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Abstract: The aim of the study is to model and to simulate the thermal and electrical efficiencies of the cogeneration plant of a paper mill. The final purpose is the benefits optimization by adjusting production to the amount of energy to be sold. It is necessary to know it because the sale price goes down when the actual production of electrical energy does not match the scheduled power. [Copyright &y& Elsevier]

Highlights: [•] Estimation of GHG emission and energy consumption in wastewater treatment plants. [•] On-site and off-site emissions of carbon dioxide, methane, and nitrous oxide. [•] Higher GHG emission in anaerobic and hybrid plants due to higher CH4 generation. [•] Recovery and use of biogas satisfy the energy demands of treatment systems. [•] Higher off-site than on-site GHG emissions due to the use of fuel and material. [ABSTRACT FROM AUTHOR]

Among all public buildings, on account of their educational purpose, school buildings have a major social responsibility. Therefore energy performance in this type of building is of great importance. The overall purpose of this research is to achieve a functional benchmarking, based on the real operation conditions of school buildings, by the exploitation of the results made public, through an intensive literature survey on energy consumptions in schools. The survey was made to gather data that is relative to energy consumption in school buildings, documented in the most diverse fields and units: global energy consumption values, electrical energy consumption; fuel consumption for heating, energy data consumption of schools expressed in annual cost per unit of heated/cooled surface area ($/m 2 ) or per unit of heated/cooled volume ($/m 3 ) or, finally, as the annual cost per student ($/student). The literature was analyzed to determine if a worldwide comparison among the published data could be established. The results suggest that when attempting to determine an energy benchmark some considerations should not be forgotten: standard indoor environmental conditions (IEC) for classrooms (set-point for indoor operative temperature of 20 °C in winter and 26 °C in summer as suggested in EN 15251:2007), electrical and heating consumption values should be kept separately, different education levels usually require different energy consumption values. A good way to normalize heating energy consumption is going through a climatic adjustment based on Heating Degree Days (HDD). For an impartial data comparison, based either on an operating rating or on a simulation carried out for reference conditions, benchmark reference values should be expressed in terms of billed energy data. [ABSTRACT FROM AUTHOR]

This paper presents a critical advancement in Building Energy Modeling (BEM) through an empirical validation approach using a high-quality dataset from a multizone commercial office building in Oak Ridge, TN, USA. BEM is widely utilized in diverse construction applications, but its effectiveness relies on the accuracy of its predictions. The study focuses on empirical validation of input parameters in BEM, including building envelope data, infiltration modeling, and rooftop unit system performance curves. The validation of simulation input parameters leads to substantial improvements in the accuracy of simulation results. Notable both NMBE and cv (RMSE) values are reduced by 0.5 % for indoor air temperature and 17 % for indoor air relative humidity compared to the previous model. At the system level, both NMBE and cv (RMSE) values are reduced by 2 % for fan energy consumption and 4 % for cooling energy consumption, compared to the previous model. A literature review highlights a significant gap in empirical validation studies, which predominantly concentrate on either component-level or whole building validation. Furthermore, many studies employ simplified setups that may not faithfully represent the complexities of multizone commercial buildings. This paper distinguishes itself by emphasizing the critical importance of component-level input parameter validation. It underlines the need to validate data related to building envelope components and HVAC system performance curves, resulting in more accurate simulation outcomes. The utilization of actual multizone commercial building data enhances the study's practical relevance. In summary, this research underscores the pivotal role of input parameter validation in enhancing the accuracy and reliability of BEM. • The EnergyPlus simulation model input parameters have been empirically validated. • Building envelope input parameters have been evaluated. • Tracer gas and blower door tests have been performed to update infiltration model. • The rooftop unit performance curve has been developed using field datasets. • The simulation results are well-matched with field data at zonal- and system-level. [ABSTRACT FROM AUTHOR]

Highlights • Fault leads to reduction in motor's efficiency which increases its energy consumption and CO 2 emission. • As the fault propagates, these losses increase further and are generally ignored by the industries. • Efficiency monitoring based CBM has been proposed as a part of motor maintenance strategy. • Proposed strategy considers the faulty motor running loss for planning maintenance action. Abstract Induction motors are the major source of energy consumption in industries. Research work available on motor efficiency and energy consumption advocates the use of energy efficient motors to reduce the power consumption. However, these motors are also prone to faults which affects their operational efficiency. Over a period of time, the propagation of fault in the motor leads to the further drop in the efficiency which increases motor running loss. This loss is generally ignored by most of the researchers and managers and is a hidden cost borne by the industries. In this paper running of faulty induction motors and its associated financial losses have been addressed. It has been assumed that for a motor running at constant load, fault propagation leads to further drop in its efficiency. Three simulated scenarios: linear, exponential and quadratic drop in efficiency have been considered for estimation of running loss. An algorithm has also been proposed for planning maintenance actions based on operational losses due to faulty motor. This paper also highlights how efficiency and condition monitoring helps in reducing CO 2 emission. [ABSTRACT FROM AUTHOR]

Abstract Solar aided (coal-fired) power generation (SAPG) system has been proved to be an efficient way to utilize the solar energy for power generation. Due to the instability of the solar radiation, a SAPG system generally operates under transient working conditions. In this paper, performance simulation sub-models of main components in a SAPG plant are established based on the lumped parameter assumption. A 330 MW SAPG power plant as a case study is simulated. The variations of the performances, main parameters of the plant with the solar field heat output and the dynamic responses under a typical day are analyzed. The results show that when the heat output of the solar field changes from 0 kJ/h to 2.13 × 108 kJ/h, the coal saving rate will increase to 6.4%, and the solar power generation share (the proportion of the power from the solar energy to the total power from the SAPG plant) will increase to 7.74%. During the analysis process, in order to optimize the solar field, the concept of the solar field equivalent efficiency (SFEE) is proposed and the optimal velocity of heat transfer fluid (HTF) in absorber tube is obtained. Highlights • The transient model of a solar aided power generation (SAPG) system is developed. • The concept of solar field equivalent efficiency (SFEE) is proposed in this paper. • The optimal velocity of heat transfer fluid in the absorb tube is obtained. • Performances of SAPG system with different solar field heat output are revealed. • The dynamic responses of the SAPG system under a typical day are analyzed. [ABSTRACT FROM AUTHOR]

Past studies of hybrid power cycles using multiple heat sources of different temperatures focused mainly on case studies and almost no general theory about this type of systems was developed. This paper is a first comprehensive study of their general thermodynamic performance, with their comparison to their corresponding single temperature heat source reference system, focusing on three types of power cycles: simple Rankine cycle, Rankine cycle with reheat and Rankine cycle with heat regeneration. The generalized expressions for the energy and exergy efficiency differences between the hybrid and the corresponding single heat source system were developed. A number of simulation case studies were performed to help the understanding and confirm the thermodynamic generalization of the results. The results show that the energy and exergy efficiencies of the hybrid systems are higher than those of their corresponding single heat source reference systems if and only if the energy andexergy conversion efficiency (defined in the paper) of the additional heat source (AHS) is larger than that of the original heat source. The conditions that defined the effects of the AHS temperature and heat addition rate on the energy and exergy efficiencies of the hybrid systems as convex or concave curves were described. Comparisons across the first two types of hybrid power cycles were made, showing that the energy and exergy efficiencies of the reheat Rankine cycle is generally higher than that of the simple Rankine cycle as AHS is changed. Recommendations were made for obtaining the maximal energy and exergy efficiency as a function of the AHS temperature, of the heat addition rate by the AHS, and of the AHS position in the power cycle flow sheet. For the hybrid power generation systems with heat regeneration it was found that when using an AHS to raise the net system power by a given amount, using it to replace the higher-pressure extracted steam will result in a higher system energy efficiency than when using it to replace lower-pressure extracted steam. Hybrid cycles can have significantly lower emissions, cost, and fuel depletion. [ABSTRACT FROM AUTHOR]

This paper presents a review of the design parameters, mathematical techniques and simulations used in the design of parabolic trough solar systems, along with a review on their applications. Recent studies that analyze the deployment of solar parabolic trough collectors (SPTC) in different countries and the operational SPTC plants are also presented and discussed. The paper also discusses the different kinds of software and test methods of solar collectors developed since 1981 which can be distinguished by their particular mathematical models or tracking techniques. In particular, since the mathematical models are especially required for the design, analysis, testing and validation of the systems results as they provide an approximation of the dynamic behavior of the physical properties of the system, they are discussed in depth. The mathematical models allow the calculation of different parameters of the solar parabolic trough system, the angle of inclination of the collecting surface and the forces acting on the system. The validity and experimental validation of the major mathematical models on practical solar parabolic trough concentrators, receivers and other components of different dimension are also reviewed. The paper showed the optical efficiency values are close to 63% and the theoretical peak optical efficiency reached 75%. [ABSTRACT FROM AUTHOR]

The hydrogen storage phase of an energy storage plant based on metallic hydrides has a strong influence on the total efficiency of storage power plants as well as on their response time. The technique presented in this paper uses a hydrogen-metal chemical bond during its storage. This paper describes a metal hydride cylinder modeled and simulated by using the main quantities involved in the adsorption and desorption processes as well as in an analysis of the influence of thermal quantities involved in these processes. As a result, a proposal for automation of the thermal exchange of the modeled cylinder is presented and the possibilities of evaluation of this technique. [ABSTRACT FROM AUTHOR]

An electric aircraft propulsion system utilizes a high efficiency motor to generate thrust for electric aircraft. However, it can be challenging to maintain high efficiency for the fixed pitch propeller, which is commonly used in electric aircraft, through all phases of the flight. This paper investigates the power demands of the electric aircraft during the climb and the cruise phases according to the flight profile, and presents a model to estimate the energy consumption per flight. Simulation results suggest that the efficiency in the climb and the cruise phases can affect the energy consumption of an electric aircraft. Efficiency during the climb phase can have a significant effect on the capacity of the electric aircraft propulsion system. Based on the aforementioned results, this paper proposes a novel approach to achieve high efficiency, in which the optimal efficiency points of the electric aircraft propulsion system in the climb and the cruise phases can be obtained by solving an optimization problem with minimizing the energy consumption per flight as the object function and under the constraints that the climb and cruise phases must be successful. For testing purposes, the proposed method is adopted to the design of the electric aircraft propulsion system on a specific two-seater electric aircraft. Experimental results obtained from real flights suggest that the proposed method can reduce the energy consumption of the electric aircraft by over 10%, while reducing the capacity demand for the electric aircraft propulsion system. [ABSTRACT FROM AUTHOR]

As we all know, how to achieve better energy savings has been mentioned on various countries’ energy schedules. Public buildings as a large energy consumption. It’s air conditioning system has a lot of energy-saving space, and air-conditioning chilled water system to optimize energy-saving control is an important measure to achieve energy-saving air-conditioning system initiatives. This paper mainly focuses on the control system of variable frequency pump in chilled water system. For the water pump control strategy, the secondary pump frequency control strategy is discussed, in order to obtain a better control strategy, in detail the current commonly used differential pressure control strategy. In this paper, five kinds of differential pressure control strategies are analyzed, and then the simulation model is simulated by the established mathematical model. The input energy consumption model of the inverter - motor - water pump micro - system is obtained and the simulation results are analyzed. [ABSTRACT FROM AUTHOR]

S-Transform method can be regarded as an extension to the ideas of the Windowed Fourier Transform (WFT) method and the Wavelet Transform (WT) method, which gives consideration to both local frequency concept of WFT and the multi-resolution strategy of WT. It has been introduced in optical 3D shape measurement recently. However, the S-Transform method suffers from poor energy concentration when some kind of signal is treated with. In order to enhance energy concentration to provide more accurate estimation of the instantaneous frequency, a modification to the existing 2D S-Transform is proposed in this paper. Two additional parameters are introduced to respectively optimize the window width in x and y direction. The paper gives the expression of 2D S-Transform with optimized window and its performance in 3D surface reconstruction. The application of proposed method is demonstrated on both simulation and experiment by comparing with traditional 2D S-Transform method. The improved performance of optimized 2D S-Transform for 3D surface shape measurement shows its feasibility and veracity. [ABSTRACT FROM AUTHOR]

In this paper, a method is presented to reduce the power consumption of the two-stage dynamic comparators. In the two-stage dynamic comparators, the first stage (pre-amplifier stage) amplifies the input differential voltage. Then the second stage (latch stage) is activated and finishes the comparison. When the comparison is about to finish, the balance of the positive feedback of the latch stage tends to tilt toward one of the outputs; after this, to the end of the comparison, there is no need for additional pre-amplification gain which causes excess power consumption. In this paper, a method is proposed to eliminate this part of power consumption. It is shown that while reducing the power consumption significantly, the method does not affect the dynamic behavior of the comparator such as speed or offset voltage. This method reduces the power consumption by 30% to 58% . Post Layout Simulations as well as analytical derivations and schematic simulations prove the beneficial performance of the proposed method. [ABSTRACT FROM AUTHOR]

Power split configurations exhibit potential on decreasing fuel consumption. However, how to select the best power split configuration among all the possible configurations still need to be explored. In this paper, a one-dimensional searching ECMS (Equivalent Consumption Minimization Strategy) is developed to evaluate fuel consumption for input power split configuration. Additionally, a battery degradation model based on experimental data is applied to evaluate the battery degradation for input power split configuration. According to one-dimensional searching ECMS and battery degradation model, the impact of different input power split configurations on fuel consumption and battery degradation is investigated. Simulations show that configuration T1 has fuel consumption and battery degradation advantages for PHEV city bus application in China. These advantages are observed because the system efficiency operation points of configuration T1 are closer to the high efficiency area than the system efficiency operation points of other input power split configurations. Furthermore, according to the lever model and one-dimensional searching ECMS method, a power split configuration selection method is provided in this paper. The simulation results based on configuration selection method still indicate that configuration T1 appears to have the best fuel economy for PHEV city bus application. Moreover, configuration T5, with a lever length close to 0, exhibits the worst fuel consumption and battery degradation. [ABSTRACT FROM AUTHOR]

This paper describes the Energy and Daylighting optimization of a fixed inclined panel which shades an office room with a south exposed window. The window features also user deployable internal Venetian blinds. Energy analysis takes into account the primary energy required for heating, cooling and artificial lights. Different numerical codes have been employed in order to perform the simulations required by the optimization process: Daysim estimates the artificial light consumption based on daylighting distribution, ESP-r computes heating and cooling loads and modeFRONTIER integrates the simulation codes in an automatic optimization loop. The performance of an algorithm specifically designed to deal with problems involving long simulation times (combining response surfaces and genetic algorithms) has been successfully evaluated; the algorithm has then been applied in the optimization loop. The optimized solutions are analysed in this paper, in particular three solutions have been selected: minimum primary energy consumption, minimum hours of blind deployed and an intermediate solution. The analysis compares the primary energy consumption and daylighting performance on the basis of the Useful Daylight Illuminance indicator and the time history of illuminance on predefined locations. [ABSTRACT FROM AUTHOR]

This paper studies the performance of a coal-fired power plant integrated with Ca-looping CO 2 capture system with recarbonation process. The Ca-looping CO 2 capture system with/without the recarbonation process are simulated using the ASPEN PLUS™ software and integrated in a coal-fired power plant with the net system efficiency of 41.57%. Simulation results of the two systems are compared, and a sensitivity analysis of the key parameters is taken. The results show that, when the CO 2 capture rate is 85%, the net system efficiency of the coal-fired power plant integrated with the traditional Ca-looping CO 2 capture system without recarbonation process is 30.66%. The efficiency penalty is 10.91% compared with that of the benchmark coal-fired power plant without CO 2 capture. While the net efficiency of the coal-fired power plant integrated with the Ca-looping CO 2 capture system with recarbonation process is 34.3% and the efficiency penalty is only 7.27%. The analysis results show that reducing the amounts of both calcium sorbents and the fresh sorbent supplement in cycles can further improve the efficiency of the overall system. The achievements from this paper will provide the valuable reference for the CO 2 capture from the coal-fired power plant with lower energy consumption. [ABSTRACT FROM AUTHOR]

Organic Rankine cycle (ORC) can improve engine power by recovering exhaust energy. This paper co-optimizes the engine-ORC combined system's power and NOx emission, with decision variables of the engine's excess air ratio, spark advance angle, as well as ORC's pump and expander speeds. Firstly, a simulation model of the combined system is established and validated. Then, the initial dataset is generated by the D-optimum Latin hypercube method and simulation model. The artificial neural network (ANN) prediction models of NOx emission and power are established based on these datasets. Finally, the co-optimization is conducted using the ANN prediction model and genetic algorithm. Focusing on maximizing the combined system's power results in an 18.30 % increase in power, and a significant reduction in brake-specific fuel consumption (BSFC) and brake-specific NOx (BSNOx) by 10.10 % and 71.30 %, respectively, compared to the unoptimized basis. Targeting the lowest BSNOx leads to a limited 1.20 % increase in power output; however, it results in a 19.50 % increase in BSFC. When optimizing for both system output and BSNOx, the output remains 13.5 % above the unoptimized basis. Meanwhile, up to 89.8 % of BSNOx can be eliminated with negligible deterioration in BSFC. This study could be used for engine performance enhancements. • A data-driven ANN prediction model of engine-ORC combined system is established. • ANN cooperates with GA to co-optimize Combined system's power and NOx emission. • The optimum engine and ORC parameters for the different goals are obtained. [ABSTRACT FROM AUTHOR]

This paper presents simulation of thermal stratification heat storage water tank with an inside cylinder with openings by three-dimensional Computational Fluid Dynamics (CFD) methods. Specifically, this paper focuses both on investigating the influence of the inner cylinder's design and operating parameters and on the water flow characteristic, thermal stratification and overall performance of the hot heat storage water tank during heat charging operation process installed in thermal energy systems. Validation of CFD results with experimental data found in the literature has a good consistency. In order to visually compare the efficiency of the energy storage tank with thermal stratification, and the dimensionless fluid temperature, one of existing methods for calculating stratification efficiencies is applied to hypothetical storage process of charging in this paper. Cylinder insides the tank plays a role of uniform diffuser, so that the water in the tank is formed thermal stratification. [ABSTRACT FROM AUTHOR]

Connected vehicle technology (CVT) is being tested at various research laboratories across the United States for its real-world applications. The aim is to properly know its benefits in order to make travel safe, reliable and environment-friendly. Although, with time, vehicles are becoming eco-friendlier and resourceful in energy consumption and utilization, majority of vehicles today still operate on fossil fuels and the resulting emissions are a by-product. Thus, most affordable cars and even trucks in future will continue to run on fossil fuels and might simultaneously be equipped with CVT features. Fossil-fuel dependent vehicles when fully equipped with CVT would need to accelerate or decelerate appropriately around critical junctions and locations of a network to avoid collisions. CVT in vehicles will be most appreciated for safety reasons at least at the roadway merge locations of the network. However, frequent accelerations and decelerations of the vehicles at merge points such as from ramp to freeway will also lead to increase in emissions and fuel consumption. This is precisely what this paper explores and investigates. A computer-based simulation exercise is carried out using an example of a ramp to Interstate 405 freeway merge location in Long Beach, California. Based on some basic but realistic assumptions for vehicular motion made in his paper, it is found that benefit from CVT in emission reduction is marginal for the three traffic conditions of free-flow, transitional period and rush-hour congestion. These findings will help engineers to prepare vehicles with a more sophisticated CVT that can provide better emission reductions and fuel savings at several ramp-to-freeway merge locations that exist across the city of Long Beach. [ABSTRACT FROM AUTHOR]

Many studies have been carried out separately on combined heat and power and district heating. However, little work has been done considering the heat source, the district heating network and the heat users simultaneously, especially when it comes to the heating system with large-scale combined heat and power plant. For the purpose of energy conservation, it is very important to know well the system performance of the integrated heating system from the very primary fuel input to the terminal heat users. This paper set up a model of 300 MW electric power rated air-cooled combined heat and power plant using Ebsilon software, which was validated according to the design data from the turbine manufacturer. Then, the model of heating network and heat users were developed based on the fundamental theories of fluid mechanics and heat transfer. Finally the combined heat and power based district heating system was obtained and the system performances within multiscale scope of the system were analyzed using the developed Ebsilon model. Topics with regard to the heat loss, the pressure drop, the pump power consumption and the supply temperatures of the district heating network were discussed. Besides, the operational issues of the integrated system were also researched. Several useful conclusions were drawn. It was found that a lower design primary supply temperature of the district heating network would give a higher seasonal energy efficiency of the integrated system throughout the whole heating season. Moreover, it was not always right to relate low design supply temperatures to high pump power consumptions and high heat losses in the district heating network, since the results showed that the seasonal pump power consumption and the heat loss would decrease with a lower design primary supply temperature. Therefore, from the perspective of seasonal consideration, low temperature district heating has an even more bright future compared to just considering the design heat load condition. Both the combined heat and power plant and the low temperature district heating network were simulated in detail and integrated, including the part heat load conditions, which is one novelty of this article. The simulation in this paper could be considered as the basis for the further improvement and optimization of combined heat and power based district heating systems. [ABSTRACT FROM AUTHOR]

INTRODUCTION This paper mainly researches the practical engineering about Simulation of air-soil heat pump system in an office building of Shenyang, China. This system in the winter uses the air source as the main heat source and soil source as the auxiliary heat source for heating, in the summer only uses the soil source heat pump to refrigerate. METHODS This paper mainly applies DEST software and TRNSYS software to study engineering air simulated analysis of soil heat pump system and compare with a single heat source. Analyzing the energy consumption of the dual heat sources pump system and its results were compared with the single soil source heat pump system to draw a conclusion. RESULTS Analysis of energy consumption of dual-source heat pump system in summer and winter. And energy consumption analysis of single soil source heat pump system in summer and winter. CONCLUSIONS In terms of energy consumption, the annual energy consumption of dual heat source heat pump system is 25962.23 kWh. The annual energy consumption of single soil source heat pump system is 45573.78 kWh, saving about 43.03% of energy consumption. The superiority and development prospects of the dual heat source heat pump system is obvious and promising, in the operating cost and conservation area. This project was financially supported by the National science and technology support plan sub-topic (2011BAJ05B01-04). [ABSTRACT FROM AUTHOR]

This paper introduces a new system named solar energy and gas heat pump, based on the solar heat pump system driven by electricity. The study established the models of the system according to the using of TRNSYS and SIMULINK. This paper mainly studies on the performance parameters of the new system, such as evaporation temperature, COP and heating capacity. At the same time, the paper makes a comparison of COP and PER between gas heat pump and solar energy heat pump, solar energy and gas heat pump. The results show that the evaporating temperature increases by 0.84°C when the thermal storage tank temperature increases by 1°C and the condensing temperature increases by 1.46°C when the condenser inlet temperature increases by 1°C. The COP of the new system can reach 4.76 and the primary energy ratio of the system is up to 1.96, which is superior to the other two systems obviously. [ABSTRACT FROM AUTHOR]

Clustering techniques in wireless sensor networks enables energy efficient coordination among the densely deployed nodes for data delivery till the base station. Many clustering protocols have been suggested in the recent past. The topology of the nodes, mostly seen in the literature, is of random type. This paper analyzes the performance aspects of various centralized clustering techniques for wireless sensor networks. LEACH-Centralized, KMeans-CP, FCM-CP and HSA-CP protocols have been compared with respect to clustering and data delivery process for various realistic topologies. The simulations were performed for these protocols and performance of the protocols has been critically analyzed. HSA-CP clustering method performs better compared to other techniques for almost each topology examined in the paper. [ABSTRACT FROM AUTHOR]

This paper presents the modeling methodology and performance evaluation of the resonance-enhanced dual-buoy WEC (Wave Energy Converter) by HEM (hydrodynamic & electro-magnetic) fully-coupled-dynamics time-domain-simulation program. The numerical results are systematically compared with the authors' 1/6-scale experiment. With a direct-drive linear generator, the WEC consists of dual floating cylinders and a moon-pool between the cylinders, which can utilize three resonance phenomena from moon-pool dynamics as well as heave motions of inner and outer buoys. The contact and friction between the two buoys observed in the experiment are also properly modeled in the time-domain simulation by the Coulomb-friction model. Moon-pool resonance peaks significantly exaggerated in linear potential theory are empirically adjusted through comparisons with measured values. A systematic comparative study between the simulations and experiments with and without PTO (power-take-off) is conducted, and the relative heave displacements/velocities and power outputs are well matched. Then, parametric studies are carried out with the simulation program to determine optimum generator parameters. The performance with various wave conditions is also assessed. • Dual-cylinder wave energy converter with moon-pool is designed to use three resonances. • Interaction between the dual cylinder and the linear generator is solved in time domain. • The proposed simulation model correlated to the experiments provides coincided results with experiments. • Moon-pool and guiding mechanisms between the cylinders influence dynamic response and power notably. • Optimum parameters of the linear generator are found using the correlated model. [ABSTRACT FROM AUTHOR]

Energy simulation, the virtual representation and reproduction of energy processes for an entire building or a specific space, could assist building professionals with identifying relatively optimal energy conservation measures (ECMs). A review of current work revealed that methods for achieving simultaneous high accuracies in different levels of simulations, such as building level and zone level, have not been systematically explored, especially when there are several zones and multiple HVAC units in a building. Therefore, the objective of this paper is to introduce and validate a novel framework that can calibrate a model with high accuracies at multiple levels. In order to evaluate the performance of the calibration framework, we simulated HVAC-related energy consumption at the building level, at the ECM level and at the zone level. The simulation results were compared with the measured HVAC-related energy consumption. Our findings showed that MBE and CV (RMSE) were below 8.5% and 13.5%, respectively, for all three levels of energy simulation, demonstrating that the proposed framework could accurately simulate the building energy process at multiple levels. In addition, in order to estimate the potential energy efficiency improvements when different ECMs are implemented, the model has to be robust to the changes resulting from the building being operated under different control strategies. Mixed energy ground truths from two ECMs were used to calibrate the energy model. The results demonstrated that the model performed consistently well for both ECMs. Specific contributions of the study presented in this paper are the introduction of a novel calibration framework for multi-level simulation calibration, and improvements to the robustness of the calibrated model for different ECMs. [ABSTRACT FROM AUTHOR]

In this paper simulation results of two typical houses in St. John's are presented using BEOpt (Building Energy optimization) software. Simulation is done using one-year weather data, typical thermostat settings and occupation of two houses. BEopt provides capabilities to evaluate residential building designs and identify cost-optimal solution at various levels of whole-house energy savings along the path to zero net energy. It was noticed that the annual energy consumption determined using simulation in BEopt is almost same as the actual energy consumption, logged with a sampling time of 2 minutes for both the houses. This simulation, analysis and a comparison is necessary to validate the thermal model of houses. The developed model of the houses could be used to design a renewable energy system or study human behaviour impact on the house energy consumption. Simulation results and a detailed analysis of the logged data are presented in the paper. [ABSTRACT FROM AUTHOR]

A critical step in the design of a Net-Zero Energy building is the reduction of energy consumption, so that consumption can be cost-effectively offset by renewable energy production. In this paper, we present a method to inform the design of Net-Zero Energy buildings through the identification of influential energy efficiency measures. A regression-based global sensitivity analysis is used to quantify the relative importance of both individual design parameters and bilinear interactions between parameters. This allows for the identification of the specific two-way interactions between parameter pairs, rather than an evaluation of the influence of interactions for each parameter in a lumped manner as is commonly used in building performance simulation. The relative importance of both building control and architectural design parameters are assessed, and are used to help evaluate the importance of utilizing an integrated design method for reducing building energy consumption. The case-study building investigated is a primary vaccine warehouse, a vital part of the vaccine cold chain in the developing world. As this building type has not received adequate attention in the field of building performance simulation, this paper makes a significant contribution towards an improved understanding of the energy efficient design of these warehouses. [ABSTRACT FROM AUTHOR]

This paper introduces a temperature-based approach – called the Days Exceeding Threshold-Toa (DET-Toa) method to detect persisting small increase or decrease in the normal building energy consumption. This method identifies an abnormal energy consumption fault when the deviation between the measured and simulated consumption is greater than one standard deviation of the residuals in the baseline period and persists for at least 20 days which are consecutive when ordered according to increasing or decreasing outside air temperature. The fault detection capability of the method is evaluated with simulation tests with two on-campus buildings. Ten synthetic control changes were assumed to happen and lasted for one year for each building. In the test, the DET-Toa method showed superior capacity for detecting abnormal building energy consumption compared with the DET-Date method. It successfully detected 19 synthetic control changes in the 20 simulation test cases. The reason for the better performance of the DET-Toa method is discussed and demonstrated in an example case. The smallest faults that could be identified by the DET-Toa method in the two analyzed buildings and their related energy consumption impact statistics are also provided in the paper. [ABSTRACT FROM AUTHOR]

The paper presents a simplified analytical method to examine the energy absorbing mechanisms of small-scale stiffened plate specimens, quasi-statically punched at the mid-span by a rigid indenter with a knife or a flat edge shape. To validate this method, experiments and numerical simulations are conducted on specimens scaled from a tanker side panel limited by one span between the web frames and the stringers. Therefore, the paper provides practical information to estimate the extent of structural damage within ship side panels during collision accidents. The experimentally obtained force–displacement responses and shapes of the deformation show good agreement with the simulations performed by the explicit LS-DYNA finite element solver. The numerical results manage to describe the process of initiation and propagation of the material fracture in the side panel specimens and provide detailed information of the energy dissipated by each structural component and its contribution to total energy during the entire deformation process. The analytical method derives expressions to estimate the relation between the plastic deformation and the energy dissipation of the stiffened plates. Both the plate and the stiffener elements dissipate the energy through rotation of the plastic hinges at the applied load and the support and the membrane tension over the plastically deformed region between the loading and the supports. The proposed simplified expressions give a good agreement with the experimental and numerical results. [ABSTRACT FROM AUTHOR]

This paper proposes a method to resolve a strong coupling between temperature and relative humidity in drying room control systems. The coupling issue not only affects the control accuracy but also causes system instability, unnecessary adjustment, and extra energy consumption. A real-time temperature and relative humidity decoupling control method is reported in this paper. An improved aspirated psychrometer was used as a relative humidity measurement unit, which achieved relative humidity measurement accuracy of ±0.7%. The decoupling approach was developed based on a large real-time drying room, whose physical size was 22 × 15 × 3.5 m. A decoupling approach was developed using the adaptive neuro-fuzzy inference system for the control of temperature and relative humidity in the drying room. The simulated result shows that after the decoupling treatment, the relative humidity fluctuation was reduced from ±2.5% to ±0.6%. [ABSTRACT FROM AUTHOR]

Global biofuel consumption has been growing in recent years as different countries worldwide have been exploring alternatives and complements to gasoline and diesel fuel for transport. This is due to a hike in oil prices and their increasing volatility as well as both a high dependence of the transport sector on oil and also because, arguably, the supply chain of biofuels emits less CO 2 than that of fossil fuels. Biofuels have been available around the world for a while, with the aid of some government support. Brazil pioneered this renewable solution for transport, from the early 1930s, as the country had little access to local fuels, while oil and other alternatives became more expensive. Biofuels are currently widely considered as part of the solution to affordable fuels for transport. This paper makes use of a system dynamics model to analyse the current leading policies aiming at increasing the penetration of biofuels. In this context, and given multiple uncertainties that include technology evolution and fuel prices, scenario analysis has been considered for the examination of different, extreme, though plausible, futures. Simulations, under extreme scenarios, helped in assessing the possibility of removing incentives (that is, leaving decisions to an open market) and a partial reduction of subsidies. This paper concludes that for the case of Colombia, the potential of biofuels seems promising. [ABSTRACT FROM AUTHOR]

The main objective of this paper is to contribute to the discussion on the role of Net Zero Energy Buildings (Net ZEBs) on future energy systems by the interplay between on-site generation and the building loads, often called load matching, and the resulting import/export interaction with the surrounding electricity grid, commonly named grid interaction. This investigation analyzes five case studies with high resolution data, three of which are based on real monitored buildings. The research aims at selecting and suggesting a limited set of quantitative indicators that: (a) can provide practical information for building as well as grid designers and operators, and (b) are understandable for a wider audience and do not require complex simulation tools or additional resources. This paper also presents novel graphical representations describing the yearly or daily variation of the indexes in an understandable manner. It has been found that the hourly values of the cover factors (namely, the load cover factor and the supply cover factor) provide quite a good picture of the correlation between on-site demand and supply of energy. These factors illustrate both the daily and seasonal effect, the production pattern of different renewable energy technologies, and applied operation/control strategies. The loss-of load probability factor shows how often the on-site supply does not cover the on-site demand but it provides limited information. Several grid interaction indicators are presented in a normalized form based on the connection capacity between the building and the grid. The generation multiple is an index that compares peak values of exported/imported energy; it may also be used with generation/load values. The dimensioning rate and the connection capacity credit relate the building with the electrical grid. These indexes can be used to analyze individual buildings and extend their use in the case of cluster of buildings. Although some general trends have been identified in the results and the usefulness of these indicators is demonstrated, it should be noted that further studies are needed in order to define reference values for particular building topologies, clusters of buildings and climates, which could be used as a rule-of-thumb for grid/building designers. [ABSTRACT FROM AUTHOR]

This paper investigates several actions for the energy refurbishment of some buildings of the University Hospital Federico II of Naples. The analysis focuses on a specific lot of 4 buildings, representative of the whole district hospital. For those structures, sustainable energy savings actions are investigated. They regard the installation of: i) roofs thermal insulation; ii) a substation climatic 3-way valve; iii) radiators thermostatic valves; iv) AHU (air handling unit) time-programmable regulation. This paper aims at presenting an investigation methodology, useful for designers and other stakeholders involved in hospital energy refurbishments, based on an integrated approach which combines dynamic energy performance simulations and experimental campaigns. In order to measure all the simulations' missing input parameters, a suitable experimental analysis, including measurements of temperature, humidity, flow rate and density of construction materials, is performed. A thermographic investigation is also performed for investigating the building envelope performance. This analysis showed that significant savings can be achieved especially by adopting radiators thermostatic valves and AHU regulations. Coherently, the installation of a 3-way valve in the substation does not determine significant additional savings when radiators thermostatic valves are already installed. For high-rise buildings, roofs insulation returns only marginal reductions of space heating and cooling demands. [ABSTRACT FROM AUTHOR]

This paper investigates the impact of flameless oxy-fuel combustion on the thermal performance of a pilot-scale steel reheating furnace. A comprehensive mathematical model, based on the zone method of radiation analysis, was developed, which takes into account the non-grey behaviour of the furnace atmosphere under oxy-fuel combustion conditions. The model was subsequently used to simulate the temperature profile of an instrumented slab used in the experiment. The results showed that the predicted slab temperature profile along the furnace is in good agreement with measurement. However the model over predicted the absolute slab temperatures due to the influence of formation of oxide scales on the slab surface, which was not taken into account in the current model. When compared to air-fuel combustion simulation, the results of oxy-fuel combustion also indicated a marked improvement in the furnace specific fuel consumption (approximately 16%). This was mainly due to the enhanced radiative properties of the furnace atmosphere and reduced exhaust energy losses as the result of less dilution effect from nitrogen. This resulted in reduction in the overall heating time by approximately 14 min. Furthermore, if the economics of carbon capture is taken into consideration, theoretically, the energy consumption per kilogram of CO 2 captured can be reduced from 3.5 to 4.2 MJ kg−1 to 0.96 MJ kg−1. In conclusion, the current studies support the view that oxy-fuel combustion retrofitting to reheating furnaces is a promising option, both from a technical and from an environmental point of view. • Previous work on reheating furnace modelling, control, and optimisation was reviewed. • A mathematical model was further developed to simulate the oxy-fuel reheating furnace. • The model was validated using the heating curves collected during real trials. • The specific energy consumption reduces by about 16% (0.18 GJ tonne−1). • Should CO 2 capture be considered, the cost can be as low as 0.96 MJ kg−1. [ABSTRACT FROM AUTHOR]

Abstract: Alternative fueled engines offer greater challenges for engine control courtesy of uncertain fuel composition. This makes optimal tuning of input parameters like spark advance extremely difficult in most existing ECU architectures. This paper proposes the use of grey-box extremum seeking techniques to provide real-time optimization of the spark advance in alternative fueled engines. Since practical implementation of grey-box extremum seeking methods is typically done using digital technology, this paper takes advantage of emulation design methods to port the existing continuous-time grey-box extremum seeking methods to discrete-time frameworks. The ability and flexibility of the proposed discrete-time framework is demonstrated through simulations and in practical situation using a natural gas fueled engine. [Copyright &y& Elsevier]

Abstract: The academic community has already taken notice of the interactions between information technologies (IT), information systems (IS), business organizations and the environment. Despite the interest garnered, research and modelling approaches on the environmental impact of IT/IS are usually explored only through qualitative approaches. This paper introduces a way for researchers and practitioners to engage with the environmental impact of IT/IS solutions in a more quantitative manner using flow based life cycle assessments (LCA). Distinct from other life cycle assessment studies, this research paper confirms that integration of information flows within life cycle inventory analysis can be both useful and viable. Our work presents a conceptual framework for flow-based LCA within the context of IT/IS consisting of possibilities for defining functional units, a meta model for building symbiotic inventory models, the use of established software tools and databases as well as concrete actions to apply our framework within simulation studies. We hope that better knowledge of the environmental impact of IT/IS solutions will facilitate an effort for more sustainable solutions. The framework was derived by literature review, design science research and evaluated via a simulation. [Copyright &y& Elsevier]

Abstract: Wireless sensors networks (WSNs) are traditionally composed of large number of low-cost and tiny homogenous sensors nodes connected through a wireless network that gather data to be treated locally or relayed to the sink node through multi-hop wireless transmission. Moreover, such issues are very critical due servers resources constraints like efficient energy, stock limitation and lifetime of network. Several solutions were proposed to minimize the traffic into network. Clustering algorithms have been widely used to reduce energy consumption. In this context, the key point in such topology is to select a cluster. One of solutions is to select a cluster alternately. However, this choice does not consider the energy as important criteria in actual papers. In order to limit energy consumption, our new method is proposed in this paper to optimization Low Energy Adaptive Clustering Hierarchy (O- LEACH) to improve existing LEACH and LEACH-C by selecting cluster according to the residual energy of nodes dynamically. The simulation results show that proposed algorithm achieve longer stability by comparison to original LEACH and LEACH-C. [Copyright &y& Elsevier]

Abstract: Energy security, environmental concerns, thermal comfort, and economic matters are driving factors for the development of research on reducing energy consumption and the associated greenhouse gas emissions in every sector of the economy. Building energy consumption estimation has become a key approach to achieve the goals on energy consumption and emissions reduction. Energy performance of building is complicated since it depends on multiple variables associated to the building characteristics, equipment and systems, weather, occupants, and sociological influences. This paper aims to provide an up-to-date review on the basics of building energy estimation. Regarding models, a classification for energy estimation models is proposed based on the different classifications found in the literature review. The paper focuses on models developed with whole building energy simulation software and their validation. This focus is justified because of the importance that whole building energy tools have gained on areas such as green building design, and analysis of energy conservation strategies and retrofits. Since a suitable weather file is a major component for reliably simulations, the section about weather data provides pertinent information. [Copyright &y& Elsevier]

Abstract: The worldwide water supply represents a significant portion of the global energy consumption. This energy consumption, related to the collection, treatment and transportation of water, entails a large amount of costs. However, these costs are liable to be minimised with and/or without reduction on energy consumption. The purpose of this paper is to provide a review about measures and methods to achieve water supply systems efficiency. The paper summarises and compares previous investigations in order to provide the state-of-the-art to the reader. Measures with and without investment in order to reduce costs and energy consumption are presented. The paper also explores the use of hydraulic simulation and optimisation strategies in water supply systems, involving topics such as demand prediction, networks design, pumps operation, real-time operations and renewable energy production. Although the great advances in the area, there are unexplored (or poorly explored) methodologies that can be tested and maybe applied in a large number of water systems. There are also some important issues, mentioned in this paper, which must be considered in order to attend specific requirements of the water industries. [Copyright &y& Elsevier]

Abstract: Microturbines offer new perspectives in small-scale heat and power production however their profitability depends strongly on the yearly amount of running hours. The non-continuous heat demand often leads to a reduction in running hours. This paper proposes an alternative by recuperating the lost thermal power through the injection of heated water in the micro Gas Turbine (mGT). Water injection is considered a successful way to increase power and efficiency in industrial gas turbines and similar effects are expected for microturbines. This paper reports on a series of simulations of water injection performed on a Turbec T100 mGT. The goal of this study was to investigate the potential of water injection in the mGT cycle using an adiabatic black box method in the Aspen® process simulation tool. Past experiments with steam injection on the T100 demonstrated the potential of introducing steam/water in the microturbine cycle. Calculations revealed that the key parameters for maximum heat recuperation are stack and pinch temperature. Simulations showed that most of the exhaust heat can be recovered through injection of heated water after the compressor, resulting in an 18% decrease in fuel consumption and an absolute increase in electrical efficiency of 7%. [Copyright &y& Elsevier]

Abstract: Scale fouling and power consumption are one of the most important parameters in reverse osmosis (RO) desalination. To reduce scale problems in RO, single or central feeds to the pressure vessel were suggested instead of using end feed. In this paper Reverse Osmosis System Analysis (ROSA) software was used to simulate the differences between single, central and end feed designs. The effect of feed Silt Density Index (SDI) and number of the RO elements in the pressure vessel were investigated here. Feed SDIs 5, 3, and 1 were considered in this paper. To study the effect of the numbers of RO elements, 6 RO and 8 RO elements per pressure vessel were simulated. The simulation results showed that the power consumption in the end feed design was lower than in the single and central feed designs. The simulation results showed that Langelier Silt Index (LSI) and Stiff & Davis Stability Index (SDSI) were lower in the single than central feed design which in turn was lower than in the end feed design. These results indicated that although the power consumption in the single and central feed designs was higher than in the end feed design; the former designs were more efficient in rescuing the RO scale problems. [Copyright &y& Elsevier]

Abstract: HCCI combustion can substantially reduce NOx and soot emissions of diesel engines. However it is hard for diesel HCCI to obtain the same level of fuel economy as traditional diesel engines. This paper presents a way to improve the fuel economy of diesel HCCI by adopting Integrated Starter Generator (ISG). A set of diesel parallel hybrid power system (in this article, we name it “hybrid engine”) is constructed by installing an ISG motor on a diesel engine, which applies HCCI–CI combined combustion. Based on a lot of investigation on diesel HCCI, this paper is focus on improving HCCI engine performance, especially the fuel economy, by adopting ISG motor assist control. The coordination control strategies of engine and ISG motor in HCCI transient states, HCCI–CI transition, engine quick start and braking energy regeneration are developed. The results of equivalent New European Driving Cycle (NEDC) tests show that, by using ISG assistance, the fuel consumption of the diesel HCCI engine is greatly reduced. Meanwhile the NOx and soot emission are also improved. [Copyright &y& Elsevier]

Abstract: The adoption of irrigation control strategies, aimed at attaining the desired level of humidity for each plant type, can improve the costs and energy consumed in small-scale site-specific irrigation systems. The paper presents a knowledge-based and distributed framework that simulates the behaviour of an irrigation system and permits accurate determination of irrigation timing. Several agents, which represent the actors involved in this problem, coordinate their activities in order to evaluate different irrigation strategies. A common ontology shares the knowledge required in the agent-based framework, which can be tuned according to the particular circumstances of the field. The usefulness of the developed system is demonstrated in three case studies, in which the simulations performed by the system provide the answer to different questions (length of irrigation time, comparison of a fixed and a dynamic irrigation policy, and most efficient configuration of a garden). The system simulates the behaviour of the irrigation system for the possible solutions and finds the most efficient one in terms of water consumption. Although only at small areal scale, this paper shows how agent-based simulation techniques can be successfully used to solve agricultural problems. [Copyright &y& Elsevier]

Abstract: In the present paper, a five-column heat integrated methanol distillation scheme is proposed with the aid of process simulation and pinch analysis. Unlike the popular four-column (or 3 + 1 column) scheme, a medium-pressure column is added after the light ends column in this novel scheme. The overhead vapor of the medium-pressure column integrates with the light ends column, and an inter-reboiler is attached to the atmospheric column. Another highlight is that the water column produces fusel oil instead of the methanol product at the top. Analyses show that the energy consumption of the five-column scheme can be reduced by 15.23%, and that the total exergy loss can be decreased 21.5% in comparison to the popular improved four-column scheme, which is taken as the control flowsheet in this paper, and producing the same product methanol purity and yield. [Copyright &y& Elsevier]

Abstract: Previous works in IEEE 802.16e power saving mainly focused on standard Type I or Type II power saving class. The limitation of adopting Type I or Type II is discussed in the paper, and the idea of Load-Based Power Saving (LBPS) is proposed. The base station in LBPS measures the traffic load and estimates the sleep window size for mobile subscriber stations by setting a threshold for data accumulation. A basic version of LBPS, LBPS-Aggr, is presented in the paper, in which all of the traffic in the network is treated as a single aggregate flow in estimation of the sleep window size. Adopting the idea of group splitting or merging in sleep schedule, two enhanced versions namely LBPS-Split and LBPS-Merge are proposed. Simulation results demonstrate that better power saving efficiency can be achieved by proposed LBPS schemes than standard Type I and Type II. [Copyright &y& Elsevier]

Abstract: This paper presents the key factors methodology that supports energy managers in determining the optimal building operation strategy in relation to both energy consumption and thermal comfort. The methodology is supported by the utilization of calibrated building energy simulation models that match measured data gathered by an extensive measurement framework. Building management systems, do not allow energy managers to test the impact of changes in control settings of energy systems on energy consumption and thermal comfort. The proposed methodology and prototype tool chain enables energy managers to virtually develop and test the impact of proposed changes to the control settings in the building energy systems prior to their implementation in the physical building. The paper outlines the proposed methodology defining the underpinning concepts and illustrating the performance metrics required to capture the effect of different building operation strategies. A case study is discussed to demonstrate the application of the methodology. [Copyright &y& Elsevier]

Abstract: This paper presents a review of existing and current developments and the analysis of Hybrid-Electric Propulsion Systems (HEPS) for small fixed-wing Unmanned Aerial Vehicles (UAVs). Efficient energy utilisation on an UAV is essential to its functioning, often to achieve the operational goals of range, endurance and other specific mission requirements. Due to the limitations of the space available and the mass budget on the UAV, it is often a delicate balance between the onboard energy available (i.e. fuel) and achieving the operational goals. One technology with potential in this area is with the use of HEPS. In this paper, information on the state-of-art technology in this field of research is provided. A description and simulation of a parallel HEPS for a small fixed-wing UAV by incorporating an Ideal Operating Line (IOL) control strategy is described. Simulation models of the components in a HEPS were designed in the MATLAB Simulink environment. An IOL analysis of an UAV piston engine was used to determine the most efficient points of operation for this engine. The results show that an UAV equipped with this HEPS configuration is capable of achieving a fuel saving of 6.5%, compared to the engine-only configuration. [Copyright &y& Elsevier]

Abstract: Solar thermal plants are among the most promising technologies to replace fossil fuel stationary applications, and within solar thermal technologies, parabolic troughs are considered the most mature application in the market. This paper compares different solar field technologies, in terms of both performance at design conditions and annual energy production; an in-house code, PATTO, was used to perform energy balances. We considered a reference case reflecting state-of-the-art Nevada Solar One, which showed a design efficiency and annual average efficiency of 22.4% and 15.3%, respectively, in agreement with actual performance. If solar salts are used as heat-transfer fluid instead of synthetic oil (e.g. ARCHIMEDE plant), the efficiency improved within the range of 6% due to the higher maximum temperature. Further thermodynamic advantages can be achieved with a direct steam generation plant; the main drawback is the more complex transient control and no commercially available storage systems. We propose the innovative Milan configuration, which combines advantages of direct steam evaporation and the use of a heat-transfer fluid, to investigate both synthetic oil and solar salts for steam superheating and reheating. Results for this configuration are very promising, with a sun-to-electric annual average efficiency of 17.8%, which is 16% higher than the reference case. Detailed daily simulations showed that advantages are more significant at low radiation. However, the plant should be optimized on an economic basis and we will discuss this in a future paper. [Copyright &y& Elsevier]

Abstract: An important performance in building thermal control is to ensure thermal comfort with minimal energy consumption. Model Predictive Control (MPC) is considered to be one of the most suited solutions for this due to its ability to use occupancy schedule and weather forecasts for optimal temperature control. MPC relies on a dynamical model of the building, which is the main difficulty of applying it. Therefore, this paper treats the problems related to building modeling and model parameters identification. A robust model of the building is obtained in two stages: firstly physical knowledge is used to determine the structure of a low-order model, then least squares identification method is applied to find the numerical values of the model parameters. In order to perform the identification usually there are required input/output data records having variations which generally are not accepted in inhabited buildings because of imposed comfort conditions. Also inhabited buildings contain unmeasured disturbance sources which may degrade the identified model quality. Therefore this paper proposes to use detailed building models, implemented in dedicated simulation tools, to generate the required input/output data records instead of measuring them on real buildings. This allows us to apply desired input signals and to eliminate disturbance sources. Additionally, the paper presents a method to identify the nonlinearity existing in building thermal behavior, which permits to represent the building by separated linear and nonlinear blocks. This model representation, used along with the linearization method proposed in Part II, permits to design the temperature controller without resorting to the nonlinear system theory. [Copyright &y& Elsevier]