Usage of the Wind Energy for Heating of the Energy- Efficient Buildings: Analysis of Possibilities

The paper analyzes and compares the energy demand for heating purpose of new buildings with different energy perfomance rates. Article studies global renewable energy sources innovations, statistics and scientific and engineering experience to ensure the building's thermal energy needs, produced by transforming wind energy.Distribution of the potential of one renewable source – wind energy – during the year is similar to the energy necessary for the building heating, thus production of the heating energy from mechanic energy of the wind is chosen for further scientific investigations. Wind power plant, generating 2 kW of heat power, installed as a heating source for the analysed individual house, can cover from 40 to 76% annual heat needs of the building, subject to its energy-efficiency class, respectively 1.5 kW – from 31 to 68%, 1 kW – from 22 to 53%

Conversion of lowland river flow kinetic energy

This paper presents the analysis of possibilities and feasibilities of the extraction of kinetic energy from lowland rivers, which are slow and shallow and their water may contain organic fibres of water vegetation and solid particles of soil. In these rivers the existing hydrokinetic energy converters are not optimised for use because at small flow velocity the efficiency of such converters is very low. The depth of a shallow river flow may be not deep enough to install the converters. The latter are sensitive to jamming by water plant fibres. To overcome the difficulties in developing river flow kinetic energy the structures, the advantages and disadvantages of commonly used converters have been analysed A conveyor type converter has been found to be the most suitable for use in shallow rivers. Results of our field and laboratory studies of hydrokinetic energy converters have confirmed the anticipated difficulties when applying the commonly used converters in lowland rivers. The validity of our proposed method has allowed to reduce the number of mobile elements and friction couples in our novel converter and to increase its reliability. A particular approach to the principle of kinetic energy extraction from a river flow has been developed and a novel converter has been invented. To increase the efficiency of the river flow kinetic energy conversion a new conveyor technology has been proposed. This converter allows the extraction of kinetic energy from the river flow almost without affecting the river and the surrounding environmentVytauto Didžiojo universitetasŽemės ūkio akademij

Lowland river flow control by an artificial water plant system

This article concerns the influence of water plants on the river flow. It is known that the influence of the plants is rather strong. Colonies of water plants with long afloat culms create considerable forces of resistance to the flow. They reduce flow velocity and increase a stream depth, what often is desirable. Water plants location in a stream is uncontrollable. They appear in not suitable locations of the river and mostly obstruct than help to control the river flow. Water plants and their colonies served for us as a prototype for creation of the flow control system. A method of computation and field tests that enables designing and arranging an artificial water plant system is presented in this article, and it may be used successfully to increase the river flow depth and to improve navigation, free-flow (kinetic) hydropower development and recreation conditions. The suggested system for river flow control is simple, cheap and friendly to the environmentKauno technologijos universitetasVytauto Didžiojo universitetasŽemės ūkio akademij

Analysis of Drain Water Heat Exchangers System in Wellness Center

Drain water heat exchangers worldwide are used since the end of the twentieth century. Different drain water heat exchangers have been installed in Lithuania in last five years. Performance of these systems varies depending on the type of energy users, equipment and design of the systems, as well as their maintenance. The aim of this paper was to analyze different types of drain water heat exchangers and operational systems from the perspective of energy saving and temperature effectiveness. One drain water heat exchanger system in Lithuania was selected for the analysis. Calculation of temperature effectiveness showed that in most cases it is possible to save energy for hot water preparation

Field Measurements and Numerical Simulation for the Definition of the Thermal Stratification and Ventilation Performance in a Mechanically Ventilated Sports Hall

Sports halls must meet strict requirements for energy and indoor air quality (IAQ); therefore, there is a great challenge in the design of the heating, ventilation, and air conditioning (HVAC) systems of such buildings. IAQ in sports halls may be affected by thermal stratification, pollutants from different sources, the maintenance of building, and the HVAC system of the building, as well as by the activities performed inside the building. The aim of this study is to investigate thermal stratification conditions in accordance with the performance of the HVAC systems in the basketball training hall of Žalgirio Arena, Kaunas in Lithuania. Field measurements including temperature, relative humidity, and CO2 concentration were implemented between January and February in 2017. The temperature and relative humidity were measured at different heights (0.1, 1.7, 2.5, 3.9, 5.4, and 6.9 m) and at five different locations in the arena. Experimental results show that mixing the ventilation application together with air heating results in higher temperatures in the occupied zone than in the case of air heating without ventilation. Computational fluid dynamics (CFD) simulations revealed that using the same heating output as for warm air heating and underfloor heating, combined with mechanical mixing or displacement ventilation, ensures higher temperatures in the occupied zone, creating a potential for energy saving. An increase of air temperature was noticed from 3.9 m upwards. Since CO2 concentration near the ceiling was permissible, the study concluded that it is possible to recycle the air from the mentioned zone and use it again by mixing with the air of lower layers, thus saving energy for air heating

The Influence of Boiling on the Streamlined Body Drag Force and Falling Velocity

This article presents the results of numerical investigation of the influence of the streamlined body temperature on drag force and on the falling velocity in a water channel. The experimental data reflecting the cooling dynamics and body temperature influence on the falling velocity are presented as well. k − ε turbulence model and homogenous heat transfer model were chosen for the numerical 3D simulation. Drag force changes induced by the alteration of the body temperature were investigated. Velocity of the streamlined body under different temperatures of water was investigated experimentally, and the results were compared to the data obtained during the numerical simulation. The increase of the falling velocity and decrease of drag force were found to have been affected by the increase of the body temperature, which had influence on the change of the water parameters (density, phase, etc.) near the surface of the body. Simulation showed that the drag force and a velocity also depended on the water temperature. The drag force of the streamlined body decreased by 32% in comparison to the cold body for the body temperature equal to 150 °C and water temperature close to the saturation temperature (98 °C). Experimentally, it was determined that the velocity of the streamlined body covered by vapor film depended on the falling time and increased by 10–30%. Velocity difference was very small for the cold and hot bodies at the initial moment of the drop; however, it reached 20% and more after 0.3 s of the falling process

Research Challenges and Advancements in the field of Sustainable Energy Technologies in the Built Environment

Inevitably, the 21st century has initiated a series of developments in the construction industry, leading to its digitalization and resulting in a series of innovative approaches and practices. At the same time, the construction industry, being one of the main global environment polluters, should fulfil well-established, as well as novel, sustainability requirements in order to evolve in harmony with the rising concerns on the availability of natural resources. This overview study aims to present the main developments, research, and scientific challenges in the field of sustainable construction, emphasizing the field of energy. The study aims to present a state-of-the-art scientific discussion on the sustainable built environment topic by analyzing cutting edge topics in the fields of building elements and whole building energy assessment, of indoor air quality and low carbon buildings, as well as on sustainable energy systems and smart buildings. The study also presents the state-of-the-art in existing tools which are adopted for the assessment of the sustainable built environment, including the use of digital tools and building information modelling for the energy assessment of the built environment, as well as the application of Life Cycle Assessment on building-related processes. Cross cutting issues related to the analysis of the building sector in the Industry 4.0 era, such as sustainability management topics and environmental geomatics are also discussed. The study concludes in those fields which will be of interest of the scientific community in the following years, towards achieving the goals of the sustainable development of the building sector