Iranica Journal of Energy & Environment
Volume:15 Issue: 3, Summer 2024

In waste heat recovery from a heavy-duty diesel engine, with a focus on engine speed's impact, is explored. The critical problem of enhancing energy efficiency and reducing emissions through waste heat utilization is addressed. Waste heat in internal combustion engines, vital for sustainable energy use and environmental preservation, is investigated. Experimental analysis and thermodynamic modeling introduce Organic Rankine Cycle (ORC), Steam Rankine Cycle (SRC), and Combined Steam and Organic Rankine Cycle (CSO) for waste heat recovery. A non-linear relationship between engine speed and waste heat is identified.  Waste heat increases up to 1600 rpm and decreases thereafter. The CSO cycle outperforms ORC and SRC cycles, achieving 43.4% higher efficiency. Fuel energy savings demonstrate CSO's superior economy, along with excellence in Annual Carbon Dioxide Emissions Reduction (ACO2ER). Waste heat recovery knowledge is advanced by introducing the efficient CSO cycle, contributing significantly to existing research.

In this paper, a feasibility study is conducted on a photovoltaic-low-speed wind turbine-battery zero-energy building for a 175 m2 residential house in Gorgan. First, the climatological data of Gorgan City related to the amount of solar radiation and wind speed for the past 50 years have been extracted and then they are analyzed annually, monthly, and hourly using Climate Consultant software to check how Renewable resources can be used to produce clean energy. To determine the number of devices required, the annual energy requirement of the residential unit should be estimated. For this purpose, the power and energy consumption of the residential unit has been estimated based on its consumption data in the last year and analyzed using RETScreen1 software. The designed zero energy system has energy exchange with the grid and sends excess energy to it. The results of climate data analysis show that there is a possibility of wind and solar energy efficiency in this region. Although the price of energy in the region is low, due to economic efficiency, the lack of non-renewable energy resources, and the need to replace these resources, the use of wind turbines and solar panels to supply the required electrical energy is necessary.

In this paper, an axial flux permanent magnet generator for a 30 kW direct drive wind turbine is designed and the design parameters were optimized with the aim of achieving high efficiency. In order to reduce the cogging torque and electromagnetic torque ripple components, the air core topology has been used, and with the aim of increasing the power capacity of the generator, a modular structure has been used. The advantage of the modular design is that each module can be considered as a generator unit and depending on the wind speed conditions, the number of units corresponding to the wind speed can be placed in the circuit and the generator will always work with maximum efficiency. First, by using the governing equations, the dimensions and performance characteristics of the generator are determined, and then a generator prototype is fabricated based on the electromagnetic design. In order to evaluate the output performance of the generator, machine simulation was performed in Maxwell finite element analysis software and the characteristic curves of voltage, current and ohmic losses were extracted. In order to evaluate the accuracy of the results, the outcomes of the analytical method have been compared with the experimental tests results.

The electric energy demand has been increasing, following digitalization and development of urbanization, which has led to functional enhancement of home energy management system (HEMS) and its subsystems. A great amount of the produced electricity is used for household loads, whereas self-sufficient smart homes can supply all or a large portion of their electricity consumption by using renewable energy resources. In this study, an MILP model is formulated for energy scheduling on a 24-hour time horizon, to achieve the optimal performance of each home appliance for minimizing the smart home energy bill. The studied smart home can exchange electrical energy with the upstream network. A sensitivity analysis has been performed to show the impact of the changes in scheduling and energy prices on the electricity energy bill. The impact of the presence of renewable resources and electrical storage is studied on the electricity energy bill and the electrical energy sales profit of the house in different scenarios. Numerical results show that using the proposed model in the self-sufficient smart home reduces the amount of  power purchased from the grid by 45%, transfers energy to the grid at some hours, and the energy bill is reduced by 65%.

In this paper, a novel approach is introduced for Fault Detection and Fault Location in power systems that incorporate Large-Scale Photovoltaic Power Plants (LSPPPs). Given that short-circuit (SC) characteristics in photovoltaic systems differ significantly from those observed in traditional Synchronous Generators (SGs). The increasing integration of LSPPPs into the power grid is anticipated to have an impact on the performance of conventional protection relay systems; initially designed for SG-dominated setups. Therefore, the proposed method revolves around analyzing the influence of LSPPPs on the alteration of observed transmission line impedance to identify and locate faults accurately. Furthermore, the methodology takes into consideration factors such as fault location, fault resistance, fault type, changing the LSPPP generation, and noise conditions. when calculating the phase angle of the fault loop current. The effectiveness of this approach was assessed through testing and evaluation on 2-bus and IEEE 39-bus test systems connected to an LSPPP, simulated using PSCAD/EMTDC and MATLAB/SIMULINK.

Wind energy is a prominent renewable energy source, and Vertical Axis Wind Turbines (VAWTs) offer distinct advantages, including adaptability to changing wind directions and reduced noise levels. This paper conducts a numerical investigation into the impact of flat and curved stator blades on VAWTs, specifically the Savonius turbine, under 2D, viscous, turbulent, and steady flow conditions. Four stator blade configurations were examined, including no stator blades, smooth stator blades, twisted stator blades (Case A), and both blades being concave (Case B). The study reveals that curved stator blades enhance VAWT performance, with Case B exhibiting the most efficient performance. The results show pressure distribution on the turbine blades is non-uniform, with high and low-pressure zones, predominantly on the windward side. The presence of stator blades enhances pressure on all turbine blades, with Case B exhibiting the most optimal pressure distribution. Detailed observation of streamline and velocity distribution reveals improved flow lines for Case B, leading to more effective turbine blade performance. Case B consistently produces the highest turbine torque, with a maximum value of approximately 2.1 N·m achieved at Re = 15750. The torque demonstrates a positive correlation with increasing Reynolds numbers.  The study further introduces a non-dimensional torque ratio analysis, where Case B attains 7.59 times higher torque than the reference case at Reynolds number 15750. The sensitivity of torque increase with respect to Reynolds number change highlights that Case B (with a slope of torque increase at around 4.5e-04)  is the most responsive within the studied Reynolds number range.

Environmentally sustainable metropolitan environments are characterized by their ability to effectively produce and distribute power while reducing their impact on the environment. Smart homes are essential in smart cities since they enhance sustainability and efficiency in urban settings. A key advantage of smart homes is their capacity to diminish energy use and carbon emissions. This is accomplished by optimizing energy consumption in home appliances, which is customized to fulfill the individual requirements and preferences of consumers. However, there is still a need for further academic research to investigate and improve the functioning of intelligent residential homes in microgrids. To efficiently manage microgrids, it is crucial to gather and analyze large amounts of electrical data related to power production from microgrid sources and energy consumption of the loads. This study examines the use of Non-Intrusive Load Monitoring (NILM) methods to monitor electrical parameters of different loads in microgrids. The research focuses on the application of affordable smart meters that are equipped with Internet of Things (IoT) capabilities. An empirical study showcases the possibility of collecting significant data on microgrid operation via the deployment of an operational microgrid that integrates a hybrid wind-solar power source with a variety of home appliances.

The research aims to develop sustainable daylighting strategies for contemporary buildings by drawing inspiration from traditional vernacular housing solutions. In this study, the daylight factors of a contemporary residential space with a central courtyard which is located in Kerman, Iran is evaluated. After modeling the building in Design Builder software, the U-values of the external walls, roof, floor and windows based on the available materials in the market of Iran are calculated. The results of daylight simulations are presented in term of Average DF (%), Work plane Illuminanace (Lux) and Uniformity Ratio as well as annual Indicators of daylight such as sDA and UDI. Zone 3 in the ground floor which is a space under top lit atrium acts as a source of daylight. Although, Zone 5 in the ground floor has reasonable daylight factor, the uniformity ratio is not acceptable due to simultaneously existing the areas of little and high illuminance. Zone 7 in the first floor as a public sapce can provide large potential for daylight utilization with DF equal to 2.6% and average WPI with 826 Lux because there is a possibility to receive daylight from east direction with designing central courtyard in the first floor plan.

The ability to convert mechanical energy into electrical energy by piezoelectric materials makes them suitable alternatives to use in energy harvesters. So, the efficiency of a piezoelectric energy harvester is the main limitation. One of the desired approaches to increase efficiency is using a piezoelectric array in the harvester. In this paper, a numerical method has been used for the comparative study of series and parallel array behavior in different types of input force. The effect of input force type, frequency of input force, and type of array connection on energy harvester efficiency with the proposed design have been investigated. Numerical results have been verified with experiments. Results indicated that a series connection can produce 2.2 times the maximum voltage larger than a parallel connection. Also, they show that the input force shape function is the effective parameter for a piezoelectric energy harvester with an array structure. The results show a similar effect of the input force shape function on the behavior of piezoelectrics in both types of electric connections (parallel or series). In general, it can be seen that the waveform of the output voltage after applying the load with a square function was similar to its function. Also, the change in the parameters of the input force with the sinusoidal function causes a direct change in the same character of the generated voltage waveform.

The charge transfer coefficient is a dimensionless coefficient used in the kinetics of chemical reactions. In this paper, the effect of the charge transfer coefficient on hydrogen fuel cell characteristics such as polarization curve and power diagram in terms of current density and losses is investigated. The charge transfer coefficient affects the activation losses of the fuel cell and therefore affects the performance of the fuel cell. For this investigation, a basic sample is selected and the changes of charge transfer coefficient are studied on its characteristics. The obtained results show that with an increase in this factor, the activation loss decreases. In addition, increasing the charge transfer coefficient increases the maximum power point. The increase in the power of this point is more visible in lower values of the charge transfer coefficient and when this coefficient exceeds the value of 0.5, this effect becomes very small. Also, the appropriate value of this coefficient is determined to maintain the balance of the chemical reaction. The activity of the fuel cell is disrupted due to an excess amount of the coefficient.

This research, conducted in Gotvand, southwest Iran, evaluated the energy balance of a field system which watermelon produced in it. In the current research, energy inputs of watermelon planting were measured. To reach this goal, questionnaires were given to the farmers to record the amount of energy input to their watermelon planting field. Statistical analysis of the data revealed that nitrogen was the input with the highest consumption of energy (4175 MJ.ha-1) followed by diesel fuel. About 90% of the consumed energy of watermelon planting system was seen for energies which cannot be renewed. The results showed that the efficiency of energy consumption was positive, indicating that the amount of output energy was higher than that of input energy. With each unit of energy was consumed, 4.86 units of energy were produced, which indicates high energy efficiency. For improving the efficiency of energy usage in the watermelon planting system, nitrogen application to the system should be reduced and it can be reached by suitable rotation which diminish the nitrogen needs.