Open Journal of Energy Efficiency

Journal Information
ISSN / EISSN : 2169-2637 / 2169-2645
Published by: Scientific Research Publishing, Inc. (10.4236)
Total articles ≅ 122
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Latest articles in this journal

Bazkir Ozcan, Meric Seval
Open Journal of Energy Efficiency, Volume 11, pp 108-121;

Photovoltaic (PV) modules performance testing and energy rating as described in IEC 61853-1 standard depend on electrical performance parameters (short-circuit current, open-circuit voltage, maximum-power) of PV modules as a function of temperature and irradiance. In this work, in order to precisely determine the effects of temperature on the electrical parameters of a monocrystalline PV module, the temperature controlled, xenon light based solar simulator system with irradiance attenuating masks was used. This solar simulator, according to the IEC 60904-9 standard in terms of spectral match, spatial non-uniformity and temporal instability has A+A+A+ classes which are two times better than the standard requirements for a solar simulator to be used in PV module measurements. Moreover, the thermal chamber used in this work is a closed type chamber with fast opening door for not allowing the distortion of temperature uniformity over the surface of PV modules under test. Within about 2 m × 2 m area within 15°C to 75°C temperature interval, the temperature uniformity obtained for this system is less than 1.0°C which is almost two times better than the IEC 60891 standard requirements (±2.0°C). The temperature and irradiance dependent measurements of the electrical performance parameters of a mono-crystalline PV module at various irradiance levels and the evaluation of its temperature coefficients [α (% °C-1), β (% °C-1) and δ (% °C-1)] were done by implementing the interpolation method described in IEC 60891 standard.
Andrew Sherren, Kyle Fink, Joshua Eshelman, Luay Yassin Taha, Sohail Anwar, Craig Brennecke
Open Journal of Energy Efficiency, Volume 11, pp 24-36;

In recent years, road piezoelectric energy harvesting (RPEH) has attracted great attention from industry and academia, as it can provide power to traffic ancillary facilities and low-power wireless sensor devices to support car networking and intelligent transportation. The output power of RPEH in a recent research project demonstrated a watt level RPEH. In this proposal, we propose to harvest energy from piezoelectric modules (also called stacks) to power selected highways, tolls, and bridges in Pennsylvania. The project incorporates electrical, mechanical, and civil engineering works. The proposed smart highway RPEH will be conducted using optimization parameters to evaluate the system performance and trade-offs. MATLAB will be used with other optimization solvers in problem modeling and optimization. During this project, an RPEH hardware system will be constructed. The system will include a piezoelectric module, rectifier (AC-DC), Storage battery, data acquisition system (DAQ), and computer. The captured data will be analyzed using MATLAB/Simulink. The results show that optimum harvested parameters were addressed when the thickness is selected as 2 mm.
Gift Mwalule, Maureen Kapute Mzuza
Open Journal of Energy Efficiency, Volume 11, pp 1-9;

Challenges with access to electricity are global but becoming increasingly high in Malawi where more than 96% of the electricity is produced from hydro generation. Energy sources for electricity production can be renewable or non-renewable. Due to many challenges facing hydropower production such as water levels, debris in the inlet ponds, etc., renewable energy sources that produce clean energy such as solar power are becoming common. However, despite such opportunities, access to electricity whether renewable (solar) or non-renewable (hydro production) to many people in urban areas in Malawi is still a challenge. A household survey was carried out involving 100 households aimed to establish factors that influence the use of solar energy technology in Machinjiri, one of the townships in the city of Blantyre, in southern Malawi. Only 32% of the households have access to solar energy. Results indicated that the level of education attained has an influence on the peoples’ choices to use solar technology. In this regard, respondents with basic primary school certificate reported 8% while those with college education reported 32% and those with higher education, Malawi School Certificate of Education (MSCE) reported 52% use of solar energy for lighting. Some of the reasons for not using solar energy include: low production during winter (55%), not durable (23%), no knowledge (18%) and others mention combined reasons (4%). Only a few people use solar energy for lighting. Therefore, there is a need for the government and non-governmental organizations to continue sensitizing people on the importance of using renewable energy such as solar energy. Furthermore, the government should create deliberate conditions to make solar energy equipment affordable to many Malawians with low incomes.
Meric Seval, Bazkir Ozcan
Open Journal of Energy Efficiency, Volume 11, pp 71-87;

One of the most important parameter used for the evaluation of the energy rating of PV modules is, their spectral responsivities which are the measure of electrical performance parameters per incident solar radiation. In this work, spectral responsivity measurements of a mono-crystalline, a poly-crystalline, a CIGS thin film and a bifacial module were measured using xenon-based flash type solar simulator system and a set of band pass filters. For the comprehensive characterization of parameters that may influence the spectral responsivity measurements, initially the simulator system was characterized both optically and thermally according to the IEC60904-9 and IEC60891 standard requirements. The optical characterizations in terms of spectral match, spatial non-uniformity and temporal instability indicate that the measured results (~3.0%, ~0.30% and ~0.20%) according to the IEC 60904-9 standard’s classification requirements correspond to A+A+A+ classes. Moreover, thermal characterizations in terms of the temperature uniformity show that over the 2 × 2 m area temperature uniformity of simulator system’s light distribution (1ºC) is almost two times better than the IEC 60891 standard requirements (±2ºC). Next, PV modules were electrically stabilized according to the IEC 61215-2 standard requirement’s (stability test) to reduce the fluctuations in their electrical performance parameters. Then, using the band pass filters, temperature controlled xenon-based solar simulator system and a reference PV module of the spectral responsivity of PV modules were measured from 400 nm to 1100 nm with 50 nm steps with relative uncertainty of 10-3 level.
O. O. Ighodaro, E. I. Aburime, A. A. Erameh
Open Journal of Energy Efficiency, Volume 11, pp 88-107;

Gas turbines are considered as one of the leading internal combustion engines in modern air transportation due to its favourable power to weight ratio and its continuous combustion process. Recent research focus has been concerned with performance improvements aimed at reduced fuel consumption and hence reduced impact on the environment. This study is aimed at using theoretical and computational methods to model the operation and performance a turbojet gas turbine engine. The commercial software GasTurb13 was used for the theoretical simulation while Microsoft Excel was used for the analytical study. GasTurb13 solved the model using pseudo-perfect gas models i.e. component maps since the specific gas ratio could not be inputted into the solver. The effect of changes in the Mach number and altitude on the engine performance was studied. Also the effect of changes in the compressor pressure ratio, the turbine inlet temperature and the afterburner exit temperature were also studied. Results obtained showed the optimum pressure ratio at maximum thrust constraint to be 16.78 for the turbojet engine operating at Mach number (Ma) = 0.8 and altitude = 10,000 m, Turbine inlet temperature (TIT) = 1200 K and Afterburner exit temperature = 1800 K.
Ioannis Zavos, Dmitri L. Danilov, Peter H. L. Notten
Open Journal of Energy Efficiency, Volume 11, pp 37-53;

Self-reconfigurable batteries represent a new and promising technique of electrochemical storage. The application of self-reconfigurable batteries can resolve the challenge of efficient renewable storage in solar-powered installations. In this paper, the problem of solar panel’s Maximum Power Point (MPP) tracking utilizing self-reconfigurable batteries is explored through modeling. The efficiency of energy storage is improved by removing the intervening DC/DC converter, which is usually necessary for solar PV applications. To make such a system functional, a Switching Battery Management System (SBMS) is proposed instead of a traditional couple of DC/DC converter and usual BMS. This system allows the series connection of multiple battery modules of different sizes, States-of-Charge (SoC), and States-of-Health (SoH). Two main challenges arise by the proposed implementation: tracking MPP of solar panels through battery cell switching and maintaining an equal (balanced) SoC of the separate cells/modules. The theoretical investigation includes developing the distinct software parts: digital twins of the battery module and solar PV modules that interact with the SBMS and the algorithm according to which the proposed SBMS will operate. The SBMS algorithm, based on sorting the battery cells according to their SoC, resolves both challenges. Having this promising theoretical starting point, a working prototype was developed. The prototype worked as expected and was tested under field conditions, being integrated into the power grid as part of a virtual power plant.
Jovana Jovanovic, Xiaoqin Sun, Milena Đukanović
Open Journal of Energy Efficiency, Volume 11, pp 11-23;

This manuscript addresses the futuristic energy savings by impregnating building elements with PCM formations. Two structured gypsum building walls were monitored under the transient heat mode in the conducted experiments. One wall included (phase-change material) spheres, integrated into one styrofoam layer, installed at different positions, from 1 to 5, from the outside to the inside of the room. The other wall included one styrofoam insulation layer, perforated with holes, with changeable positions, from 1 to 5, from the outside to the inside of the room. The temperatures in the experiment corresponded to high summer temperatures in the tropical or subtropical zones. The obtained experimental results were further analyzed, while HVAC is off, for an indoor thermal comfort range, from 20˚C to 25˚C. This manuscript has analyzed the thermal comfort, effectiveness and optimal position of PCM spheres, incorporated in styrofoam thermal insulation, for a previously determined temperature range. The wall with integrated PCM should not be thick, (in total), but rather slender so that PCM can show its effectiveness. The farthermost position of the PCM layer should be the third because PCM combined with a lot of thermal insulation is not so effective and the thermal insulation has a buffer effect. The honeycomb or hollow-core thermal insulations should be avoided to put alone, because of natural air convection in them, which raises the heat flow. The monthly monetary saving, for a PCM-integrated wall, is calculated and amounts to 55.5 $, which shows that the integration of PCM in building walls, in hot summer locations, is very beneficial.
Andrew Sherren, Kyle Fink, Joshua Eshelman, Luay Yassin Taha, Sohail Anwar, Craig Brennecke, Hussein M. Abdeltawab, Shihui Shen, Faeze Ghofrani, Cheng Zhang
Open Journal of Energy Efficiency, Volume 11, pp 122-141;

This project strived to develop a prototype road piezoelectric energy harvester RPEH system using five Lead Zirconate Titanate (PZT) PZT 5H modules (stacks) that are embedded in the road by means of a housing unit to harvest energy from vehicles stressing the modules. The work is an extension of our previous published work in the same journal. The design considered many factors to optimize the harvested energy. The proposed system first captures mechanical energy using a designed module that transfers the energy to the piezoelectric stacks. Then the captured energy will be converted into electrical energy by the piezoelectric phenomenon. The harvested energy is stored in a storage device, then analyzed by an oscilloscope through the acquisition of the harvested voltage, current, power, and energy. When testing the RPEH with the wheel tracking machine, varying resistor loads where connected to the output of the RPEH to address the optimum power delivered to the load. The optimum load was found to be 950 kΩ, and the optimal harvested energy was recorded as 45 uJ.
Peng Liu, Shaopeng Wang, Cheng Guo, Li’An Zhang, Hebing Tang
Open Journal of Energy Efficiency, Volume 11, pp 142-157;

KL16 (Kenli 16) oilfield is located in Bohai Sea, close to Laizhou Bay depression, with favorable reservoir forming conditions. The lower member of Shahejie Formation (lower sub member of the third member of Shahejie formation) has shallow burial, complex structural sedimentary evolution, diverse reservoir lithology types, and unclear reservoir distribution laws, which restrict the exploration and development process. Comprehensive use of core, seismic, logging and analytical laboratory data, through the combination of structural recovery and stratigraphic recovery, the micro paleogeomorphology of the lower member of Shahejie Formation in the sedimentary period is finely restored, and the sedimentary system and sedimentary model in the study area are defined. The study shows that during the sedimentary period of the lower member of Shahejie formation, four geomorphic units were developed in the study area: uplift, slope, platform and depression; Under the control of paleogeomorphology, three different sedimentary environments are developed: Braided River Delta is developed in the west, shore shallow lake mixed beach bar is developed in the middle, and fan delta is developed in the south. Based on the analysis of regional geology and sedimentary characteristics, the principal component coupling technology based on the constraint of sedimentary facies belt is optimized for reservoir distribution prediction, and the application effect is good.
François Yonga, Colince Welba, Theodore Louossi, Noël Djongyang
Open Journal of Energy Efficiency, Volume 11, pp 55-70;

In this paper, we present the study, modelling and simulation of the duty cycle modulation (DCM) based on SVPWM control technique using Matlab/Simulink software. It is one of the most advanced control techniques of space vector modulation (SVM), which can be used for controlling static converters or for controlling electrical machines to achieve better dynamic performance. DCSVM is a control technique that generates control signals for the two-level voltage converter as well as for the intermediate times. The main advantage of this control technique is the reduction of the number of calculations, especially for the trigonometric functions and the generation of the reference voltage. In order to reduce the computational effort, we have designed a DCSVM controller that is able to faithfully reproduce the same vectors and output quantities as a classical SVM. In order to test the functionality and validity of the DCSVM control, we have developed different simulations that result in a total harmonic distortion (THD) of the voltage and current of 41.19% and 15.19% respectively with fundamental values of 61.51 V for the voltage and 2.80 A for the current; in contrast to the SVM which gives 47.27 V for the voltage and 2.01 A for the current with THDs of 77.16% for the voltage and 16.00% for the current. This results in an improvement in the distortion rate of around 25.5%. The results obtained are very satisfactory. The DCSVM is a real competitor to the SVM and its various variants.
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