scholarly journals Geothermal System Study Case near Bucharest

2019 ◽  
Vol 111 ◽  
pp. 06058
Author(s):  
Galina Prică ◽  
Lohengrin Onuțu ◽  
Grațiela Țârlea
Keyword(s):  
Thermal Response ◽  
Hot Water ◽  
Geothermal System ◽  
System Study ◽  
Accurate Calculation ◽  
Good Efficiency ◽  
Efficient System ◽  
One Step ◽  
Study Case ◽  
Geological Formations

The article shows a study case of a geothermal system near Bucharest. In the paper it is shown that for a good efficiency of a geothermal system for heating and air conditioning, it is important to follow a few steps. One step is a very accurate calculation of the heat and cold load. In the next step it is important to use a specific equipment to obtain the Thermal Response Test (TRT) of geological formations crossed by the borehole. TRT is helpful in providing information related to the evolution of the soil temperature while introducing a thermal load. All information that can be obtained or calculated from the TRT will provide how the climate system will function in time and its efficiency. Furthermore, the effective thermal conductivity and thermal resistance of the well will be determined, extremely important parameters in designing the correct length of the geoheat exchanger. The article used specific software to simulate the evolution of parameters in time, for soil and heat pump. Earth Energy Design offer information for the number of needed boreholes, the depth and the yearly evolution of the soil’s temperature in time for the system etc. Following all these main steps, finally a very efficient system can be designed, that can ensure the heating and produce hot water for the consumption of a house, office building or of other destination buildings.

Revised hydrogeological model of the hydrothermal system Waiwera (New Zealand)

2021 ◽  
Author(s):  
Andreas Grafe ◽  
Thomas Kempka ◽  
Michael Schneider ◽  
Michael Kühn
Keyword(s):  
Water Management ◽  
New Zealand ◽  
Water Level ◽  
Hot Water ◽  
Hydrogeology Journal ◽  
Natural State ◽  
Geothermal System ◽  
Geological Model ◽  
Species Transport ◽  
Study Region

<p>The geothermal hot water reservoir underlying the coastal township of Waiwera, northern Auckland Region, New Zealand, has been commercially utilized since 1863. The reservoir is complex in nature, as it is controlled by several coupled processes, namely flow, heat transfer and species transport. At the base of the aquifer, geothermal water of around 50°C enters. Meanwhile, freshwater percolates from the west and saltwater penetrates from the sea in the east. Understanding of the system’s dynamics is vital, as decades of unregulated, excessive abstraction resulted in the loss of previously artesian conditions. To protect the reservoir and secure the livelihoods of businesses, a Water Management Plan by The Auckland Regional Council was declared in the 1980s [1]. In attempts to describe the complex dynamics of the reservoir system with the goal of supplementing sustainable decision-making, studies in the past decades have brought forth several predictive models [2]. These models ranged from being purely data driven statistical [3] to fully coupled process simulations [1].<br><br>Our objective was to improve upon previous numerical models by introducing an updated geological model, in which the findings of a recently undertaken field campaign were integrated [4]. A static 2D Model was firstly reconstructed and verified to earlier multivariate regression model results. Furthermore, the model was expanded spatially into the third dimension. In difference to previous models, the influence of basic geologic structures and the sea water level onto the geothermal system are accounted for. Notably, the orientation of dipped horizontal layers as well as major regional faults are implemented from updated field data [4]. Additionally, the model now includes the regional topography extracted from a digital elevation model and further combined with the coastal bathymetry. Parameters relating to the hydrogeological properties of the strata along with the thermophysical properties of water with respect to depth were applied. Lastly, the catchment area and water balance of the study region are considered.<br><br>The simulation results provide new insights on the geothermal reservoir’s natural state. Numerical simulations considering coupled fluid flow as well as heat and species transport have been carried out using the in-house TRANSport Simulation Environment [5], which has been previously verified against different density-driven flow benchmarks [1]. The revised geological model improves the agreement between observations and simulations in view of the timely and spatial development of water level, temperature and species concentrations, and thus enables more reliable predictions required for water management planning.<br><br>[1] Kühn M., Stöfen H. (2005):<br>      Hydrogeology Journal, 13, 606–626,<br>      https://doi.org/10.1007/s10040-004-0377-6<br><br>[2] Kühn M., Altmannsberger C. (2016):<br>      Energy Procedia, 97, 403-410,<br>      https://doi.org/10.1016/j.egypro.2016.10.034<br><br>[3] Kühn M., Schöne T. (2017):<br>      Energy Procedia, 125, 571-579,<br>      https://doi.org/10.1016/j.egypro.2017.08.196<br><br>[4] Präg M., Becker I., Hilgers C., Walter T.R., Kühn M. (2020):<br>      Advances in Geosciences, 54, 165-171,<br>      https://doi.org/10.5194/adgeo-54-165-2020<br><br>[5] Kempka T. (2020):<br>      Adv. Geosci., 54, 67–77,<br>      https://doi.org/10.5194/adgeo-54-67-2020</p>

scholarly journals Performance Analysis of Single-Well Enhanced Geothermal System for Building Heating

2020 ◽  
Vol 2020 ◽  
pp. 1-8
Author(s):  
Haijun Liang ◽  
Xiaofeng Guo ◽  
Tao Gao ◽  
Lingbao Wang ◽  
Xianbiao Bu
Keyword(s):  
Volume Flow Rate ◽  
Water Reservoir ◽  
Hot Water ◽  
Heat Extraction ◽  
Geothermal System ◽  
Enhanced Geothermal System ◽  
Artificial Reservoir ◽  
Reservoir Volume ◽  
Thermal Output ◽  
Single Well

Deep borehole heat exchanger (DBHE) technology does not depend on the existence of hot water reservoir and can be used in various regions. However, the heat extraction from DBHE can hardly be improved due to poor thermal conductivity of rocks. Here, a single-well enhanced geothermal system (SWEGS) is proposed, which has a larger heat-exchange area of artificial reservoir created by fracturing hydrothermal technology. We find that, due to heat convection between rocks and fluid, the extracted thermal output for SWEGS is 4772.73 kW, which is 10.64 times of that of DBHE. By changing the injection water temperature, volume flow rate, and artificial reservoir volume, it is easy to adjust the extracted thermal output to meet the requirement of building thermal loads varying with outdoor air temperature. Understanding these will enable us to better apply SWEGS technology and solve the fog and haze problem easily and efficiently.

RESISTIVITY, SELF‐POTENTIAL, AND INDUCED‐POLARIZATION SURVEYS OF A VAPOR‐DOMINATED GEOTHERMAL SYSTEM

Geophysics ◽  
1973 ◽  
Vol 38 (6) ◽  
pp. 1130-1144 ◽  
Author(s):  
A. A. R. Zohdy ◽  
L. A. Anderson ◽  
L. J. P. Muffler
Keyword(s):  
Geothermal Field ◽  
Induced Polarization ◽  
Hot Water ◽  
Thermal Waters ◽  
Geothermal System ◽  
Electrical Soundings ◽  
Lateral Extent ◽  
High Concentrations ◽  
Lake Deposits ◽  
Self Potential

The Mud Volcano area in Yellowstone National Park provides an example of a vapor‐dominated geothermal system. A test well drilled to a depth of about 347 ft penetrated the vapor‐dominated reservoir at a depth of less than 300 ft. Subsequently, 16 vertical electrical soundings (VES) of the Schlumberger type were made along a 3.7‐mile traverse to evaluate the electrical resistivity distribution within this geothermal field. Interpretation of the VES curves by computer modeling indicates that the vapor‐dominated layer has a resistivity of about 75–130 ohm‐m and that its lateral extent is about 1 mile. It is characteristically overlain by a low‐resistivity layer of about 2–6.5 ohm‐m, and it is laterally confined by a layer of about 30 ohm‐m. This 30‐ohm‐m layer, which probably represents hot water circulating in low‐porosity rocks, also underlies most of the survey at an average depth of about 1000 ft. Horizontal resistivity profiles, measured with two electrode spacings of an AMN array, qualitatively corroborate the sounding interpretation. The profiling data delineate the southeast boundary of the geothermal field as a distinct transition from low to high apparent resistivities. The northwest boundary is less distinctly defined because of the presence of thick lake deposits of low resistivities. A broad positive self‐potential anomaly is observed over the geothermal field, and it is interpretable in terms of the circulation of the thermal waters. Induced‐polarization anomalies were obtained at the northwest boundary and near the southeast boundary of the vapor‐dominated field. These anomalies probably are caused by relatively high concentrations of pyrite.

Integration of geophysical methods and fractures study for the Vallès geothermal system characterization (NE Spain)

2020 ◽  
Author(s):  
Gemma Mitjanas ◽  
Juanjo Ledo ◽  
Pilar Queralt ◽  
Gemma Alías ◽  
Perla Piña ◽  
...  
Keyword(s):  
Fluid Flow ◽  
Geophysical Methods ◽  
Normal Fault ◽  
Hot Water ◽  
Fault System ◽  
Geothermal System ◽  
Thin Sections ◽  
Main Structure ◽  
Geological Map ◽  
Ne Spain

<p>The Vallès geothermal system is located in the Catalan Coastal Ranges (CCR) (NE Spain). The CCR are formed by horst and graben structures limited by NE-SW and ENE-WSW striking normal faults, developed during the opening of the Valencia Trough (northwestern Mediterranean) (Gaspar-Escribano et al., 2004). In the Vallès Basin area, the thermal anomaly is located in the northeastern horst-graben limit, where a highly fractured Hercynian granodiorite is in contact with Miocene rocks by a major normal fault. This main structure seems to control the heat and the hot-water flow, nevertheless, the geological structure of this area, as well as the role of the Vallès normal fault, is poorly understood.</p><p>Magnetotellurics and gravity methods together with a detailed geological map have been applied in this area to understand the main structure. Although the geophysical part makes up most of the study, we are also elaborating a detailed geological map of the area, making a fractures study at different scales. We are working with DEM alignments analysis, and fractures study from outcrops and thin sections.</p><p>Our preliminary results in gravity show a strong gravity gradient in the NE-SW Vallès half-graben system and the recent MT profiles image the main fault of that system (Vallès normal fault). These results show a basin geometry with the major thickness of the basin towards the depocenter, disagreeing with the roll-over geometry assumed in previous works.</p><p>Interpretations of the fractures study, together with geophysical data and models, have allowed a preliminary characterization of damage zones associated with the fault system, which are directly related to the fluid flow and the hot springs. The nature of this damage zones could be related to relay ramps, commonly regarded as efficient conduits for fluid flow (Fossen and Rotevatn, 2016).</p>

A seismic and gravity study of the McGregor geothermal system, southern New Mexico

Geophysics ◽  
2001 ◽  
Vol 66 (4) ◽  
pp. 1002-1014 ◽  
Author(s):  
T. M. O’Donnell ◽  
K. C. Miller ◽  
J. C. Witcher
Keyword(s):  
New Mexico ◽  
Heat Flow ◽  
Water Table ◽  
Alluvial Fan ◽  
Hot Water ◽  
Thermal Waters ◽  
Small Scale ◽  
Geothermal System ◽  
Velocity Models ◽  
Basin Fill

Seismic and gravity studies have proven to be valuable tools in evaluating the geologic setting and economic potential of the McGregor geothermal system of southern New Mexico. An initial gravity study of the system demonstrated that a gravity high coincides with the heat‐flow high. A subsequent seismic reflection survey images a strong reflector, interpreted to be associated with a bedrock high that underlies the gravity and heat‐flow highs. A single reflection, which coincides with the water table, occurs within the Tertiary basin fill above bedrock. This reflector is subhorizontal except above structurally high bedrock, where it dips downward. This observation is consistent with well data that indicate a bedrock water table 30 m lower than water in the basin‐fill aquifer. Velocity models derived from seismic tomography show that the basin fill has velocities in the range of 800 to 4000 m/s and that the bedrock reflector coincides with high velocities of 5000 to 6000 m/s. Low‐velocity zones within the bedrock high are interpreted as karsted bedrock with solution‐collapse breccias and cavities filled with hot water. Higher velocity material that flanks the bedrock high may represent an earlier stage of basin fill or older alluvial‐fan deposits. The heat‐flow anomaly appears to be constrained to the region of shallowest bedrock that lacks these deposits, suggesting that they may act as an aquitard to cap underlying bedrock aquifers or geothermal reservoirs. Taken together, these observations suggest that the geothermal system is associated with karsted and fractured structurally high bedrock that serves as a window for upwelling and outflow of thermal waters. Thermal waters with a temperature as high as 89°C have the potential for space heating, geothermal desalinization, and small‐scale electrical production at McGregor Range.

scholarly journals Natural State Modeling of Singapore Geothermal Reservoir

2012 ◽  
Vol 3 ◽  
pp. 34-40
Author(s):  
Hendrik Tjiawi ◽  
Andrew C. Palmer ◽  
Grahame J. H. Oliver
Keyword(s):  
Hot Springs ◽  
Hot Spring ◽  
High Heat ◽  
Hot Water ◽  
Geothermal Reservoir ◽  
Natural State ◽  
Geothermal System ◽  
Fuel Price ◽  
The Cost ◽  
Engineered Geothermal System

 The existence of hot springs coupled with the apparent anomalous high heat flow has sparked interest in the potential for geothermal development in Singapore. This geothermal resource may be potentially significant and could be exploited through Engineered Geothermal System (EGS) technology, i.e. a method to create artificial permeability at depth in granitic or sandstone formations as found under Singapore. The apparently ever-increasing fossil fuel price has made the cost of using the EGS technology more viable than it was in the past. Thus, to assess the resource, a numerical model for the geothermal reservoir has been constructed. Mass and heat flows in the system are simulated in 2D with AUTOUGH2.2, and the graphical interface processed through MULGRAPH2.2. Natural state calibration was performed to match both the observed and the expected groundwater profile, and also to match the hot water upflow at the Sembawang hot spring, with simulated flowrate matching the hot spring natural flowrate. The simulation gives an encouraging result of 125 - 150 °C hot water at depth 1.25 – 2.75 km.

scholarly journals Continuous-Flow Synthesis of Thermochromic M-Phase VO2 Particles via Rapid One-Step Hydrothermal Reaction: Effect of Mixers

2019 ◽  
Vol 2019 ◽  
pp. 1-10
Author(s):  
Xiaojie Yan ◽  
William Trevillyan ◽  
Ioannina Castano ◽  
Yugang Sun ◽  
Ralph Muehleisen ◽  
...  
Keyword(s):  
Continuous Flow ◽  
Hydrothermal Reaction ◽  
Xrd Analysis ◽  
Single Step ◽  
Hot Water ◽  
Scanning Calorimetry ◽  
Smart Windows ◽  
M Phase ◽  
One Step ◽  
Resident Time

VO2 particles are promising materials for thermochromic smart windows that reduce building energy loss. Continuous-flow hydrothermal processes showcase advantages for synthesizing VO2 particles compared with traditional batch reaction systems. Mixers play a crucial role in particle fabrication in continuous-flow systems. In this study, a Center T-Mixer and a Collision Cross-Mixer are developed and implemented in a hot water fluidized suspension reaction (HWFSR) system. The influence of the resident time on the particle phase and size was evaluated, and properties of particles derived from systems equipped with differing mixers were compared. The resulting particles were characterized using techniques of X-ray powder diffraction (XRD) analysis, scanning electron microscopy (SEM), and differential scanning calorimetry (DSC). When compared with the Center T-Mixer, results indicate that the Collision Cross-Mixer has better control regarding the morphology and size distribution of resulting particles while improving the transition temperatures of the as-synthesized materials. HWFSR systems containing novel mixer designs are capable of producing pure M-phase VO2 particles in a single step contrary to the current reactor design that use a second postheat treatment step, and they are capable of synthesizing many other nanoparticle species, especially those requiring high temperature and pressure reaction conditions.

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