Stainless Steels as Erosion Resistant Materials for Hydraulic Machines

2017 ◽  
Vol 750 ◽  
pp. 75-79
Author(s):  
Brandusa Ghiban ◽  
Carmen Anca Safta ◽  
Vlad Motoiu
Keyword(s):  
Steam Turbine ◽  
Geothermal Energy ◽  
Electric Energy ◽  
Heat Energy ◽  
Hydrodynamic Cavitation ◽  
Metallic Surface ◽  
Working Fluid ◽  
Corrosion Mechanism ◽  
Hydraulic Machines ◽  
Abrasive Erosion

The corrosion phenomena lead to serious modifications in the structure of metallic materials from which are manufactured the important active components of hydraulic machines. There are two important types of corrosion: cavitation and silt erosion (abrasive erosion), that are specific to machines which are producing energy [1, 2, 3]. As a corrosion mechanism, in hydrodynamic cavitation [4, 5], when cavitation bubbles implode on the solid surface of hydraulic machine component, the local pressure developed is high and can exceed the fatigue strength, yield point or compression strength of the material. Cavitation phenomenon can be produced in different ways. Four types of cavitation are described in the literature, looking for the method of producing, [6]: hydrodynamic cavitation, particle cavitation, acoustic cavitation, and optic cavitation. Abrasive erosion is the gradual degradation of a structure under the action of solid particles suspended in the working fluid. Impact and sliding erosion are the main categories of abrasive erosion approached in the literature by considering the mechanisms of which the abrasive particles act on the metallic surface, [2]. In the last decades the abrasive erosion phenomenon became a serious problem for the efficient operation of power plants, for instance in hydropower plants [7, 8]. Geothermal energy is the heat energy of the earth given by capturing the springs of heat water. In Romania the geothermal energy is used only for heating because the water has a low temperature and cannot be used to produce electric energy, only heat energy. So, although Romania is the third highest potential geothermal in Europe, practically electric energy from geothermal resource has a low thermal potential, [9]. A steam turbine is working at high rotational speed, high temperatures and using the working fluid which could be steam or wet steam. The working fluid is composed of corrosive chemicals with an aggressive pH. For this reason the common problems of the geothermal steam turbine failures are given by fractures of the blades (rotor blades or stator blades).

Assessing elastic properties of cracks in rock samples subjected to thermo-hydro-chemo-mechanical damage

2021 ◽  
Author(s):  
Anthony Clark ◽  
Tiziana Vanorio ◽  
Andrey Radostin ◽  
Vladimir Zaitsev
Keyword(s):  
Elastic Properties ◽  
Geothermal Energy ◽  
Environmental Science ◽  
Cold Water ◽  
Extreme Temperature ◽  
Mechanical Damage ◽  
Rock Physics ◽  
Seismic Attributes ◽  
Working Fluid ◽  
Rock Samples

<p>An understanding of micro- and macrofracture behavior in low porosity rocks is pertinent to several areas of energy and environmental science such as petroleum production, carbon sequestration, and enhancement of technologies based on geothermal energy, etc. For example, the carbonate reservoirs in dolomitic or micritic formations with matrix porosities below 6% suggest the importance of fracture-augmented permeability in production. Similarly, hydrocarbons have been found on nearly every continent in tight basement rocks, all of which have little matrix porosity and their permeability therefore rely solely on hydraulic connectivity from fractures. For geothermal energy, various igneous and sedimentary rocks (granites, basalts, and limestones) are being exploited across the globe, with some of the lowest porosity and permeability. In all these cases, fractures are necessary to improve rock permeability and thermal exchange between the rock and working fluid, which can be enabled by hydraulic stimulation, as well as by secondary cracking due to extreme temperature gradients from the injection of cold water. The fracture geometry, density, and distribution all together control not only fluid and thermal transport in the rocks, but also their seismic attributes that can be used to extract information about the fractures. <br>In order to accurately interpret the seismo-acoustic data (usually, the velocities of compression and shear waves) reliable rock physics models are required. Here, we report the results of interpretation of such experimental data for both as-cored rock samples and those subjected to thermo-hydro-chemo-mechanical damage (THCMD) in the laboratory. For interpretation, we use a convenient model of fractured rock in which fractures are represented as planar defects with decoupled shear and normal compliances. The application of such an approach makes it possible to assess and compare the elastic properties of fractures in the rocks before and after application of THCMD procedures. For the analyzed samples of granites, basalts, and limestones it has been found that for a significant portion of rocks, the ratio of normal-to-shear compliances of cracks significantly differ from the value typical of conventionally assumed penny-shape cracks. Furthermore, for some samples, this ratio appears to be noticeably different for fractures existing in the as-cored rock and arising in the same rock after THCMD procedures. These results indicate that damage to a rock typically changes its compliance ratio since the old and new cracks are likely to have different elastic properties. Our results are also consistent with the notion that a specific damage process occurring for a given microstructure will consistently create cracks with a particular set of elastic properties. The proposed methodology for assessment of elastic properties of cracks in rock samples subjected to thermo-hydro-chemo-mechanical damage has given previously inaccessible useful information about the elastic properties of fractures and can be extended to interpretation of seismic attributes of rocks for a broad range of other applications.</p>

scholarly journals Experimental investigation of domestic micro-CHP based on the gas boiler fitted with ORC module

2016 ◽  
Vol 37 (3) ◽  
pp. 79-93 ◽  
Author(s):  
Jan Wajs ◽  
Dariusz Mikielewicz ◽  
Michał Bajor ◽  
Zbigniew Kneba
Keyword(s):  
Energy Demand ◽  
Electricity Generation ◽  
Electric Energy ◽  
Organic Rankine Cycle ◽  
Rankine Cycle ◽  
Future Generation ◽  
Working Fluid ◽  
Ethanol Vapour ◽  
System User ◽  
Generation Unit

AbstractThe results of investigations conducted on the prototype of vapour driven micro-CHP unit integrated with a gas boiler are presented. The system enables cogeneration of heat and electric energy to cover the energy demand of a household. The idea of such system is to produce electricity for own demand or for selling it to the electric grid – in such situation the system user will became the prosumer. A typical commercial gas boiler, additionally equipped with an organic Rankine cycle (ORC) module based on environmentally acceptable working fluid can be regarded as future generation unit. In the paper the prototype of innovative domestic cogenerative ORC system, consisting of a conventional gas boiler and a small size axial vapour microturbines (in-house designed for ORC and the commercially available for Rankine cycle (RC)), evaporator and condenser were scrutinised. In the course of study the fluid working temperatures, rates of heat, electricity generation and efficiency of the whole system were obtained. The tested system could produce electricity in the amount of 1 kWe. Some preliminary tests were started with water as working fluid and the results for that case are also presented. The investigations showed that domestic gas boiler was able to provide the saturated/superheated ethanol vapour (in the ORC system) and steam (in the RC system) as working fluids.

An Improved Closed-Loop Heat Extraction Method From Geothermal Resources

2013 ◽  
Vol 135 (4) ◽  
Author(s):  
Arash Dahi Taleghani
Keyword(s):  
Contact Area ◽  
Geothermal Energy ◽  
Closed Loop ◽  
Produced Water ◽  
Heat Extraction ◽  
Working Fluid ◽  
Induced Earthquakes ◽  
Geothermal Resources ◽  
Major Mechanism ◽  
Pressure Changes

Disposal of produced water and induced earthquakes are two major issues that have endangered development of the geothermal energy as a renewable source of energy. To avoid these problems, circulation of a low-boiling working fluid in a closed loop has been proposed; however; since the major mechanism in this method for heat extraction is conduction rather than convection and additionally the heat conduction is limited to the wellbore surface. To overcome this shortcoming, the formation can be fractured with high conductivity material (for instance, silicon carbide ceramic proppants or cements with silane and silica fume as admixtures) to artificially increase the contact area between the “working fluid” and the reservoir. Our calculations show that fracturing increases the contact area by thousand times, additionally, the fracturing materials reinforce and stressed the formation, which reduce the risk of seismic activity due to temperature or pressure changes of the system during the production.

scholarly journals Engineered Lateral Roughness Element Implementation and Working Fluid Alteration to Intensify Hydrodynamic Cavitating Flows on a Chip for Energy Harvesting

Micromachines ◽  
2019 ◽  
Vol 11 (1) ◽  
pp. 49 ◽  
Author(s):  
Moein Talebian Gevari ◽  
Ali Hosseinpour Shafaghi ◽  
Luis Guillermo Villanueva ◽  
Morteza Ghorbani ◽  
Ali Koşar
Keyword(s):  
Energy Harvesting ◽  
Microfluidic Devices ◽  
Surface Cleaning ◽  
Hydrodynamic Cavitation ◽  
Working Fluid ◽  
Wall Roughness ◽  
Cavitating Flows ◽  
Roughness Elements ◽  
Fluid Alteration ◽  
On Chip

Hydrodynamic cavitation is considered an effective tool to be used in different applications, such as surface cleaning, ones in the food industry, energy harvesting, water treatment, biomedical applications, and heat transfer enhancement. Thus, both characterization and intensification of cavitation phenomenon are of great importance. This study involves design and optimization of cavitation on chip devices by utilizing wall roughness elements and working fluid alteration. Seven different microfluidic devices were fabricated and tested. In order to harvest more energy from cavitating flows, different roughness elements were used to decrease the inlet pressure (input to the system), at which cavitation inception occurs. The implemented wall roughness elements were engineered structures in the shape of equilateral triangles embedded in the design of the microfluidic devices. The cavitation phenomena were also studied using ethanol as the working fluid, so that the fluid behavior differences in the tested cavitation on chip devices were explained and compared. The employment of the wall roughness elements was an effective approach to optimize the performances of the devices. The experimental results exhibited entirely different flow patterns for ethanol compared to water, which suggests the dominant effect of the surface tension on hydrodynamic cavitation in microfluidic channels.

Thermal Heat Storage Gain of Salinity Gradient Solar Pond Using Evacuated Tube Solar Collectors

2015 ◽  
Vol 1113 ◽  
pp. 800-805 ◽  
Author(s):  
Baljit Singh ◽  
Muhammad Fairuz Remeli ◽  
Alex Pedemont ◽  
Amandeep Oberoi ◽  
Abhijit Date ◽  
...  
Keyword(s):  
Large Scale ◽  
Heat Storage ◽  
Salinity Gradient ◽  
Heat Energy ◽  
Working Fluid ◽  
The Sun ◽  
Solar Ponds ◽  
Solar Pond ◽  
Evacuated Tube Collectors ◽  
Evacuated Tube

This paper investigates the capability of running a system which uses hot fluid from solar evacuated tube collectors to boost the temperature and overall heat storage of the solar pond. The system is circulated by a solar powered pump, producing heat energy entirely from the incoming solar radiation from the sun. Solar evacuated tube collectors use a renewable source of power directly from the sun to heat the working fluid to very high temperatures. Solar ponds are emerging on the renewable energy scene with the capacity to provide a simple and inexpensive thermal storage for the production of heat on a large scale. The results of the performance of the system show a significant heat energy increase into the solar ponds lower convective region, increasing the overall performance of the solar pond.

Design of the Thermoelectric Generator

2010 ◽  
Vol 143-144 ◽  
pp. 543-546
Author(s):  
Gui Lin Yang
Keyword(s):  
Thermoelectric Power ◽  
Thermoelectric Generator ◽  
Block Diagram ◽  
Electric Energy ◽  
Thermoelectric Module ◽  
Heat Energy ◽  
Operational Principle ◽  
Power Modules ◽  
Current Limiting ◽  
Natural Temperature

Thermoelectric Generator is a device using the widespread natural temperature to generate electricity. On the basis of investigations and experiments, this paper fully expounded thermoelectric generator’s significance, system block diagram, circuits, operational principle, application foregrounds and etc. Semiconductor thermoelectric module and the controller compose the thermoelectric generator, semiconductor thermoelectric power modules change heat energy into electric energy, the electric energy is stored in the controller's battery by the charging circuit. The controller has many functions such as current limiting, under voltage and other functions. At the same time, we had also designed the step-up circuit, in this way, the thermoelectric generator can output higher voltage. The experiment results and application show the thermoelectric generator has good performance and powerful function, it is worth spreading.

Research on Microgrid System in the DC-Building

2014 ◽  
Vol 596 ◽  
pp. 678-681
Author(s):  
Ya Ning Yuan ◽  
Ming Meng
Keyword(s):  
Energy Saving ◽  
Control Strategy ◽  
Integrated Management ◽  
Storage System ◽  
Management Strategies ◽  
Electric Energy ◽  
Energy System ◽  
Heat Energy ◽  
High Quality ◽  
Bidirectional Power Flow

In order to achieve the objectives of energy-saving and emission reduction for modern buildings and provide high quality power supply, a DC microgrid system of thermoelectric energy comprehensive control is proposed. The system includes two subsystems of electric energy and heat energy system, and realizes electric and heat energy transformation and combination through cogeneration unit and electronic heating device. To achieve efficient use of energy, integrated management strategies is also proposed. Distributed generations are controlled by the maximum power tracking strategy, and the hybrid energy storage system uses droop control strategy to stabilize DC bus voltage. In the connection point between the grid and microgrid, the bidirectional converter uses vector decoupling control strategy with double closed loop for pulse width modulation (PWM) to solve the problem of bidirectional power flow with the grid. The simulation results indicate that the system can provide high quality, energy saving, stable power for the modern building.

scholarly journals Utilization Waste Brine Water Separator for Binary Electric Energy Conversion in Geothermal Wells

2021 ◽  
Vol 16 (4) ◽  
pp. 411-420
Author(s):  
Herianto
Keyword(s):  
Heat Exchanger ◽  
Electric Energy ◽  
Thermodynamic Cycle ◽  
Geothermal Field ◽  
Working Fluid ◽  
Fluid Temperature ◽  
Binary Cycle ◽  
Water Separator ◽  
Geothermal Wells

Nowadays, geothermal is one of the most environmentally friendly energy that can replace the role of fossils energy by converting steam to electricity. Brine is one of the by-products of the production of geothermal wells that are generally not used or simply re-injected. In fact, brine can be converted into electricity using the binary cycle process. In binary cycle, brine from separator is used as a heater of working fluid and transform it into a vapor phase. The vapor will be used to turn turbines and generators to produce electricity. The working fluid selection in accordance with the heating fluid temperature becomes important because it results in optimization of the thermodynamic cycle. The temperature of the wellhead in the geothermal field will decrease 3% per year and reducing the heating fluid temperature in heat exchanger. So, in this paper intends to utilizes brine to heat the heat exchanger by using iso-butane, n-pentane, and iso-pentane because its critical temperature can be stable at 193℃ wellhead temperatures. From the results of predictions from brain 2 production well for 17 years with iso-butane in this binary cycle planning, can utilize waste brine water separator to converse electric energy to produce 4 MWh electricity.

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