Reduction Of Electric Energy Consumption Research Articles

Performance evaluation of the displacement ventilation combined with evaporative cooled ceiling for a typical office in Beirut

Displacement ventilation (DV) system combined with a novel evaporative cooled ceiling (ECC), Maisotsenko cycle (M-cycle), is a passive technique proposed to enhance the load removal in spaces beyond the conventional DV limit of 40W/m2. In this study, predictive mathematical models of the conditioned space and the evaporative cooled ceiling were developed to study the performance of the integrated system. The integrated DV/ECC mathematical model was validated experimentally showing good prediction of ceiling temperature and room conditions at different space loads.A parametric study was done in order to study the limitations of the system, where it showed better efficiency at higher supply flow rates and lower supply air relative humidity. The validated DV/ECC system model was applied for a typical office in the city of Beirut, where a control strategy of increasing the supply flow rate was implemented to the DV system, while maintaining a stratification height of 1.5m. The integrated system is operated only when the DV system cannot attain comfort in the space anymore. The load removal by the DV/ECC reached 50W/m2, exceeding by 20% the maximum limit of 40W/m2 of the unaided DV system. Moreover, the proposed DV/ECC system resulted in 36.2% reduction in electric energy consumption in the summer months when compared with a conventional DV and chilled ceiling system.

EDITORIAL

The need for diversification of the global energy grid is present in the speeches of most governments, the motivation of scientists and the perception of a growing segment of the population. Even so, the dependence on non-renewable fuels, such as fossil fuels, has been increasing progressively due to the rapid global growth, rising consumption and increasing purchasing power of the population. Besides searching global solutions to resolve the energy quest, efforts must be directed to short-term actions, taking advantage of the available scientific and technological knowledge to improve the performance of existing systems and in use today. Improving the efficiency of cooling systems, which are responsible for much of the world electricity consumption through intelligent control of compressors can reduce up to 50% electricity consumption, and thus provide economic and strategic advantages to countries that encourage this type of initiative. Likewise, the reduction of electricity for domestic heating or showering can be obtained by waste heat recovery, solar heating or the use of heat pumps with immersed condensers, among others, contributing to the reduction of electric energy consumption. A challenge to be overcome is the popularization of such technologies in the form of final product at affordable costs. Also, for popular use, it is the important the interest of nation leaders in order to drive the use of those technologies through tax incentives and public policies. Other advances could be achieved by the use and improvement of biotechnological processes, coupling the treatment of emissions and effluents to the production of biofuels, as well as high aggregated value products. Through exergy analysis, thermoeconomics, mathematical modeling, simulation and optimization, thermal engineering is able to contribute to the efficient coupling of such different biotechnological processes and contribute to decreasing dependence on fossil fuels.

Numerical investigation about the improvement of the thermal potential of an Earth-Air Heat Exchanger (EAHE) employing the Constructal Design method

The Earth-Air Heat Exchanger (EAHE) is a device used to improve the thermal condition of built environments, allowing the reduction of electrical energy consumption of traditional air conditioner systems. Fundamentally, its operational principle is based on fluid mechanics and heat transfer, areas in which Constructal Design has been widely used to seek for the optimal geometries, i.e., which leads to the best performances. In spite of this fact, the employment of Constructal Design for improvement of the EAHE thermal potential has not been performed into literature. Therefore, the main purpose of this work is to perform a numerical investigation on different geometrical configurations of an EAHE using the Constructal Design to obtain the highest thermal potential. Results indicated that, for the same area occupied by the ducts and fixed mass flow rate of air, the increase of the number of ducts (complexity of geometry) improved the EAHE thermal performance up to approximately 73% for cooling and 115% for heating.

Energy Savings through Integration of the Illumination Natural and Artificial, Using a System of Automatic Dimming: Case Study

The reduction of electrical energy consumption in buildings is a subject of great interest in the international scientific community. In buildings with a lot of available natural light, designed with large glazed surfaces, the artificial lighting system is often oversized and cannot be divided into segments to meet lighting demands during daylight hours.This article presents an experimental study, conducted in a university lecture hall that has a glazed surface covering the whole wall at one end, which provides a level of internal illumination that is only sufficient for the area next to the window itself, even when the outside lighting conditions are very bright. It is therefore necessary to turn on the artificial lighting system.The mathematical approach used in this paper has been successfully applied by the authors in other fields of science [1-2].Using an automatic dimmer system, the calibration of which is based on experimental measurements, the lighting is arranged in such a way as to illuminate the most disadvantaged areas of the room, and then to extend itself gradually to the whole of the room, over the period of time that the lecture hall is in use.

Optimization of the magnetic losses of electrical steels through addition of Al and Si using a hot dipping process

A major concern of society nowadays is the issue of sustainable development, which includes energy conservation. In order to induce a reduction of electrical energy consumption, governments across the world have pressured the appliance makers to increase in energy efficiency of electric engines. One of the ways to improve the performance of electric engines is to use steels with lower magnetic losses. The typical electrical steels are steels with about 3.5wt.% Si. It is well known that an increase in Si content decreases magnetic losses. The purpose of this work was to evaluate the decrease of magnetic losses after increasing the Si and Al content in electrical steels by hot dipping, using an Al–Si alloy bath followed by a thermal treatment. A reduction of eddy current losses, for 60Hz and 400Hz, was observed in the steel after addition of Al and Si to about 4.5wt.% Al and 4.8wt.% Si.

Exergy and energy analysis of an AC steel electric arc furnace under actual conditions

The energy and exergy analyses of an existing steel Electric Arc Furnace (EAF) are performed to estimate the potential for increasing the furnace efficiency. To obtain realistic results, the effect of air infiltration into the furnace was taken into account. The results of the analyses revealed that the energy and exergy efficiencies of the furnace are low and should be increased. The main sources of energy waste are stack gases followed by heat transfer to the cooling water, while the main sources of exergy destruction are combustion and heat transfer. Hot stack gases contain 18.3% and 12.2% of the total input energy and exergy, respectively. Increasing the air infiltration reduces the energy and exergy efficiencies of the EAF. By using the energy of flue gas to preheat the sponge iron, the electrical energy consumption of the furnace can be reduced by 89 GJ, dictating a 21.4% reduction in electrical energy consumption and a 13.6% increase in steel production.

USING A HEAT PUMP AS AN ALTERNATIVE TO SUPPORT SOLAR COLLECTOR FOR WATER HEATING IN BRAZIL

With related greenhouse effect environmental issues linked to the constant problems of the fluctuations in oil prices, the use of solar energy is an important renewable energy source. Brazil is a country which is privileged considering the high rates of solar irradiation present throughout almost the entire national territory. Nevertheless, during certain times of the year, there is a solar energy deficit, which leads solar systems to require electrical resistance support at these times. The use of electrical resistance represents 23.5% of electric energy consumption and it presents a low residential energy efficiency. The purpose of this work is an alternative technical design for reduction of electric energy consumption through the use of a solar energy system together with a generating heat pump for water heaters for households, as well as the financial feasibility study on the use of this system. One such heat pump has been designed, constructed and tested experimentally. The average performance coefficient is equal to 2.10, a low value due to the use of a hermetic reciprocating compressor. Despite this low moderate price coefficient of acquisition and installation of a heat pump, one can allow a return on investment in from 2.1 to 3.3 years, whereas the equipment has a useful life of about 20 years, this period of return on investment is interesting.

The Application of Femtocells as a Technical Solution for a Telecomunication Provider

The technology of femtocell application will most likely enable reduction of costs for telecommunications provider. This paper presents the installation and use of femtocells, as well as the problems one may encounter during this process. It also offers a technical solution, with its basic characteristics and the possibility of realization at a particular location, illustrated by the example of a telecomunications provider. The possibilities of implementation of new equipment to existing mobile networks are also discussed, followed by the comparative analysis which aims at emphasizing the significant reduction of electrical energy consumption between GSM macro base stations and femtocell application.

Integration of hydrogen production and waste heat recovery in electrochemical wastewater treatment

Electrochemical wastewater treatment using thin-film diamond electrode has been applied in industrial wastewater treatment where highly toxic organic compounds are present. In these applications, reduction of electric energy consumption and recovery of waste heat energy are key factors that impact the competitiveness of electrochemical wastewater treatment. This paper presents design, fabrication and testing of the electrochemical reactor for wastewater treatment along with hydrogen production and waste heat recovery. Experiments were carried out to measure the decrease of COD concentration on anode, the simultaneous formation of hydrogen on cathode and the increase of electrolyte temperature. The impact of electric current density on electrolyte temperature was studied. Experimental study and energy efficiency analysis on hydrogen production and waste heat recovery have shown that the technology presented in this study is feasible, allowing us to achieve both economic and environmental benefits.

Control system for forced-air cooling of horticultural products

This work is a study of the implementation of a classical controller using a tuning method referred to as IMC (Internal Model Control) and aimed at the reduction of electrical energy consumption by the appropriate relation between energy consumption and the cooling time with forced air. The supervisory system installed was able to manipulate the variable of frequency of the signal power of the exhaust fan engine (forced air module), to accelerate or decelerate the loss of heat from the product to be cooled by airflow variation that passes through the mass of the produce. The results demonstrated a reduction in energy consumption from 64% and an increase of only 8% in the cooling time to the system using PI/IMC (Proportional - Integral with IMC) tuning method compared with the system in its operating nominal condition. This PI/IMC control may be implemented directly in a frequency converter, without the need to purchase a computer or PLC (programmable logic controller) to run the dedicated application, increasing its economical viability.

Energy saving potential of an indirect evaporative cooler as a pre-cooling unit for mechanical cooling systems in Iran

The performance of indirect evaporative cooling system (IEC) to pre-cool air for a conventional mechanical cooling system has been investigated for four cities of Iran. For this purpose, a combined experimental setup consisting of an IEC unit followed by a packaged unit air conditioner (PUA) was designed, constructed and tested. Two air simulators were designed and used to simulate indoor heating load and outdoor design conditions. Using of experimental data and an appropriate analytical method, the performance and energy reduction capability of combined system has been evaluated through the cooling season. The results indicate IEC can reduce cooling load up to 75% during cooling seasons. Also, 55% reduction in electrical energy consumption of PUA can be obtained.

Effect of Envelope on Residential Cooling Load Coupled with Use of Solar/Photovoltaic Panels

Three identically oriented homes were used for the study. Two of the homes were identically constructed using wood frame/stucco construction while the third used a wall of sandwiched Styrofoam in between concrete layers. It was found that the concrete house on the average consumed about 15% less energy for HVAC operation than the wood frame houses. Also the photovoltaic array placed on the roofs of two of the houses indicated a reduction in electrical energy consumption from the grid of about 20% of the HVAC electrical energy consumed. TRACE-700 simulation runs were made on both types of houses to determine the design cooling load for each of the houses and the total consumed electrical energy for each house over the whole year on a monthly basis. It was found that in the summer a 20% reduction of electrical energy for HVAC is predicted due to the use of the concrete house as compared to the wood frame homes. In addition a linear correlation was found to represent reasonably well the variation of the daily kilowatt hour versus the daily degree day value for a typical summer month in the Las Vegas, Nev. valley for all three houses. The slope of that line for the concrete home was about 24% less steep than the line for the wood frame construction confirmation in part theoretical calculations that this wall construction is more energy conserving than the base case.

Rapid prototyping: energy and environment in the spotlight

PurposeTo discuss integration of the rapid prototyping environmental aspects with the primary focus on electrical energy consumption.Design/methodology/approachVarious manufacturing parameters have been tested on three rapid prototyping systems: Thermojet (3DS), FDM 3000 (Stratasys) and EOSINT M250 Xtended (EOS). The objective is to select sets of parameters for reduction of electrical energy consumption. For this, a part is manufactured in several orientations and positions in the chamber of these RP systems. For each test, the electrical power is noted. Finally, certain rules are proposed to minimize this electrical energy consumption during a job.FindingsIt is important to minimize the manufacturing time but there is no general rule for optimization of electrical energy consumption. Each RP system must be tested with energy consumption considerations under the spotlight.Research limitations/implicationsThe work is only based on rapid prototyping processes. The objective is to take into consideration the complete life‐cycle of a rapid prototyped part: manufacturing of raw material as far as reprocessing of waste.Practical implicationsReduction of electrical energy consumption to complete a job.Originality/valueCurrently, environmental aspects are not well studied in rapid prototyping.

閉鎖型苗生産システムにおけるサツマイモ増殖体生産数と電気エネルギ消費量に及ぼすトレイのセル容積の影響

Reduction in electric energy consumption is important for minimizing resources used for sweetpotato propagule production in a closed transplant production system. The objective of this study was to test whether or not an increase in cell volume of a tray can reduce electric energy consumption for sweetpotato (Ipomoea batatas (L.) Lam.) vegetative propagation in a closed transplant production system. Single node cuttings each with one unfolded leaf were used as propagules and grown for 18 days at cell volumes of 20, 40, 60 or 80 mL with the same planting density of 643 m-2 in all treatments (number of cells per tray was 98) . The number of harvestable propagules per stock plant did not differ significantly among cell volumes 6 and 10 days after planting, but increased with increasing cell volume 14 and 18 days after planting. The electric energy consumption per propagule for cell volumes of 20, 40, 60 and 80 mL was 0.54, 0.42, 0.34 and 0.26 MJ, respectively, corresponding to electricity costs of 2.2-2.4, 1.7-1.8, 1.4-1.5 and 1.0-1.1 Japanese Yen, respectively, 18 days after planting. Thus, increasing the cell volume of a tray is a useful method for reducing electric energy consumption per propagule for sweetpotato vegetative propagation in a closed transplant production system.

Monitoring and control systems to minimise the influence of mining plants on environment

Mining carries a great number of noxiousnesses for the environment. In the deep coal mines, there are many hazards in underground workings and on the surface around mining plants. The mine ventilation systems emit to the atmosphere large quantities of air including mine air constituents from which methane, CO or CO2 have an effect on air pollution around the surface ventilation stations. The noxiousnesses of ventilation stations are equally vital owing to considerable consumption of electric energy and noise making. One of the possible minimisation forms is complex monitoring of ventilation stations within the range of upcast air parameters, reduction in electric energy consumption by the control systems of the fan motors. The scattered monitoring system of ground deformations and damages to industrial objects, apartment buildings and housing estates can be used for observation of mining activity on the surface. Coal preparation plants are the essential sources of environment pollution. It is considered to monitor and control coal quality parameters underground.

Study on Reduction of Energy Consumption in Pulsed Corona Discharge Process for NOx Removal

We investigated the reduction of electrical energy consumption in thepulsed corona discharge process for the removal of nitrogenoxides. Hydrocarbon chemical additives used in the laboratory-scaleexperiment are responsible for the enhancement of the NO conversionthrough the chain reactions of free radicals, such as, R, RCO, RO,and others. Electrical energy consumption per converted NO moleculehas a minimum value of 17 eV when pentanol is injected. When ethyleneand propylene are injected, 30 and 22 eV of electrical energy consumptionare required for the conversion of a NO molecule, respectively. The ratioof the pulse-forming capacitance (Ce) to the reactor capacitance (CR)plays an important role in the energy transfer efficiency to thereactor. The maximum energy transfer efficiency of approximately 72%could be obtained by the pulse-forming capacitance, which is 3.4 timeslarger than the reactor capacitance; the maximum NO conversionefficiency was also observed with the same condition.

閉鎖型苗生産システムのエネルギおよび物質収支 （第１報） エネルギ収支

The energy balance of a closed-type transplant production system with artificial lighting was investigated. Sweetpotato (Ipomoea batatas (L.) Lam. cv. Beniazuma) plants were grown for 15 days at photosynthetic photon flux on the tray surface of 100, 200 and 300 μmol m-2 s-1 on days 0-2, 3-11 and 12-14, respectively, air temperature of 30°C, CO2 concentration of 1000 μmol mol-1, relative humidity of 80/100% (photoperiod/dark period) inside the system and photoper-iod of 16 h d-1. The amount of electric energy consumption during the 15 days for lighting, cooling and the other equipment per planting area were 375.5, 80.8 and 41. 1 MJ m-2, respectively. Electric energy consumption per plant was 1.8 MJ (0.5 kWh), and its cost was approximately 4-5 Japanese Yen. Coefficient of performance for the cooling system was approximately 4.7, which was 2 times higher than the value described in the catalog, partly because the air temperature inside the system was higher than that of outside the system. The ratio of electric energy consumption to chemical energy assimilated by plants (energy use efficiency of the system) was 0.006. These results show that the closed-type transplant production system is feasible for the commercialization. Methods for further reduction of electric energy consumption (increasing the energy use efficiency of the system) and electricity cost are discussed.

97/02896 Electrical energy and cost savings potential at DOD facilities

The US Department of Defense (DOD) has been mandated to reduce energy consumption and costs by 20% from 1985 to 2000 and by 30% from 1985 to 2005. Reduction of electrical energy consumption at DOD facilities requires a better understanding of energy consumption patterns and energy and financial savings potential. This paper utilizes two independent studies--EDA (End-Use Disaggregation Algorithm) and MEIP (Model Energy Installation Program)--and whole-installation electricity use data obtained from a state utility to estimate electrical energy conservation potential (ECP) and cost savings potential (CSP) at the Fort Hood, Texas, military installation and at DOD nationwide. At Fort Hood, the authors estimated an annual electricity savings of 62.2 GWh/yr (18%), a peak demand savings of 10.1 MW (14%), and an annual energy cost savings of $6.5 million per year. These savings could be attained with an initial investment of $41.1 million, resulting in a simple payback of 6.3 years. Across the DOD, they estimated an annual electricity savings of 4,900 GWh/yr, a peak demand savings of 694 MW, and an annual energy cost savings of $316 million per year. The estimated cost savings is 16% of the total nationwide DOD 1993 annual energy costs. These savings could be attainedmore » with an initial investment of $1.23 billion, resulting in a simple payback of 3.9 years.« less

Energy management for rational electricity use-reducing cost and consumption at SECIL's Outao cement plant/Portugal

Compania Geral de Cal e Cimento SARL (SECIL) is in the process of implementing a comprehensive and modern energy management project for rational use of electricity. A step in energy management implementation is the reduction of electric energy consumption (kWh/t). The preparation and first results of this new effort is the major topic. Emphasis is placed on extensive electronic energy metering and process data recording. These data are processed and refined to energy information that, in effect, uncovers hidden savings potentials. Energy information and related saving measures are introduced into daily organizational operating procedures and are backed up by a permanent energy management team. More than a 6% per annum electric energy cost reduction has already been achieved. Additionally, a 3 to 6% reduction of specific electric energy is a projected savings objective. >

The Effect of Wood and Coal Stoves on Household Use of Electricity

Since the energy crises of the 1970s, price increases have induced many forms of electric energy saving by households. Among these is the use of wood and coal stoves, which are an important alternative space heating system in regions where these fuels are readily available. A stove may substitute to various degrees for the major heating system built into the dwelling, depending on the characteristics of the dwelling and household usage patterns. The study of detailed household data makes it both possible and desirable to give wood and coal stoves adequate consideration. The reduction in electric energy consumption of a household due to the use of a stove is estimated in this study to exceed the average kilowatt-hour (kWh) use of a wide range of electric appliances that are more usually treated in electricity demand studies.' The decision to install a stove and the decision determining the level of operation of a stove are related to, among other things, the price of electricity. When the price of electricity increases, other things being equal, stove ownership and use increase and electric heating consumption is suppressed. The aim of this paper is to quantify these effects, which are part of the long-term adjustment to an electric price increase. The results obtained here ultimately bear upon utility rate and system planning decisions, and also upon questions of energy policy, which require information concerning household fuel substitution and responsiveness to price.2 The body of the paper has three sections. The first explains the analysis of kWh demand, conditional upon equipment stocks. The second explains the stove ownership models. The third briefly explains the construction of a residential simulation model and reports the results of an experiment which quantifies the reduction in kWh consumption due to the use of stoves.