Features of Fabrication Technology and Properties of Wicks of Heat Pipe Receivers for Solar Dish/Stirling Systems

Solar Energy ◽  
2005 ◽  
Author(s):  
Volodymyr Baturkin ◽  
Vladylen Zaripov ◽  
Charles E. Andraka ◽  
Timothy A. Moss
Keyword(s):  
Heat Pipe ◽  
Thermal Power ◽  
Substrate Material ◽  
Future Application ◽  
Stainless Steel 316L ◽  
Two Phase ◽  
Extensive Program ◽  
Definition Of

Elaboration of robust and reliable capillary systems for solar energy heat pipe receivers is the important step for future application of this product for systems with thermal power of 30–80 kW. The paper considers a new approach to fabrication of capillary structure of heat pipe receivers on the basis of discrete metal fibers with diameter of 30 microns made of stainless steel 316L, and describes some of methods of wicks characterization as well. This technology has been demonstrated by fabrication of porous 4 mm thick wicks with bulk porosity about 0.82 applied to convex surfaces of dome-shaped receivers with radius 178 mm/height 119 mm (thermal power 36 kW) and radius 247 mm/height 173 mm (thermal power 68 kW) and for inner surface of tube with length 450 mm and diameter 73 mm (thermal power 14 kW). The distinction of the proposed technology is in the use of discrete fibers, which are felted on the curved surface in a special way and in the combination of procedures of the felt formation and their sintering to the surface (substrate material is Haynes Alloy 230). Execution of an extensive program of experimental characterization of a wick layer attached to the substrate has been developed and completed. The characterization of applied wicks determines a definition of their structural (local porosity, thickness of porous layer), mechanical (quality of wick bonding to substrate) and hydrodynamic properties (pumping diameter, one-phase and two-phase permeability). Initial estimation of wick performance was performed on the basis of methods developed at the National Technical University of Ukraine for two main modes of receiver operation — with return of sodium to a point on the dome (reflux) and without it. Prediction of receiver thermal performance, when they operate as a part of solar concentration assembly, was determined by specialized heat pipe performance software /Sandia National Laboratories, C. Andraka, 1999/.

scholarly journals PECULIARITIES OF PROCUREMENT FOR DETERMINING THE CONTRACTOR OF ENGINEERING AND GEODESIC WORKS

2020 ◽  
Vol 1 (1) ◽  
pp. 31-41
Author(s):  
Anton V. Nikonov
Keyword(s):  
Power Plants ◽  
Thermal Power ◽  
Thermal Power Plants ◽  
Factors Affecting ◽  
Quality Of Work ◽  
Maximum Price ◽  
Definition Of ◽  
Price Offer

The article describes the difficulties faced by organizations engaged in engineering and geodetic work at power plants, with participation in procurement. It is shown that the majority of procurement participants are representatives of small and medium-sized businesses. The factors affecting the reduction in the price offer are given. It is noted that a decrease in the initial (maximum) price during the procurement procedures varies from 75 to 90%, which cannot but lead to a decrease in the quality of work, and often to falsification of reporting documentation. Conclusions are made on the example of three realized purchases by the definition of the contractor for geodetic work at thermal power plants.

The characterization of volatile molecular substances

1993 ◽  
Vol 443 (1918) ◽  
pp. 313-332 ◽  
Keyword(s):  
Subjective Evaluation ◽  
Sensor Arrays ◽  
Intrinsic Property ◽  
Wide Range ◽  
The Laplace Transform ◽  
Molecular Substances ◽  
Definition Of ◽  
Enclosed Space

Diffusion for gaseous sources comprising more than one type of substance is examined to show how relative concentrations change with time and distance. The large variations which are predicted make nonsense of the popular assumption that odour or smell is an intrinsic property of the source material. However, some characterization of volatile chemical substances is needed. It is shown that this is possible by creating a uniform and stable atmosphere after the relapse of sufficient time by introducing the gas mixture into an enclosed space. In this investigation the situation is analysed for a spherical enclosure using Fourier analysis techniques for the long timescale behaviour and the Laplace transform for the short timescale solution. The measurement of odours via the response of sensor arrays within a spherical enclosure is considered and a proposal is made for utilizing such an enclosure in a definition of volatile molecular substances (analogous to biological ‘smell’). The conditions for optimum compatibility between an array of sensors and a set of calibrands are discussed and the practical means of effecting such measurements are considered in relation to known types of sensor. It is concluded that the quality of volatile molecular substances is definable and measurable down to very low gas concentrations in air: probably below 10 parts per billion for a wide range of gas mixtures unconstrained by such limitations associated with a biological nose such as toxicity, temperature and subjective evaluation.

scholarly journals An Ultrasonic-Capacitive System for Online Characterization of Fuel Oils in Thermal Power Plants

Sensors ◽  
2021 ◽  
Vol 21 (23) ◽  
pp. 7979
Author(s):  
Mateus Mendes Campos ◽  
Luiz Eduardo Borges-da-Silva ◽  
Daniel de Almeida Arantes ◽  
Carlos Eduardo Teixeira ◽  
Erik Leandro Bonaldi ◽  
...  
Keyword(s):  
Flow Rate ◽  
Total Mass ◽  
Power Plants ◽  
Thermal Power ◽  
Electric Energy ◽  
Thermal Power Plants ◽  
Heating Value ◽  
Fuel Oils

This paper presents a ultrasonic-capacitive system for online analysis of the quality of fuel oils (FO), which are widely used to produce electric energy in Thermal Power Plants (TPP) due to their elevated heating value. The heating value, in turn, is linked to the quality of the fuel (i.e., the density and the amount of contaminants, such as water). Therefore, the analysis of the quality is of great importance for TPPs, either in order to avoid a decrease in generated power or in order to avoid damage to the TPP equipment. The proposed system is composed of two main strategies: a capacitive system (in order to estimate the water content in the fuel) and an ultrasonic system (in order to estimate the density). The conjunction of the two strategies is used in order to estimate the heating value of the fuel, online, as it passes through the pipeline and is an important tool for the TPP in order to detect counterfeit fuel. In addition, the ultrasonic system allows the estimation of the flow rate through the pipeline, hence estimating the amount of oil transferred and obtaining the total mass transferred as a feature of the system. Experimental results are provided for both sensors installed in a TPP in Brazil.

Polytropic Change of State Calculations With Condensation or Evaporation and its Use for Thermal Power Cycles

2015 ◽  
Author(s):  
Hans E. Wettstein
Keyword(s):  
Dissipation Rate ◽  
Recursive Algorithm ◽  
Thermal Power ◽  
Initial Pressure ◽  
Two Phase ◽  
Power Cycles ◽  
Change Of State ◽  
Vapor Fraction ◽  
Definition Of ◽  
Discharge Pressure

In the paper [1] three polytropic change of state calculation methods for air gases and CO2 are compared. The conclusions are that the most used formulas can produce with the same input data deviations in terms of polytropic efficiency up to 1.5% points even for nearly ideal gases like nitrogen. The paper suggests therefore a recursive algorithm, which is based directly on the classic definition of a polytropic change of state. This definition assumes a constant dissipation rate during an adiabatic change of state. The proposed algorithm can be applied for any gas with an equation of state, which is an unambiguous function of the two variables pressure p and temperature T. The latter condition is not fulfilled by steam in the wetness range because the specific volume v depends not only from p and T but also from the vapor fraction x. The aim of this paper is the development of an analogous recursive “constant dissipation rate algorithm” for a two phase mixture assuming equilibrium conditions between the vapor and the liquid fractions. The method shall be demonstrated with expanding wet steam. The result of the algorithm will be the discharge enthalpy, temperature and the discharge vapor fraction for given initial pressure and temperature, discharge pressure and polytropic efficiency. Based on the developed formulas some well-known but nevertheless paradoxically perceived results and comparisons with expanding dry air can be shown.

scholarly journals The efficiency of transcritical CO2 cycle near critical point and with high temperature

2021 ◽  
Vol 345 ◽  
pp. 00005
Author(s):  
Sindu Daniarta ◽  
Attila R. Imre ◽  
Piotr Kolasiński
Keyword(s):  
Power Generation ◽  
Heat Source ◽  
Thermal Power ◽  
Organic Rankine Cycle ◽  
Investment Project ◽  
Rankine Cycle ◽  
Working Fluid ◽  
Two Phase ◽  
Energy Conversion Systems

Efficiency is a key parameter used to assess the quality of operation of power generation systems and devices applied for converting one type of energy to the other. Although, in the end, an investment project is mainly evaluated by economic aspect. Furthermore, many researchers have been investigating the possible types of energy conversion systems and devices applied for power generation and utilizing different types of working fluids. This paper presents the inside into transcritical carbon dioxide (CO2) cycle and the gradients of its efficiency. Transcritical CO2 cycle (TCO2C) here refers to a CO2-based thermal power generation cycle absorbing heat from a heat source (ideally with constant pressure) till the supercritical state is reached. It is followed by an expansion to a sub-critical superheated or even two-phase (wet) state. As alternatives, trilateral flash cycle (TFC) and organic Rankine cycle (ORC) utilizing CO2 are also introduced in this paper. The calculation in this study is computed based on MATLAB integrated with thermophysical properties like CoolProp and REFPROP, the mathematical models of the system are built and calculated with the same heat sink temperature of 224.41 K, and the heat source temperature is varied between 274.41 K and 500 K. At a certain temperature, the obtained result shows that the efficiency of the TCO2C is lower than the efficiency of ORC. Another result proves that the quality of working fluid at the end of the expansion process significantly influences the efficiency of the cycle.

Synthesis of Object-Oriented Software Structural Models Using Quality Metrics And Co-Evolutionary Genetic Algorithms

2010 ◽  
pp. 50-75
Author(s):  
André Vargas Abs da Cruz ◽  
Dilza Szwarcman ◽  
Thiago S. M. Guimarães ◽  
Marco Aurélio C. Pacheco
Keyword(s):  
Genetic Algorithms ◽  
Software Engineering ◽  
Object Oriented ◽  
Evolutionary Model ◽  
Quality Metrics ◽  
Software Modeling ◽  
Software Quality Metrics ◽  
Definition Of

One of the biggest challenges for the developer of object-oriented software is the modeling and developing of the objects themselves, so that they are easily reusable in complex systems. The final quality of the software depends mostly on the quality of the modeling developed for it. Modeling and specification of software are fundamental steps for making the software development an activity of engineering. Design is the activity in which software behavior and structure are elaborated. During this phase many models are developed anticipating several views of the final product and making software evaluation possible even before the software is implemented. Consequently, the synthesis of a software model can be seen as a problem of optimization, where the attempt to find a better configuration among the elements chosen through the object-oriented paradigm, such as classes, methods and attributes that meet quality design criteria. This work studies a possibility to synthesize higher quality modelings through the evolution of Genetic Algorithms, a technique that has proved to be efficient in dealing with problems involving large search spaces. The work was divided in three main stages: a study of object-oriented software engineering; the definition of a model using genetic algorithms; and co-evolution of species for the synthesis of object-oriented software modeling, aiming at quality improvement; and at the implementation of a model for case study. The study of object-oriented software engineering involved the establishment of software development phases and the characterization of the representation used in modeling phase and, in particular, the characterization of class diagrams based on UML. The study also investigated software quality metrics such as Reutilization, Flexibility, Understandability, Functionality, Extensibility and Effectiveness. The specification of genetic algorithm consisted in the definition of the structure of the chromosome that could provide a good representation of modeling diagram and a function of evaluation of the design that could take the software quality metrics in to consideration. As a result, the chromosomes represent metadata of a simplified UML diagram of classes, which may later be used as an entry of a CASE (Computer Aided Software Engineering) Tool that can create the implementation code in the chosen pattern. The evaluation function was defined focusing at the synthesis of a higher quality object-oriented software modeling. In order to observe the use of more than one objective at the same time the Pareto technique for multi objective problems was used. The evolution is directed towards the improvement of quality metrics by searching for a qualitatively better modeling, based on Bansiya’s (Bansiya and Davis, 2002) study. The construction of a co-evolutionary model consisted in defining distinct species so that each one would represent part of the problem to be evolved, thus enabling a more efficient representation of the model. The co-evolutionary model allowed the evolution of more complex structures, which would not be possible in a simple Genetic Algorithm. The chromosomes related to each species codify metadata and that is why the solution assembly (design) makes use of a decoder. A case study was done to synthesize the modeling of an elevator controller. The results achieved in this section were compared to the modelings produced by specialists, and the characteristics of these results were analyzed. The GA performance in the optimization process was compared to that of a random search and, in every case, the results achieved by the model were always better.

Immunoferritin localization of intracellular antigens in positively stained frozen sections

1978 ◽  
Vol 36 (2) ◽  
pp. 168-169
Author(s):  
K. T. Tokuyasu
Keyword(s):  
Surface Tension ◽  
Water Surface ◽  
Thin Layers ◽  
The Other ◽  
Positive Staining ◽  
Frozen Sections ◽  
The Past ◽  
Ultrathin Frozen Sections ◽  
Definition Of

During the past investigations of immunoferritin localization of intracellular antigens in ultrathin frozen sections, we found that the degree of negative staining required to delineate u1trastructural details was often too dense for the recognition of ferritin particles. The quality of positive staining of ultrathin frozen sections, on the other hand, has generally been far inferior to that attainable in conventional plastic embedded sections, particularly in the definition of membranes. As we discussed before, a main cause of this difficulty seemed to be the vulnerability of frozen sections to the damaging effects of air-water surface tension at the time of drying of the sections.Indeed, we found that the quality of positive staining is greatly improved when positively stained frozen sections are protected against the effects of surface tension by embedding them in thin layers of mechanically stable materials at the time of drying (unpublished).

Lithography below 100 nm

1983 ◽  
Vol 41 ◽  
pp. 96-99
Author(s):  
L. D. Jackel
Keyword(s):  
Spatial Distribution ◽  
Electron Beam ◽  
Electron Scattering ◽  
Electron Beam Lithography ◽  
Substrate Material ◽  
Local Electron ◽  
Electron Dose ◽  
Positive Resist ◽  
Exposure Process

Most production electron beam lithography systems can pattern minimum features a few tenths of a micron across. Linewidth in these systems is usually limited by the quality of the exposing beam and by electron scattering in the resist and substrate. By using a smaller spot along with exposure techniques that minimize scattering and its effects, laboratory e-beam lithography systems can now make features hundredths of a micron wide on standard substrate material. This talk will outline sane of these high- resolution e-beam lithography techniques.We first consider parameters of the exposure process that limit resolution in organic resists. For concreteness suppose that we have a “positive” resist in which exposing electrons break bonds in the resist molecules thus increasing the exposed resist's solubility in a developer. Ihe attainable resolution is obviously limited by the overall width of the exposing beam, but the spatial distribution of the beam intensity, the beam “profile” , also contributes to the resolution. Depending on the local electron dose, more or less resist bonds are broken resulting in slower or faster dissolution in the developer.

The Influence Of The Led Luminaires Electrical Parameters On Their Correlated Colour Temperature During Operation Mode

2020 ◽  
pp. 89-96
Author(s):  
Sergei S. Kapitonov ◽  
Alexei S. Vinokurov ◽  
Sergei V. Prytkov ◽  
Sergei Yu. Grigorovich ◽  
Anastasia V. Kapitonova ◽  
...  
Keyword(s):  
Operation Mode ◽  
Light Sources ◽  
Electrical Parameters ◽  
Colour Temperature ◽  
Radiation Spectra ◽  
Service Period ◽  
Close Proximity ◽  
Definition Of ◽  
Comprehensive Study

The article describes the results of comprehensive study aiming at increase of quality of LED luminaires and definition of the nature of changes in their correlated colour temperature (CCT) in the course of operation. Dependences of CCT of LED luminaires with remote and close location of phosphor for 10 thousand hours of operation in different electric modes were obtained; the results of comparison between the initial and final radiation spectra of the luminaires are presented; using mathematical statistics methods, variation of luminaire CCT over the service period claimed by the manufacturer is forecast; the least favourable electric operation modes with the highest CCT variation observed are defined. The obtained results have confirmed availability of the problem of variation of CCT of LED luminaires during their operation. Possible way of its resolution is application of more qualitative and therefore expensive LEDs with close proximity of phosphor or LEDs with remote phosphor. The article may be interesting both for manufacturers and consumers of LED light sources and lighting devices using them.

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