Journal of Energy Engineering

It has become more and more demanding to investigate the impacts of wind farms on power system operation as ever-increasing penetration levels of wind power have the potential to bring about a series of dynamic stability problems for power systems. This paper undertakes such an investigation through investigating the small signal and transient stabilities of power systems that are separately integrated with three types of wind turbine generators (WTGs), namely the squirrel cage induction generator (SCIG), the doubly fed induction generator (DFIG), and the permanent magnet generator (PMG). To examine the effects of these WTGs on a power system with regard to its stability under different operating conditions, a selected synchronous generator (SG) of the well-known Western Electricity Coordinating Council (WECC three-unit nine-bus system and an eight-unit 24-bus system is replaced in turn by each type of WTG with the same capacity. The performances of the power system in response to the disturbances are then systematically compared. Specifically, the following comparisons are undertaken: (1) performances of the power system before and after the integration of the WTGs; and (2) performances of the power system and the associated consequences when the SCIG, DFIG, or PMG are separately connected to the system. These stability case studies utilize both eigenvalue analysis and dynamic time-domain simulation methods.

This study analyzed the effect of the environmental conditions on the thermal efficiency of an active solar wall with forced convection. The analyzed system is comprised of a double glass glazing and a massive wall with an opening and central channel in it. In order to increase the efficiency, we provided a fan at the bottom vent of the wall. The active solar wall is more advanced compared to the simple Trombe solar wall with a relatively low thermal resistance, which we took as a reference in our experimental analysis. This paper presents a one-dimensional steady-state mathematical model for simplified analysis of the efficiency of active solar wall air heating systems. We analyzed the obtained results in order to predict the effects of environmental parameter variations, such as solar radiation, ambient temperature, and wind velocity, on thermal efficiency.

In order to increase the performance of solar collectors, multipurpose solar collectors were investigated experimentally by combining the solar water collector and solar air collector. In this design, the storage tank of the conventional solar water collector is modified as riser tubes and header, which is fitted in the bottom of the solar air heater. These were tested as a solar water heater and air heater simultaneously with both load and no load conditions. The results reveal that the maximum efficiency was 67.69% for the mass flow rate of $0.015\mathrm{kg}/\mathrm{s}$ in the multipurpose water heater. The maximum efficiency of multipurpose solar air heater was reached as 85.1% at 14:00 hour for the mass flow rate of $0.0104\mathrm{kg}/\mathrm{s}$ at load condition. The maximum stagnation temperature of the multipurpose solar air heater was 88°C for the overall heat loss co-efficient of $12.83\mathrm{W}/{\mathrm{m}}^2\text{-}\mathrm{K}$ at no load condition. The heat removal factor based on the air inlet and outlet temperature, as well as the collector efficiency factor for different mass flow rates, were also determined. The results show that the efficiency of the multipurpose solar heating system increased with an increasing mass flow rate compared with the conventional one.

With regard to the risks of investment planning during the construction process of wind power projects, this paper introduces the income risks of investment planning for wind power, analyzing wind power’s investment income through the establishment of a benefit-risk evaluation model. In accordance with China’s current wind power investment, this paper calculates the wind power benefit risk of different resource areas, taking the price risk, risk of project cost, and risk of abandoned wind as analysis factors. By comparative analysis of the economic benefits of each resource area, the economic benefits of investment in a wind power project in resource areas 3 and 4 are better than resource areas 1 and 2. Simultaneously, taking into account the future wind power project’s cost trends and China’s wind power investment planning trends, the writers suggest that China’s wind power project investment focus should shift from resource areas 1 and 2 to resource areas 3 and 4.

In this paper, the performance of the regenerative organic rankine cycle (ORC) working with R123 is experimentally analyzed at different heat source temperatures of approximately 85, 95, 110, and 130°C. The higher heat source temperature leads to higher turbine inlet temperature, turbine inlet pressure, and turbine rotation speed. The regenerator and the increment of turbine inlet temperature can both increase the efficiency of the system. The experimental data of ORC are compared with that of the conventional Rankine cycle (CRC), which employs water as the working fluid. The results indicate that the thermal efficiency and the turbine isentropic efficiency of the ORC are higher than that of the CRC by approximately 5.9 and 24%, respectively. A numerical model is built by interconnecting different submodels: a turbine model, a volumetric pump model, and the heat exchanger models. The numerical results show a good agreement with the experimental data in terms of system efficiency. The model is finally used to calculate the pressure drop and pump power of the system.

Optimal thermal and ecological performance tests of a solar-driven heat engine system were conducted in various optimization scenarios. For this, thermal and ecological models were developed for the solar-driven heat engine, and three objective functions (including thermal efficiency, output power, and ecological function) were obtained for the proposed system. In the present investigation, thermodynamic analysis and an evolutionary algorithm (EA) were employed to optimize the dimensionless ecological function, thermal efficiency, and dimensionless power of a solar-driven engine system. Four scenarios were conducted for optimization of the solar heat engine. In the first three, a traditional single-objective optimization was employed separately with each objective function, regardless of other objectives. In the fourth scenario, efficiency and power objectives were optimized simultaneously using a nondominated sorting genetic algorithm (GA) called the nondominated sorting genetic algorithm (NSGA-II). As in multiobjective optimization, a set of optimal solutions called the Pareto optimal frontier was obtained instead of a single final optimal solution obtained in traditional single-objective optimization. Therefore, a process of decision making was employed for selecting a final optimal solution. Three decision-making procedures were applied to find optimized solutions from the Pareto optimal solutions in the objectives’ space. The results obtained from four optimization scenarios were compared and discussed using a deviation index introduced in this paper. It was shown that the optimal results obtained in single-objective optimization with an ecological objective are very close to the corresponding results obtained in the multiobjective optimization, in that the power and thermal efficiency are optimized simultaneously. Finally, an error analysis was performed, indicating that the error in evaluating the final solution was less than 0.3%.

This work has shown the feasibility of a soil-based battery, in which the electrolyte (soil) was continuous throughout the anode, cathode, and electrolyte. The soil contained 49 wt.% water. The battery was in the shape of a soil-based monolithic slab and involved an anode (zinc, particle size 7 μm, acetic acid washed), a cathode (${\mathrm{MnO}}_2$, particle size 40 μm), and an electrically conductive additive (carbon black, particle size 30 nm). A battery was composed of three successive layers: a cathode layer (a soil-matrix ${\mathrm{MnO}}_2$ particle composite, 12 wt.% ${\mathrm{MnO}}_2$, 15 mm thick), an electrolyte layer (soil, 2 mm thick), and an anode layer (a soil-matrix zinc particle composite, 9 wt.% Zn, 5 mm thick). After assembly, it was compacted at a pressure of 1.67 MPa. The soil electrolyte exhibited resistivity of $220\mathrm{\Omega }·\mathrm{cm}$ and a relative dielectric constant of 29 (1 kHz). The soil-based battery discharged at 10 mA ($0.25\mathrm{mA}/{\mathrm{cm}}^2$) and exhibited open-circuit voltage up to 0.24 V, initial running voltage up to 0.17 V, power output up to $43\mu W/{\mathrm{cm}}^2$, capacity up to 179 mAh, and fraction of zinc consumed up to 0.06. The running voltage decreased continuously during discharge. The soil-based battery was much superior to a previously reported cement-based battery.

The application of the exergy and exergoeconomic analysis for energy conversion systems is growing steadily. This analysis is particularly useful for energy conversion systems such as the combined-cycle power plant (CCPP). This paper deals with exergy and exergoeconomic analysis of a combined-cycle power plant with supplementary firing. A process simulation program, IPSE Pro, is used to model the combined-cycle power plant. Exergy and exergoeconomic analysis is carried out by developing a Matlab code. Three configurations of the combined-cycle power plant are investigated and the effect of the configurations of a heat recovery steam generator (HRSG) and performance parameters such as fuel mass flow rate of duct burner and pressure ratio of compressor on combined-cycle performance have been studied. Exergy and exergy cost destruction rates are also calculated. Finally, the cost of generated power for the three configurations of combined-cycle power plant is calculated and the best location for the duct burner in HRSG is proposed.

This paper is focused on accessing the benefits of incorporating an air humidifier with a cooled gas turbine cycle. Air transpiration cooling has been adopted as the cooling technique for gas turbine blades. A parametric study of the effect of compressor pressure ratio ($r_{p,c}$), compressor inlet temperature (CIT), turbine inlet temperature (TIT), inlet temperature ratio ($r_{\mathrm{IT}}$), ambient relative humidity, and ambient temperature on performance parameters of plant has been carried out. Evaporative inlet air cooling has been observed to improve the plant efficiency of a transpiration cooled gas turbine plant by 4.84% and plant specific work by 9.68% at an ambient temperature of 313 K and ambient relative humidity of 0.2. The effects of variation of ambient parameters on cycle performance are found to be more pronounced at higher turbine inlet temperature and higher compression ratio ($r_{p,c}$). The work ratio increases with an increase in the value of $r_{\mathrm{IT}}$ up to 5.6 after which it decreases. There exists an optimum $r_{\mathrm{IT}}$ at any $r_{p,c}$ with reference to the maximum work ratio. The heat rate increases with an increase in $r_{\mathrm{IT}}$ and a decrease in $r_{p,c}$. For all values of TIT there exists an optimum $r_{p,c}$ at which plant efficiency is at its maximum.

Many reservoirs of hydroelectric power plants currently operate with outdated data due to the continuous sedimentation process. This fact demands management and operation policies for these reservoirs based on data different from those actually found. This paper presents a case study of Três Irmãos Reservoir (in São Paulo state, Brazil), where a bathymetric survey was conducted in 2008. From the comparison of the data obtained in the survey and data from 1975 (provided by the power supplier), it was possible to estimate the reservoir losses of total, active, and inactive capacities. From the observation of changes in the reservoir’s operational data, a simulation of the power plant and the reservoir operation was conducted using MODSIM/AcquaNet software to analyze the interference of the reservoir sedimentation with the generation of electricity.

This paper presents a new power generation system under the principle of organic Rankine cycle which can generate power with a low-temperature heat source. A prototype was built to investigate the proposed system. In the prototype, an air screw compressor was converted into an expander and used as the engine of the power generator. The style of the preheater was a shell and tube heat exchanger, which could provide a long path for the working fluid. A flooded heat exchanger with a high heat transfer coefficient was taken as the evaporator. R134a was used as working fluid for the Rankine cycle in the system. This study compared and analyzed the experimental performance of the prototype at different heat source temperatures. The results show that the preheater and flooded evaporator was used for sensible heating and latent heating of the working fluid, respectively, as expected. When the temperature of the heat source increased, the pressure at the inlet of the screw expander increased, and the mass flow rate of the working fluid increased as well. The fluid at the outlet of the expander is superheated with an average superheating of 2.6°C. In the range of 55–65°C of the heat source, the average isentropic efficiency of the screw expander was 68%, and the efficiency of power generation varies from 1.2 to 4.56%. The highest value of thermodynamical perfectness was 29.06%. It can be concluded that organic Rankine cycle could be competitive for recovering low-temperature heat source to electrical power.

In this paper, a product life cycle design template used to assist in the development of a product knowledge base is introduced. The paper argues that following this model should result in a focus on real-world product behavior beyond the expected product performance by directing the questions from what should happen when the products interact in the universe to what can happen at each design juncture. The template may be simply used as a thought process with a pad and pencil for recording notes for simple or on-the-fly design decisions. The idea of using the templates as a tool could be more formalized for larger designs and knowledge-base development. In this paper, the concept has been demonstrated in building the knowledge base for the geosolar exergy storage technology (GEST) house.

Cold airflow experiments were performed using a 1:10 scale model of a down-fired, pulverized coal 350-megawatt (MW) supercritical utility boiler incorporating multiple-injection and multiple-staging combustion technology. The effects of varying the overfire air (OFA) ratio on the aerodynamic flow fields in the furnace were investigated using ratio settings of 1.9, 9.6, 19.1, and 28.7%. The results showed that, at ratios of 9.6, 19.1, and 28.7%, symmetrical flow fields were present in the lower furnace, whereas a deflected flow field was observed at a ratio of 1.9%. At OFA ratios of 19.1% and above, suitable horizontal airflow penetration depth was observed, and the flow fields were symmetrical. The velocities in the region $H/H_0=0–0.4$ were fit by linear functions, which showed that the vertical velocity of the overall airflow along the arches was linear in this section of the furnace, and that the slope of the linear function was reduced from 3.63 to 2.70 as the OFA ratio was increased, indicating that the rate of decay was reduced. Based on an overall consideration of the symmetrical flow field and appropriate airflow penetration depth, the optimal OFA ratio required for operation of this furnace is greater than 19.1%.

In this paper, the inherent mechanism of social benefits associated with smart grid development is examined based on the pressure state response (PSR) model from resource economics. The emerging types of technology brought up by smart grid development are regarded as pressures. The improvements of the performance and efficiency of power system operation, such as the enhanced capability of accommodating renewable energy generation, are regarded as states. The effects of smart grid development on society are regarded as responses. Then, a novel method for evaluating social benefits from smart grid development is presented. Finally, the social benefits from smart grid development in a province in northwest China are carried out by using the developed evaluation system, and reasonable evaluation results are attained.

Wind power prediction has received extensive attention in recent years. In the open literature, problems such as imprecise statistical data and inaccurate prediction models still exist. To solve these problems, the authors first used $k$-means algorithm to cluster the measured data and initialized the centers by simulated annealing. Second, considering the co-occurrence information between wind power output and the relevant parameters, several matrices are introduced to calculate the co-occurrence number. Finally, a co-occurrence predictor was designed to calculate the wind power output by the approximate posterior probability. Experiments were conducted on a set of measured data. Experimental results suggest that this method outperforms the state of the art. Specifically, one only needs to calculate the co-occurrence tables, so the calculation of this model is less than any of the other wind power prediction model.

Sugarcane bagasse ash (SBA), which is otherwise landfilled, was utilized to develop construction material that serves a purpose of disposal of solid waste management and energy efficient alternate construction material. SBA was characterized using particle size distribution, scanning electron microscopy (SEM), X-ray fluorescence (XRF), X-ray diffraction (XRD), and thermogravimetric analysis (TGA). SEM monographs show the rough surface with plenty of fine pores. XRF, XRD, and physicochemical properties of the SBA prove its suitability as a pozzolanic or cementitious material. TGA confirms thermal stability till 650°C. On the suitability of principal raw material, SBA–quarry dust (QD)–lime (L) bricks were developed with a constant composition of lime (20% by weight) and tested for physicomechanical (weight, dry density, water absorption, efflorescence, and compressive strength), functional (thermal conductivity, $k$), durability (chloride, sulfate, and carbonation), and environmental [toxicity characteristics leaching protocol (TCLP)] properties as per recommendations. The developed (SBA-QD-L) bricks were further analyzed for technical feasibility with commercially available and accepted masonry products like clay and fly ash bricks. The experimental results showed that the SBA-QD-L combination brick is lighter in weight, durable, nonhazardous, energy efficient, has lower $k$ value, and meets the necessary physicomechanical properties of the standards.

Multifarious proposals for siting, design, construction, and operation of onshore and offshore liquefied natural gas (LNG) import terminals in California have recently undergone a rigorous federal and state regulatory appraisal. The regulations call for compliance with various environmental, public safety, and security mandates encoded in legal statutes. Public safety from the hazards of a large-scale LNG spill over water, during LNG tanker transit or marine terminal operation, emerged as the dominant concern for the affected local communities. To address their apprehension, extensive modeling of potentially perilous beyond design basis spill scenarios, ensuing from natural, accidental, and malevolent intentional events was conducted. It entailed finite element modeling for vessel collision with diverse LNG tanker types and applying computational fluid dynamics to predict the extent of LNG spread over water, atmospheric dispersion of vapor cloud, and the consequences of ignition. The objective was to appraise the adverse impacts of cryogenic fluid, fire propagation, and thermal radiation on humans and property not associated with these LNG terminals. Based on insights from risk analyses for three LNG projects in California, challenges in developing complex mathematical models, assessing public safety, and specification of safety criteria are delineated to benefit others planning similar ventures in California or elsewhere.

The objective of this paper is to provide a review of in-stream hydrokinetic power, which is defined as electric power generated by devices capturing the energy of naturally flowing water—stream, tidal, or open ocean flows—without impounding the water. North America has significant in-stream energy resources, and hydrokinetic electric power technologies to harness those resources have the potential to make a significant contribution to U.S. electricity needs by adding as much as $120\mathrm{TWh}/\mathrm{year}$ from rivers alone to the present hydroelectric power generation capacity. Additionally, tidal and ocean current resources in the U.S. respectively contain $438\mathrm{TWh}/\mathrm{year}$ and $163\mathrm{TWh}/\mathrm{year}$ of extractable power. Among their attractive features, in-stream hydrokinetic operations do not contribute to greenhouse gas emissions or other air pollution and have less visual impact than wind turbines. Since these systems do no utilize dams the way traditional hydropower systems typically do, their impact on the environment will differ, and a small but growing number of studies support conclusions regarding those impacts. Potential environmental impacts include altered water quality, altered sediment deposition, altered habitats, direct impact on biota, and navigability of waterways.

In this paper, a new multiagent-based voltage control scheme is proposed. The algorithm dynamically adapts the settings of control devices, such as the automatic voltage regulator of generators, transformer with under-load tap changer, and flexible alternating current transmission systems (FACTS), to optimize operational objectives. The objectives are controlling the generator excitation current, reducing transmission power loss, maintaining voltage stability, and improving voltage profile. The constraint is to keep the technical capability limits of system equipment and the transmission line power-flow limits. Furthermore, the effect of load model on voltage control dynamics is addressed. Peer-to-peer device communication is developed to facilitate information exchange among agents. The proposed scheme coordinates the operation of installed voltage control devices on both low voltage and high voltage levels. A simulation test model is implemented using a parallel computing arrangement for a 30-bus standard test system to evaluate the proposed voltage control scheme.

Demand for electrical power across the Middle East and North Africa (MENA) region is growing rapidly because of rising population, growing urbanization, and economic growth driven by industrialization. The objective of this paper is to analyze the market requirements and trends for the different types of fuels and power generation technologies that can be utilized in the coming years to meet the growing demand for power generation for the Gulf Cooperation Council (GCC) countries and Iran, Iraq, and Egypt (referred to in this report as GCC+ countries). The GCC+ countries have historically relied on fossil fuels for power generation, but these fuels are becoming increasing costly for power generation as a result of import costs for fuel importing countries and opportunity costs for fuel exporting countries. The hydrocarbon fuels considered in this study are both conventional and nonconventional, including sweet gas, sour gas, tight gas, shale gas, crude oil, heavy fuel oil, and diesel oil. We assess the availability of these fuel types for power generation and consider alternative power generation technologies, primarily nuclear and renewable energies, which are aligned with national energy strategies and projected resource availabilities. The analysis provides an understanding of the current and projected fuels available for power generation in the GCC+ countries and suggest the unconventional hydrocarbons will play a key role in future energy systems of many MENA countries.

In the electricity market environment, load-serving entities (LSEs) will inevitably face risks in purchasing electricity because there are a plethora of uncertainties involved. To maximize profits and minimize risks, LSEs need to develop an optimal strategy to reasonably allocate the purchased electricity amount in different electricity markets such as the spot market, bilateral contract market, and options market. Because risks originate from uncertainties, an approach is presented to address the risk evaluation problem by the combined use of the lower partial moment and information entropy (LPME). The lower partial moment is used to measure the amount and probability of the loss, whereas the information entropy is used to represent the uncertainty of the loss. Electricity purchasing is a repeated procedure; therefore, the model presented represents a dynamic strategy. Under the chance-constrained programming framework, the developed optimization model minimizes the risk of the electricity purchasing portfolio in different markets because the actual profit of the LSE concerned is not less than the specified target under a required confidence level. Then, the particle swarm optimization (PSO) algorithm is employed to solve the optimization model. Finally, a sample example is used to illustrate the basic features of the developed model and method.

Generation company (Genco) bidding in an electricity market (EM) aims to maximize its profit under uncertain market characteristics and a regulated bidding mechanism. This paper addresses the strategic bidding for a large price maker Genco and empirically investigates the effect of a step-wise multiple segment bidding mechanism and EM characteristics, such as demand and rivals’ behavior, on its market power (MP) potential and efficiency. The methodology of using novel hybrid differential evolution with biogeography-based optimization (DE/BBO), employing the sinusoidal migration model, is proposed for strategic bidding. DE exploration with BBO exploitation enhances global optimization. Uncertain rival behavior is modeled as normal distribution and simulated by the Monte Carlo technique. The proposed approach is validated for large Genco bidding in spot EM, under changing market characteristics and bidding segments. The implicit MP potential and efficiency of Genco for corresponding strategies is assessed using the criteria of expected profit, risk of profit variance, and failure rate of Genco. This assessment discovers an underlying correlation between the market characteristics and bidding segments, which would aid Genco in optimizing its bidding strategy and market performance.

The effects on the strength, hardness, and ductility of a series of well-annealed palladium-silver alloys due to hydrogen exposure were investigated at various temperatures. The results indicate that the temperature at which hydrogen exposure occurs can have a significant effect on the degree to which these mechanical properties are altered. At relatively low temperatures, it was found that the strength and hardness of the alloy are increased, while ductility is decreased upon hydrogen exposure. In alloys where such changes are observed, the magnitude of these changes was found to diminish as the silver content increases. Above a certain hydrogen exposure temperature—the value of which decreases with increasing silver content—the strength, hardness, and ductility of the alloy show no significant changes as a result of hydrogen exposure.

Thermal analysis of a novel integrated system of a desiccant wheel, a solar collector, a heat exchanger, a ground heat exchanger, and a water spray evaporative cooler is performed for air conditioning cooling systems. The effects of the following parameters were studied: inlet air temperature $T_{\mathrm{in},\mathrm{air}}$, the inlet air humidity ratio ${\omega }_{\mathrm{in},\mathrm{air}}$, regeneration temperature $T_{\mathrm{Reg}}$, heat exchanger effectiveness ${\epsilon }_{HE}$, solar radiation $G_t$, cooling coil unit effectiveness ${\epsilon }_{\mathrm{ECCU}}$, and evaporative cooler effectiveness ${\epsilon }_{EC}$ on the behavior of supplied air temperature $T_{\sup ,\mathrm{air}}$, supplied air humidity ratio ${\omega }_{\sup ,\mathrm{air}}$, cooling water flow rate ${\dot{m}}_w$, area of solar air collector $A_{\mathrm{Sol}}$, efficiency of solar air collector ${\eta }_{\mathrm{Sol}}$, and desiccant wheel effectiveness ${\epsilon }_{DW}$. The system with geothermal energy was found to be more efficient and to provide more human thermal comfort than the system without geothermal energy. This novel hybrid system significantly decreased the supplied air temperature from 10 to 19.5°C. The simulation results revealed that the novel integrated system can provide comfortable conditions.

In the present study, the thermal and effective thermal efficiencies of a double-flow packed-bed solar air heater with an external recycle are investigated theoretically. An analytical model capable of predicting the thermal and effective thermal performances of the heater is presented. The effects of the mass flow rate, the recycle ratio, and the bed porosity on the thermal and effective thermal efficiencies of the heater are investigated. It is indicated that the recycle ratio significantly improves the thermal performance of a double-pass packed-bed solar air heater. The results revealed that the thermal and effective thermal efficiencies of the heater are about 21.3 and 25.4% higher when compared to a conventional-type solar air collector of the same size with an external recycle. The optimum values of the recycle ratio, the mass flow rate, and the bed porosity, at which the heater yields the maximum value of effective thermal efficiency, are identified and presented. The results of the thermal and effective thermal efficiencies of the heater compared with a parallel-flow packed-bed solar air heater without recycle are also delineated.

To evaluate the economic feasibility of energy efficiency or renewable energy upgrades, a variety of tests are used such as payback period, cost-benefit ratio, and return on investment. All of these tests require an estimate of the capital cost of the upgrade. However, it is not always possible to reliably estimate the capital cost of a potential energy upgrade. To deal with such situations, an alternative approach is proposed that involves the calculation of the tolerable capital cost (TCC) of the upgrade. The use of the TCC approach to evaluate economic feasibility is demonstrated with a case study involving photovoltaic panel installations in Canadian houses.