Additional Electric Power Research Articles

Modelling the performance of an SOEC by optimization of neural network with MPSO algorithm

This paper studies the Solid Oxide Electrolyzer Cell as a promising system in the sustainable development for the hydrogen economy and energy systems as a robust system. The Solid Oxide Electrolyzer Cell converts the steam and carbon-dioxide directly to functional fuels through consumption of the additional electrical power of green power sources or off-peak network powers. The present paper evaluates the static efficiency of the SOEC under four various gas mixtures. Modeling of this system is performed using Elman neural network (ENN) and modified particle swarm optimization (MPSO) algorithm. The MPSO algorithm is utilized to determine the optimal values for ENN adjustable parameters. It's known from the empirical results that the steam and carbon-dioxide concentrations can affect the SOEC efficiency. The operational potential and volume share of the hydrogen, carbon dioxide and steam are considered as the system inputs, and efficiency (current) is remarked as its output. The correlation factors of the achieved model are greater than 0.999, and its MSE (mean squared error) is lower than 0.017. It reveals that the forecasted values are almost equal to the empirical data. Subsequently, the efficiency of the SOEC is studied using the achieved model of the MPSO-based ENN in various feedstock concentrations. Thus, this dataset that is used for ENN model can be desirable for different applications of fast-modeling in a standalone group. It as well can be useful for cost, computing-time, and computing burden reduction in a model construction in the efficiency analyzing and system-level designing processes.

Thermoeconomic Analysis of Different Exhaust Waste-Heat Recovery Systems for Natural Gas Engine Based on ORC

Waste-heat recovery (WHR) systems based on the organic Rankine cycle (ORC) improve the thermal efficiency of natural gas engines because they generate additional electric power without consuming more gas fuel. However, to obtain a cost-effective design, thermoeconomic criteria must be considered to facilitate installation, operation, and penetration into real industrial contexts. Therefore, a thermo-economic analyses of a simple ORC (SORC), ORC with recuperator (RORC) and a double-pressure ORC (DORC) integrated with a 2 MW Jenbacher JMS 612 GS-N. L is presented using toluene as the organic working fluid. In addition, the cost rate balances for each system are presented in detail, with the analysis of some thermoeconomics indicator such as the relative cost difference, the exergoeconomic factor, and the cost rates of exergy destruction and exergy loss. The results reported opportunities to improve the thermoeconomic performance in the condenser and turbine, because the exergoeconomic factor for the condenser and the turbine were in the RORC (0.41 and 0.90), and DORC (0.99 and 0.99) respectively, which implies for the RORC configuration that 59% and 10% of the increase of the total cost of the system is caused by the exergy destruction of these devices. Also, the pumps present the higher values of relative cost difference and exergoeconomic factor for B1 (rk = 8.5, fk = 80%), B2 (rk = 8, fk = 85%).

Analysis of a PMSG Based Six Level Multilevel Inverter Fed From Wind Turbine

This paper confers about a six level flying capacitor multilevel inverter with POD-PWM modulation that is fed from a PMSG and it is driven by a wind turbine. The PMSG machine is the most efficient of all electric machines since it has a movable magnetic source inside it. Use of permanent magnets for the excitation consumes no additional electrical power. Matlab simulation is also carried out for a PMSG generator driven by a wind turbine with even harmonic injection and fundamental sine injection from that a comparison of THD is also done.

Exact approach for charging of PEVs with V2G capability to improve micro‐grid reliability

Nowadays, the major proportion of fossil fuels is consumed in the transportation systems. Plug-in electric vehicles (PEVs) can play a significant role in reducing the petrol consumption. A large amount of additional electrical power demand needed for the charging of PEVs may adversely affect the electric grid reliability. Using the charging station in the micro-grids (MGs) to minimise the total system operation cost in the presence of PEVs with vehicle to grid (V2G) capability is becoming vitally important. In this work, a practical model for charging strategy of PEVs based on typical charge and discharge profiles given by the battery producers is considered. The problem is constrained by the loss of load probability index of reliability. The proposed strategy makes it possible to handle the generation shortage due to the outage of conventional units and intermittency of wind turbine units. Mixed Integer Non-linear programming is used for the optimal planning of MG in the presence of PEVs. Results show that an appropriate charge and discharge strategy may lead to a significant improvement in the reliability of the considered MG as well as a reduction in the operational cost of the total system.

Cooling Computer Chips with Cascaded and Non-cascaded Thermoelectric Devices

Thermoelectric devices are currently being used in cooling and generating electricity applications. This study mainly focuses on using thermoelectric devices for both applications towards cooling down computer chips; especially, that the very large scale integration technology has reached high advancement where more than 100 million transistors can be fabricated in 1 mm2. Reducing the non-uniformity of the chip temperature is important so as to decrease the induced thermal stress in this chip and consequently reduce its failure rate. To simultaneously reduce both the non-uniformity of the temperature distribution in the chip and the power requirements for the cooling system, thermoelectric generators can be installed on the cooler chip areas to harvest electrical power from the chip wasted heat. Thereafter, the chip hotspot areas are cooled down using thermoelectric coolers that are powered by the harvested electrical power from the thermoelectric generators in order to maintain the temperatures of these hotspots to be less than or equal a certain temperature threshold. Because no additional electrical power requirement is needed to cool down the hotspots, this cooling technique is called in this paper as “sustainable self-cooling framework for cooling chip hotspots”. However, the question is that can the harvested electrical power by the thermoelectric generators be enough to power the thermoelectric coolers for different computer chips at a given operating condition? As such, one of the objectives of this paper is to develop a three-dimensional numerical and optimization model to predict the thermal and electrical performance of cascaded and non-cascaded thermoelectric generators and cascaded and non-cascaded thermoelectric coolers for cooling chip applications. Then, validate the developed model against experimental data. The results showed that the predictions of the developed model were in good agreement with the experimental to within ± 4%. After gaining confidence in the developed model, it was used for a given chip operating condition to conduct a case study for a sustainable self-cooling framework in order to answer the raised question above. The results showed that the self-cooling framework can successfully cool down the hotspot at an acceptable temperature with not only no need for additional electrical power requirements but also for reducing the non-uniformity in the chip temperature distribution.

Loading Effect with Distributed Generation (DG) Injection on Distribution System on Temperature and Breakdown Voltage of Oil Transformer in Distributed System

Increasing of load demand causes the greater electrical power needed. When the transformer operation in overload conditions and hottest-spot temperature, it will accelerate the aging and failure in oil insulation of transformer. Application of distributed generation (DG) can provide the additional electrical power supply to the loads (household). So that, it can relieve the workload power transformer and reduce the acceleration of aging in oil insulation of transformer. This research will analysed the effect of loading capacity with DG injection using a PV generator on the condition of oil insulation on 150 / 20kV of electricity distribution system using ETAP software. Tests of this research are carried out on 24 hours of loading conditions on the distribution system. The calculation of isolation oil temperature was carried out using a mathematical formula according to the IEEE, and oil insulation would be tested with a breakdown voltage (BDV) test.

Performance optimization of cascaded and non-cascaded thermoelectric devices for cooling computer chips

Abstract Thermoelectric devices are currently being used in the applications of cooling and generating electricity. This study mainly focuses on using these devices for both applications toward cooling down computer chips. An important aspect in designing the cooling system is to minimize the non-uniformity of the temperature distribution in the computer chip so as to reduce the thermal stresses in it. Another aspect in designing the cooling system is to minimize its power requirements. To investigate these two aspects, the temperatures of the cold chip areas can be allowed to increase, but not to exceed a certain temperature threshold, by installing Thermoelectric Generators (TEGs) on these areas that can harvest electrical power from the chip wasted heat. Thereafter, the chip hotspot areas can be cooled down by installing Thermoelectric Coolers (TECs) on these areas that can be powered by the harvested electrical power from the TEGs in order to maintain the temperatures of these hotspots to be less than or equal a certain temperature threshold. This cooling technique is called “sustainable self-cooling framework” for cooling chip hotspots. However, the question is: can the harvested electrical power by the TEGs be enough to power the TECs for cooling chip hotspots? In this study, a 3D model is developed to optimize the performance of both TEGs and TECs. Thereafter, this model is validated against experimental data of TEC and TEG. The results showed that the model predictions were in good agreements with the experimental data to within ±4%. Also, considerations are given in this study to optimize the performance of cascaded and non-cascaded TEGs and TECs for future use them to develop sustainable self-cooling frameworks for cooling chip hotspots at different operating conditions. Finally, a case study is conducted in this paper for a sustainable self-cooling framework in order to address the question above. The results showed that the self-cooling framework can successfully cool down the hotspot at an acceptable temperature with not only no need for additional electrical power requirements but also for reducing the non-uniformity in the chip temperature distribution.

Numerical study and optimization of thermoelectric-hydraulic performance of a novel thermoelectric generator integrated recuperator

Abstract Thermoelectric modules are usually sandwiched between hot-side and cold-side heat exchangers to generate electrical power. But the sandwiched structures are unsuitable for recuperators because large thermal resistance caused by the thermoelectric modules significantly reduces the heat transfer efficiency. In order to maintain heat transfer efficiency and generate more electrical power, a novel concept of a thermoelectric generator integrated recuperator is proposed, with fins made of thermoelectric materials rather than steel. A numerical model is developed using FLUENT software with User Defined Function codes. Compared with conventional plate-fin recuperators, the new recuperator has similar thermal-hydraulic performance and generates additional electrical power. The effects of Reynolds number on open circuit voltage, internal resistance, heat transfer, output power, and pumping power are studied. The optimum hot gas velocity is 1.5 m/s, which produces a temperature difference of 147.6 K, an open circuit voltage of 31.5 mV, and an output power of 0.23 mW. The Taguchi method is employed to design numerical cases for geometrical optimization. Results show that the effect order is: channel width > TE fin thickness > TE fin height. The optimum values of channel width, fin thickness, and height are 1 mm, 3 mm, and 1 mm, respectively.

The Impact of Parallel Energy Consumption on the District Heating Networks

Abstract The aim of this study is to evaluate and compare the impacts of heat recovery ventilation (HRV) and exhaust air heat pump (EAHP)-based solutions used in renovated buildings, which make it possible to reach performance class C in district heating (DH) area CO2 emissions, primary energy consumption and total energy costs for consumers. Evaluation is based on the methodology presented in the previous research paper [1]. Calculation results show that the use of EAHP has a negative impact on DH sustainability (heat losses in the DH network, DH heat price, reduced consumption of DH heat) and CO2 emissions related to energy delivery (heat and electricity) to consumers in the DH area. Positive aspects of the EAHP use include the fact that almost the same primary energy consumption level can be achieved with lesser (up to 7 %) annual costs (annual capital costs, DH heat costs and electricity costs) and lower initial investments (about 10 %). At the same time, every renovated building with EAHP will experience a negative impact on heat prices. In DH areas where almost all buildings are renovated with EAHP, cost savings are not as evident compared to buildings with HRV in DH areas where the use of parallel consumption solutions (EAHP) is minimized. It is reasonable to promote these renovation packages and solutions that benefit the building’s primary energy reduction, and also do not increase electric energy consumption (additional electric power generators are needed) and do not damage DH networks.

Re-assessment of station blackout accident in VVER-1000 NPP with additional measures following Fukushima accident using Relap/Mod3.2

The Fukushima accident indicated that the safety systems of nuclear power plants should be re-assessed against site-specific extreme natural hazards using additional BDBA management equipment and organizational measures. The occurrence of loss of power supply (SBO) accident in VVER-1000 NPP, which is the most contributor to the total core damage frequency, is the focus of this study. The SBO accident analysis of the reference plant with and without operator actions are investigated by Relap5 code to identify the characteristics of additional measures, available times for operator actions (critical time points) as well as scenarios to manage the accident consequences. The additional BDBA management equipment includes robust and reliable portable additional electrical power backup sources and water supplies into the primary and secondary cooling system to remove the residual heat of the core. The main purpose of this study is an evaluation of efficiency and sufficiency of additional equipment and organizational measures at NPP site based on deterministic safety analysis during SBO accident. This analysis is also expected to prepare a useful guideline for the SBO management in VVER-1000/V-446 NPP. A validated Relap5 model of VVER-1000 is employed to implement the proposed SBO accident scenarios consisting of residual heat removal through primary and secondary cooling systems as well as additional measures to mitigate this accident. The main thermal-hydraulic parameters of NPP in response to SBO accident are compared with specified acceptance criteria. The deterministic safety analysis demonstrates the provided accident scenarios with specified additional BDBA management equipment ensures the long-term reliable cooling of the reactor core under loss of power supply condition. The result also illustrates that a high degree of confidence in the robustness of the VVER-1000 NPP could be achieved against SBO accident with the inclusion of additional measures.

Improvement of Efficiency of Coal-Fired Steam Power Plant by Reducing Heat Rejection Temperature at Condenser Using Kalina Cycle

This paper proposes an approach for improving the plant efficiency by reducing the heat rejection temperature of power cycle using Kalina Cycle System 11 (KCS11) which is integrated at the steam condenser of a 500 MWe SubC (subcritical) coal-fired power plant. It is modelled by using power plant simulation software ‘Cycle Tempo’ at different plant operating conditions. Results show that the additional net electric power of 5.14 MWe from KCS11 improves the net energy and exergy efficiencies of the power plant by about 0.302 % point and 0.27 % point, respectively at full load over the stand-alone coal-fired steam power plant. Thereby, the carbon dioxide (CO2) emission is reduced by about 2.02 t/h at full load. Combined plant efficiencies decrease with decrease in evaporator outlet temperature due to decrease in vapour quality of binary mixture at turbine inlet and higher steam turbine back pressure. Levelized Cost of Electricity (LCoE) generation and payback period of the combined cycle power plant are about Rs 1.734 and 4.237 years, respectively and the cost of fuel saving is about Rs 0.685 per kg of coal which is lower than the fuel cost.

Efficiency of a photovoltaic thermal stepped solar still: Experimental and numerical analysis

In this study, the performance of a stepped solar still connected to photovoltaic thermal (PVT) water collector was numerically and experimentally analyzed. By considering energy balance for the different components of solar still system, a transient thermal model was achieved (i.e. PVT water collector, saline water, glass cover, absorber plate). Moreover, an expression for the system energy efficiency was obtained. An experimental setup was designed and manufactured. The simulation results were validated with experimental data. Then, parametric studies were performed and the influence of various design and operating parameters on the freshwater productivity, energy efficiency and output electrical power were studied. It was shown that there would be a desired value for the area of PVT water collector and mass flow rate of saline water maximizing the energy efficiency. The mass flow rate and PVT water collector area desired value was 0.068 kg/min and 1.33 m2, respectively. Moreover, connecting the PVT water collector to stepped solar still enhanced the energy efficiency and freshwater productivity and for other uses could provide additional electrical power.

Energy efficient primary atomization of viscous food oils using an electrostatic method

Food oil coating applications typically require spraying with relatively viscous liquids. Traditional spray methods can by inefficient, requiring a large amount of energy to produce a uniform coating and/or producing a significant degree of overspray. The electrostatic charge injection atomization technique is shown to be appropriate for these viscous and dielectric food oils, where an additional electrical power of ≈0.1W is required. Electrical performance data and also spray imaging and quantitative drop size measurement using phase Doppler interferometry are presented for atomizer orifice diameters of 150 and 250 μm and liquid injection velocities of 10 m/s. The typical average drop diameter is typically 70% of the orifice diameter. The results show the atomization performance is independent of liquid viscosity over a viscosity range of factor 50.

Thermodynamic analysis of small-scale externally fired gas turbines and combined cycles using turbo-compound components for energy generation from solid biomass

This paper proposes the implementation of cost-effective commercially available automotive components in small-scale power plants for the energy generation from carbon-neutral biomass. Specifically, a turbocharger and a power turbine of turbo-compound systems are proposed to be coupled with an external combustor and a high temperature heat exchanger in order to obtain a cheap externally fired gas turbine capable of producing about 30 kW of electrical power from the combustion of pruning residues. The externally fired gas turbine cycle can be combined either with a final heat exchanger to generate useful thermal power or with a bottoming cycle to generate useful thermal power and an additional electrical power of about 15 kW. Two plant configurations are proposed for the bottoming cycle: the first is a water Rankine cycle employing the “green steam turbine” as the steam expander, whereas the second is an organic Rankine cycle using an axial turbine and toluene as the working fluid. The results of the simulations, obtained through a detailed thermodynamic model, show that the use of a combined cycle is fundamental to maximize the primary energy savings of the power plant. In the case of negligible pressure losses, the use of a bottoming water Rankine cycle leads to a maximum second law efficiency of about 0.25 and maximum primary energy savings of about 0.23. Instead, a bottoming organic Rankine cycle employing a single stage turbine can increase the second law efficiency and the primary energy savings up to about 0.27 and 0.26, respectively. It is also demonstrated that the use of a two-stage turbine for the organic Rankine cycle can further enhance the plant performance. The effects of the pressure drops in the system are investigated in detail to point out that the minimization of the pressure losses is fundamental to improve the performance parameters of all the proposed configurations.

Power generation from fluegas waste heat in a 500 MWe subcritical coal-fired thermal power plant using solar assisted Kalina Cycle System 11

This paper proposes a solar assisted Kalina Cycle System 11 (KCS 11) driven by fluegas waste heat of 500 MW Subcritical (SubC) coal-fired thermal power plant for additional electrical power generation. A computer simulation programme has been developed in MS-Excel and VBA to calculate and optimize system performance at different conditions. Results show that net electric power generation of about 516.52 kWh can be added with main plant generation for improving the plant net energy and exergy efficiencies by about of 0.040% and 0.036% point, respectively. This will reduce the annual CO2 emissions by about 1008.28 ton. Solar assisted KCS11 is more energy efficient but less exergy efficient compared to standalone KCS11. About 0.76 is the optimum ammonia mass fraction that yields the maximum efficiency at the operating pressure of 17.54 bar. System performance increases with increase in cooling water flow rate and is optimum at 92.80 kg/s. Power generation cost and payback period of the proposed system are about of Rs. 2.163 per unit generation and 12.44 years, respectively. The levelized cost of electricity (LCoE) for additional generation by solar heater is about Rs. 10.99 per kWh which is about 8.80% lower than conventional solar thermal power plant.

Experimental performance characterisation of a Hybrid Photovoltaic/Solar Thermal Façade module compared to a flat Integrated Collector Storage Solar Water Heater module

A modular Hybrid Photovoltaic/Solar Thermal (HyPV/T) Façade technology that utilizes Integrated Collector Storage (ICS) solar technology, providing cost effective solar PV and thermal energy collection for direct use in the building, whilst providing significant thermal insulation has been developed and evaluated experimentally at Ulster University. The HyPV/T system, based upon a patented ICS solar thermal diode concept and shaped into a flat modular profile incorporating PV cells/module can provide space heating, domestic water heating and power generation. The complete system is designed to be compatible with traditional façade structures and fenestration framing arrangements, facilitating direct integration into new and retrofit building applications.The experimental performance of HyPV/T unit has been determined and compared with a flat Integrated Collector Storage Solar Water Heater (ICSSWH) under constant indoor solar simulated conditions. The daily thermal collection efficiencies for the ‘traditional’ flat ICSSWH units performed better than the unglazed HyPV/T, by 5–10%. However, when the additional electrical power produced by the HyPV/T is included, the overall system collection efficiencies are more equal. The heat retention performance shows that's the unglazed (bare) ICS unit had a retention efficiency of 8.3% whilst the ICS unit with a single transparent cover was 23.6% and double glazed unit was 28%. The HyPV/T heat retention efficiencies were approximately 65% over the same cool-down period.

Thermodynamic and economic evaluation of reheat and regeneration alternatives in cogeneration systems of the Brazilian sugarcane and alcohol sector

This work makes a technical and economic evaluation of incorporation of reheating and regeneration, as a way to increase efficiency of energetic systems and bagasse surplus, in cogeneration systems of Brazilian sugar and ethanol sector. Four scenarios were analyzed: Conventional (C0), with Reheat (C1), Regenerative (C2) and with Reheat and Regeneration (C3). Some of thermodynamic indicators used in evaluation were Surplus Bagasse Index and Exergetic Efficiency, for economic evaluation the Monte Carlo Method was used to give a Net Present Value (NPV) > 0 for each scenario. Technical evaluation indicates that Reheating (C1) increases bagasse surplus by 39.9% and exergetic efficiency by 1.90%, with respect to C0. Incorporation of 1–8 regenerators (C2) increases surplus bagasse and exergetic efficiency in the ranges of 103–160% and 5.03–8.07%, respectively. Reheat stage incorporation of 1–8 regenerators (C3) increases surplus bagasse in the range of 121–166% and increases exergetic efficiency in a range of 5.91–8.46%. Finally, it was estimated the potential of additional electric power generation during off-season and second generation ethanol production from surplus bagasse, with satisfactory results.

Efficiency enhancement of solar chimney power plant by use of waste heat from nuclear power plant

Abstract A solar chimney power plant (SCPP) offers an efficient method of converting solar irradiation to electrical power. It can be combined with a nuclear power plant to improve its efficiency and minimize its environmental impact. Rather than dumping the waste heat rejected by a nuclear power plant to a wet cooling tower, a better solution may be to connect it to an SCPP. This is particularly true in arid regions. The SCPP can serve the function of a dry cooling tower and produce additional electrical power. In a solar chimney power plant, the energy of buoyant hot air is converted to electrical energy. SCPP includes a collector at ground level covered with a transparent roof. The sun heats the air inside the collector and the ground underneath. A tall chimney is placed at the center of the collector, with a turbine located at the base of the chimney. In this investigation, the surplus heat from the nuclear cycle is used to increase the temperature of the air in the collector and therefore produce more electricity in the solar chimney power plant. The efficiency of the nuclear plant will be lowered due to the higher temperature of the condenser, but the loss can be made up by the increased power of the solar chimney. Heat from the sun is always free once the solar plant has been constructed and is not normally considered in the efficiency calculation. Computational fluid dynamics (CFD) and thermal analysis have been performed to apply the available surplus heat from the nuclear cycle and to measure the available kinetic energy of air for the turbine of the solar chimney power plant system. The feasibility of the system is evaluated, and the thermal efficiency of the combined power plant has been computed. By applying this idea to a typical 1000 MW nuclear power plant with a nominal 35.3% thermal efficiency, its efficiency can be increased to 42.0%. The combined cycle as presented is advantageous in environments where water is scarce. The cooling tower is replaced by the solar chimney power plant utilizing the surplus heat from the available warm steam in the secondary loop of the reactor.

Experimental performance assessment of a photovoltaic/thermal stepped solar still

In this paper, the performance analysis of a stepped solar still connected to photovoltaic thermal collector is carried out numerically and experimentally. A transient thermal model is obtained by writing energy balance for the various components of solar still system (i.e. glass cover, saline water, absorber plate, photovoltaic thermal collector). Also, an expression for the energy efficiency of system is derived. An experimental setup is designed and fabricated. The simulation results are validated by the measured experimental data. Finally, parametric studies are carried out and the effect of various operating and design parameters on the energy efficiency, freshwater productivity, and output electrical power is investigated. It is observed that there is a desired value for the mass flow rate of saline water and the area of photovoltaic thermal collector, which maximizes the energy efficiency. The desired value of the mass flow rate and photovoltaic thermal collector area is 0.068 kg/min and 1.33 m2, respectively. Furthermore, the connection of photovoltaic thermal collector to the stepped solar still improves the freshwater productivity and energy efficiency and it provides additional electrical power for other applications.

Microbial Photoelectrotrophic Denitrification as a Sustainable and Efficient Way for Reducing Nitrate to Nitrogen.

Biological removal of nitrate, a highly concerning contaminant, is limited when the aqueous environment lacks bioavailable electron donors. In this study, we demonstrated, for the first time, that bacteria can directly use the electrons originated from the photoelectrochemical process to carry out the denitrification. In such photoelectrotrophic denitrification (PEDeN) systems (denitrification biocathode coupling with TiO2 photoanode), nitrogen removal was verified solely relying on the illumination dosing without consuming additional chemical reductant or electric power. Under the UV illumination (30 mW·cm-2, wavelength at 380 ± 20 nm), nitrate reduction in PEDeN apparently followed the first-order kinetics with a constant of 0.13 ± 0.023 h-1. Nitrate was found to be almost completely converted to nitrogen gas at the end of batch test. Compared to the electrotrophic denitrification systems driven by organics (OEDeN, biocathode/acetate consuming bioanode) or electricity (EEDeN, biocathode/abiotic anode), the denitrification rate in PEDeN equaled that in OEDeN with a COD/N ratio of 9.0 or that in EEDeN with an applied voltage at 2.0 V. This study provides a sustainable technical approach for eliminating nitrate from water. PEDeN as a novel microbial metabolism may shed further light onto the role of sunlight played in the nitrogen cycling in certain semiconductive and conductive minerals-enriched aqueous environment.