Reduction Of Electric Energy Consumption Research Articles

FUZZY SLIDING-MODE TEMPERATURE-CONTROL SYSTEM FOR SOAKING AND GERMINATION OF RICE SEEDS

The soaking and germination process of rice seeds is the starting point in rice cultivation in cold regions and has a significant effect on grain yield. Efficient techniques for controlling the water temperature in the seed tank are required to enhance germination quality. This paper introduces a fuzzy theory for designing a fuzzy logic-based sliding mode controller (SMC) system for a rice seed soaking and germination device. The proposed system was theoretically and experimentally investigated to determine the efficiency of the soaking temperature-control system. A modified fuzzy SMC based on exponent approaching law is also presented for optimizing the proposed controller. A proportional integral derivative (PID) controller was designed to identify and compare the advantages of the proposed controllers. A comparative study of the computer simulation demonstrates that the performance of fuzzy SMC and modified fuzzy SMC are acceptable, and that both SMCs are superior to the PID controller. Furthermore, compared with the fuzzy SMC system, a reduction in electric energy consumption was observed for the modified fuzzy SMC. Moreover, both SMCs yielded similar soaking qualities.

Parametric Analysis of Architectural Elements on Daylight, Visual Comfort, and Electrical Energy Performance in the Study Spaces

The quality of visual comfort has always been an essential element considering human comfort. Providing visual comfort in a living environment reduces the need for artificial lighting, which subsequently has a direct relationship with energy consumptions and its expenses. Besides, the maximum possible usage of daylight instead of artificial lighting significantly contributes to providing a favourable condition in terms of visual comfort for the residents. This essential factor is manifested in public spaces, such as libraries that are associated with students and the quality of their study time. The main aim of this paper is to provide applied solutions to use more natural lighting strategies as an alternative for artificial lighting, which helps to reduce electric energy consumption while providing visual comfort for users. The role of architectural elements, such as the position and dimensions of the windows, reflectivity of materials, layout of surfaces, and appropriateness of space in line with the objectives as mentioned earlier are examined thoroughly. For this purpose, literature studies, as well as computer simulations via Relux software, are utilized to investigate the set research objectives. Finally, the simulation results suggest that the best orientation to achieve the optimal model using daylight in study spaces is northern-southern orientation. In addition, using windows with maximum height in the middle of the transverse front of buildings with window to wall ratio of 35 to 45 percent along the vertical and horizontal divisions (grid) is suitable for such places. Design criteria include the higher access to daylight, visual comfort, and reduction of electrical energy consumption. The reflectivity coefficients for roof materials, floor, and walls are 0.6, 0.4, 0.4, and 0.6, respectively, and transparency for windows is 80%. The obtained results also suggest the length-to-width ratio and height-to-width ratio are 6-to-5 while horizontal and vertical surfaces in near windows and in middle space along the longitudinal direction are optimal for research purposes.

Installation and Implementation of Energy Management Sytem in the Residential Buildings for Sustainable Development

This paper presents the details of the installation of the energy management system in the buildings of a typical Residential Building Residential Building in India and consequently the reduction of electrical energy consumption. Increasing People intake, the introduction of new courses, research centers and laboratories, and the rapid expansion of Residential Building infrastructure, are rapidly increasing the demand for electricity in universities. Most of the electrical energy consumed in universities in India is for air conditioning and lighting purposes. Established Building Energy Management System (BMS) continuously monitors the electrical load demand of air handling units (AHUs) and room lighting in buildings and reduces the load demand by fitting the AHU thermostats based on the work schedule. One day and on / off control of occupancy based on occupancy in different rooms from remote server rooms via Ethernet. Preliminary findings suggest that a significant reduction in load demand can be achieved in any Residential Building in India through the implementation of BMS, thereby contributing to the reduction of domestic oil consumption. If most universities in the country installed BMS on their Residential Buildinges, it would be possible for electric utilities to use real-time meter data, technology-enabled dynamic pricing, and decisive direct load control for fuel management. There are Residential Buildinges. This paper also highlights the future trend in BMS implementation in universities, as the Residential Building's DSM has a secure Residential Building area network that can effectively use demand response when enabled by high-bandwidth, two-way, end-to-end. Can. Communication in a smart grid environment.

Economic Feasibility Study Generated on Replacing Tubular Fluorescent Lamps with Led Lamps in a Commercial Building

The present study has as main objective to verify the reduction of electric energy consumption, allied to the possible economic-financial and environmental benefits that are associated with the use of LED lamps in a commercial building, where it develops office activities covering only part of the building. , which served as the experimental basis for the application of the case study, initiated after a survey of the electrical and constructive characteristics of the luminaires installed on site. In research conducted in the local market specialized in the subject, we selected lamps that are more easily found, analogous to those already installed, manufactured by traditional companies in the field. The monitoring of lighting loads was made by measuring by specific equipment and simulation of energy billing according to the rules of calculations established in rules governed by government agencies and tariff framework in which the building is in both scenarios, before and after lamp replacement. Providing financial technical evaluation through the use of indicators that show the viability of this substitution.

Electrochemical/Fe3+/peroxymonosulfate system for the degradation of Acid Orange 7 adsorbed on activated carbon fiber cathode.

Acid Orange 7 (AO7), as a most common and widely used synthetic dyes in the printing and dyeing industry, was hardly degradable by traditional wastewater treatment methods. Here, activated carbon fiber (ACF) as an in-situ regenerated cathodic adsorbent in the electrochemical/Fe3+/peroxymonosulfate process (EC/ACF/Fe3+/PMS) was firstly investigated for AO7 removal and compared with several different processes. The results indicated that the effective adsorption of AO7 on ACF can be enhanced under electrolytic conditions, while the adsorbed AO7 on ACF can be completely degraded and mineralized in EC/ACF/Fe3+/PMS process resulting in the in-situ regeneration of ACF. Besides, the electrical energy per order values were investigated, which showed an apparent reduction of electrical energy consumption from 0.42831 to 0.09779 kWh m-3 when ACF-cathode replaced Pt-cathode. Further study revealed that higher conversion rate of Fe2+ from Fe3+ was observed with ACF-cathode. It deserved to be mentioned that the removal efficiency of AO7 was satisfactory and stable even after reusing ACF cathode for 10 times. Furthermore, structure and elements of ACF surface were investigated, which indicated the structure of ACF was intact in EC/ACF/Fe3+/PMS due to inhibition of ACF corrosion by electron migration at cathode. In addition, the total iron content of the effluent in EC/ACF/Fe3+/PMS was lower than that of EC/Fe3+/PMS due to the deposition of iron on ACF-cathode surface. Therefore, advantages of EC/ACF/Fe3+/PMS for AO7 degradation were not only a much higher oxidation efficiency and in-situ regenerated cathodic adsorbent, but also a lower electrical energy consumption and lesser iron ions contents in the effluent.

Determining Factor/s of Window Glazing Regarding Reduction in Electrical Energy Consumption

Abstract Among all building envelops, windows are typically the weakest barrier to heat ingress. The building energy consumption of any conditioned building located in the tropical country is deeply governed by the amount of heat gain inside the building because heating ventilation and air-conditioning (HVAC) system is a major energy consumer. Hence, it can be easily inferred that the energy consumption of a building can be reduced through judicial selection of window glasses. This paper illustrated the importance of thermal transmittance (U-value) and solar heat gain coefficient (SHGC) value of window glazing in detail and also demonstrated the energy savings potential of various types of commercially available windowpanes. The electric energy savings potential of various types of windowpanes such as tinted, reflective, single glazing, and double glazing glasses have been analyzed through eQUEST energy simulation software for a building, situated in the tropical region of India. Building architectural data and all other information regarding HVAC, lighting, etc. have been collected during the energy audit and trained in the eQUEST simulation for further analysis. The calibration of simulation model has been done using actual monthly electricity consumption data of the case building. This study depicts the percentage decrease in electrical energy consumption due to retrofitting of various commercially available window glasses compared with base building. The study also compares the importance of main two determining factor(s) U and SHGC value behind the judicial selection of proper window glazing.

Integrated membrane distillation-reverse electrodialysis system for energy-efficient seawater desalination

Although desalination market is today dominated by Seawater Reverse Osmosis (SWRO), important technological issues remain unaddressed, specifically: relatively low water recovery factor (around 50%) and consequent huge amount of brine discharged, and energy consumption (3–5 kWh/m3) still far from the minimum thermodynamic value (∼1 kWh/m3). Herein, the energy performance of an innovative systems combining SWRO, Membrane Distillation (MD) and Reverse Electrodialysis (RED) for simultaneous production of water and energy is investigated. The valorization of hypersaline waste brine by Salinity Gradient Power production via RED and the achievement of high recovery factors (since MD is not limited by osmotic phenomena) represent a step forward to the practical implementation of Zero Liquid Discharge and low-energy desalination. The analysis is supported by lab-scale experimental tests carried out on MD and RED over a broad set of operational conditions. Among the different case studies investigated, exergetic efficiency reached 49% for the best scenario, i.e. MD feed temperature of 60 °C, MD brine concentration of 5 M NaCl, RED power density of 2.2 W/m2MP (MP: membrane pair). Compared to the benchmark flowsheet (only SWRO), up to 23% reduction in electrical energy consumption and 16.6% decrease in specific energy consumption were achieved when including a RED unit. The analysis also indicates that optimization of thermal energy input at the MD stage is critical, although it can potentially be fulfilled by low-grade waste heat or solar-thermal renewable sources. Overall, the proposed integrated system is coherent with the emergent paradigm of Circular Economy and the logic of Process Intensification.

تأثیر خانههای هوشمند در مدیریت و کاهش مصرف انرژی الکتریکی

تأثیر خانههای هوشمند در مدیریت و کاهش مصرف انرژی الکتریکی

Influence of Various Forms Voltage of the Pow-er Converter in the Complex of Fans of the Main Air Handling

Mining enterprises are examples of energy-intensive enterprises. At the same time, in the total volume of electric energy consumption, they consume about 80% such as: a crushing and sorting factory, a main drainage system, skip hoisting installations and main ventilation installations. In particular, ventilation plants consume approximately 30% of the total electricity consumption, this fact is due to the fact that according to the technology of underground mining, the iron ore mines are aired around the clock, and the electrical capacities of these plants reach 2 MW.Electromechanical complexes of fan installations, in turn, are equipped with synchronous drive electric motors. In order to regulate the performance of the main ventilation unit, inefficient measures are used: turning fan blades, and opening and turning working flaps. Meanwhile, with an increase in the depth of production of iron ore below 1500 m, the effectiveness of the existing ventilation process of underground workings is complicated, and these measures become even more ineffective.The process of the necessary improvement of ventilation systems in iron ore mines and the development of appropriate energy efficient systems to control the rotational speed of the synchronous drive motor of the main ventilation unit must be carried out in a plane of reach to reduce the electrical energy consumption of these units, in turn, will lead to the desired reduction of electrical energy consumption by iron ore mines at all. One of the real directions to achieve this goal is the creation of high-voltage converters, which will increase the energy efficiency of the electric drive of the main fan systems as a whole. In this study, based on the analysis, the possibility of using a power converter based on a multi-level cascade voltage inverter is considered. The proposed method of controlling and shaping the high-voltage supply voltage of the converter will increase the efficiency of the electromechanical system as a whole, as well as reduce the weight and volume of transistor modules and filter components, in the final form will achieve the desired level of performance of electromechanical complexes and all main fan systems as a whole.The prospect of introducing a controlled electric drive for main ventilation installations in underground mining enterprises is a priori economically viable measure that will significantly reduce power consumption by main ventilation systems, facilitate the start-up of synchronous motors and reduce starting currents. In addition, an adjustable electric drive increases the static efficiency and the range of technological use of the main ventilation systems, and, thereby, further reduces power consumption. Meanwhile, to achieve the desired level of electrical energy efficiency of electrical systems, as the entire complex of the main ventilation systems, it is necessary to develop sufficiently efficient circuits of voltage converters.Ref. 12, fig. 5, tabl. 2

Internet of Things Based on Situation-Awareness for Energy Efficiency

The reduction of electric energy consumption is considered as one of the main challenges in diverse sectors of the economy. To residential customers, the management of energy consumption can bring significant costs reduction and decreased environmental impact. This work presents a solution based on the use of situation-awareness applied in IOT that helps the users to reduce the consumption of electric energy through its own residence. The practical results obtained in the application of this proposal in a real-live scenario confirmed the option of collecting information directly of electrical appliances and inform the user of their energy expenditures in real-time, allowing the knowledge and the management of their expenses.

Rotor speed control strategy to avoid resonance frequencies of turbo-molecular pump

A novel design of composite turbo-molecular pump (CTMP) is proposed. The major configuration of CTMP is composed by a coarse pump, a turbo-molecular pump (TMP) and a magnetic gear unit (MGU) capable of speed amplification. The modal analysis and the study on rotor/bearing dynamics are undertaken at first to estimate the resonance frequencies of the TMP blade rotor itself solely and the interactive dynamics of blade rotor/radial active magnetic bearing (BR/RAMB) subsystem. Secondly, an economical and efficient method by adjusting the angular acceleration speed of BR, namely RDPS, is proposed to ensure the natural frequencies of BR/RAMB sub-system are not driven by the rotor speed all the time. Besides, a speed route of rotor during the take-off cycle of TMP is proposed to satisfy the requirements of system stiffness and prevention of system resonance being driven. Finally, a position conversion method is introduced to solve the problem of distinct locations of gap sensors and the actual gap between rotor and the auxiliary bearings such that the measurement feedback to the controller, RDPS, becomes applicable to formulate the correct actions for providing enough gap margin to prevent collision of rotor against bearings. To sum up, the CTMP possesses the merit of reduction of electrical energy consumption by 17%, compared with the conventional TMP unit. By intensive computer simulations, the RDPS indeed manifests its outstanding performance to efficiently skip or bypass the natural frequencies of the closed-loop system within a very short time period and guarantee the system stability.

Reducing cooling load of buildings in the tropical climate through window glazing: A model to model comparison

The comparison studies among various building simulation models are always the research interest for various researchers though most of them are based on a general overview. Here we compared two popular building simulation models TRNSYS & eQUEST for a multizone building to judge the relative accuracy of the models. The base case building having 1465.8m2 area is situated in a tropical climate zone of India. Both the models were validated with actual and simulated annual energy consumption data of the case building and a model to model comparison has also been performed. The RMSE values for both TRNSYS & eQUEST were found varying between 2.1–12.5% and the Relative Error was found varying −19.6% to 18.0% respectively. It was also found that TRNSYS predict more accurately the total energy consumption of building than eQUEST in this case study. However the main aim of this paper is to quantify the energy saving potential of five different type of single and double glazing glasses especially in case of tropical climate condition through two types of simulation models. Five different types of commercially available window glasses were designed using LBNL-Window7 simulation tool and validated with lab tested results. The percentage reduction of electrical energy consumption due to retrofitting of five types window glasses have also been presented separately for both the simulation models. Both the models revealed that SHGC is more dominating factor than U-value to reduce cooling load of building energy.

The End-use Electric Energy Consumption in Urban Areas: A GIS-based methodology. An application in the city of Naples.

This work is part of the scientific research sector concerning the Government of Urban and Territorial Transformations in order to promote efficiency and reduction of energy consumption in urban areas. The contribution proposes a further deepening of the research work already carried out under the project Pon Smart Energy Master by the research group of the Laboratory of Territory, Mobility and Environmental (TeMA Lab) of Department of Civil, Architectural and Environmental Engineering, University of Naples Federico II. The aim is to assist public authorities, that also deal with the Urban Energy Governance, in determining the quantitative distribution of domestic and non-domestic electric energy consumption. Toward this goal, we use the Big Data, the Open Data and the Geographic Information System (GIS) techniques. In particular, this work developed a innovative GIS-based methodology that allows the knowledge, classification and representation of real electric energy consumption at micro scale for the domestic and non-domestic. Also, we validate the GIS-based methodology by an application at the city of Naples. We used the electric energy consumption data of year 2011 were given by Municipality Authority and Italian Revenue Agency. This will allow the identification of the electric energy problems present in the area of analysis in order to plan any intervention strategies. This contribution is divided into three main parts. In the first part, an analysis of the scientific literature is proposed on the theme of the Government of urban and territorial transformations and opportunities arising by Big Data, Open Data and GIS in the reduction of electric energy consumption. The second part explains the theoretical and technical phases that led to the development of the GIS-based methodology. In the last part, the application of the GIS-based methodology at the City of Naples is described.

Experimental Study of Hydroxy Gas (HHO) Production with Variation in Current, Voltage and Electrolyte Concentration

In this paper, work has been carried out experimentally for the investigation of the effects of variation incurrent, voltage, temperature, chemical concentration and reaction time on the amount of hydroxy gas produced. Further effects on the overall electrolysis efficiency of advance alkaline water is also studied. The hydroxy gas (HHO) has been produced experimentally by the electrolysis of alkaline water with parallel plate electrode of 316L-grade stainless steel. The electrode has been selected on the basis of corrosion resistance and inertness with respect to electrolyte (KOH). The process used for the production of HHO is conventional as compared to the other production processes because of reduced energy consumption, less maintenance and low setup cost. From the experimental results, it has been observed that with increase in voltage, temperature and electrolyte concentration of alkaline solution, the production of hydroxy gas has increased about 30 to 40% with reduction in electrical energy consumption.

Consequences of a price incentive on free riding and electric energy consumption

This article shows that a simple monetary incentive can dramatically reduce electric energy consumption (EEC) in the residential sector and simultaneously achieve a more desirable allocation of EEC costs. The analyses are based on data from a policy experiment conducted in 2011 and 2012 by a private housing company in about 1,800 apartments. Roughly 800 of the tenants (treatment group) were subject to a change from having unlimited EEC included in their rent to having to pay the market price for their own EEC. This change was achieved by installing EEC meters in each apartment. Tenants in the other 1,000 apartments (control group) experienced no policy change and were subject to apartment-level billing and metering during the entire study period. Using a quasiexperimental research design and daily data on EEC from 2007 to 2015, we estimate that apartment-level billing and metering permanently reduce EEC by about 25%. Moreover, we show that households reduce EEC immediately after being informed that they will be billed for EEC, the reduction is larger when the production cost is higher, and the reduction in EEC comes almost exclusively from households with very high EEC before the policy change. Finally, we show that apartment-level billing and metering are cost-effective, with a cost per reduced kilowatt hour of US$0.01, and for each invested dollar, the social value of reductions in air pollution, including CO2 emissions, is $2.

Low dosage sulfite pretreatment at different refining temperatures in mill scale TMP production

This thesis focuses on the electric energy efficiency of single stage double disc refining for production of printing grade mechanical pulp from Norway spruce wood chips. The thesis is based on the hypothesis, that more energy efficiency refining can be attained by balanced increases of wood softening and refining intensity. Five mill scale trials were performed where wood softening and refining intensity was varied by applying or changing the following process parameters and variables:Chip pretreatment/impregnation with waterLow dosages of sodium sulfite (Na2SO3) added to impregnationTemperature and retention time in the atmospheric preheater binRefining temperature (housing pressure)Feeding segment design combined with increased production rateBy combining suitable increases in wood softening and refining intensity, it was possible to reduce the specific electric energy consumption in refining by 15% (~290 kWh per bone dry ton (bdt)) while preserving important pulp properties within ±5%, compared to the standard double disc refining process. This was done by combining chip impregnation, using an addition of 0.36% (on bone dry basis) sodium sulfite, with a new feeding segment design which enabled 25% higher production rate.When using the new feeding segment design at an increased production rate at unchanged wood softening, it led to reduced fiber length and increased sheet light scattering coefficient at certain tensile index, compared with the standard segment design at normal production rate. This is consistent with the effects normally seen when the refining intensity is increasing. The specific electric energy consumption was 8% lower at a tensile index of 43.5 Nm/g (on Rapid Kothen laboratory sheets) compared to refining at lower intensity using the standard segment design at normal production rate.Mechanical chip pretreatment with subsequent water impregnation showed a reduction in specific electric energy consumption of 6% (~120 kWh/bdt). When chip impregnation was applied in a later trial with a milder chip compression, it led to increased wood softening seen as better preserved fiber length and reduced light scattering coefficient. This resulted in a reduction in tensile index at certain specific electric energy consumption when applied with the standard refining condition but to an increase in tensile index when applied with refining at higher intensity using the feeding segment design at higher production rate.An addition of 1.2% sodium sulfite during impregnation led to a sulfonate content of pulps of ~0.28% (as Na2SO3 equivalents, including post sulfonation) and an average increase in tensile index of about 8.3 Nm/g, when compared to unsulfonated pulps at certain specific electric energy consumption. The increase in tensile index correlated with increased delamination and internal fibrillation of fibers (measured by Simon’s staining), which indicate that the increase in tensile index for sulfonated pulps was a result of improved fiber flexibility and collapsibility. The reduction in disc gap at certain specific electric energy consumption in refining due to an increased wood softening after sulfonation may explain the increase in delamination and internal fibrillation for sulfonated pulps. The smaller disc gap probably led to a more intense refining, i.e. loading at higher deformation rates due to a higher degree of deformation in bar crossings.Different temperatures (80 vs. 97°C) and retention times (6 vs. 9 min.) in the atmospheric preheater bin were studied. This showed that the lower temperature and shorter retention time was beneficial for the tensile strength and light scattering of pulp when applying low dosage sodium sulfite pretreatment. This was most likely a result of too high degree of wood softening prior to defibration in the breaker bar zone when combining low dosage sodium sulfite pretreatment with the higher preheating bin temperature at longer retention time.Different refining temperatures (4.6 and 6.4 bar(g) refiner housing pressure) were evaluated both without and with low additions (0.6% and 1.2%) of sodium sulfite. Raising the refining temperature increased tensile index by 3.2 Nm/g and the addition of 1.2% sodium sulfite by 8.6 Nm/g. The combined increase (~12 Nm/g) was similar to the effect of increasing the specific electric energy consumption by 380 kWh/bdt, when comparing pulps at equal tensile index. However, the pulps produced with increased refining temperature and sodium sulfite addition had lower light scattering coefficient at certain tensile index. The combination of increased refining temperature and addition of 0.6% sodium sulfite was interesting and resulted in pulp with higher tensile index, light scattering coefficient and brightness together with lower shives content at certain specific electric energy consumption, compared with pulp produced at the lower refining temperature without addition of sodium sulfite.Finally, an implementation of the technology presented here is discussed in relation to the Braviken mill (Holmen Paper AB, Norrkoping, Sweden) concerning reduction in electric energy consumption and steam recovery. The technology has potential to reduce the electrical energy use by ~100 GWh/year at the Braviken paper mill, where this study was performed.

An Experimental Study of the Impact of Dynamic Electricity Pricing on Consumer Behavior: An Analysis for a Remote Island in Japan

The aim of this research was to investigate how consumer behavior changes after application of dynamic electricity pricing and the persistence of those changes. Based on the investigation results, the authors also discuss the policy implications of demand management to shift consumption to days that have more solar radiation, while at the same time reducing overall consumption. The dynamic pricing experiment was implemented on Nushima Island, located in the center of Japan, with the participation of 50 households. The methodologies used in this study are panel analysis with random effects, and the difference in differences method. Several linear regression analyses are performed to predict hourly electricity usage from a number of explanatory variables, such as life-style factors, the frequency of access to the visualization website, control for weather factors (wind speed and temperatures), and other attributes of the households to predict the log of hourly electric energy consumption. The results show that dynamic pricing brought about 13.8% reduction of electric energy consumption in comparison with the pre-experiment period. Also, by applying a new experimental design approach, this study finds data supportive of habit formation by participants. Based on the findings, this research tries to develop a policy for sustainable energy conservation in remote islands.

Análise numérica da influência de parâmetros operacionais e construtivos no funcionamento de trocadores de calor solo-ar

<div><p class="SPabstract">A busca pelo conforto térmico em ambientes construídos eleva o consumo de energia elétrica, devido à necessidade de climatização para se atingir uma temperatura agradável: resfriamento no verão e aquecimento no inverno. A fim de reduzir o consumo de energia elétrica nos condicionadores de ar, surge o trocador de calor solo-ar (TCSA), que utiliza a radiação solar que incide sobre a superfície do solo como uma fonte de energia limpa e renovável. Assim, o ar que escoa no TCSA é direcionado para o interior de edificações, proporcionando uma melhoria significativa na sua condição térmica. Isso é possível devido à inércia térmica do solo, que possui temperatura mais amena se comparada à temperatura do ar ambiente. Dessa forma, o objetivo deste trabalho é avaliar numericamente a influência da velocidade do ar em escoamento no duto e do espaçamento entre dois dutos em paralelo no desempenho térmico do TCSA. Para isso um modelo computacional, verificado e validado, desenvolvido no software FLUENT, que é baseado no Método dos Volumes Finitos (MVF), foi usado. Os resultados mostram que durante os períodos mais quentes a menor velocidade de escoamento do ar analisada conduz a um melhor desempenho térmico do TCSA. Também foi observado que a partir de 1 m de afastamento entre os dutos, a troca térmica entre cada duto e solo não é afetada de forma significativa.</p></div>

Estudo numérico da influência de condições de contorno na modelagem computacional de trocador de calor solo-ar

<div><p class="SPabstract">O trocador de calor solo-ar (TCSA) é um dispositivo utilizado para a melhoria da condição térmica de ambientes construídos, contribuindo na diminuição no consumo de energia elétrica dos equipamentos tradicionais de condicionamento de ar. Assim, os objetivos deste trabalho são de avaliar a influência da condição de contorno térmica de fluxo prescrito nulo no potencial térmico (PT) do TCSA, que é imposta nas superfícies laterais do domínio computacional, e de estudar a efeito do tipo de condição de contorno térmica imposta na superfície inferior do domínio computacional no tempo de processamento da simulação numérica de um TCSA. Para isso, um modelo computacional, validado e verificado, desenvolvido no software FLUENT, que é baseado no Método dos Volumes Finitos (MVF), foi empregado. Os resultados mostraram que o PT das instalações de TCSA analisadas é afetado para um espaçamento horizontal, entre o duto e a parede do domínio computacional, inferior a 2,00 m. Além disso, foi observado que a utilização da condição de contorno de temperatura prescrita imposta na superfície inferior do domínio computacional contribuiu para a redução do tempo de processamento da simulação numérica em 18%, quando comparada com a utilização da condição de contorno térmica de fluxo prescrito nulo.</p></div>

Degradation of Reactive Yellow 145 dye by persulfate using microwave and conventional heating

Degradation of C. I. Reactive Yellow (RY 145), a bi-functional dye containing azo chromophore has been attempted in the presence of potassium persulfate (KPS) as an initiator in the presence of microwave irradiation. The conditions of degradation were optimized and its kinetics was studied. Complete dye degradation was observed in 3600 and 280 s, respectively, using conventional and microwave heating at the original pH (5.8) of the dye solution with COD removal of 60 and 66.5%. Under optimized conditions, efficiency of H2O2 was also compared for degrading the dye. Pseudo-first-order kinetics with higher kinetic rate constant (0.0165 × 102s−1) and maximum energy efficiency (67.6%) was achieved through microwave assisted KPS system. Additional benefit of microwave approach was accrued by the extensive reduction in electrical energy consumption by 10638.32kWh/m3. The effect of addition of SO42− and CO32− anions to the dye solution has indicated that the former enhances the degradation, whereas the latter reduces it. The temperature study using Arrhenius equation indicated decrease in the activation energy for the microwave system along with 2.6 times higher frequency factor than that for conventional heating. Thus, the microwave radiation assisted KPS system has been found to be the most cost effective and environmentally benign for the dye degradation process.