In Jordan, the residential sector is responsible for 43% of all power use and 21% of total energy usage. The use of energy for space heating and cooling accounts for more than 60% of residential energy use. The computer-generated residence, a typical one-storey Jordanian home with a functional floor area of 186 m2, is located in Amman and was modelled to be more energy efficient by incorporating renovating techniques to lower heating and cooling demand, attain marginal energy demand, and produce a high-quality indoor living environment. To get at the idea of passive design houses as appropriately depicted in this paper, various passive design tactics and methodologies were employed. Using DesignBuilder simulation software, Revit modelling software, solar energy analysis software, and assessment of the total energy consumption before and after the deployment of passive design approaches, the effects of each retrofit method were evaluated. The results of this study show that the yearly energy savings for heating is about 78%, and the indoor air quality and temperature of the residence can be significantly enhanced compared to its original situation. The total employed energy in the virtual building was scaled down from 56.57 kWh/m2 to 15.25 kWh/m2 each year.

Keywords: Induction motor, windings, phase-shifting capacitor, efficiency, positive and reverse sequence currents
 Induction motors consume almost 70% of the world’s electricity as they are the driving force behind the vast majority of rotary mechanisms [1]. For industrial and domestic purposes alone, about a million new electric motors are commissioned annually. Single-phase induction motors (SPIMs) are superior to all other types of electrical machines that operate on a single-phase AC voltage network because of their simple and robust design and low cost. Therefore, a small improvement in the SPIM energy performance can have a strong impact on energy consumption worldwide and ultimately reduce emissions of harmful substances into environment. This article presents a technique for optimizing SPIM windings in order to maximize efficiency with a given and fixed phase-shifting capacitor. The positive effect of the application of the proposed method is confirmed by the results of SPIM industrial tests with various powers and rotor speeds.

Straipsnyje nagrinėjamos ūkinės veiklos neteisėtų veiksmų sukeltos žalos hidroelektrinių vandens telkiniams, kaip kraštovaizdžio objektams, nustatymo problemos. Siūloma žalą upei, ežerui ar tvenkiniui skaičiuoti priklausomai nuo vandens telkinio vertės, kurią lemia teritorijos gamtosaugos tikslai, vandens telkinio dydis ir būklė bei pažaidos lygis. Paliekant galioti dabartinius žalos kraštovaizdžio kompleksams ir objektams nustatymo pagrindinius principus Lietuvoje, siūlome pasitelkti patikimus hidrografijos šaltinius, objektyvius, nuotoliniu būdu stebimus, hidrologijos rodiklius ir hidroenergetikos duomenis. Svarbiausias upės, ežero ar tvenkinio morfometrinis rodiklis yra vandens paviršiaus plotas, kuris nustatant žalą patikimai ir objektyviai paimamas iš upių, ežerų ir tvenkinių kadastro. Ežero (tvenkinio) vandens lygio ar upės debito pokyčiai dėl neteisėtos ūkinės veiklos stebimi nuotoliniu būdu ir registruojami. Skaičiuojant žalą, vietoje absoliučios vandens lygio pokyčių reikšmės siūlome vertinti pažeidimą santykiniu lygio arba debito pokyčiu, apskaičiuotu kaip neteisėto lygio ar debito pokyčio santykis su maksimaliu ežero (tvenkinio) gyliu arba atitinkamai reglamentuotu upės debitu. Toks santykinio pokyčio vertinimas atspindi esminį vandens telkinio režimo skirtumą tarp didelių bei gilių ir mažų bei seklių telkinių. Straipsnyje pasiūlyta žalos kraštovaizdžiui dėl neteisėtos ūkinės veiklos vandens telkiniuose vertinimo metodika, paremta objektyviais hidrologiniais ir morfometriniais rodikliais bei stebėjimų duomenimis.

Direct piezoelectric conversion is very popular in generating power from mechanical stress. There is continuous progress in power harvesting from mechanical vibration. In this article, experimental tests on a piezoelectric circular plate, to evaluate the electric power produced by the piezoelectric conversion at low acceleration over a wide range of ambient vibration frequency, are presented. The experimental analysis is presented and discussed. The results demonstrate the potentiality of using low-cost piezoelectric diaphragms to harvest energy from ambient vibration. Under low acceleration (5.36 m/s2), the vibration frequency was varied in the range of 10– 200 Hz and the generated power was measured. Under a very small dynamic force (less than 0.06 N), the output power of 1.5 mW was obtained with an 8.5 mm drum harvester across a load resistance of 17.8 kΩ at a frequency of 173 Hz.

The energy management system (EMS) of an electrical distribution system (EDS), with the integration of distributed generation (DG) and distribution static compensator (DSTATCOM), provides numerous benefits and significantly differs from the existing EDSs. This paper presents an optimal integration of DG based on photovoltaic (PV) solar panels and DSTATCOM in EDS. A single objective function, based on maximizing the active power loss level (APLL) in EDS, is deployed to find the optimal size and location of photovoltaic DG and DSTATCOM simultaneously in different study cases using various particle swarm optimization (PSO) algorithms. These PSO algorithms are the basic PSO, adaptive acceleration coefficients PSO (AAC-PSO), autonomous particles groups for PSO (APG-PSO), nonlinear dynamic acceleration coefficients PSO (NDAC-PSO), sine cosine acceleration coefficients PSO (SCAC-PSO), and time-varying acceleration PSO (TVA-PSO). These algorithms are applied to the standard IEEE 33- and 69-bus EDSs, which are used as test systems to verify the effectiveness of the proposed algorithms. Simulation results prove that the TVA-PSO algorithm exhibits higher capability and efficiency in finding optimum solutions. Comparing the simulation results attained for different study cases leads to the conclusion that DG and DSTATCOM were optimally-allocated simultaneously, which resulted in a significant reduction of power losses and an enhancement of the voltage profile.

Straipsnyje pateikti dyzelinio variklio „4ČN 79,5/95,5“, konvertuoto veikimui naudojant dvejopas dyzelinas (D)–gamtinės dujos (GD) kurą (D/GD), kogeneracinio ciklo energetinių parametrų tyrimų rezultatai. Tyrimų tikslu tapo variklio, veikiančio naudojant D ir dvejopą (D/GD) kurą, kogeneracinio ciklo antrinių energijos išteklių (išmetamųjų dujų ir aušinančio kontūro vandens) energijos efektyvumo panaudojimo rodiklių palyginamoji analizė. Eksergijos balanso energetinės sudedamosios ištirtos plačiuose apkrovos (pme = 1,98–5,99 bar) ir D/GD sudėties (100/0–20/80) bei variklio reguliavimo parametrų pasikeitimo diapazonuose. Eksergijos balanso suminio naudingumo koeficiento (ηExΣ), įvertinančio elektros ir šiluminės energijos panaudojimo efektyvumą, sumažėjimas neviršijo 3–4 % ir 22 % atitinkamai aukštos ir žemos jėgainės apkrovos režimuose. Mažėjant eksergijos panaudojimo efektyvumo rodikliams (ηExe, ηExΣ), absoliutus eksergijos potencialas praktiniam panaudojimui dėl šiluminės energijos sudedamosios augimo didėja nuo 3–18 % aukštos apkrovos režimuose ir iki 14–58 % žemos apkrovos režimuose. Nustatyta, kad santykinai mažesni absoliučių eksergijos balanso rodiklių pasikeitimai būdingi dyzelinėms jėgainėms su didesne indikatorinio proceso dinamika. Tai leidžia teigti, kad kogeneracinio ciklo energetinių sudedamųjų gerinimo potencialas yra didinant indikatorinio proceso dinaminius rodiklius (pvz., ankstinant dyzelino įpurškimo paskubos kampą φinj).

In order to mitigate climate change, more attention every year is being given to wind energy. However, despite minimal impact of wind turbines on the environment, there is a negative side as well. Wind speed variations are a stochastic process, and it is difficult to predict wind power accurately. Therefore, unpredictable power can disbalance the power grid; besides, huge power reserves are necessary. Wind energy can be forecasted based on statistical, physical or hybrid methods and models. However, all methods and models generate power prediction errors during different time horizons. The paper presents an analysis of wind power prediction errors determining factors based on statistical, physical and hybrid approaches. Investigation revealed that combination of statistical methods – nonlinear regression, model output statistics, the most suitable power curve and wind speed correction methods – reduced wind power prediction errors up to 1.5%. A detailed evaluation of relief variations and surface roughness increased wind power accuracy by 2%. Considering the local conditions of the western part of Lithuania, the best suitable tool for a short-term wind power prediction is a hybrid model including a detailed description of topographical conditions and the most precise statistical methods.

Fly ash-derived zeolites may become an attractive alternative for natural zeolites as well as for zeolites produced out of pure chemicals. A growing awareness of the need to protect the environment is an incentive for the use of waste materials as raw materials for production of microporous, multi-application materials – zeolites. Additionally, environmentally friendly actions undertaken in order to reduce air pollution intensify needs to search for new options for capturing hazardous air pollutants out of flue gases. Zeolites can be used as air pollutants sorbents. In this work there are presented results of sulphur dioxide, one of flue gases components, sorption experiments. The adsorbent used was zeolite synthesized form fly ash from a selected Polish power plant. For the purpose of investigation there were chosen fly ash zeolite samples synthesised with the use of different methods. Parameters were selected in such a way that one type of zeolite material was received. For the purpose of description of received results the mathematical model was used. As a result of experiments carried out it was found that the synthesized materials may be used as sulphur dioxide sorbent. It was found that the sorption capacity is highly connected with the zeolite synthesis method. Despite the fact that the same type of zeolite was received, samples presented differentiated values for capture, due to different conversion factors of fly ash into zeolite materials.

The representation of wind power plants electricity generation in economic models for energy planning is problematic, since generation in wind power plants is variable and it is not possible to predict accurately enough wind fluctuations for more than a few days. Often, wind power plants generation patterns from a single historical year are repeated throughout the modelled time period. Typically, this method is used when analysing power system operation in hourly time intervals for all days in a year for each year. However, hourly time resolution is not feasible in large-scale models, which tend to require considerable amounts of computing power. Thus, some kind of time aggregation is needed. On the other hand, currently used methods for models with less than hourly temporal resolution are becoming inadequate because of increasing share of fluctuating electricity production from wind in total power generation. In this article, a methodology for evaluation of wind power plants stochastic electricity generation in power system development models is described. The methodology is based on evaluation of how much time single or multiple wind power plants generate a certain output range during a season or some time period within a year, modelling of output distribution for a typical day of the selected time period, and preparation of electricity output curves. These electricity output curves when modelling wind power plants in models with aggregated time allow to assess fluctuations in generation, observable regularities and enhance the objectivity of balancing power demand assessment, also ensure that electricity generated during a typical day corresponds to electricity generated during the selected time period. This methodology will help to determine the rational perspective power generation mix more accurately and make a better assessment of cost-effectiveness of wind power plants in economic models for energy planning, without significantly increasing the size of already large-scale models.

In addition to conventional exergy-based methods, advanced exergetic analyses consider the interactions among components of the energy-conversion system and the real potential for improving each system component. The paper demonstrates the results of application of a detailed advanced exergetic analysis to a wastewater source heat pump providing space heating in the built environment. In order to determine thermodynamic parameters of the refrigeration vapour compression cycle in different operating modes, the simulation model has been used. The analysis includes splitting the exergy destruction within each component of a heat pump into unavoidable, avoidable, endogenous and exogenous parts as well as detailed splitting of the avoidable exogenous exergy destruction. Besides, variabilities of heating demands of a building within both the chosen heating season and also from year to year are taken into account. Distribution of the split exergy destructions during different periods of time is also presented for the analysed cases of the heat pump and built environment. It is shown that in the investigated system only about 50% of the total annual destruction in components of the heat pump can be avoided. About 30…40% of this avoidable thermodynamic inefficiency is caused by interactions among components. Based on the applied advanced exergetic analysis it is possible to receive more precise and useful information for better understanding and improving the design and operation of the analysed energy-conversion system.