposed multi-form thermochemical energy storage. The water uptake contributions of physisorption, chemisorption and absorption of the composite sorbent were measured by a “three-step” hydration method. The multi-step desorption processes measured by TG at an extremely slow heating rate shows the apparent decrease of decomposition temperature of MgCl2 hydrates in zeolite matrix. The maximum sorption capacity of the MgCl2@zeolite composite sorbent without solution leakage is as high as 0.55 g/g and its gravimetric and volumetric thermal energy densities reach 1368 kJ/kg and 308 kWh/m3 respectively with charging temperature of 200 °C. This gravimetric energy density is about 2.26 times higher than that of pure zeolite 13X. The experimental results verified that the proposed multi-form thermochemical energy storage is an effective method to improve sorption capacity and to achieve high energy-density thermal storage.

Hydrogen is a key raw material for many chemical processes and a clean fuel for various power generation strategies. Coal-to-hydrogen (CTH) conversion is an alternative way to produce hydrogen that is applicable to the abundant coal reserves in China. The use of fossil energy has contributed to severe environmental problems, which drives the development of potential hydrogen production processes. Biomass is a promising renewable energy as well as an attractive resource for producing hydrogen, and it may address some of these environmental problems. In this paper, the simulation results of the biomass-to-hydrogen (BTH) and CTH processes were validated using available experimental data from the literature. Based on the simulation results, a techno-economic analysis was conducted from the viewpoints of the first and second laws of thermodynamics. The techno-economic analysis included determination of the energy efficiency, material consumption, total capital investment, production cost and carbon tax. The energy efficiencies of BTH and CTH were 37.88% and 37.82%, respectively. The BTH process had a larger raw material consumption and total capital investment (TCI) than the CTH process. However, the BTH process had a lower production cost and GHG emissions than the CTH process. The results of energy analyses of the BTH and CTH processes showed that the energy efficiency can be improved from a thermodynamic perspective. The combination of thermodynamic analysis and techno-economic performance evaluation provides insights into the improvement and operation of clean hydrogen production.

Integrating evaporative cooling with loop thermosyphon can significantly improve the free cooling ability. In this paper, a loop thermosyphon with evaporative condenser is investigated experimentally. The mist water flow out of a single nozzle is observed and analyzed. The performance and annual free cooling potential of the system are investigated, compared with conventional loop thermosyphon. The results show that the evaporative cooling effect of the locations below the horizontal level of the nozzle is more significant due to gravity. With the increase of horizontal distance from the nozzle, the temperature decreases and then increases and the optimal distance is 200–400 mm. The heat capacity of LTEC increases with the increase of indoor and outdoor temperature difference while it decreases with the increase of humidity. Evaporative cooling can enhance the heat transfer of LTEC by 7%–33% compared with loop thermosyphon with conventional condenser, and this value is larger for smaller indoor and outdoor temperature difference and higher indoor temperature. LTEC can expand the annual free cooling time by 7%–14% compared with LTCC and the effect is more significant in regions with drier weather.

This paper proposed an absorption refrigeration system which employed two ejectors as cycle power source instead of mechanical pumps. Ammonia/lithium nitrate and ammonia/sodium thiocyanate solutions are applied as working pairs as well as an air-cooled type absorber are put up in this system. The liquid-vapor ejector is located at the inlet of the absorber, the steam-driven jet pump is set at the up-stream of the back flow of solution heat exchanger. Thermodynamic performance of this absorption refrigeration system has been comprehensively studied by numerical method; thus, comparison has been made with the conventional absorption refrigeration system. The result indicates that, compared with conventional air-cooled absorption refrigeration cycles, this novel combined double-ejector refrigeration cycle (DEARC) sacrifices part of refrigerant which leads to a decline of system COP value. But still, COP of DEARC can reach 0.6354, which is sufficient for practical use under exhaust heat conditions. Pressure ratio of liquid-vapor and the absorber outlet solution temperature are both two factors which make it possible to improve the system performance furthermore. Vapor consumption ratio is another key factor which has great influence to system performance. The wider range of generating temperature and the air-cooled type absorber of DEARC make it easy for the whole system to achieve miniaturization and simplification.

The objective of this work was to compare the effect of diethyl ether (DEE) and methyl tertiary-butyl ether (MTBE) addition to biodiesel and diesel blends on diesel engine. The ethers concentration have been varied in proportion of 5% and 10% on volume basis with biodiesel by keeping the diesel concentration as 50% for all ternary blends preparation. Experimental results revealed that D50-B45-DEE5 ternary blend has shown 5.3% increase in thermal efficiency compared to other ternary blends. On the other hand, D50-B45-MTBE5 and D50-B45-DEE ternary blends have reduced CO emission by 8.1% and 14.8% respectively when compared to high speed diesel fuel. Furthermore, the D50-B40-DEE10 blend and D50-B40-MTBE10 reduce the NOx emission by 32% and 8.8% when compared to HSD at maximum load condition. Significant reduction is noted in HC emission for all ether added ternary blends than that of HSD and biodiesel fuels. However, the smoke emission is decreased marginally for D50-B45-DEE5 than that of HSD fuel. Finally, it is evident that both the DEE and MTBE could be used as viable additive with diesel or biodiesel in binary and ternary forms for diesel engine applications.

This paper investigates the volatility spillover effects and dynamic correlations between China’s emissions allowances and fossil energy markets by employing the dynamic conditional correlation (DCC) generalized autoregressive conditional heteroscedasticity (GARCH) model. Thermal coal futures, South Sea crude oil and liquefied natural gas markets confirm short-term and long-term persistence on the Beijing, Shanghai, Guangdong and Shenzhen emissions allowances pilots, while those fossil energy markets demonstrate long-term persistence on Hubei’s emissions allowances pilot. The dynamic correlations between fossil energy and regional emissions allowance markets exhibit slight time-varying trends, and their dynamic correlations are at lower levels in the period considered. The prohibition of cross-region emissions allowance flow, inefficient dynamic linkage and poor price pass-through between the two markets may result in lower volatility spillover effects and dynamic correlations.

To balance the intermittent renewable energy and cope with the increasing nuclear power installed capacity in China, it is necessary for nuclear power plants (NPPs) to operate with load-following mode for enhancing economic competitiveness. The modular high temperature gas-cooled reactor (MHTGR) is an appropriate candidate for load-following operation due to the advanced features such as robust fuel elements, online fueling and full-power-range temperature negative feedback. The MHTGR-based nuclear steam supply systems (NSSS) which produces superheated steam flow for electricity, is the core for any NPPs. The proper control of NSSS is the prerequisite for the safe, stable and efficient load-following operation. However, in current engineering practice, the set-point trajectories of neutron flux, primary coolant temperature, primary and secondary flowrates are just the curves by linking the referenced steady values from the thermal hydraulic design, which are further determined by the thermal power requirement. Thus, it is meaningful to investigate an optimization-oriented control method to improve the operation efficiency. Motivated by this, two dynamic matrix control (DMC) with cascade structure are presented to improve both thermal power and steam temperature of the MHTGR-based NSSS. The thermal power is optimized by the first DMC through adjusting the set-point of nuclear flux. The second DMC is then designed based on the integration of the NSSS, the proportional-integral-derivative (PID) and the first DMC to improve the steam temperature response by adjusting the feed-water flowrate. The control performance during wide range operation is shown and discussed with the simulation results of a large-scale MHTGR plant model.

CO2 dilution is an effective strategy for combustion control. To understand the detailed dilution effects of CO2 (including physical effects and chemical effects) on CH4 and H2 combustion, an open-source CFD package laminarSMOKE was utilized to simulate the transient one-dimensional outwardly spherical flame combustion process in a closed chamber under 0–15% CO2 dilution mole fraction (α), at 293 K, 1 bar, stoichiometric ratio. The overall CO2 dilution effects decrease the unstretched/stretched flame propagation speed, maximum combustion pressure and prolong the combustion duration. In most conditions, physical effects play a dominant role and chemical effects amplify the dilution effects. Typically, the maximum combustion pressure of CH4-CO2-air flame at α = 15% reduces 1.15 bar compared with the undiluted case, the reduction percentage caused by physical and chemical effects is 12% and 1.5%, respectively. In addition, opposite overall effects of CO2 dilution on Markstein length (Lb) of CH4 flames and H2 flame are performed. The physical effects of CO2 dilution increase the Lb of CH4 flames but decrease that of H2 flames. Chemical effects are similar to physical effects for CH4 flames, but non-monotonic behavior is performed for H2 flame due to the combined effects of density ratio and mixture reactivity changes.

The integration of thermodynamic systems in industrial processes can help increasing the energy recovery and provide more integration opportunities. However, designing such technologies in a simultaneous mass and heat integration is a large-scale and complex problem. Indeed, the heat requirements created by the mass allocation network are unknown prior to the whole design. Besides, designing sequentially the mass allocation network (MAN) and the heat exchanger network (HEN) can lead to sub-optimal solutions. This paper proposes a three-step methodology based on mixed-integer-linear-programming (MILP) models to evaluate economically suitable technologies, reducing strongly the computational time. After a preliminary step, a first MILP model evaluates economically a great number of technologies simultaneously. In this model, the simplified total cost, including thermodynamic systems capital costs, is minimized. Then, the best thermodynamic systems candidates are identified and used in a second MILP solving the larger problem including the simultaneous MAN and HEN design. The performances of the methodology are assessed on an ammonia recovery case study: 3 economically relevant technologies among 74 are selected in a few seconds. Then, the MAHEN (mass allocation and heat exchange network) is designed with these technologies, showing a decrease of total annualized cost of 3.6%.

Long-term joint scheduling of hydropower station group (LJSHSG) is a constrained optimization problem, which suffers from a variety of complex and time-state coupling constraints. It is beset with difficulties to solve LJSHSG problem owing to these equality constraints, rigid constraints and flexible constraints of hydropower station group (HSG). The new hybrid constraint handling method combining e-constraint (EC) and penalty functions (PF) (named EC-PF) is proposed to deal with these constraints in this paper. In the proposed EC-PF, all equality constraints are forced to satisfy according to the equation; EC handle all rigid constraints with minimizing the value of constraint violation and constraint relaxation rule; and the unique flexible constraint, guaranteed output constraint, is processed by PF. Then the proposed EC-PF is compared with the superiority of feasible solutions (SF), stochastic ranking (SR), PF, EC and lexicographic method (LM) in the application to LJSHSG problems; the experimental results verify the superiority of the proposed method. Moreover, the conclusions that it is necessary to deal with rigid constraints from flexible constraints differently in LJSHSG problem are obtained. On this basis, in view of the defect that guaranteed output constraints are difficult to satisfy in LJSHSG, the LJSHSG with the cooperative mode to handle guaranteed output constraints (named LJSHSG-cm) is puts forward. The comparative experimental results of LJSHSG and LJSHSG-cm show that LJSHSG-cm can increase the power generation by 0.3% while increasing the satisfaction rate of guaranteed output constraints by 78.56% compared with LJSHSG for long sequence calculation from 1959 to 2014. These are fully illustrated that the hybrid constraint handling method EC-PF and LJSHSG-cm with the cooperative mode to handle guaranteed output constraints are valid and reliable practical tools in solving LJSHSG.

Both numerical simulations and experiments were conducted in a heavy-duty DICI engine, with PRF81 as a gasoline surrogate, to investigate how the fuel stratification, auto-ignition and combustion are affected by the start of injection (SOI). The intake air temperature was adjusted to keep the combustion phasing constant when the SOI was swept from − 100 to − 20 oCA ATDC, covering different regimes of combustion, from HCCI to PPC. It is found that in the HCCI regime the combustion process is less sensitive to the variation of SOI since the fuel/air mixture is fairly homogeneous. The fuel/air mixture is under fuel-lean condition and the required intake temperature for a constant CA50 is the highest. In the PPC regime there is an optimal SOI window, within which the required intake temperature is the lowest to maintain a constant CA50 and the engine thermal efficiency is the highest. The optimal operation window starts at the SOI when all fuel is injected into the piston bowl and ends when the fuel injection is towards the bottom wall of the piston bowl, which results in a high heat transfer losses. The SOI window for optimal engine operation is expected to be fuel injector and piston bowl geometry dependent. During the transition regime, the fuel is injected towards the piston head in the squish region. The combustion process is highly sensitive to SOI due to the high sensitivity of fuel distribution in the cylinder to SOI. The engine thermal efficiency is the lowest due to the incomplete oxidation of fuel in the squish region.

It is highly important to clarify the determinants of China’s energy consumption for the smooth implementation of energy conservation. For this purpose, this paper discusses the contribution of China’s different economic sectors to decoupling progress. Then, it uses an extended logarithmic mean Divisia index (LMDI) method to decompose China’s energy consumption into seven factors. The major findings indicate that during the 2000–2016 period, (1) the decoupling status between China’s economy and energy consumption were determined largely by the secondary industry; (2) the positive contribution of three sectors to the decoupling process was ranked as follows: primary industry>tertiary industry>secondary industry; (3) China’s energy consumption showed a growing trend, and the expansion of per capita fixed asset investment was the main factor responsible for the energy consumption increase, especially in some provinces whose investment structure was skewed towards energy-intensive industries. Additionally, population growth had mild positive impacts on the energy consumption increase; (4) declines in energy intensity and investment efficiency were two major contributors to energy-saving. However, economic structure, energy structure, and spatial structure adjustment failed to reduce energy consumption but had overall positive impacts on the energy consumption increase. Finally, several policy recommendations related to reducing energy consumption are proposed.

This study proposes an optimization-based approach for strategically planning a biomass-based hydrogen energy network. In achieving this goal, the superstructure of a biomass-based hydrogen energy system is proposed, which includes different biomass resources (biomass waste and energy crops) and various technologies (production, storage and terminal, refueling station, and transportation). A multi-site and multi-period optimization model is then developed using a mixed integer linear programming to determine the optimal investment timing and regional allocation alongside the selection of proper biomass types and technology combinations. The capability of the proposed approach is validated through a case study of Jeju Island, Korea. As a result, it was identified that the optimal network configuration as well as the investment and operation strategies are determined by the biomass type and regional biomass availability. In addition, the sustainability of the proposed energy system was analyzed using the criteria such as energy security and environmental protection, as well as economics.

The pyrolysis characteristics of sewage sludge, wheat straw and its mixture were studied by non-isotropic thermogravimetric analysis (TGA). In the temperature range of 400 K–950 K, 40 K/min, 45 K/min and 50 K/min heating rate were set respectively, in N2 atmosphere and CO2/N2 mixed atmosphere. According to the thermal analysis chart obtained from TGA, it was observed the vast majority of mass loss spread at the range of 450–800 K in all samples. The Co-pyrolysis kinetics of sewage sludge and wheat straw was described by a fourth-order DAEM model. It is proved that the model can well match the TG experimental data. The results obtained from the optimized parameters show that the activation of sewage sludge is lower than that of wheat straw, and the activity of the mixture gradually increased with the increase of wheat straw content. The presence of CO2 has a slight inhibitory effect on the pyrolysis of the mixture below 900 K compared to that in an N2 atmosphere, but with temperature increasing, CO2 will have a secondary reaction with biochar.

In the Republic of Djibouti, due to increasing electricity demands, the government has planned to increase power supply by using renewable resources such as geothermal, solar and wind energy. This work presents the first wind resource assessment in the Republic of Djibouti using measured wind speed data for the period of three years by meteorological stations at eight locations. The results confirmed that three of the eight locations (i.e. GaliMa-aba, Ghoubbet and Bada Wein) have the best resource, with mean annual wind speeds of more than 6.0 m/s. Wind simulations using NCEP-CFSR and ERA5 models reanalysis shows that the seasonal variations are stable between different years and are broadly consistent with the observed wind speed. The feasibility of three wind farms with total capacity of 275 MW at GaliMa-aba, Ghoubbet and Bada Wein is examined. Using the WindPRO program and two commercial wind turbines in according to IEC 61400-1 design criteria, the electricity generation were technically assessed. These wind farms can produce 1073 GWh of electricity per year, approximately equal to Djibouti's expected average annual electrical demand in 2030. The economic evaluation using the present value cost (PVC) method estimate that the generation cost per kWh at these locations varies from 7.03 US.$ cent/kWh to 9.67 US.$ cent/kWh.

The methods of robust analysis and stability analysis of natural gas supply system are proposed. Using this method, the integration of bifurcation theory and Lyapunov's stability theory was performed, accounting for uncertainty and complexity. China's natural gas supply system is composed synthetic natural (SNG) and pipeline natural gas (PNG), both of which change unsteadily and interact in a nonlinear manner, making the supply process of the natural gas supply system dynamic. In light of this, and based on the Two Species Competition Model, a natural gas supply dynamics model composed of SNG and PNG is established to express the dynamics of China's natural gas supply system. Fixed points stability analysis theorems are proposed with reference to Lyapunov's stability theory, and the stability of the natural gas supply process was analyzed using these theorems, whose rationality was verified by numerical simulation. The robustness of the natural gas supply system is described in detail in terms of the external disturbance degree and the inherent invulnerability of the system, by means of bifurcation theory and the maximum Lyapunov exponent.

With the rapid development of crude oil reserves, energy consumption in heating increases gradually, so it is necessary to study heating effect and energy utilization. In this paper, a theoretical model of coil heating process for large floating roof crude oil tank is established, with dynamic thermal environment and variable physical parameters of oil products taken into consideration comprehensively. The influence mechanism of coil structure on the coupling characteristics of heat transfer and flow of crude oil during heating process is revealed. On this basis, the heating effect of crude oil in storage tank is evaluated from the point of view of time and space respectively. Simultaneously, the properties of energy and its quality are both considered, the effective energy utilization efficiency of crude oil in storage tank during heating process is analyzed, and an optimization method for heating coil of tank oil is proposed. The results show that the temperature of oil products in the center and bottom of the tank increases linearly with the influence of heat sources, and the temperature of oil products at the roof and wall of the tank is greatly affected by the dynamic thermal environment, which is showing a change regulation of fluctuating pattern. The heating effect is greatly affected by coil length. The increase of coil length can obviously improve the flow structure of crude oil in the tank. A larger eddy structure can be formed in a shorter period of time, which can increase the heating rate of crude oil and further reduce the non-uniformity of temperature field. However, effective energy efficiency is greatly affected by coil diameter. The increase of coil diameter increases the convective heat transfer coefficient between coil and crude oil, which promotes crude oil to absorb heat more easily from heat sources and improves the effective utilization of energy and exergy. Therefore, the heating effect and effective energy utilization of oil coil can be further optimized by changing the length and diameter of coil. Relevant research results can provide theoretical and technical support for improving the utilization efficiency of reserve energy and reducing the cost of reserve energy consumption.

The co-gasification of coal and dried sewage sludge (DSS) was conducted using a two-stage gasifier consisting of a fluidized bed gasifier and a tar-cracking reactor. In this study, the effect of the blending ratio of coal and DSS was investigated. Producer gases that were obtained from the tar-cracking reactor filled with active carbon contained high levels of hydrogen (maximum H2: 27.7 vol%) and low tar contents (minimum tar: 0 mg/Nm3). Upon gasification of the coal/DSS blends, the hydrogen content decreased and tar content increased with increasing DSS. Blends with coal/DSS ratios of 70/30 and 50/50 showed a synergetic effect on tar reduction, which could be attributed to the high ash content of the DSS. The gasification of the 70% DSS blend increased the condensed tar yield by only 0.1 wt%, compared to coal gasification. Lastly, a hot filter filled with Fe-impregnated active carbon was applied to completely remove tar from producer gas, which led to the production of a tar-free and hydrogen-rich gas (30 vol%). Furthermore, the Fe-impregnated active carbon reduced the H2S content to 229 ppmv. In summary, it was possible to produce a clean gas from coal and DSS blends in the UOS gasification process.

The improvement of thermal energy use in batch and semi-continuous processes utilizing established techniques such as Pinch Analysis faces challenges as direct heat recovery is restricted and schedule dependent, limiting broad industrial application. In overcoming this limitation, sensible heat storage integration has proven to be effective in achieving significant and less schedule-sensitive heat recovery but designing solutions is problematic given the complex trade-offs that occur. The presented graphical design method relies on the Indirect Sources Sinks Profiles (ISSPs) which extends the scope of time-average models and brings a systematic foundation to the design procedure. Graphical assignment zones are introduced to represent on the ISSPs constraints and degrees of freedom that apply when designing the Heat Exchanger and Storage Network (HESN) that can achieve the target heat recovery, given by ISSP overlap. A general procedure for their determination is presented, alongside resulting HESN designs for a case study process which achieve utility reductions of 35.0% up to 76.0%. Designs are automatically balanced making them functional concepts without manual adjustment, and although not cost-optimized, are inherently reduced in complexity by the method and suitable for further stepwise improvement.

Real-time control of district heating networks in the case of failures requires for accurate and fast strategies able to guarantee thermal comfort to all connected users. In this paper, we demonstrate a control framework that responds to these essential requirements. We minimize a global measure of discomfort based on a smooth maximum approximation. The optimization problem is solved through a gradient-based algorithm that can be naturally integrated with distributed meter readings leading to high accuracy of both forward and sensitivity analysis. Objective function gradients are computed by a discrete adjoint method, which is fast and nearly insensitive to the dimensionality of the optimization problem. The proposed framework is tested with numerical experiments on a reference medium-size distribution network in Turin. Results show that the thermal comfort of most critical users increases quickly, yielding to a nearly homogeneous discomfort distribution at the end of the optimization process. Studying the effect of the inlet pressure head on the optimized system performance reveals that a centralized operation results in increased robustness of the network and allows reducing backup pumping equipment. Furthermore, applying the proposed framework at the distribution network level yields remarkable benefits also in case of failures in the main transportation network.

Heat fluxes in a district heating pipeline systems need to be controlled on the scale from minutes to an hour to adjust to evolving demand. There are two principal ways to control the heat flux - keep temperature fixed but adjust velocity of the carrier (typically water) or keep the velocity flow steady but then adjust temperature at the heat producing source (heat plant). We study the latter scenario, commonly used for operations in Russia and Nordic countries, and analyze dynamics of the heat front as it propagates through the system. Steady velocity flows in the district heating pipelines are typically turbulent and incompressible. Changes in the heat, on either consumption or production sides, lead to slow transients which last from tens of minutes to hours. We classify relevant physical phenomena in a single pipe, e.g. turbulent spread of the turbulent front. We then explain how to describe dynamics of temperature and heat flux evolution over a network efficiently and illustrate the network solution on a simple example involving one producer and one consumer of heat connected by “hot” and “cold” pipes. We conclude the manuscript motivating future research directions.

Main idea of power scheduling for aero-engines is to decompose the complex nonlinear energy management and is to cover each break point in all operating conditions by digital engine control unit. In the current study, dynamic energetic and performance measures of an experimental small target drone turbojet engine are calculated at various shaft speeds in test-cell. In this context, some experiment test steps were conducted to measure the performance parameters of the engine at different shaft speeds. With the help of the calculated parameters, efficiencies, power and energy indexes of the engine are also determined. According to analysis, wasted power varies between 7.69 kW and 259.61 kW, while total power of the fluid is 10.2 kW at 25000 RPM and reaches 331.66 kW at 47500 RPM. As for engine efficiency results, with increasing RPM, thermal efficiency is strongly varying with 18.33%, whereas the change ratio of propulsive efficiency stays modest level with 5.17%. As a conclusion, it is expected that these assessments can be employed in the control law design of similar power system controller and also to increase the efficiency of existing systems.

The stiffness of Li-ion batteries is defined as the derivative of force with respect to displacement. The existing constitutive models of the jellyroll of Li-ion batteries reveal that such stiffness keeps increasing as displacement increases. In this study, quasi-static mechanical abusive tests are performed on 18650 cylindrical Li-ion batteries at different state of charge. The experimental results indicate that three distinct stages are identified in the stiffness curve corresponding to densification stage, microscopic damage stage and macroscopic failure stage, and the stiffness only increases in the first stage and decreases in the latter two stages. Therefore, this paper proposes the improved constitutive model of the jellyroll of Li-ion batteries to describe their kinematics considering microscopic damage. An explicit finite element model of a Li-ion battery is established to validate the improved constitutive model. The voltages and temperatures of Li-ion batteries are also recorded to reveal their responses at different stages. It is found that Li-ion batteries at the fully charged state initiate internal short circuit before the end of the stage 2 (microscopic damage stage) whereas Li-ion batteries at low state of charge will only initiate internal short circuit at the stage 3 (macroscopic failure stage).

To integrate more renewable energy into the power grid, thermal power plants have to accelerate the speed of power output and extend their operating ranges, and this can result in great challenges for their safe operations and even safety accidents. To this end, a gain scheduling design based on active disturbance rejection control (ADRC) is proposed for thermal power plants under full operating conditions. The urgency of the proposed control strategy is illustrated by analyzing the control difficulties of coordinated control systems. Then the scheduling parameter selection and the linear switching method for the proposed control strategy are analyzed. Moreover, the qualitative stability analysis based on the Kharitonov theorem and the quantitative calculation of stability regions are carried out to ensure the stability of the closed-loop system. Simulations of the power tracking under different load tracking rates and disturbance rejection under the coal quality variation are carried out. Simulation results show that the tracking and disturbance rejection performance in both power output and throttle pressure loops has been improved simultaneously compared with the regular ADRC and the traditional proportional-integral control strategies. Based on the verified superiority, the proposed gain scheduling design based on ADRC shows a promising potential in industrial applications.

The effect of different thermal conditions on battery performance has been evaluated by computer simulation through a thermal model coupled to the electrochemical model. Three different active materials, lithium cobalt oxide, LiCoO2, lithium iron phosphate, LiFePO4 and lithium manganese oxide, LiMn2O4, were evaluated together with two battery geometries: conventional and interdigitated. The delivered capacity of the different active materials and both geometries were thus obtained as a function of the scan rate and correlated with the produced reversible, reaction, ohmic and total heat. For isothermal conditions, the highest capacity is obtained for LiCoO2, being 739,31 Ahm−2 at 1C for the conventional geometry. Further, battery performance as a function of the scan rate is independent of the geometry and similar for the different active materials. Under adiabatic conditions and independent geometry, LiFePO4 produces lower heat in the discharge process, the temperature ranging from 298 K to 308.9 K when the battery operates up to 500C for and interdigitated geometry with eight digits, which is critical for improving battery safety. This fact is also confirmed by the ohmic heat value along the cathode at the rate of 300C, which is 42700 W m−3, 118000 W m−3 and 69000 W m−3 for LiFePO4, LiMn2O4 and LiCoO2, respectively, for a conventional geometry as at a time of 50s of battery operation. Thus, it is demonstrated how battery geometry and the intrinsic parameters of the active materials affect the heat generated by the batteries and, considering the balance between cycle performance and thermal properties, the best active material for improved battery safety and performance is LiFePO4., This work was supported by the Portuguese Foundation for Science and Technology (FCT) in the framework of the Strategic Funding UID/FIS/04650/2013. The authors thank FEDER funds through the COMPETE 2020 Programme and National Funds through FCT under the projects PTDC/CTM-ENE/5387/2014, UID/CTM/50025/2013 and PTDC/FIS-MAC/28157/2017 and grant SFRH/BPD/112547/2015 (C.M.C.). Financial support from the Basque Government Industry Department under the ELKARTEK and HAZITEK programs is also acknowledged.

Radiant cooling systems (wall and ceiling) are low exergy systems which can help in solving efficiently the comfort needs of occupants. However, a complex energy and exergy analysis should be done in the design phase of such cooling systems in order to choose the most appropriate solution. This paper attempts to present a mathematical model and methodology of such a complex analysis and illustrates through a case study the energy and exergy comparison of cooling systems with mechanical compression and absorption cooling systems. Simple relations were developed in order to evaluate rapidly the energy and exergy efficiency of these types of cooling systems taking into account the avoidance of surface condensation. It was proven that, besides the coefficient of performances of installed chillers, the temperatures in the generator and absorber, respectively the supply and return temperatures are the main influencing factors of the exergy efficiencies of such types cooling systems. Based on the developed mathematical method a numerical analysis was done assuming different operational parameters of the cooling system used in practice.

Borehole heat exchangers (BHEs) are often used to harvest geothermal energy at shallower depths. The standard increase in temperature with depth is generally ignored. Without high quality electricity generation as with enhanced geothermal systems (EGS) there is a lack of financial incentive for drilling deeper for higher temperatures. This temperature increase, or geothermal gradient, is rarely captured by analytical BHE models for building heating and cooling. In this paper we present a new analytical model for a coaxial borehole heat exchanger (CBHE) that specifically considers geothermal gradient. We first verify our model output by comparing results with existing numerical and experimental results under the same configuration of CBHE. To further investigate our model's sensitivity towards fluid flow direction, geothermal gradient, and borehole thermal resistance, we also compare the temperature distributions and rate of heat gain/loss along the flow direction within the entire proposed CBHE. We identify the best flow direction with annulus as inlet in heat extraction mode, confirm positive influence of increasing geothermal gradients towards the heat extraction, and confirm a nonlinear correlation between the borehole thermal resistance with the output fluid temperature and amount of heat extracted. This study can provide a useful analytical simulation tool and important guide to design of CBHE.

In DI diesel engine, air-fuel mixing is a major parameter that affects the performance, emissions parameters and combustion characteristics. In-cylinder air motion and proper mixing of fuel have a strong effect on BTE, BSFC, UHC, CO, smoke and NOx emissions, because of improvement in the combustion of fuel. In this experimental investigation in order to enhance the performance of biodiesel-fueled diesel engine, the engine was tested using piston having internal air jets using 20% Jatropha Oil Methyl Ester-diesel blend (B20 JOME). For this purpose, the piston of the standard engine having Hemispherical Combustion Chamber (HCC) was reformed into Toroidal Re-entrant Combustion Chamber with internal air jets (TRCC-IAJ) that has the same volume as baseline HCC. The tests were performed at IMEP of 1.7, 3.2, 4.7, 6.2 and 7.7 bar with the standard injection timing and pressure. The test results show that the BTE and BSFC provide the best result for the modified piston compared to the original. The TRCC-IAJ reduced the smoke, CO and HC; while it showed the opposite effect with a sharp increase in NOx emissions. In overall, the results show that the modified piston TRCC-IAJ has improved the overall performance and emissions of the JOME-diesel blend.

Black soldier fly larvae containing high lipids had been considered an novel sustainable feedstock for lipid extraction to biofuels. The insect lipid was extracted with microwave assisted solvent extraction method. The energy consumption of this way was analyzed to determine the feasibility of the lipid extraction process. The comparison of the effects of different extraction conditions (dehydration methods, water content, extraction temperature, extraction time, equipment power, and solute-solvent ratio) on the energy consumption of lipid extraction from the energy insect was investigated systematically. The dewatering of the insect biomass was the most energy consuming step via a dry extraction method in this paper, constituting about 40–80% of the total energy consumption demand. Within the ranges of extraction factors values compared in this analysis, the microwave radiation powder and lipid extraction temperature had a pronounced effect on the total energy consumption in the ranges of investigated parameter. At last, the lipid extraction yield-dependent evolution of energy consumption for different extraction conditions was also investigated. Anyway, the economic and environmental aspects of lipid extraction from the energy insect needed to be further improved for its large scale implementation in the future.

The paper deals with the formation of a list of critical facilities in Russia's gas transportation system in terms of energy security, and the substantiation of potential ways to minimize the negative effects of emergency situations on operation of these facilities. To date the lists of critical facilities in the energy systems have been formed on the basis of the performance analysis of certain facilities. The paper addresses the problem of identification of such facilities depending on their impact on overall operability of the system. This is accomplished by analyzing the level of negative impact caused by termination or disturbance of operation of a certain facility on consumers. The analysis employs the software “Russia's Oil and Gas” (“ROG”). The principles of identifying critical facilities in Russia's gas transportation system are demonstrated, specific examples are shown, and potential ways to mitigate the negative impact of emergency situations at such facilities on gas consumers are formulated.

This study explored the optimization of pretreatment of pineapple peel for biogas generation. Pretreatments were carried out sulfuric acid and alkaline hydrogen peroxide prior to anaerobic digestion while the response surface methodology (RSM) was used for optimization of the pretreatment procedures. The physical, chemical, proximate and structural compositions of the peels were determined prior to and at the end of the pretreatment procedures. The dynamics of microorganisms in the reactors were also evaluated by rapid molecular methods while the Fourier Transform Infra-red (FTIR) spectroscopy was employed in the identification of the chemical changes as a result of pretreatments. The use of H2O2 pretreatment caused enormous lignin solubilization in the pineapple peel. In comparison, biogas production was 67% more in the alkaline pretreated pineapple peel than the biomass treated with acid and also 51% over the untreated samples. The total biogas volume produced from the acidic pretreated, alkaline pretreated, not sifted untreated and sifted untreated samples are 194.2 ± 3.0, 587.5 ± 5.2, 287.8 ± 2.1 and 245.4 ± 3.1 respectively. Thus, the alkaline pretreated experiment used lower retention time to achieve maximum gas production in this study. The use of alkaline H2O2 on lignocelluloses has remained unpopular prior to this study. However, its usage in this study yielded better result than all the conventional treatments in terms of lignin solubilization and improvement in methane yield. Economically, the use of H2O2 for pretreatment is adjudged feasible because the 1504 kWh t−1 TS thermal energy gain obtained from the biogas produced by the alkaline treated peel exceeded the 921 kWh t−1 TS used in the pretreatment. This gives a net thermal energy of 583 kWh t−1 TS. Whereas, the investment into acidic pretreatment of pineapple peel may not be economically justified because the total thermal energy gain of −200 kWh t−1 TS was far lower than the 1236 kWh t−1 TS thermal energy that was consumed during the pretreatment giving a net thermal energy of −1436 kWh t−1 TS. Therefore, the use of mild alkaline pretreatment is advocated in biogas generation from pineapple peel and also for biofertilizer production mostly in localities of mass production.

Regarded as a cause of energy dissipation, thermal radiation plays an important role in combustion systems. This work aims to study the flame radiation property of rectangular energy sources. Total nine n-heptane pools with the same width of 8 cm but different aspect ratios of length to width (n = l/w) from 1 to 14 were used as fire sources in open space. The mass loss rate (MLR), flame shape and radiant fluxes received by external vertical targets were analyzed. The MLR per unit length ( m ˙ l ) and flame height show three trends of decreasing slopes with increasing n, the boundary are 3 and 10 and the fuel shape becomes linear when n ≥ 10. A new method of two-dimensional description is introduced to determine the mean flame height distribution along the pool length, a piecewise function consisting of three stages is proposed. Assuming the radiative fraction of heptane is 0.3, the radiant fluxes to external targets are calculated by applying a modified weighted multi-point source (WMP) model, which extends the weight to a two-dimensional flame plane. The proposed model is validated by comparing with the other models and using the experimental data in this work.

During the preparation of nanocomposite phase change material (nanoCPCM), more attentions are focused on thermal conductivity. In fact, adding nanomaterial not only affects thermal conductivity, but also changes the other thermophysical properties of PCM and causes complicated effects on latent heat storage performance. In present study, melting behavior of pure phase change material and its four kinds of nanocomposites in a horizontal concentric tube were investigated and a new evaluation index was developed to examine the effects of nanomaterial on heat storage performance of nanoCPCM. The results show that both thermal conductivity and melting temperature have significant effects on nanoCPCM melting behavior and heat storage rate. Sometimes, although the thermal conductivity is enhanced, the heat storage rate is decreased due to its melting temperature increasing caused by nanomaterial. Especially, when the heat source temperature and PCM melting temperature is close, the variation of melting temperature is more significant. For example, nanoCPCM with SWCNT has the higher thermal conductivity, but its heat storage rate is slower than nanoCPCM with MWCNT, because of its higher melting temperature. Therefore, more attention must be paid to the variation of melting temperature caused by nanomaterial during the preparation and application of nanoCPCMs.

Accurately estimating the state-of-charge (SOC) of lithium-ion batteries under complicated temperature conditions is crucial in all-climate battery management systems. This paper proposes a model-based SOC estimation method for series-connected battery pack with time-varying cell temperature. Systematic battery experiments are conducted to investigate the influences of changing temperature on both cell characteristics and cell-to-cell inconsistencies. A normalized open-circuit voltage (OCV) model is developed and applied in cell Thevenin model to describe the temperature-dependent OCV-SOC characteristic. The battery pack SOC is analyzed considering the effect of passive balance control. Then, a lumped parameter battery pack model is established by connecting cell models in series. To reduce computational complexity, a dual time-scale parameter identification framework is proposed which is supported by an online filtering process of selecting variable reference cell (VRC). An adaptive co-estimator is presented to update pack parameters in dual time-scale using an optimized recursive least squares algorithm, and to estimate the battery pack SOC using an extended Kalman filter. Experimental verifications are conducted under time-varying environmental temperature ranging from −40 °C to 40 °C. Results indicate the established model can well describe the dynamic behavior of battery pack, and the proposed method can estimate the battery pack SOC with considerably high precision.

The electric supercharger has the advantages of reducing turbo lag and improving low-speed torque of turbocharged engine. The steady-state model using 1D simulation was performed to analyze the effect of the supercharger on the increase of BMEP and the combustion phenomena. Also, transient simulation using a mean value engine model (MVEM) was performed to analyze the improvement of engine response and fuel economy. The differences of engine performance were analyzed according to three locations (Layout A, B, and C) of the supercharger and the air-fuel ratio under controlled and uncontrolled conditions. The BMEPs increased 140.3%, 65.6%, and 17.3%, based on the maximum BMEP of the engine under the air-fuel ratio controlled condition in 1000 rpm, 1250 rpm, and 1500 rpm respectively. The validity of the BMEP analysis can be verified through the results of the combustion pressure; the results seem reasonable in this respect. The volumetric efficiency, maximum combustion temperature, and intake mass flow rate were compared to analyze the cause of volumetric efficiency change by using the supercharger and air-fuel ratio control. In addition, the total fuel consumption decreased by 18 g from 574 g to 556 g owing to the effect of the supercharger in the NEDC simulation.

Having in view the current balance of natural resources, uncertain economic conditions and the expansion of gas infrastructure, it seems reasonable to have a significant number of gas power plants incorporated into the existing power system. The purpose of this paper is to show, through quantification of impacts of the integrated gas and electric power network, that the failures of the radial gas subsystem, in terms of security, as a rule, are more critical for the integrated electric power system than failures in the electric power subsystem. In the second part of the paper the predictive control actions are analyzed in order to minimize the negative impact of failures in the gas subsystem. In such a way the optimal operation of the gas power subsystem can be achieved. This approach is feasible under the condition that gas power plants are included in smart grid with continuous data acquisition from the gas plants and the pipeline system.

Combined methane reforming with a mixture of methane combustion products and steam over a commercial Ni-based catalyst is studied both experimentally and theoretically. The 7-holes cylinder of NiO-αAl2O3 catalysts is used as the pellets. The thermodynamic analysis of the reforming process was carried out by total Gibbs free energy minimization to determine the maximum achievable methane conversion in the reformer. The reforming performances were determined for various amount of extra steam in inlet reaction mixture (from 0 to 2 mol of H2O per mole of CH4). The methane conversion is increasing when steam is added to the reaction mixture at a fixed temperature. The methane conversion reaches a maximum value (about 1) at the temperature range above 800∘C. Based on experimental results, the approximation functions of the methane conversion versus the residence time for the various temperatures and methane-to-oxidizer ratio were obtained. The methane conversion reaches the value that is close to equilibrium at the residence time above 4.0 kgcat⋅s/mol. The effect of pressure (in the pressure range from 1 to 5 bar) on methane conversion is insignificant and is no more than 1–2%. The values of the methane conversion can be used for the energy analysis of the thermochemical recuperation system by methane reforming with steam and flue gases.