Concept Of Energy Conservation Research Articles

Low exergy systems for high-performance buildings and communities

There is an obvious and indisputable need for an increase in the efficiency of energy utilisation in buildings and in the energy supply system within communities. Heating, cooling and lighting appliances in buildings account for more than one third of the world's primary energy demand. In turn, building stock is a major contributor to energy-related environmental problems and CO 2 emissions. There are great potentials to be obtained through a more efficient supply of energy and rational use of energy in buildings. An optimisation of the exergy flows in buildings and related supply structures, similar to other thermodynamic systems such as power stations, can help in identifying the potential of increasing efficiency in energy utilisation. Through analyses, it can be shown that calculations based on the energy conservation and primary energy concept alone are inadequate for gaining a full understanding of all important aspects of energy utilisation processes. The high potential for a further increase in the efficiency of; for example, boilers, cannot be quantified exclusively by performing energy analyses—the energy efficiency is close to 100%; however, this potential can be demonstrated by using an exergy analysis, whereby the exergy efficiency of a common gas boiler is about 8%. It is necessary to work out new and more efficient ways to supply energy to satisfy the demand for energy services. This paper outlines the international co-operative work in the general framework of the International Energy Agency (IEA), the ECBCS Annex 49 “Low Exergy Systems for High Performance Buildings and Communities” [Annex 49, Energy Conservation in Buildings and Community Systems—Low Exergy Systems for High Performance Buildings and Communities, homepage: http://www.annex49.com, 2007].

Introducción para enseñar el concepto de conservación de la energía mecánica, mecanismo biela-manivela

This paper proposes a strategy to introduce the concept of mechanical energy conservation in physics teaching. We start from the historical-epistemological point of view of the concept around the so-called simple machines. With regard to the concrete activity, we work with the crank-crank mechanism, from which very interesting questions arise, and students can work carefully and conscientiously; in this way, construct new concepts or reconstruct old concepts.

Therapeutic Efficacy of a Therapeutic Cooking Group from the Patients’ Perspective

The purpose of this study was to evaluate the therapeutic efficacy of the cooking group from the burn survivors' perspective. By incorporating concepts of kitchen skills, energy conservation, and desensitization techniques, the cooking group can assist patients with the functional use of their hands, standing tolerance, return to former vocational activities, and socialization with other patients. A questionnaire was developed based on commonly expressed benefits of cooking group. Areas of interest included decreasing anxiety in the kitchen, distraction from their burns, socializing with other burn survivors, and the physical benefits of participating in the group. The results of this study indicate that participants regard the therapeutic cooking group as a valuable treatment modality that effectively combines functional activities with socialization to decrease burn related anxiety and increase motion in a supportive environment for patients with burns.

The effect of efficient lighting on the environment: pilot project in Palestine

In this paper, we present the results and experience gained through the Energy Conservation Pilot Project in the Town of Salfeet/Palestine. Also, we describe five case studies of energy-efficient programs in five countries—Mexico, China, Philippines, Poland and Vietnam. The project was funded by the UNDP/GEF and executed within the framework of the cooperation between An-Najah National University, the UNDP/GEF, and Salfeet Municipality. The project aims mainly to draw the public attention towards the importance of energy conservation in reducing pollution as well as running cost. In fact, a major component of the project was the replacement of the incandescent lamps for about 40% of the residents of Salfeet (626 families), the 40–100 W lamps were replaced by 18 W compact florescent lamps (CFL). Each benefited family was given three to five CFL free of charge depending on number of persons per family. It is found that the total energy saved because of lamp-replacement in Salfeet is about 5,000 kWh/month, and the total emission saved of CO2 is about 5,792 kg as coal is burnt to generate electricity. Furthermore, the project has improved public awareness about energy conservation concepts and their positive impact on local and global climate changes.

Preface

Professor Chang-Lin Tien's untimely death on October 29, 2002 sent a shock wave throughout the world. People from all over the world mourned the loss of a great educator, pioneer, mentor, people's diplomat, and friend. The heat transfer community felt even a stronger pain with the loss of a great leader and an inspirational mentor. Chang-Lin had an immense and long-lasting impact on the heat transfer community through his pioneering research and community service in heat transfer. This series, itself, was a product of Chang-Lin's leadership and dedicated service. It is thus fitting that we devote this volume in memory of him. We have decided to use this volume as a bridge between the past and the future, by summarizing Chang-Lin's contributions and reviewing current and future research directions in areas in which Professor Tien made a significant impact. What could be a better way of demonstrating Chang-Lin's long-lasting contributions! We have roughly divided his contributions into six topical areas: (I) radiation and combustion, (II) micro/nanoscale heat transfer, (III) phase change and heat pipes, (IV) porous media, (V) materials processing and laser materials interactions, and (VI) energy systems. His contributions in each area are briefly summarized, followed by several review papers that cover recent developments and future directions. Contributors are mainly from Chang-Lin's former students, postdocs, close colleagues, and collaborators. The volume starts with a transcript of Professor Tien's invited talk at the 1999 national heat transfer conference, the last time he attended a heat transfer conference, followed by two memorial articles, one by Dr. Henry Yang, Chancellor of University of California at Santa Barbara, and one by Dr. Dan Mote, President of the University of Maryland. Both of them had close association with Chang-Lin. Their articles provide a peek at the broader contributions of Professor Tien and his personalities. Thermal radiation is a central topic spanning several decades of Chang-Lin's research career. His contributions in the area of radiation and combustion are reviewed by Buckius, followed by three reviews of recent developments in this field. Modest discusses the modern spectral method for the prediction of radiative heat transfer rates within combustion media. Chan summarizes the role of radiative transfer in flame structure, pollution emission, and flame extinction. Brewster and Jackson summarize advances in the modeling and numerical simulation of solid propellant combustion. The last passion of Chang-Lin's research was in micro- and nanoscale heat transfer, a field that he pioneered and nurtured. His contributions in this area are reviewed by Chen, Majumdar, and Lukes. This section is followed by seven review articles. Li and Majumdar review thermal conductivity of superlattices, nanowires, and nanotubes. McConnel and Goodson summarize thermal conductivity and heat conduction in silicon nanostructures. Narayanaswamy and Chen discuss the direct calculation of thermal emission from nanostructures. Lukes, Abramson, and Weng present recent advances in molecular dynamics simulations of nanoscale thermophysical phenomena. Guo reports on some microscale convection phenomena. Phelan, Bhattacharya, and Prasher review recent experimental data and potential explanations on the heat transfer characteristics of nanofluids - fluids seeded with nanoparticles. Tsourkas and Rubinsky develop an evolutionary computational technology, in conjunction with the concept of energy conservation, to study Darwinian evolution. Chang-Lin has made lasting contributions in phase-change heat transfer, including in the areas of rewetting and flooding; heat pipes and thermosyphons; and condensation, boiling, and other two-phase flows. His contributions to these topics are reviewed by Gerner, Peterson, and Carey. Following the review, Suh and Gerner report recent progress in the area of microscale heat pipes. Heat transfer and fluid flow in porous media is another area that Chang-Lin made groundbreaking contributions, which are reviewed by Khanafer and Vafai. They also contributed a review summarizing the state-of-the-art in this area. Norris and Shrivanasan summarized the fascinating properties and applications of a special kind of porous media - the ultralight aerogel. Chang-Lin's deep insights are again seen in his approach to laser-materials interactions. Longtin, Phinney, and Qiu reviewed Professor Tien's contributions to the understanding of laser-materials interactions including nonequilibrium between electrons and phonons, and nonlinear laser materials interactions. Longtin follows up with a review of nonequilibrium phenomena in laser-materials interactions. Grigoropoulos updates recent progress in pulsed-laser material processing and nanomachining processes. Chang-Lin's fundamental research in heat transfer has tremendous implications for various energy systems. His particular contributions to the cryogenic systems and solar systems are reviewed by Phelan. Chow, Kapat, and Kota discuss mesoscopic energy systems and changes in the design paradigm brought about by miniaturization. Bejan and Lorente review the main features of current research in engineering thermodynamics. Pierre and Cravalho present models on the thermodynamic and kinetic behavior of fuel cells and apply them to the design of novel electrodes. The list of Chang-Lin Tien's publications concludes the memorial volume.

Anaerobic growth of Methanosarcina acetivorans C2A on carbon monoxide: An unusual way of life for a methanogenic archaeon

All methanogenic Archaea examined to date rely on methanogenesis as their sole means of energy conservation. Among these are ones that use carbon monoxide as a growth substrate, producing methane via a pathway that involves hydrogen as an intermediate. To further examine the role of hydrogen in this process, we tested the ability of Methanosarcina acetivorans C2A, a metabolically versatile methanogen devoid of significant hydrogen metabolism, to use CO as a growth substrate. M. acetivorans grew on CO to high cell densities (approximately 1 x 10(8) per ml) with a doubling time of approximately 24 h. Surprisingly, acetate and formate, rather than methane, were the major metabolic end products as shown by 13C NMR studies and enzymatic analysis of culture supernatants. Methane formation surpassed acetate/formate formation only when the cultures entered stationary growth phase, strongly suggesting that M. acetivorans conserves energy by means of this acetogenic and formigenic process. Resting cell experiments showed that methane production decreased linearly with increasing CO partial pressures, consistent with inhibition of methanogenesis by CO. Transposon-induced M. acetivorans mutants with lesions in the operon encoding phosphotransacetylase and acetate kinase failed to use either acetate or CO as growth substrates, indicating that these enzymes are required for both aceticlastic methanogenesis and carboxidotrophic acetogenesis. These findings greatly extend our concept of energy conservation and metabolic versatility in the methanogenic Archaea.

Optical Theorem for Electromagnetic Scattering by a Three-Dimensional Scatterer in the Presence of a Lossless Half Space

The classical optical theorem for a scatterer in free space is useful in computing the total extinction cross section when the scattering amplitude in the forward scattering direction is known. In this letter, the classical optical theorem is extended to the case of a scatterer in the presence of a lossless half space. The extended optical theorem is derived based on energy conservation concepts, and the method of stationary phase is employed to obtain the final form. It is found that the total extinction cross section is related to the scattering amplitudes in the specular directions for reflected and transmitted fields. Numerical results are presented to illustrate use of the theorem for evaluating the energy conservation properties of an electromagnetic simulation.

Concepts for modeling impacts without friction

There are three basic equations in mechanics for treating collisions: the law of impact, kinematic compatibility, and energetic consistency. In this paper, the conditions are examined under which a natural extension of the dynamics at an impact is possible without taking additional impact laws, and which additional assumptions have to be made to solve the impact for different classes of systems. It will be shown that Newton’s law of impact for two colliding point masses can be derived from the concept of energy conservation and the principle of maximum dissipation, and has therefore not to be regarded as an independent equation. Moreover, it can be assigned to single-contact impacts in multibody systems as soon as the classical definition of perfect constraints is being extended to impulsive dynamics and unilateral contacts. It will further be shown that the principle of maximum dissipation leads to a unique post-impact velocity in the case of multi-contact collisions. In all other cases, however, the velocities remain undetermined, and laws of impact have to be postulated as additional and independent equations, whereas the classic definition of the restitution coefficient as a dissipation parameter can still be kept.

The stochastic Gross–Pitaevskii equation: II

We provide a derivation of a more accurate version of the stochastic Gross–Pitaevskiiequation, as introduced by Gardiner et al (2002 J. Phys. B: At. Mol. Opt. Phys. 35 1555). Thisderivation does not rely on the concept of local energy and momentum conservation and isbased on a quasiclassical Wigner function representation of a ‘high temperature’master equation for a Bose gas, which includes only modes below an energy cut-offER that are sufficiently highly occupied (the condensate band). The modes above this cut-off(the non-condensate band) are treated as being essentially thermalized. The interactionbetween these two bands, known as growth and scattering processes, provides noise anddamping terms in the equation of motion for the condensate band, which we call thestochastic Gross–Pitaevskii equation. This approach is distinguished by the control ofthe approximations made in its derivation and by the feasibility of its numericalimplementation.

Tracking analysis of the NLMS algorithm in the presence of both random and cyclic nonstationarities

Tracking analysis of the normalized least mean square (NLMS) algorithm is carried out in the presence of two sources of nonstationarities: 1) carrier frequency offset between transmitter and receiver; 2) random variations in the environment. A novel approach to this analysis is carried out using the concept of energy conservation. Close agreement between analytical analysis and simulation results is obtained. The results show that, unlike in the stationary case, the steady-state excess MSE is not a monotonically increasing function of the step size. Moreover, the ability of the adaptive algorithm to track the variations in the environment is shown to degrade with increasing frequency offset.

A Model of Venous Return While Utilizing Vacuum Assist During Cardiopulmonary Bypass

In order for vacuum-assisted venous return (VAVR) to be used safely and efficiently during cardiopulmonary bypass (CPB), a full understanding of venous return is necessary. The focus of this work was to use the concepts of energy conservation and viscous energy dissipation in the development of a theoretical model of venous return utilizing vacuum assist. The effectiveness and accuracy of this model has been verified through in vitro laboratory investigations and statistical analysis. Although VAVR can provide higher flows through smaller venous cannula, vacuum assist may lead to increased levels of wall shear stress as shown in this work. The clinical implications of VAVR have yet to be investigated, but may lead to an exacerbation of the detrimental effects of CPB during cardiac surgery.

Review of Open Channel Hydraulics , by Terry W. Sturm

Despite the proliferation during recent years of textbooks on the topic of open channel hydraulics, many academics and professionals are still waiting for a book of the caliber of Henderson’s and Chow’s texts to use in the classroom or to modernize their reference library. In Sturm’s Open Channel Hydraulics, aimed at senior undergraduates and first-year graduate students, the author attempts to fill this niche by initially approaching open channel hydraulics from a fundamental perspective of fluid mechanics, and leading through to practical applications and computational solutions. He has provided chapters on introductory steady flow topics, unsteady flow theory, and numerical solutions. He also discusses flood routing and unsteady flow approximations, and the important practical consideration of flow in alluvial channels. Sturm opens with a very nice introduction that includes a brief history of our knowledge of open channel hydraulics. The introduction is followed by an overview of the topic, given in terms of definitions of the various flow approximations commonly applied in practice, placing them in their proper theoretical context. The overview is followed by a derivation of the fundamental equations of mass, momentum, and energy conservation, done reasonably, particularly with the explanation of momentum conservation, and derivation of Bernoulli’s equation and momentum’s ultimate link to the concept of energy conservation. He is perhaps a bit too succinct with the derivation of the equation of conservation of energy itself, though this is understandable given the complexity of this undertaking from a pedagogical perspective. The author takes this opportunity to impress upon the student some important fundamental concepts, including the significance of the kinetic energy and momentum correction coefficients for nonuniform velocity distributions, a highly favorable approach for an educational text, and the concepts of surface resistance versus form drag. He then provides the student with an excellent explanation and justification of the need for, and details of the application of, dimensional analysis techniques. Rather useful practice problems, particularly for the dimensional analysis technique, are provided. Following in the form of Henderson, the next two chapters introduce the reader to energy and momentum concepts. The author brings a fresh approach to these topics and presents them in an interesting manner, with immediate reference to specific examples. In addition, the complexities raised by overbank flows are introduced ~specifically in terms of multiple minimum specific energies!. The inclusion of weirs, stilling basins, and supercritical expansions and contractions in these chapters put the theory in context, and also challenges the student with complex, as well as simpler, applications of the fundamental theory. The next two chapters cover uniform and gradually varied flow, again working from a fundamental level including dimensional analysis and fluid mechanics in the case of uniform flow,

TEACHING NOTES

The text of the article is available in the PDF.

Energy Efficiency Manual

Review: Energy Efficiency Manual By Donald R. Wulfinghoff Reviewed by Irwin Weintraub Brooklyn College Library, USA Wulfinghoff, Donald R. Energy Efficiency Manual. Wheaton, MD: Energy Institute Press, 1999. 1536 pp. ISBN 0-9657926-7-6. US$199.95 In today’s fast paced world where we spend a good part of each day in buildings at work and play, it is important to plan building energy systems that meet our needs for heating, cooling, air flow, and lighting successfully and efficiently. The Energy Efficiency Manual offers up-to-date and practical solutions for energy planning applicable to building environments in one comprehensive volume. Wulfinghoff presents the information you need to plan, design, and construct efficient energy systems in homes, businesses, institutions, factories, farms, and other buildings. This easy-to-read, heavily illustrated work will be used over and over again by architects, engineers, contractors, code officers, environmental advocates, students, and homeowners who are dedicated to producing energy activities that save resources, are cost effective, reliable, and function at maximum efficiency. Nontechnical language is used throughout and terms are explained and illustrated when appropriate. Thus, the volume will appeal to a wide audience of users who are involved in building maintenance and those who just want to read it and learn more about energy conservation concepts. The Manual is arranged in two parts. Part I, Energy Measures, presents 400 specific energy efficiency improvements and cost saving activities. The measures are arranged under 10 sections covering boiler plants, chiller plants, service water systems, air handling systems, air conditioning systems, building air leakage, building insulation, control and use of sunlight, artificial lighting, and independent components such as motors and pumps. Since many energy projects serve several parts of a building or facility, readers will find practical solutions to all their energy efficiency questions in this section. I chose some entries at random and was impressed with the wide coverage of nearly all aspects of energy design. There are measures for efficient operation of low load heating systems; managing refrigerants in cooling equipment; reducing energy consumption of water pumps; regulating outside air intake and building pressurization; improving the efficiency of heating with radiators and convectors; reducing air leakage through windows and window frames; insulating roofs to prevent heat loss during cold weather; using daylight to save energy in open buildings; spatial layout of fixtures and wiring to provide efficient lighting; and eliminating excess output in constant flow fans. Each measure gives an explanation of

Genetics of energetics: transcriptional responses in cardiac metabolism.

Recent evidence suggests that energy substrate metabolism forms the link between gene expression and contractile function of the heart. This hypothesis draws on three seemingly unconnected observations, made in 1941 by three different investigators. The first gave rise to the concept of the dynamic nature of body constituents, the second to the concept of one gene for one enzyme, and the third to the concept of energy conservation in the phosphate bond of adenosine triphosphate (ATP), the "approximate P." The heart employs different mechanisms to adapt to acute and to sustained changes in energy demand. While acute changes in energy demand are met by the coordinated activation or inactivation of enzymes, chronic changes in energy demand are met by adjustments in the rate of "metabolic" gene expression which are often isoform specific. Transcriptional analysis by quantitative polymerase chain reaction (PCR) defines changes in energy substrate metabolism in response to an altered physiologic environment at the transcriptional level. The paradigm of cardiac hypertrophy and atrophy has revealed a surprisingly uniform and rapid response in cardiac gene expression including the reactivation of fetal metabolic genes. The physiologic consequences are revealed in a shift in substrate utilization from fatty acids to glucose. Clinical consequences include a change in metabolic gene expression of the failing human heart, including the downregulation of glucose transporters and the enzymes of fatty acid metabolism. Although it is possible to study regulation of metabolism at the level of gene expression, the complexities of the interactions between metabolic intermediates and transcription factors may be difficult to elucidate by simple reductionist approaches. A model of feedback/feedforward between genes and proteins is needed to explain the principle of reestablishing homeostatic control of metabolism as cellular and external environments change.

Pin-hole water flow from cylindrical bottles

We performed an experiment on elementary hydrodynamics. The basic system is a cylindrical bottle from which water flows through a pin-hole located at the bottom of its lateral surface. We measured the speed of the water leaving the pin-hole, as a function of both the time and the current level of water still inside the bottle. The experimental results are compared with the theory. The theoretical treatment is a very simple one based on mass and energy conservation, corresponding to a widespread exercise usually adopted in university basic disciplines of physics. We extended the previous experiment to another similar system using two identical bottles with equivalent pin-holes. The water flowing from the first bottle feeds the second one located below it. The same concepts of mass and energy conservation now lead to a non-trivial differential equation for the lowest bottle dynamics. We solved this equation both numerically and analytically, comparing the results with the experimental data.

Hemodynamics of Stenotic Infrainguinal Vein Grafts: Theoretic Considerations

We developed a theoretic model of arterial stenosis to study the relationship between perfusion pressure and regional hemodynamics in stenotic infrainguinal vein grafts in an attempt to identify grafts at high risk for failure. Our model was based on the concept of energy and mass conservation of the flowing blood. We used the modified Bernoulli equation (delta P = 4 delta V2) to calculate the maximum possible intrastenotic peak systolic velocity (PSV) from the systolic blood pressure. PSV was measured by means of duplex ultrasonography in infrainguinal bypasses up to the time of revision (nine grafts) or spontaneous thrombosis (two grafts). We related arm systolic blood pressure, intrastenotic PSV, and prestenotic PSV obtained from duplex examinations conducted prior to graft thrombosis or revision and applied our model to these stenotic vein grafts. Intrastenotic PSV was consistently lower than maximum PSV predicted from the Bernoulli equation. The highest measured intrastenotic PSV of 600 cm/sec would require a minimum perfusion pressure of 144 mm Hg. The lowest measured PSV (20 cm/sec) was considered the minimum "thrombotic threshold velocity." This model predicts that for parabolic profile flow in an 80% diameter-reducing axisymmetric stenosis (96% cross-sectional area reduction), a prestenotic PSV of 20 cm/sec would produce an intrastenotic PSV of 500 cm/sec requiring the equivalent potential energy of 100 mm Hg systolic blood pressure. Our theory implies that in patients with nocturnal hypotension thrombosis of stenotic vein grafts may occur.

An international perspective on the future of power generati

This paper reports that on June 5, 1990, the Advisory Committee for Energy to the Minister of International Trade and Industry submitted a report (the Outlook) entitled The Challenge of New Trends in Energy. Quite obviously, it is difficult to define future policy by only a single set of data in the current dynamic international energy situation. That is to say, the Outlook is a form of policy intended as a reference. The Outlook has been made public to educate people as to how critical the energy issue has now become. Three major policy agendas are set forth in the Outlook: Effective use of energy, Appropriate energy supplies or the best mix, and Active promotion of international cooperation in all energy areas. The concept of energy conservation must be understood in a positive sense, whereby it is seen as the creation of energy in that energy conserved today can be saved for the use in the future. Since the oil crisis in 1973, oil dependence in Japan has decreased from 77.6% to 57.3%. In the meantime, it has become difficult to maintain traditional means of supply, due to the intensified antinuclear movement and concern over CO{sub 2} emissions. Therefore, themore » so-called new energies (solar, wind, methanol fuel, etc.) must be introduced to the greatest degree possible. From a practical point of view, appropriate energy supply sources need to be established as the best mix through a combination of conventional, large scale, reliable and economical energy sources such as nuclear, LNG, coal, and hydroelectric power.« less

Impact Parameters of Spherical Viscoelastic Objects and Tomatoes

ABSTRACT A microcomputer and digital oscilloscope were used to measure and analyze impact data from tomatoes and spherical non-biological viscoelastic materials. A simple model was used to determine the acceleration, velocity, and displacement of the impacting sphere. Concepts of momentum, restitution, and energy conservation were used to evaluate the impact system, the analytical procedures, and the test objects. Easily measured or observed parameters of the force versus time curve were correlated with the properties of the sphere.

Improved nonlinear buckling analysis of structures

The theory of structural stability is both an important and a difficult subject, whose main field of application is found in the design of thin wall lightweight structures and shells. It is unavoidable to employ nonlinear model and to use finite element numerical method in order to obtain the critical load under the action of which the instability of structures will occur. Thus, it becomes very important how to simplify such a nonlinear problem that appears in instability analysis. In this paper, an improvement on previous nonlinear buckling analysis is proposed, in which the emphasis is on the shortcut of calculation of pre-buckling fundamental path. The nonlinear equation used to solve the displacement vector is translated into the linear one to solve the load factor by means of the concept of energy conservation. The detailed procedure to calculate the nonlinear buckling load is presented and two simple examples are also shown as the application of suggested method. The theoretical analysing and numerical examples show that the suggested method is valid for predicting the nonlinear critical loads of structures.