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• Design of a non-intrusive device to intelligently control electric water heaters. • Development of a machine-learning tool to forecast residential hot water demand. • Details and results of a six-month pilot study where the device was implemented. • Heating demand reduced by an average of 26.43% and cost saving of 35.54% per device. • Device is cost-effective and can reduce the need for imported fossil-fuel generation. Water heating accounts for approximately 25% of household energy use in developed countries. Therefore, the optimal control of water heating through the deployment of intelligent residential Electric Water Heaters (EWH) brings significant benefits. This paper presents an innovative design and implementation of an easy-to-use device for intelligent residential water heating. The device relied upon machine learning techniques to forecast a consumer's hot water demand and optimize the operation of an EWH using a novel data collection process that relied on non-intrusive vibration data alone. The device was deployed in a six-month pilot project on the island of São Miguel, Portugal. The major difficulties were the novel use of vibration data to forecast the volume of hot water used and the uncertain behavior of the consumers. The challenges of only using vibration data were solved by careful data collection and artificial intelligence methods. To tackle the issue of uncertain consumer behavior, an innovative 'heat now' function was incorporated into the device to override the novel control framework. Results show that the device could accurately forecast hot water demand and optimally operate the EWH to meet this demand. The results showed an average reduction of 1.33 kWh/day per consumer, which equates to an average decrease of 35.5% in water heating costs. Calculations show that these devices can reduce the total energy used by 2832 kWh daily or 0.21% of total electricity generated. Furthermore, a fleet of these devices could reduce thermal generation by 0.37%, reducing emissions by 693.31 tons of CO 2 per year. The results from the consumer survey show that the device did not affect the consumer's comfort, validating the benefits and efficacy of the proposed device. Hence, the paper shows that a simple-to-use, novel device using an innovative forecasting algorithm based on non-intrusive vibration data brings numerous quantifiable benefits to actual consumers and electrical utilities. [ABSTRACT FROM AUTHOR]

Individual metering and charging of heat and domestic hot water is one of the possibilities for reducing the energy consumption in existing multifamily buildings and, with this aim in mind, the EU-directive 2012/27/EU enforced the installation of individual heat consumption meters. Even though some experimental evaluation of energy savings that may be achieved in multifamily buildings with individual metering & charging systems can be found in the literature, the majority of these research pieces are focused on case studies or taking into consideration conditions related to cold climates, and there is still a lack of studies focused on evaluating its effects in more temperate climates that can be also found in Europe. Thus, in this paper, the potential of individual metering and charging of heat and hot water for saving energy in residential buildings in temperate climates is evaluated and quantified. To do so, a literature review on implementation of this system is carried out and presented firstly to get a better understanding of its implications on energy consumption in buildings. Afterwards, heating and hot water consumption data collected in a multifamily building where individual metering and charging system was implemented is evaluated in detail. With the aim of quantifying its effect on heating and hot water consumption, data corresponding to four complete heating seasons (two heating seasons prior to its implementation, and the two first heating seasons after implementing it) have been evaluated in detail, following a specific method described in the paper. Results show that individual metering and charging has brought a reduction of normalized energy consumption of 15–20% during the first two years after implementing it, and simple payback periods are around 10 years. These results confirm that individual metering and charging affects directly on user behaviour encouraging inhabitants to change their habits to reduce their energy consumption, and this effect is significant even in European temperate climates, such as the evaluated case study shows. [ABSTRACT FROM AUTHOR]

• TIP-EMS enhances EV energy efficiency by integrated prediction and energy management. • Significant driving economy boost; 1.6%-4.2% better than state-of-the-art PEMS. • TIP-EMS shows robust performance with varying prediction weight adjustments. To enhance the energy efficiency of electrified vehicles (EVs), developing effective energy management strategies (EMS) for hybrid storage systems is essential. Predictive EMS (PEMS) that foresee future vehicle speeds have demonstrated substantial potential in boosting EMS performance. However, traditional PEMS models, employing a sequential approach of speed prediction followed by energy allocation, are hampered by cumulative errors. These errors from the initial speed predss this issue, this paper introduces a novel solution: the trainable integrated preiction negatively impact the efficiency of subsequent energy management. To addrediction and energy management strategy (TIP-EMS). Contrasting with conventional sequential PEMS, TIP-EMS features a dual-branch, integrated neural network, which is fully trainable. This network processes driving status inputs via attention layers, with one branch dedicated to energy management objectives using a reinforcement learning (RL) algorithm, and the other to vehicle speed prediction. Both branches are trained simultaneously, but post-training, only the RL branch is activated for energy management. Implemented with a soft actor-critic RL algorithm, TIP-EMS is applied to a fuel cell EV for optimized energy management. The validation involved training TIP-EMS using 27 driving profiles, which developed its prediction and energy management capabilities, followed by tests in untrained scenarios. The results show that TIP-EMS surpasses conventional sequential PEMS by up to 4.2% in scenarios where prediction accuracies are comparable, highlighting the efficacy of the trainable integrated mechanism. In addition, TIP-EMS exhibits superior energy conservation compared to non-predictive RL strategies. Lastly, TIP-EMS exhibits robustness to adjustments in the weight given to the prediction objective, further confirming its practical applicability. [ABSTRACT FROM AUTHOR]

[Display omitted] • Feasibility of using organic wastewater as renewable energy source is verified. • ＞99% COD, TOC removal rate in the experimental platform. • Up to 78.75% of the energy recovery efficiency of the SCWO system. The degradation of high concentration organic wastewater and the recovery of energy using supercritical water oxidation (SCWO) technology have the potential to become viable in the future. High concentration organic wastewater contains a significant amount of energy. This paper focuses on utilizing high concentrated wastewater as a renewable energy source, from an energy system perspective, an experimental rig was designed to determine the optimal working conditions. The experiments were conducted with an oxidation coefficient of 1.1, a flow rate of high concentration organic wastewater of 9 ml/min, a heating temperature of 400 °C, and a reaction pressure of 25 MPa. Under these conditions, the COD and TOC removal rates of the high concentration organic wastewater were found to be 99.383 % and 99.876 % respectively. Additionally, the phenomenon of "Abnormalities in pressure sensitivity" observed during high concentration organic wastewater the experiment was further explained through additional experiments. Finally, by comparing the experimental energy recovery with the simulation results, an energy recovery efficiency of 78.95 % was achieved. The feasibility of the simulated energy recovery in practice was verified, confirming the potential to convert the previous energy-consuming wastewater treatment process into a productive one. This study provides a theoretical and experimental foundation for further related research. [ABSTRACT FROM AUTHOR]

• Hybrid energy harvester with quasizero system is designed. • Different strategies for orbit jump using impulses are proposed and summarized. • A step-by-step method of correcting solutions is proposed. • Coexistence of chaotic and periodic solutions are checked. • Various parameters of quasizero system were analyzed. Energy harvesters based on non-linear systems are promising devices for extracting energy from mechanical vibrations. This paper presents a new design of energy harvester consisting of two coupled nonlinear systems; the Duffing oscillator and a system with quasizero stiffness. A numerical analysis of the dynamics of the harvester is carried out, presenting coexisting solutions and their energy efficiencies in both chaotic and periodic motion zones. The root mean squared (RMS) voltage results depend on the dimensionless excitation frequency, where high-energy orbits are coexisting with low-energy orbits. Therefore, the second part of the paper focuses on various strategies for jumps between the orbits using impulses. Different impulse characteristics and their sequences for periodic and chaotic zones are analyzed. Therefore, a detailed analysis is presented for many strategies using an impulse excitation diagram (IED) as a numerical tool for accurately estimating the amplitude of the impulse, its duration, and the moment of initiation. The probability of achieving a given solution is also determined. The simulation results show that achieving the most effective orbit with a single impulse, as well as several impulses, requires similar energy. However, the advantage of the step-by-step method is the lower energy required to initiate a single impulse which enables the use of a smaller regulator. This work can be a valuable tool for designing various systems and strategies for changing the orbit of a solution. [ABSTRACT FROM AUTHOR]

Optimizing consumptions in the field of civil construction led to define energy labels for residential buildings. To calculate the building energy demand the EPgl was determined, i.e. the annual consumption per m 2 of primary energy. This paper examines the technical solutions useful to optimize the energy demands for heating during space-heating season and domestic hot water production (thanks to energy analysis softwares as MC11300 and TRNSYS) and, at the same time, to take into account the financial issues those interventions implied. The total inside heated surface of the building case study is 1204.00 m 2 , hence the inside heated volume is about 3250.80 m 3 . Besides the more traditional interventions concerning the building envelope and its systems, the paper examined the performance of a system obtained through the combination of a cogenerator (CHP) and a heat pump (HP), thus, substituting the conventional boilers of the buildings. CHP+HP solution increases the most the energy label of the building (from a D class with EPgl = 59.62 kW h m −2 year −1 , to an A class, with EPgl = 25.64 kW h m −2 year −1 ), determining an annual energy cost saving of 3,114 € year −1 , allowing to amortize installation costs (54,560 €) in a reasonable payback period, i.e. 15.4 years. This innovative solution in the residential sector can be realized through retrofit interventions on existing buildings, hence it leads the current dwelling towards nZEB with a remarkable benefits for the environment. [ABSTRACT FROM AUTHOR]

• Advanced climate-resilient energy retrofit technology reduces the use of non-renewable energy in the building sector. • Renewable District Heating as an optimal technology in deep energy renovation strategies. • Sustainable cities and buildings are feasible by Centralised District Heating system powered by biomass. • Key Performance Indicators (KPIs), to achieve nZEB performances established in the European legislations. This paper presents the implementation of a biomass-fuelled District Heating System (DHS), as a part of a deep energy renovation exercise to achieve a climate-resilient campus with minimum carbon dioxide emissions. The case study is carried out for the University of Valladolid, an average-sized university in Spain, with a continental weather climate. Prior to renovation, the different building blocks had a wide-ranging level of fossil fuel consumption for space heating and domestic hot water ranging between 60 and 430 kWh/m2·year. The application of this centralised heating system allows to achieve the minimum threshold for near zero-energy buildings (nZEB) of 100–120 kWh/m2, in accordance with the Spanish Standards. These values correspond to the maximum European indicators for offices in continental weather conditions. Results of this comprehensive study show that 15 out of the 19 buildings reached the nZEB target, due to the proposed strategy. The overall carbon dioxide emissions have dropped by 92.69% as compared to the original fossil-fuel powered boiler, thus bringing carbon dioxide emissions down to 1.57 kgCO 2 /m2·y. Therefore, it is shown that deep energy renovation strategies through renewable energy DHS have the potential of achieving nZEB for universities in continental weather conditions. [ABSTRACT FROM AUTHOR]

Traditional olefins production is heavily dependent on oil. In the background of the scarcity of oil and richness of coal in China, olefins production from coal has been attracting more attention of the chemical process industry. The first coal based methanol-to-olefins (CMTO) plant has been commercialized in China. For shorter process route and lower capital cost, Fischer–Fropsch has been put forward in the last few years. The coal based Fischer–Tropsch-to-olefins (CFTO) process is designed in this paper and then its techno-economic and environmental performance was detailed studied in this paper, in comparison with the CMTO. Results show that at the present olefins selectivity, the CFTO suffers from relative lower energy efficiency and higher CO 2 emissions. In economic aspect, the capital investment and product cost of the CFTO are roughly equivalent to that of the CMTO. Although the conversion route of the CFTO is shorter, its techno-economic performance is still inferior to that of the CMTO. It is also found that increase of olefins selectivity by cracking oil or decrease of CO 2 selectivity by improving catalyst could significantly improve the performance of the CFTO. [ABSTRACT FROM AUTHOR]

The negative environmental impacts of burning fossil fuels have forced the energy research community seriously to consider renewable sources, such as naturally available solar energy. Thermally powered refrigeration technologies are classified into two categories: thermo-mechanical technology and sorption technology (open systems or closed systems). This paper provides a detailed review of the solar closed sorption (absorption and adsorption) refrigeration systems, which utilise working pairs (fluids). After an introduction of the basic principles of these systems, the history of development and recent advances in solar sorption refrigeration technologies are reported. The adsorption cooling typically has a lower heat source temperature requirement than the absorption cooling. Based on the coefficient of performance (COP), the absorption systems are preferred over the adsorption systems, and the higher temperature issues can be easily handled with solar adsorption systems. The thermodynamic properties of most common working fluids, as well as the use of ternary mixtures in solar-powered absorption systems, have been reviewed in this study. The paper also refers to new approaches to increase the efficiency and sustainability of the basic adsorption cycles, such as the development of hybrid or thermal energy storage adsorption systems. This research shows that solar-powered closed sorption refrigeration technologies can be attractive alternatives not only to serve the needs for air-conditioning, refrigeration, ice making, thermal energy storage or hybrid heating and cooling purposes but also to meet the demands for energy conservation and environmental protection. [ABSTRACT FROM AUTHOR]

In this paper, four energy control strategies are proposed and analyzed for the standalone Renewable/Fuel Cell Hybrid Power Source (RES/FC HPS). The concept of the load following (LF) and Maximum Efficiency Point Tracking (MEPT) is used to control the fueling rates. A standalone RES/FC HPS uses at least one Renewable Energy Sources (RES) and a Polymer Electrolyte Membrane (PEM) Fuel Cell (FC) as backup source. Photovoltaic (PV) array and wind turbines (WT) farm are used as RES and the surplus of energy during light load stages is stored in hydrogen tank via water electrolysis to fuel the PEMFC. Small-scale RESs and commercially available PEMFCs are interfaced to the common DC bus via power converters and then to the single-phase distribution grid through a voltage source inverter. RES/FC HPS seem to be an efficient alternative for supplying smart houses and isolated sites. This paper proposes a new supervision strategy of the Energy Management Unit (EMU) based on the LF control approach that assures a charge-sustaining (CS) mode for the Energy Storage System (ESS). So, the capacity of the batteries stack can be reduced at minimum if it is directly connected to the DC bus. The ultracapacitors stack compensates dynamically the power flow balance on the DC bus, regulating the DC voltage via a bidirectional buck-boost power converter. Thus, a semi-active hybrid topology is adopted for the ESS having the batteries stack. The MEPT loops ensure an optimized energy management of the RES/FC HPS. The LF strategy designed based on the power flow balance guarantees the load demand through the efficient management of the power flow from RES, FC and ESS, adapting FC energy production to load profile. The FC energy production is controlled via the fueling rates (one is controlled in the LF loop and the other is controlled in the MEPT loop) to maximize the energy consumption indicator: the ratio of the produced energy and the fuel consumed by the FC system during a load cycle. Thus, this paper evaluates the control performances of the four control topologies to fuel the FC stack during an variable RES and load profile. The MATLAB-Simulink® software package is used to model the RES/FC HPS and develop the four EMU strategies. Simulation results shown comparatively the performance of the EMU strategies proposed under different scenarios of RES power generation and load demand. [ABSTRACT FROM AUTHOR]

• The proposed modelling allows Energy Efficiency Measures to be dynamically analysed. • The proposed recovery system reduces the energy consumption up to 55%. • The new dynamic energy behaviour is settled for the process and recovery system. • The payback of the proposed measure is 3 years and saves 300 MWh/year. • Energy Efficiency Measures are evaluated in energy, production and economic terms. Energy efficiency in industry is not as elevated as it should be. The aim of this paper is to present a process evaluation based on modelling as well as a waste heat recovery evaluation for a continuous heat treatment process of an Aluminium Die-Casting plant. The process is represented by production and energy dynamic (time-dependent) models combining thermal phenomena with production and economic considerations. These models allow the energy consumption, resource utilization and the production schema to be evaluated. Simulated theoretical phenomena were compared and validated with real data measurements. Once validated, the model of the heat treatment process was applied to search the best work configuration and to identify, quantify and evaluate the impact of a waste heat recovery system. Based on simulation results, their viability (energy savings or productivity increase) was quantified. The assessment shows a potential to reduce the natural gas consumption in the aging heat treatment process up to 55%, with approximately a 3-years payback period and savings of 300 MWh/year. The new working way of the process is assessed. The burners of the aging treatment process present energy reductions from 50% to 80% depending on the burner position. The new waste heat recovery system provides up to 63% of the new energy required by the aging furnace. [ABSTRACT FROM AUTHOR]

• The retrofit of urban lighting systems is a means of improving their performance. • An original method for structuring the design process is presented. • A pilot installation has been realised and monitored to test pre-design assumptions. • The test installation has also been used to conduct a survey about user satisfaction. • Final design will ensure user satisfaction, energy saving and economic features. The retrofit of urban lighting systems is often an advantageous means of achieving notable energy savings and improvements in the quality of light. User habits, expectations and lifestyle can contribute to the design of these systems, for example in deciding on the most appropriate control strategies or the light quality. The influence of such variables can be extended to the overall system performance. This paper presents a method of street lighting design based on two kinds of analysis carried out in a defined test area: measurements (by means of a monitoring study) and user preferences (by means of a survey). The results of this data analysis create the basis for the final design step. The proposed method is applied in a case study: the lighting system of the outdoor areas of the University of Palermo campus (Italy). The results show that the proposed method can be used to optimise the performance of a lighting plant in terms of energy saving and quality of light, while also taking into account the opinions of local users. Indeed, the results of the survey show that 81% of the users feel safe in test areas, 80% declare very good satisfaction with the project, and the totality of the sample would like the implementation of new features embedded in the lighting infrastructure. Expected results of energy savings in the entire campus will be about 70% with a short investment return time (3–4 years). [ABSTRACT FROM AUTHOR]

• Exhaust air heat recovery systems can significantly lower building air humidity. • Maintaining building air humidity requires make-up water that must be evaporated. • Water evaporation energy input to maintain building air humidity can be significant. • Energy penalties are largest during winter, with low ambient absolute humidity. • Integration with moisture recovery and recirculation is recommended. One modern method of lowering building energy use is heat exchange between outgoing and incoming air. Exhaust air moisture (partly) condenses in the heat exchanger, giving liquid water to be removed. With low absolute humidity of inlet air especially at low outdoor temperatures, a significant drying effect results for the air inside the building. Increasing air humidity by, for example, spraying water or increasing watering of plants will give an energy penalty. This paper presents an analysis of the energy efficiency (recovered versus input exergy) of a modern house equipped an exhaust air heat recovery system and external heating supplied by a geothermal heat pump. Indoor temperature is 22 °C and relative humidity is 50 or 30%. Temperature and humidity of inlet air and ventilation flow rates are variable and the effects on power use by the heat pump are assessed. Results show that without moisture recirculation a water loss up to 1 kg/h from the building may occur. Several kWh of electricity may be consumed daily by a (geothermal) heat pump supplying heat depending on outdoor temperature, and indoor and outdoor air humidity. Besides water consumption, this may imply 10–15% of total electricity use. [ABSTRACT FROM AUTHOR]

• GP-PLS is the integration of Gaussian process (GP) and partial least squares (PLS). • The GP-PLS method realizes the energy efficiency evaluation in large-scale plants. • Without specific structures, GP-PLS still yields good probabilistic evaluation. • The data are selected proactively to improve the reliability and accuracy. • Accurate evaluation is estimated and the energy efficiency tendency is predicted. In the large-scale chemical plant, energy efficiency evaluation and management plays a crucial role in the sustainable development. However, most data-driven approaches to calculating energy efficiency still focus on the deterministic evaluation regardless of the effects resulting from the data quality. Besides, because of the multi-dimensional, stochastic and uncertain characteristics of the collected industrial data, it is more difficult to accurately and reliably evaluate and predict the energy usage of the complex chemical production process. To solve these limitations, a novel energy efficiency evaluation and prediction method integrated with the Gaussian process (GP) and the partial least squares (PLS) analysis, named GP-PLS method, is proposed in this paper. This integrated method can select the appropriate sampling data, construct the corresponding nonlinear model and indicate the reliability of the model. Based on the constructed models, not only are the accurate energy efficiency evaluation results calculated, but the energy efficiency tendency is also predicted. In addition, according to the reliability of the established model, the informative data are intelligently selected from the historical database to enhance the quality of the model. The effectiveness and practicality of the proposed method are demonstrated through a numerical example and a practical ethylene production. The evaluation results and the prediction values are acquired to decrease the energy consumption, guide the production process and improve the energy efficiency level in the large-scale chemical plant. [ABSTRACT FROM AUTHOR]

• CFD modelling of a smart double skin facade. • Smart DSF configuration with double heating and cooling gains. • Smart greenhouse effect control inside the DSF. • Heating and cooling loads optimization. • Smart radiative thermal building insulation. Double skin facades (DSFs) are known by their capacity to generate a natural heating energy during winter by increasing the greenhouse effect in the air cavity between the inner and the outer facade. However, this effect provides an undesirable overheating during summer. In this study, a smart DSF configuration able to control the greenhouse effect generation was numerically simulated using a two dimensional Computational Fluid Dynamic (CFD) method. The aim of these simulations is to investigate the thermal and the energetic behavior of a DSF integrating Tungsten (W) doped Vanadium dioxide (VO 2) as an optically smart thin material and a high absorbing aluminum nitride (AlN) coating. A parametric study was carried out in order to analyze the impact of the air cavity thickness on the smart DSF behavior. Four thicknesses (10, 25, 50 and 75 mm) were inspected and compared with an uninsulated massive wall configuration. Results have shown that the smart configuration reduces significantly both heating and cooling loads. Indoor surface temperature has been decreased by around 2 °C during summer and increased by around 3 °C during a sunny winter day. The air velocity results have shown that the natural convection-radiation interaction during winter is higher than during summer. Thus, the new smart DSF configuration presented in this paper can effectively control the greenhouse effect depending on external climatic conditions. [ABSTRACT FROM AUTHOR]

• The hotel system of a cruise ship was modelled by using a building simulation tool. • The modelled annual energy use was 55 MWh/passenger, with 20% for the hotel system. • Various energy efficiency measures were evaluated for the hotel system. • Heat pumps gave the largest energy savings with a 38% reduction. • Using a hot water storage tank could eliminate use of auxiliary boilers in ports. In light of climate change, the shipping industry is committed to reducing its greenhouse gas emissions. When transitioning from fossil fuels to low-carbon fuels, it is crucial to also reduce the ships' energy need. For cruise ships, the hotel system is a major energy consumer and the focus of this paper. This study aims to investigate the energy use of an existing fossil-fuelled cruise ship operating in a Nordic climate, and evaluate the effectiveness of various passive and active energy-saving measures. For this purpose, a dynamic energy model of the hotel system was developed in the building simulation tool IDA Indoor Climate and Energy (IDA ICE), including a customised weather file. Validation of the model was achieved through comparison with literature and some operational data from the actual cruise ship. Simulation results showed a total annual energy use of 55 MWh/passenger, with the hotel system accounting for 20%. The passive measures, such as increased insulation and improved windows, each resulted in less than a 1% reduction in the hotel's annual energy use. Larger energy savings were achieved by using heat pumps (38%), improved ventilation system (8–24%), and heating setback in port and during the night (5%). A hot water storage tank, charged with the engines' waste heat during sea operation, could reduce the use of auxiliary boilers, especially in port. A hot water tank of 600 m3 could cover 97% of the heating demand in port, thereby minimising the use of fuel-fired boilers. [ABSTRACT FROM AUTHOR]

• The system engineering based on photovoltaic thermal heat pump was constructed. • A new idea for the energy-saving reconstruction of district heating was introduced. • The prediction model of system heating performance was established and optimized. • The equivalent electricity consumption of heating was defined. • The economic performance of energy-saving reconstruction was studied. Actively promoting the reconstruction of clean heating is the key direction of the "Planning for clean heating in winter in northern China (2017–2021)". The photovoltaic thermal heat pump system was introduced in this paper to improve the comprehensive energy efficiency and reduce the operation energy consumption of the heat source system, which provided a new idea for the energy saving reconstruction of clean district heating. In order to verify the feasibility of the energy saving reconstruction by photovoltaic thermal heat pump, following studies were carried out in this paper: First, the integrated energy system engineering based on photovoltaic thermal heat pump was constructed to study the heating performance of the system in winter. Subsequently, the prediction model of heating performance based on back propagation neural network was established and optimized to simulate the heating performance throughout the year. Then, the calculation model of district heating system was established and the evaluation method of system operation energy efficiency and economic performance based on "equivalent electricity consumption of heating" was introduced. Finally, a residential area of Dalian was taking as an example to study the economic performance of energy saving reconstruction of district heating system based on three conventional heat sources by photovoltaic thermal heat pump. The results showed that after the capacity expansion and energy saving reconstruction based on photovoltaic thermal heat pump were conducted, the payback period of energy saving reconstruction investment was 5 years. Besides, with the increase of the configuration ratio of photovoltaic in the system from 1 to 2, the payback period was further shortened to 3 years. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Proposed hybrid heat recovery system for efficient energy utilization of spray dryer. • Proposed new performance indicator to assess sustainability in heat recovery systems. • Developed rigorous mathematical model for direct and hybrid heat recovery systems. • Investigated optimal performance of spray dryer. • Compared proposed energy recovery schemes to find best configuration. Abstract Thermal dewatering using spray dryers is an energy-intensive process, which recently, applied for removal of water from industrial effluents by evaporation. Reduction of energy consumption is vital to reduce operating cost in addition to sustainable development. In this paper, the modern integrated energy savings scheme is proposed in four parts. (i) An advanced energy saving configuration named as a hybrid heat recovery system for a spray dryer, (ii) Developed rigorous but simple mathematical model for direct and hybrid heat recovery system, (iii) A generalized performance indicator for investigation of environmental impact on energy recovery called as 'Sustainability Index' is proposed for thermal systems and demonstrated for spray dryer, and finally (iv) The proposed methods are explained with the help of an illustrative example taken from the literature. Up to 80% recirculation ratio, performance enhancement, and Sustainability Index are significantly higher for the hybrid heat recovery system than the direct heat recovery system, while for higher than 80% recirculation ratio, both are approaching towards nearly same value. Furthermore, with increasing recirculation ratio, moisture recirculation into the drying chamber also increases, which reduces the requirement of the mass flow rate of dry hot air due to the higher heat capacity of recirculated moisture. A reduction in hot air requirement reduces the high-grade blower power in addition to net heat supplied. Dryer efficiency and sustainability index, both show a strong dependency on the amount of heat recovery for spray dryer. [ABSTRACT FROM AUTHOR]

Abstract: This paper assesses impact of using phase change materials (PCM) in buildings to leverage its thermal energy storage capability. The emphasis is from an electricity demand side perspective with case studies that incorporates wholesale electricity market data of New Zealand. The results presented in this paper show that for space heating application significant advantages could be obtained using PCM built structures. These positive impacts include peak load shifting, energy conservation and reduction in peak demand for network line companies and potential reduction in electricity consumption and savings for residential customers. This paper uses a testing facility that consists of two identically designed and shaped offices built at Tamaki Campus location of the University of Auckland, New Zealand. The walls and ceilings of one office are finished with ordinary gypsum boards while the interior of the other office is finished with PCM impregnated gypsum boards. Controlled heating facility is provided in both the offices for maintaining temperature within the range of human comfort. This facility is equipped with advanced data acquisition equipment for data monitoring and archiving both locally within the offices and also remotely. Through actual observations and analysis this paper demonstrates two major impacts of DSM. First, the application of phase change material (PCM) in building environment enabling efficient thermal storage to achieve some reduction in the overall electrical energy consumption. Second, assessment of peak load shifting achieved for space heating in a PCM building during a typical winter period in New Zealand. [Copyright &y& Elsevier]

A detailed assessment analysis of 2.5 kWp photovoltaic (PV) system located in southern Algeria (Latitude 27.88 °N, Longitude −0.27 °E, Altitude 262 m) has been carried out in this paper in order to support the growth of grid-tied photovoltaic power plant implementation in the Saharan environment. The achievement of this analysis has been done by performing an accurate evaluation of the different impacts of the environment parameters on the operating performance of the grid-tied PV system. The data set covers 12 operating months and has been collected by our team from the Research Unit on Renewable Energy (URER-MS). The collected experimental data reveal that the environmental parameters variation has direct effect on the performance of both energy conversion efficiency and system losses. The grid was supplied with a power of 4322.65 kWh during the year 2015, where the annual average temperature was 28.30 °C. An important variation in performance parameters have been observed for different months. The yield values of max/min monthly average daily reference, array and final were; 7.68/5.7 kW h/kWp/day, 6.07/4.24 kW h/kWp/day and 5.75/3.98 kW h/kWp/day, respectively. The PV module, inverter and overall system efficiency reached; 14.19/11.10%, 95.34/93.94% and 13.53/10.50%, respectively. The experimental results indicate that the performance ratio (PR) varies from 66.66% to 85.93% and the annual average capacity factor was 7.91%. [ABSTRACT FROM AUTHOR]

This paper integrates solar energy, regarded as the most abundant renewable energy in the world, into oil and gas industries to produce the hydrogen required in crude oil upgrader processes. Three alternatives of producing hydrogen from solar energy were proposed, namely, Solar Steam Methane Reforming using a Volumetric Receiver Reactor (SSMR-VRR), Solar Steam Methane Reforming using Molten Salt (SSMR-MS), and Solar Thermal Power generation coupled with Water Electrolysis (STP-WE). Simulations of all alternatives have been done to produce 2577 kmol per hour hydrogen: that is, the demand in the crude oil upgrader process. The technical, economic, and environmental analysis is performed to compare the results of the alternatives with the conventional steam reforming of natural gas. The results suggest that SSMR-VRR has the lowest levelized cost of hydrogen production, which is $2.5 per kg of hydrogen; SSMR-MS has a highest energy efficiency of 68%, and STP-WE has the lowest greenhouse gas emissions. The economic analysis suggests that currently the thermochemical processes (SSMR-VRR and SSMR-MS) have potential for producing hydrogen required by the crude oil upgrader; however, as the renewable energy technologies progress that may lead to their capital cost decrease, solar thermal power with water electrolysis (STP-WE) will become a more promising sustainable option for hydrogen production. [ABSTRACT FROM AUTHOR]

Abstract: The procedure of development of energy management system applied to an existing company (Serbian car producer “Zastava”) is shown in the paper. The aim of the paper is to provide a guideline for entrepreneurs in metal-working industry in implementing energy management system. First of all, paper includes: critical analysis of existing energy management system (energy matrix), principles of effective energy management organization (with energy manager and energy team in its structure) and energy management politics. Based on the results of energy auditing and performed technological and economical feasibility studies several energy saving measures related to different energy sources (steam, hot water, compressed air, electricity and water) were proposed, implemented and valuated. The proposed measures are not exclusively related to car assembly industry; they can be easily applied to other metal-working facilities with minor modifications. Such energy management system reduces energy costs and increase profitability of a factory. [ABSTRACT FROM AUTHOR]

Abstract: Industrial plants continuously reject large amounts of thermal energy through warm liquid or gaseous effluents during normal operation. These energy losses contribute to an inflation of production costs and also threaten the environment. This paper investigates methods of recovering the residual low grade thermal energy and converting it into higher quality mechanical energy using the thermodynamic Rankine cycle principle. For the temperature range of the available thermal energy, water was shown to be a poor working fluid for the conversion system, thus several potential working fluids, including ammonia, synthetic refrigerants, and organic compounds have been considered as alternatives. A comparative analysis led to the identification of different performance evaluation criteria. For example, the water-based Rankine cycle and, to a lesser extent, the ammonia-based Rankine cycle proved to be interesting when the power generation potential per unit working fluid mass flow rate was considered. On the other hand, Rankine-like cycles using dry hydrocarbon working fluids proved much more interesting in terms of energy conversion efficiency, as well as in terms of the net mechanical power generation potential for a given heat source. All performance indicators were low at low temperatures, and improved as the primary heat source was available at higher temperatures. This paper also discusses the influence of various external and internal operating parameters, such as heat source and heat sink temperatures, turbine and pump isentropic efficiencies and the addition of an internal heat exchanger on the overall performance of the energy recovery and conversion system. [Copyright &y& Elsevier]

Abstract: Small and medium size enterprises (SMEs) have an important role in the Turkish economy because of the workforce involved. According to the size of the industrial facilities, there are different cost components related to the total production costs. Energy cost is usually a small portion of the total production cost, but the Turkish industrial sector comprises approximately 35% of Turkey’s total energy consumption and 98.8% of the total number of enterprises in Turkey constitutes the SMEs. Because of the uncertainty of energy costs in the world, it is important to take preventive measures to reduce energy costs and increase efficiencies in industry and consequently in SMEs. In this paper, medium sized enterprises are taken into consideration essentially. Because of getting homogeneity, enterprises with the number of workers between 100 and 200 in the metallic goods industry have been considered in the survey. Energy management includes increasing the profitability by reduced operational costs, and it is also a potential for improving market share. Many different evaluation models have been published in the energy management literature. However, there have not been so many systematic approaches to compare the relative efficiency of the systems. Data envelopment analysis (DEA) is a special linear programming model for deriving the comparative efficiency of multiple-input multiple-output decision making units (DMUs). An evaluation of energy efficiency in 20 medium sized companies has been conducted, and the results are discussed in this paper. [Copyright &y& Elsevier]

Abstract: Coal fired power generation will continue to provide energy to the world for the foreseeable future. However, this energy use is a significant contributor to increased atmospheric CO2 concentration and, hence, global warming. Capture and disposal of CO2 has received increased R&D attention in the last decade as the technology promises to be the most cost effective for large scale reductions in CO2 emissions. This paper addresses CO2 transport via pipeline from capture site to disposal site, in terms of system optimization, energy efficiency and overall economics. Technically, CO2 can be transported through pipelines in the form of a gas, a supercritical fluid or in the subcooled liquid state. Operationally, most CO2 pipelines used for enhanced oil recovery transport CO2 as a supercritical fluid. In this paper, supercritical fluid and subcooled liquid transport are examined and compared, including their impacts on energy efficiency and cost. Using a commercially available process simulator, ASPEN PLUS 10.1, the results show that subcooled liquid transport maximizes the energy efficiency and minimizes the cost of CO2 transport over long distances under both isothermal and adiabatic conditions. Pipeline transport of subcooled liquid CO2 can be ideally used in areas of cold climate or by burying and insulating the pipeline. In very warm climates, periodic refrigeration to cool the CO2 below its critical point of 31.1°C, may prove economical. Simulations have been used to determine the maximum safe pipeline distances to subsequent booster stations as a function of inlet pressure, environmental temperature and ground level heat flux conditions. [Copyright &y& Elsevier]

[Display omitted] • A novel Magnetic Field Pre-polarization (MFPP) method is proposed to improve the efficiency of hydrogen production. • MFPP is easy to match with high-power industrial AWE equipment. • MFPP improve the hydrogen production efficiency by a maximum of 9.2%. • The MFPP method provides a way for improving the efficiency of industrial AWE system. Water electrolysis can become a promising mean to produce clean hydrogen. Improving the efficiency of water electrolysis is of great significance for accelerating the development of large-scale hydrogen production equipment and low-carbon economy. This paper presents a novel method for enhancing the alkaline water electrolysis (AWE) efficiency by Magnetic Field Pre-polarization (MFPP), which is easily matched to high-power industrial AWE system. Firstly, compactly-assembled structure and energy consumption of industrial AWE electrolyzer are analyzed. Secondly, the MFPP method was proposed to enhance the efficiency of AWE. The structure parameters of MFPP equipment are optimized by simulation and the physical model is designed. Finally, a system-level equipment was developed to evaluate the effect of MFPP on the performance of the alkaline water electrolysis (AWE) system. Repeatability measurement, I-V characteristic analysis and error statistics were carried out under different working conditions. The effectiveness of MFPP method has been proved on industrial electrolyzer (with 22 cells). Compared with the electrolysis voltage of 40 V-42 V@22_cell, the efficiency improvement is more significant when the voltage is in the range of 42–46 V@22_cell. Under the 0.75 T MFPP, the maximum hydrogen production efficiency increased by 9.2 %. The mean absolute deviation (MAD) of test results is less than 1.88 (with a proportion of 0.11 %) and the mean squared error (MSE) is less than 0.49. [ABSTRACT FROM AUTHOR]

The need of a more persistent human presence on sea is driving the development of increasingly more efficient Autonomous Underwater Vehicles. A particularly promising solution to power these vehicles is the retrieval of energy from the ocean temperature gradient. This paper investigates the use of thermoelectric generators (TEGs) for that purpose, by presenting a complete model of thermoelectric generators embedded in the hull of an underwater glider. The model includes not only the thermoelectric generators but also the heat transfer process and the behaviour of different heat storage materials. Several simulations are performed, for each storage material, to determine the adequate design parameters leading to sufficient energy generation for a thermal glider. It is shown that the use of Phase Change Materials (PCM) as an energy storage material is highly advantageous over the use of sea water or stainless steel. Furthermore, it is shown that this approach, although leading to a high number of TEGs and mass of PCM, is compatible with current existing glider dimensions. [ABSTRACT FROM AUTHOR]

This paper analyses two Real-Time Optimization (RTO) strategies for Proton Exchange Membrane Fuel Cell (PEMFC) system which is used as main energy source for Fuel Cell Hybrid Power Source (FCHPS) of the FC vehicle (FCV). In this study the optimization function was defined as mix of the FC net power and the Fuel Consumption Efficiency by using two weighting coefficients. The Global Extremum Seeking (GES) algorithm is proposed here as RTO method for multimodal optimization surfaces having many peaks on the plateau around the optimal point that is the Global Maximum Point (GMP). One of the fueling rates is Load-Following (LF) controlled in order to adapt the FC net power to load demand and assure the charge-sustaining mode for the battery. The GES algorithm will establish the optimal duty cycle for the Boost converter, so the proposed strategies will be called the Boost-GES-RTO strategies with Air-LF and Fuel-LF, respectively. The Static Feed-Forward (sFF) control strategy will be used as reference for constant and variable load profile. The gaps in performance indicators were estimated for both Boost-GES-RTO strategies. For example, the gaps in FC system efficiency and fuel economy could be up to 1.61% and 142 lpm, and 2.65 and 114 lpm for the Boost-GES-RTO strategies with Air-LF and Fuel-LF. The performance of Boost-GES-RTO strategies was also shown by estimating the fuel economy for 6 kW FCHPS under variable load profile. [ABSTRACT FROM AUTHOR]

Utilizing the waste heat of exhausted steam in power plant as a new type of heat source is a key direction to achieve both energy-saving and clean urban heating. In order to recycle all the exhausted steam waste heat of multiple turbine units in designing condition, the authors’ research group proposed a new cascade heating system with multi-heat source and applied it in several air cooling power plants in China. This paper focused on the system integration improving and operation strategy formulating, the main studies included: (1) Established the calculation model of system heating characteristics, and analyzed the problems about energy efficiency of system and safety of air cooled condenser in full operating conditions. (2) Introduced the “equivalent electricity of heating” as the evaluation method of comprehensive energy efficiency of the new co-generation heating system. (3) Improved the integration of heating system to further realize energy cascade utilization between turbine units. (4) Aiming at the improved heating system, the comprehensive optimization ideas of operational parameters in full operating conditions were put forward. By above methods, on one hand the “equivalent electricity of heating” of the new co-generation heating system is decreased by 16%, the comprehensive energy efficiency of system is improved, on the other the freezing risk of air cooled condenser is relieved, the operation safety of system is improved. [ABSTRACT FROM AUTHOR]

Modern ways of exploring the diagnostic knowledge provided by data mining and machine learning raise some concern about the ways of evaluating the quality of output knowledge, usually represented by information systems. Especially in district heating, the stationarity of efficiency models, and thus the relevance of diagnostic classification system, cannot be ensured due to the impact of social, economic or technological changes, which are hard to identify or predict. Therefore, data mining and machine learning have become an attractive strategy for automatically and continuously absorbing such dynamics. This paper presents a new method of evaluation and comparison of diagnostic information systems gathered algorithmically in district heating efficiency supervision based on exploring the evolution of information system and analyzing its dynamic features. The process of data mining and knowledge discovery was applied to the data acquired from district heating substations’ energy meters to provide the automated discovery of diagnostic knowledge base necessary for the efficiency supervision of district heating-supplied buildings. The implemented algorithm consists of several steps of processing the billing data, including preparation, segmentation, aggregation and knowledge discovery stage, where classes of abstract models representing energy efficiency constitute an information system representing diagnostic knowledge about the energy efficiency of buildings favorably operating under similar climate conditions and supplied from the same district heating network. The authors analyzed the evolution of a series of information systems originating from the same knowledge discovery algorithm applied to a sequence of energy consumption-related data. Specifically, the rough sets theory was applied to describe the knowledge base and measure the uncertainty of machine learning predictions of current classification based on a past knowledge base. Fluctuations of diagnostic class membership were identified and provided for the differentiation between returning and novel fault detections, thus introducing the qualities of information system uncertainty and its sustainability. The usability of the new method was demonstrated in the comparison of results for exemplary data mining algorithms implemented on real data from over one thousand buildings. [ABSTRACT FROM AUTHOR]

Hydraulic excavator driven by an internal-combustion engine is widely used in the construction field. However, some problems, such as high pollutant emissions, noise and low efficiency, exist universally. To address these problems, an electric hydraulic excavator configuration combining with an independent metering in and metering out system is proposed to improve the overall energy efficiency. In this paper, a displacement variable pump driven by a speed variable electric motor is used as power source, and a matching method based on the segmented speed and continuous displacement control of the pump is proposed to meet the requirements of high dynamic, high energy efficiency and zero emission of hydraulic excavator under different working conditions. Then, an independent metering in and metering out system is employed to reduce throttling loss. A test rig with a 6-ton hydraulic excavator was built up and used to validate the proposed scheme. The energy consumption characteristics of the electro-hydraulic power source under different rotational speeds and different loads are further investigated to provide analytical and experimental references for control strategy designing. Furthermore, the working performance and energy distributions of the excavator with the pure displacement variable concept, and speed and displacement variable concept are studied comparatively. Results show that, compared with pure displacement variable concept, the electric power consumption during the idle period can be reduced from 2.05 kW to 0.7 kW, the energy saving ratio under partial load condition can be up to 33%, while it is 28.5% under digging condition. [ABSTRACT FROM AUTHOR]

• Big data methods are used to increase the efficiency of an industrial cogeneration system. • Cluster analysis is applied to energy demand data to design the cogeneration system. • The approach allows to choose the correct type of cogeneration technology. • The operation strategy of the plant and thermal storage are optimized. • The approach allows to improve energy efficiency of the cogeneration plant. In recent years, collecting energy consumption data has become easier thanks to the decreasing of smart sensors cost. Moreover, the capacity of data analysis using big data methods like machine learning and artificial intelligence has increased. Such methods are expected to be useful to increase the efficiency of energy systems. In this paper, an innovative approach based on big data analysis to design cogeneration systems is presented. More specifically, this study describes how cluster analysis can be applied to analyse energy consumption data. The aim of the method is to design cogeneration systems that can suit energy demand profiles more efficiently, choosing the correct type of cogeneration technology, operation strategy and, if they are necessary, the size of energy storages. In the first part of the paper, the method based on clustering to perform the analysis of the dataset is described. In the second part, a case study based on a cogeneration plant (a wood industry that requires low temperature heat to dry wood into steam-powered kilns) is analysed. An alternative cogeneration system is designed by means of the proposed method in terms of the choice of the cogeneration technology, the sizing of thermal storage, and the operation strategy of the plant. Thermodynamic and economic benchmarks are defined to evaluate the differences between as-is and alternative scenarios. Results show that the proposed innovative method is useful to design cogeneration systems for industry allowing energy and economic savings. [ABSTRACT FROM AUTHOR]

In this paper, the comparative study of energy and exergy performance of two weir type cascade solar stills with and without PCM storage in sunny and semi-cloudy days is carried out. The governing equations of energy analysis include a set of nonlinear equations which is obtained by writing energy balance for the various components of a solar still (i.e. glass cover, brackish water, absorber plate, phase change materials). A detailed exergy analysis is carried out and various irreversibility rates in the solar still system and its exergy efficiency are introduced. In order to solve the governing equations a computer simulation program is developed. The results of a numerical simulation of the present study are in good agreement with the experimental data of previous literatures. The numerical results of the present study show that the energy and exergy performance of solar still without PCM storage is better than the solar still with PCM storage in sunny days. On the other hand, the solar still with PCM storage is preferred for semi-cloudy days due to its better energy and exergy performance. The maximum value of the energy and exergy efficiencies of the solar still without PCM for a typical sunny day are 76.69% and 6.53%, respectively. While, the maximum energy and exergy efficiencies of the solar still with PCM for a sample semi-cloudy day are 74.35% and 8.59%, respectively. Furthermore, it is observed that the highest irreversibility rate belongs to the absorber plate and its value for the solar still without PCM on typical sunny day and the solar still with PCM on semi-cloudy days is 83.1% and 78.8% of the whole of system irreversibility rates, respectively. Whereas, the irreversibility rate of glass cover and brackish water can be neglected. [ABSTRACT FROM AUTHOR]

Stirling engines with parabolic dish for thermal to electric conversion of solar energy is one of the most promising solutions of renewable energy technologies in order to reduce the dependency from fossil fuels in electricity generation. This paper addresses the modelling and simulation of a solar powered Stirling engine system with parabolic dish and electric generator aiming to determine its energy production and efficiency. The model includes the solar radiation concentration system, the heat transfer in the thermal receiver, the thermal cycle and the mechanical and electric energy conversion. The thermodynamic and energy transfer processes in the engine are modelled in detail, including all the main processes occurring in the compression, expansion and regenerator spaces. Starting from a particular configuration, an optimization of the concentration factor is also carried out and the results for both the transient and steady state regimes are presented. It was found that using a directly illuminated thermal receiver without cavity the engine efficiency is close to 23.8% corresponding to a global efficiency of 10.4%. The components to be optimized are identified in order to increase the global efficiency of the system and the trade-off between system complexity and efficiency is discussed. [ABSTRACT FROM AUTHOR]

The feasibility of individual natural gas fired boiler-based heating systems in the retrofitting of buildings constructed in the 50–60 s in Bilbao (northern Spain) is evaluated in this paper. A holistic approach through dynamic simulations using TRNSYS is employed for the purpose. An existing dwelling previously monitored and used to validate the model applied is selected as a case study. 54 different scenarios are evaluated, which arise from the combination of 3 different envelope options, 2 types of heat production units, 3 heat production temperatures and 3 comfort temperature set-points. The cases are evaluated in terms of energy results, economic aspects, and the influence of user behaviour. Regarding the latter, the influence of the potential rebound effect is also evaluated. The results show energy savings nearby 10% when condensing boilers are compared with high efficiency boilers. In relation to hot water production temperature, energy savings between 5 and 10% are found when the temperature is lowered from 60 to 50 °C. The greatest impact on energy consumption is related to the occupants’ behaviour: reductions up to 89% are achieved if the indoor temperature set-point is lowered 2 °C. This is reinforced with the results related to the rebound effect, which show significant differences on energy consumption values. These evidences demonstrate that the user behaviour is an essential feature to be considered in studies regarding buildings energy performance. As a consequence, the holistic approach herein employed emerges as a key tool to be applied in further works related with the topic. [ABSTRACT FROM AUTHOR]

There was a rapid development of coal to synthetic natural gas (SNG) projects in the last few years in China. The research from our previous work and some other researchers have found coal based SNG production process has the problems of environmental pollution and emission transfer, including CO 2 emission, effluent discharge, and high energy consumption. This paper proposes a novel co-feed process of coal and coke-oven gas to SNG process by using a dry methane reforming unit to reduce CO 2 emissions, more hydrogen elements are introduced to improve resource efficiency. It is shown that the energy efficiency of the co-feed process increases by 4%, CO 2 emission and effluent discharge is reduced by 60% and 72%, whereas the production cost decreases by 16.7%, in comparison to the conventional coal to SNG process. As coke-oven gas is a waste gas in most of the coking plant, this process also allows to optimize the allocation of resources. [ABSTRACT FROM AUTHOR]

There was a rapid development of coal to synthetic natural gas (SNG) projects in the last few years in China. The research from our previous work and some other researchers have found coal based SNG production process has the problems of environmental pollution and emission transfer, including CO 2 emission, effluent discharge, and high energy consumption. This paper proposes a novel co-feed process of coal and coke-oven gas to SNG process by using a dry methane reforming unit to reduce CO 2 emissions, more hydrogen elements are introduced to improve resource efficiency. It is shown that the energy efficiency of the co-feed process increases by 4%, CO 2 emission and effluent discharge is reduced by 60% and 72%, whereas the production cost decreases by 16.7%, in comparison to the conventional coal to SNG process. As coke-oven gas is a waste gas in most of the coking plant, this process also allows to optimize the allocation of resources. [ABSTRACT FROM AUTHOR]

• Optimization-based comparison of natural gas liquefaction processes is proposed. • Broad process flowsheet complexity and natural gas processing scales are considered. • The AP-X process has the lowest energy consumption and cost for 8 MTPA plants. • The single mixed refrigerant process has the highest profit for small-scale plants. • Energetically better processes may not provide a higher economic return. The demand for liquified natural gas grows as it is an energy resource that has more flexible means of transport than non-liquefied natural gas, and is more eco-friendly than other fossil fuels. This paper focused on comparing five different mixed-refrigerant liquefaction processes to determine which one is the most efficient in energetic and economic terms for four different natural gas processing scales (20,000 kg/h and 2, 4, and 8 MTPA of natural gas feed). Simpler processes with one or two refrigerant cycles (single mixed refrigerant, propane pre-cooled mixed refrigerant, and dual mixed refrigerant) and more complex processes with three cycles (mixed fluid cascade and AP-X) were analyzed. All processes were simulated in Aspen HYSYS, and the energy consumption was optimized by a communication between the simulator and an optimization algorithm based on Particle Swarm Optimization coded in MATLAB. The economic analysis was performed using the CAPCOST technique and the rule of six-tenths for upscaling. In the best-optimized scenario, the results show that the most complex process, AP-X, consumes the lowest amount of energy (0.2367 kWh/kg-LNG) while the simplest one, the single mixed refrigerant, consumes the highest value (0.2561 kWh/kg-LNG). In the economic analysis, the results indicate that energetically better processes may not provide a higher economic return even on large scales. [ABSTRACT FROM AUTHOR]

• An experimentally validated system-level model of a fuel cell electric vehicle. • Fuel cell electric vehicle is simulated with a coupled multi-domain model. • Model comprises multiple scales from intra-fuel cell phenomena to the vehicle level. • Model comprises a fuel cell and battery aging model. • Model enables multi-objective optimisation of component sizing and control strategy. One of the key challenges in the design of fuel cell vehicles arises from the need for the simultaneous optimisation of their efficiency and lifetime, which is, in particular, challenging when operating under transient operating conditions; further, the minimisation of costs and the use of critical materials should be considered. To enable a more detailed virtual exploration of the design space, this paper presents a high-fidelity multi-domain and multi-scale model of a fuel cell electric vehicle that is capable of modelling the coupled phenomena from the vehicle level to intra-fuel cell level with a mechanistically based fuel cell model. The high-fidelity multi-domain and multi-scale model of a fuel cell electric vehicle is based on consistent coupling of different domains, that is, mechanical, electrical, electrochemical, gas flow, thermal, and control, which are modelled with mechanistic governing equations coupled to empirical degradation models of electrochemical devices and solved with multirate solvers ensuring flux conservations and synchronization of time steps. Establishing a consistent model based causal interactions between different domains and the significantly different scales associated with the phenomena in these domains, which more consistently virtually replicates the phenomena in a real fuel cell electric vehicle, is crucial for evaluating the impact of the parameters from high scales on intra-fuel cell spatio-temporal characteristics impacting fuel cell degradation. The results demonstrate that the application of an experimentally validated multi-domain and multi-scale model of a fuel cell electric vehicle enables the virtual exploration of interactions considering the scale of vehicle characteristics and its driving pattern to the scale of intra-fuel cell spatio-temporal characteristics and its degradation early in the development stages of the fuel cell electric vehicle. Therefore, the proposed approach represents a valuable contribution to the virtualisation of the system-level design of powertrains of fuel cell electric vehicles and supports front loading in the development process. [ABSTRACT FROM AUTHOR]

• A reversible novel reversible HTHP-ORC system was proposed. • Heat source temperature increment benefits the energy performance for both modes. • Built-in volume ratio and IHX effectiveness optimization was realised. • The novel HTHP-ORC provides a COP of 2.44 and net electrical efficiency of 8.75%. • HCFO-1224yd(Z) and HCFO-1233zd(E) are appropriate alternatives for HFC-245fa. Nowadays, a high amount of industrial thermal energy is still lost due to the lack of competitive solutions for energy revalorization. Facing this challenge, this paper presents a novel technology, based on a reversible High-Temperature Heat Pump (HTHP) and Organic Rankine Cycle (ORC). The proposed system recovers low-grade waste heat to generate electricity or useful heat in accordance with consumer demand. Compressor and expander semi-empirical models have been considered for the reversible system computational simulation, being HFC-245fa the working fluid selected. The built-in volume ratio and Internal Heat Exchanger (IHX) effectiveness have been optimized to reach the maximum energy efficiency in each operating condition. Although HFC-245fa exhibits energy performance attributes, its high Global Warming Potential (GWP) is an issue for climate change mitigation. Hence, multi-objective optimisation of the environmentally friendly working fluids Butane, Pentane, HFO-1336mzz(Z), R-514A, HCFO-1233zd(E) and HCFO-1224yd(Z) has been carried out. The results show that the system proposed, working with HFC-245fa, achieves a Coefficient of Performance (COP) of 2.44 for condensing temperature of 140 °C, operating in HTHP mode, whereas the ORC mode provides a net electrical efficiency of 8.7% at condensing temperature of 40 °C. Besides, HCFO-1233zd(E) and HCFO-1224yd(Z) are both appropriate alternatives for the HFC-245fa replacement. These working fluids provide a COP improvement of 9.7% and 5.8% and electrical net efficiency improvement of 2.1% and 0.8%, respectively, compared to HFC-245fa. This paper provides a reference study for further designs and developments of reversible HTHP-ORC systems used for industrial low-grade waste heat recovery. [ABSTRACT FROM AUTHOR]

• Integrating CO 2 capture with pyrolysis has a big potential to achieve negative emissions. • The pyrolysis reaction time shows clear impacts on CO 2 capture. • Techno-economic analysis is conducted for different technologies of CO 2 capture. • Chemical looping combustion shows the best techno-economic performance. Emerging negative emission technologies (NETs) are considered as effective measures to reduce carbon dioxide emissions to achieve the climate goal set by the Paris Agreement, and bioenergy with carbon capture and storage (BECCS) is one of the most important NETs. Integrating CO 2 capture with biomass pyrolysis (PyrCC) is attracting increasing interest, because biomass pyrolysis has been widely used to produce biooil to replace fossil fuel for decarbonizing the transport sector. In order to provide guidance to the selection of CO 2 capture technologies, this paper evaluated the technical and economic performances of PyrCC when different CO 2 capture technologies are integrated, including monoethanolamine-based chemical absorption (MEA-CA), temperature swing absorption (TSA), calcium looping (CaL), and chemical looping combustion (CLC). Generally speaking, CLC can realize the highest capture amount of CO 2 with the lowest energy penalty. Meanwhile, CLC and CaL show the lowest levelized cost of CO 2 (LCOC), which are around 56$/tCO 2 ; and on the contrary MEA-CA shows the highest one of 83$/tCO 2. In addition, the key process parameter of pyrolysis, reaction time, has clear effects on the performance of CO 2 capture as the longer reaction time leads to an increased amount of captured CO 2 and reduced energy penalty. As a result, when the reaction time increases, the LCOCs of all assessed technologies decrease. Moreover, the net present value and the payback time are also estimated for different technologies. At the carbon price of 70.1$/tCO 2 , MEA-CA and CLC show the longest and shortest payback time that are 5.9 years and 3.2 years respectively. [ABSTRACT FROM AUTHOR]

Powertrain topology design is vital for system performance of a hybrid electric vehicle. In this paper, a novel four-wheel-driven series–parallel hybrid electric powertrain is proposed. A motor is connected to the differential of the rear axle. An auxiliary power unit is linked to the differential of the front axle via a clutch. First, a mathematical model was established to evaluate the fuel-saving potential. A rule-based energy management algorithm was subsequently designed, and its working parameters were optimized. The hybrid powertrain system was applied to a transit bus, and the system characteristics were analyzed. Compared to an existing coaxial power-split hybrid powertrain, the fuel economy of the four-wheel-driven series–parallel hybrid powertrain can be at the same level under normal road conditions. However, the proposed four-wheel-driven series–parallel hybrid powertrain can recover braking energy more efficiently under road conditions with a low adhesive coefficient and can alleviate the torsional oscillation occurring at the existing coaxial power-split hybrid powertrain. Therefore, the four-wheel-driven series–parallel hybrid powertrain is a good solution for transit buses toward more robust performance. [ABSTRACT FROM AUTHOR]

Due to the adoption of EU Regulation No 517/2014, R404A is going to be banned in Europe in most of refrigeration applications, in which is typically used, due to its very high GWP value, 3943. In this paper an experimental comparison between R404A and R448A, a non-flammable alternative with GWP of 1390, is presented. The experimental tests are intended to simulate typical freezing and conservation temperatures and different condensing conditions. Despite cooling capacity of R448A is slightly below that of R404A, R448A energy consumption is even smaller; and R448A COP is higher than that obtained using R404A. Hence, it can be concluded that R448A could be an energy efficient alternative to R404A with a GWP reduction of 70%. Compressor discharge temperature remains at non-dangerous levels. [ABSTRACT FROM AUTHOR]

In this paper, a specific hybrid energy system was proposed for household applications. The hybrid energy system was assembled from a HT-PEM fuel cell stack supplied by hydrogen via a steam reformer, where finally the majority of produced electricity is used to drive a modified split heat pump system with heat recovery (that is enabled via standard modified accumulation boilers). The system is able to produce both high and low temperature heat output (in the form of hot water), cooling thermal output and electricity. Performance analysis was conducted and the specific hybrid energy system showed high value for overall energy efficiency, for the specific case examined it reached 250%. Levelized Cost of Energy (LCOE) analysis was also carried out and the proposed hybrid energy system’s cost is expected to be between 0.09 €/kW h and 0.16 €/kW h, which is certainly competitive with the current retail electricity price for households on the EU market. Additionally, the system also has environmental benefits in relation to reduced CO 2 emissions, as estimated CO 2 emissions from the proposed hybrid energy system are expected to be at around 9.0 gCO 2 /kW h or 2.6 times less than the emissions released from the utilization of grid electricity. [ABSTRACT FROM AUTHOR]

This paper proposes an advanced energy management strategy for a stand-alone hybrid energy system. The considered hybrid system includes a photovoltaic panel, a fuel cell, an electrolyzer, a battery bank and a supercapacitor. The proposed power management system aims to control the energy flow within the system and decides the amount of the load power shared with each power source. The system control is implemented in two parts: a central power flow controller that provides overall control of the power system and a local loads controller, which controls the different loads according to the energy balance of the system. The hybrid power system has been tested by simulation using models implemented in Matlab/Simulink software. The simulation is performed over a short and a long period of time in order to evaluate the performance of the dynamic controllers and the effectiveness of the management strategy. For a long simulation period, a house located in the province of Batna ( 35 ° 33 ′ N 6 ° 10 ′ E) has been taken as a case study with a deep study on real load profile for an average house with all required weather data with respect to the location. The simulation results confirm the efficiency of the proposed control strategy, as it increases the reliability of the system and improves its energy balance. [ABSTRACT FROM AUTHOR]

Ground source heat pumps (GSHP) have attracted increasing attention because of their high energy efficiencies. The aim of this paper is to study the performance of (GSHP) in future climate conditions (2040–2069) by using projected future hourly weather data of selected representative cities in the US to estimate future ground temperature change. The projected hourly weather data and estimated ground temperatures are input to an hourly simulation tool (TRNSYS and eQuest for this research), which provides reliable coupling of GSHP system and building performance. The simulation results show that global warming will decrease the energy efficiency of GSHP in US residential buildings because a rise in inlet and outlet water temperature is predicted for GSHP systems during the cooling season and because buildings will become more cooling dominated in the future. For office buildings, although the cooling performance of GSHP will not drop significantly under future climate, the overall energy efficiency for the system will decrease due to the increasing energy consumption of the ground loop pump. In the future, considering the significant ground heat imbalance for GSHP operation, GSHP will become less competitive both economically and technically than it is now in the context of US climate zones. [ABSTRACT FROM AUTHOR]

The ORC certainly represents a promising solution for recovering low-grade waste heat in industries. However, the efficiency of commercial small-scale ORC solutions is still too low in comparison with the high initial costs of the machine and the lack of simulation models specifically developed for commercial ORC systems prevents industries from defining an accurate business model to correctly evaluate the ORC integration in real industrial processes. This paper presents a techno-economic feasibility analysis of the integration of a small-scale commercial ORC in a real case study, represented by a highly-efficient industrial distillery. The integration is aimed at maximizing the electricity auto-production by exploiting the heat produced by an internal combustion engine, already partially recovered in internal thermal processes. To analyze the influence of the ORC integration on the industrial processes, a semi-empirical steady-state model of the commercial small scale ORC was created. The model made it possible to simulate the performance of the commercial ORC within a hypothetical scenario involving the use of the heat from the cooling water and from the exhaust gases of the internal combustion engine. A detailed thermo-dynamic analysis has been carried out to study the effects of the ORC integration on the plant’s energy system with particular focus on the two processes directly affected by ORC integration, namely vapor production and the drying process of the grape marc. The analysis highlighted the great importance in the business model of considering not only the direct costs (unit costs, engineering, etc.), but mainly the indirect ones and hence the need of an appropriate business model, based on the simulation of the commercial ORC behavior, to evaluate its introduction in real industrial processes. In particular, in the specific case of a highly-efficient distillery plant, the ORC integration resulted to cause an increase in inner fuel consumption, represented by dried grape marc, with a consequent economic loss not offset by a significant increase in electricity auto-production. As a consequence, the ORC integration was not economically feasible in the considered case study due to the great value in the market of the dried grape marc. [ABSTRACT FROM AUTHOR]

• The proposed approach involves multiple regression and superstructure optimisation. • Streams with evaporation and condensation are properly handled in model formulation. • The proposed approach provides better solutions with higher net power output. • The trade-off between the energy cost and the number of heat exchangers is explored. • The effect of electricity price on organic Rankine cycle integration is examined. Organic Rankine cycles can produce power from various low-to-medium temperature heat sources efficiently, and may be integrated into industrial processes to recover low-grade waste heat for improved energy efficiency. This paper presents a mathematical programming model for the synthesis of organic Rankine cycle-integrated heat exchanger networks. The model is based on an organic Rankine cycle representation of four alternative configurations and a modified stage-wise superstructure, where heat exchange between process streams and organic Rankine cycle streams can take place in all the stages. In addition, the flowrate and operating temperatures of the working fluid are treated as variables, and its thermodynamic properties (e.g. enthalpies and pump/turbine outlet temperatures) are correlated as functions of the temperatures. This allows the organic Rankine cycle and the heat exchanger network to be optimised simultaneously, with the objective of maximising the net power output or minimising the overall energy cost. Two literature examples are used to illustrate the proposed approach. The results show that apart from producing power, the organic Rankine cycle can reduce the cold utility consumption by up to 26% when integrated with a process. Furthermore, the overall energy cost can be minimised by increasing the net power output optimally (by 54.6%), despite increased hot (+38.9%) and cold utility requirements (+19.5%). The proposed approach is thus useful in assessing the benefits from process integration of organic Rankine cycles. [ABSTRACT FROM AUTHOR]

This paper describes numerical modeling of heat and mass transfer in five different exchangers utilizing the Maisotsenko cycle for indirect evaporative cooling. For this purpose, numerical models are developed based on the modified ε-NTU method to perform thermal calculations of the indirect evaporative cooling process, thus quantifying overall performance of considered heat exchangers. Numerical simulation reveals many unique features of considered devices, enabling an accurate prediction of their performance. The results of computer simulation showed high efficiency gains that are sensitive to various inlet conditions, and allow for estimation of optimum operating conditions, including suitable climatic zones for the proposed unit using. [ABSTRACT FROM AUTHOR]

The growing environmental awareness and the apparent conflicts between economic and environmental objectives turn energy planning problems naturally into multi-objective optimization problems. In the current study, mixed fuel combustion is considered as an option to achieve tradeoff between economic objective (associated with fuel cost) and emission objective (measured in CO 2 emission cost according to fuels and emission allowance price) because a fuel with higher emissions is usually cheaper than one with lower emissions. Combined heat and power (CHP) production is an important high-efficiency technology to promote under the emission trading scheme. In CHP production, the production planning of both commodities must be done in coordination. A long-term planning problem decomposes into thousands of hourly subproblems. In this paper, a bi-objective multi-period linear programming CHP planning model is presented first. Then, an efficient specialized merging algorithm for constructing the exact Pareto frontier (PF) of the problem is presented. The algorithm is theoretically and empirically compared against a modified dichotomic search algorithm. The efficiency and effectiveness of the algorithm is justified. [ABSTRACT FROM AUTHOR]