Search

This article presents an overview of airflow velocity measurement methods applied to renewable energy. Basic measurement methods used in this field are discussed: tachometric, ultrasonic, and calorimetric anemometry. The principle of operation and basic properties of anemometers are presented, and based on publications from the last decade, a systematic review of development directions and trends in this field is made. The aim of the article is to familiarize people dealing with renewable energy problems, in particular wind energy, with the current state of knowledge in the field of anemometric measurements, properties of individual types of measuring devices, as well as directions of development of measurement tools. This will allow for the optimization of processes in the field of wind energy, in particular in the selection of the location of the energy facility, implementation of investments and control, diagnostics, and monitoring during operation. The selection of metrological tools adequate to the problem also allows for ensuring an appropriate level of work safety and environmental and ecological harmony and supporting the process of sustainable development. [ABSTRACT FROM AUTHOR]

The article presents concepts and experimental studies for an energy harvester designed to convert short, pulsating, turbulent airflows into electrical energy. Such flows occur in the vicinity of roads, highways, and railway tracks, among other places, and are caused by passing vehicles. A laboratory prototype is built in the form of a pendulum deflected from an equilibrium position by the airflow. The pendulum's oscillations are converted into electrical energy using an electrodynamic transducer. The harvester uses a magnetic system that increases the frequency of the oscillations and increases the energy efficiency of the system. The harvester can be used to power local low-power electrical devices, such as highway monitoring systems. It is possible to place a set of multiple harvesters in the vicinity of the road, creating a visual effect of reeds waving in the wind. [ABSTRACT FROM AUTHOR]

Energy transformation requires replacing power plants based on fossil raw materials with renewable energy. Energy harvesting plays an important, although not fully appreciated, role here. Distributed, local power supply systems for small receivers, based on various sources which previously dissipated energy, may contribute to changing the current energy paradigm. This article presents an overview of energy harvesting technologies and various energy sources used in this process. Particular attention was paid to sources of a less conventional nature. The aim of this article is to encourage and direct scientists with the potential to explore this topic to look for new, previously unexploited energy sources and innovative and effective methods of obtaining useful energy in the harvesting process. [ABSTRACT FROM AUTHOR]

An important contemporary challenge regarding sustainable development is the analysis of the possibilities of obtaining and recovering energy, also from unconventional areas. One such issue harvests energy from roads. This idea seems to be so attractive that numerous scientific teams around the world conduct research in this area. The author's systematic analysis of review articles from the last decade raises the question, whether harvesting energy from roads is really as attractive and promising as many researchers predict in their publications. The author hypothesizes that in last decade basically no significant progress has been made in the development and improvement of energy harvesting from roads methods and systems. In many cases, the solutions presented are more technical than scientific novelties. Known solutions are modeled and tested again and again, the systems are complex and expensive, and the energy and economic efficiency is relatively low. In this article, the author focuses on critically revealing the flaws, shortcomings, weaknesses, and erroneous assumptions of large part studies conducted in this field. Based on the criticism, it is aimed to indicate prospective directions of development and encourage researchers to look for innovative, effective solutions in the field of energy harvesting from roads. [ABSTRACT FROM AUTHOR]

Hot-wire anemometric measurements are often related to the determination of flow parameters in a high frequency range. Such knowledge is particularly important when analyzing the flow phenomena in the vicinity of wind turbines. The reliability of obtained results is determined by the knowledge of the properties of the system used for measurements. It concerns both the static and dynamic characteristics of individual measurement channels. In studies of hot-wire anemometric systems, a problem related to the unstable transmission bands of such systems and their high dependence on measurement conditions and the system configuration itself has been commonly indicated. This paper presents the results of an investigation of a new type of hot-wire anemometer, allowing for automatic adjustment of its dynamic characteristics under real working conditions. The presented system is dedicated to the analysis of the wind energy spectrum in experimental laboratory tests on reduced-scale models and to specialized in situ measurements. [ABSTRACT FROM AUTHOR]

Measurements of air flow velocity are essential at every stage of the design, construction and operation of wind turbines. One of the basic measurement tools in this area is the tachometric anemometer, which is based on the simple physical phenomenon of the air kinetic energy exchange with a rotating measuring element. Tachometric anemometers have favorable operational features and good static metrological parameters. However, in the case of fast-changing flows, the measurement is burdened with a significant dynamic error, and the measured average value of the velocity is overestimated. This article presents the concept and results of pilot studies of a dynamic error correction method of tachometric anemometers. The correction consists of the precise measurement of the rotor's rotational velocity and determination of the measured air velocity, taking into account the dynamics of the instrument. The developed method can be used in tachometric anemometers intended for laboratory, technical and industrial measurements in time-varying flows. One of the important application areas is the measurement of wind energy. [ABSTRACT FROM AUTHOR]

Mechanical tachometric anemometers, based on the phenomenon of the exchange of momentum between the flow and rotating measuring element, represent an important class of instruments used in flow metrology. In particular, they are used in meteorological and ventilation measurements. Mechanical anemometers with rotating measuring element are, however, known for their drawback related to their poor dynamic properties resulting from relatively large dimensions and mechanical inertia of the measuring element. In these instruments, the phenomenon of overestimating the measured average velocity caused by the inertia of the rotor takes place. Optimization of the dynamics of the measurement process, as well as the estimation and minimization of the measurement uncertainty, can be performed based on mathematical model of anemometer. In this study, a new, original concept of optimization of dynamic properties of tachometric anemometers is proposed, and the results of model and simulation studies are presented. The new concept of measuring instrument is based on the use of feedback and active control of the rotor. The new method was tested using model research, where two types of flow velocity excitations were applied: sinusoidal and rectangular. The tests carried out showed that the developed method allows for minimization of the dynamic uncertainty of the measurement and minimizes the phenomenon of average flow velocity overestimation occurring in time-varying flows. It has been shown that the use of optimization system allows for approximately tenfold reduction of the error of average velocity measurement in the case of pulsating flows. In addition, the optimization systems allow for anemometer’s transmission bandwidth to be extended about a hundred times. This creates new application possibilities for these instruments and allows for a large reduction of measurement uncertainty. [ABSTRACT FROM AUTHOR]

Temperature waves are used in metrology to determine flow velocities, as well as the coefficient of thermal diffusion, chemical composition, and other parameters of the flowing medium. This study presents a method for precise generation of temperature waves in flows, based on digitally controlled electronic system. A mathematical model and structure of the system implementing the method is described. The system consists of a wire temperature wave transmitter, supplied by the system setting the preset temperature function in time. The mathematical model of such system, together with results of model and optimization testing are presented. The system allows one to generate temperature waves of the shape preset by a digital signal, generated by a computer-based control system. Such a system may be used in analytical instrumentation. [ABSTRACT FROM PUBLISHER]

Thermal anemometry measurements of non isothermal flows require the use of a temperature compensation or correction method. In this article, the principles of operation of methods for reduction of temperature influence on the flow velocity measurement are discussed. The study also compares the methods and discusses the conditions for their application. The advanced temperature compensation and correction methods are presented in uniform notation and concerns hot-wire anemometers operating in the most commonly used standard constant-temperature mode. [ABSTRACT FROM PUBLISHER]

The article is a synthetic review of contemporary wind energy issues. It was created on the basis of a survey of literature from the last two years, with mainly review articles. This work is intended to be a source of information for a wide group of scientists and students from various fields. The aim is to interest them in a wide range of topics related to wind energy and wind turbines. This may allow for the selection of an area and the undertaking of research in this interesting and future-oriented field. [ABSTRACT FROM AUTHOR]

Due to their common occurrence and fundamental role in human-realized processes and natural phenomena, turbulent flows are subject to constant research. One of the research tools used in these studies are hot-wire anemometers. These instruments allow for measurements in turbulent flows in a wide range of both velocities and frequencies of fluctuations. This article describes a new indirect method of determining the bandwidth shape of a constant-temperature anemometer. The knowledge of this bandwidth is an important factor in the study of the energy spectrum of turbulent flows. [ABSTRACT FROM AUTHOR]

In measurements of fast-changing flows, one of the key issues is knowledge of the anemometer frequency bandwidth. In such measurements, the measurement technique often used is hot-wire anemometry. The determination and optimization of the measurement bandwidth of the hot-wire system is very important for the quality of the measurements carried out. One of the methods used is square-wave or sine-wave electrical testing. The article proposes modification of this method, which involves applying an electrical test signal wirelessly directly to the sensor, using transformer inductive coupling. This modification may in some cases be beneficial and find application in selected metrological problems. The article describes the modified method and its example application. [ABSTRACT FROM AUTHOR]

Hot-wire anemometric measurements of non-isothermal flows require the use of thermal compensation or correction circuitry. One possible solution is a two-state hot-wire anemometer that uses the cyclically changing heating level of a single sensor. The area in which flow velocity and fluid temperature can be measured is limited by the dimensions of the sensor's active element. The system is designed to measure flows characterized by high velocity and temperature gradients, although its transmission bandwidth is very limited. In this study, we propose a method to optimize the two-state hot-wire anemometer transmission bandwidth. The method is based on the use of a specialized constanttemperature system together with variable dynamic parameters. It is also based on a suitable measurement cycle paradigm. Analysis of the method was undertaken using model testing. Our results reveal a possible significant broadening of the two-state hot-wire anemometer's transmission bandwidth.