Model calculations to evaluate the conditions of heat storage in deep aquifers

1981 ◽  
Vol 132 (2) ◽  
pp. 839-847
Author(s):  
Eckart Bütow
Keyword(s):  
Heat Storage ◽  
Model Calculations ◽  
Deep Aquifers

scholarly journals Laboratory and modelling investigations of potential geochemical reactions upon seasonal heat storage in Danish geothermal reservoirs

2020 ◽  
Author(s):  
Hanne Dahl Holmslykke ◽  
Claus Kjøller ◽  
Rikke Weibel ◽  
Ida Lykke Fabricius
Keyword(s):  
Calcium Carbonate ◽  
Elevated Temperatures ◽  
Heat Storage ◽  
Petrographic Analysis ◽  
Formation Water ◽  
Geothermal Reservoirs ◽  
Deep Aquifers ◽  
Two Samples ◽  
Geochemical Reactions ◽  
Sandstone Formation

<p>Seasonal storage of excess heat in hot deep aquifers is one of the considered solutions to optimize the usage of commonly available energy sources. This study investigates the risk of damaging the reservoir through potential geochemical reactions induced by the increased reservoir temperature upon injection of heated formation water. Three core flooding experiments were performed at reservoir conditions and temperatures up to 150°C with cores from two potential Danish geothermal reservoirs and with synthetic brine as the flooding fluid. The tested reservoir sandstones comprise two samples with different mineralogy from the Upper Triassic – Lower Jurassic Gassum Sandstone Formation and one sample from the Lower Triassic Bunter Sandstone Formation. For the calcium carbonate-containing Bunter Sandstone formation, the experiments were performed with Ca-depleted synthetic formation water to avoid loss of injectivity by calcium carbonate scaling at elevated temperatures. The interpretation of the laboratory experiments was supported by petrographic analysis of the cores prior to and after the flooding experiments and by geochemical modelling. The results show that heating induced a series of silica dissolution/precipitation processes for all three sandstones, including dissolution of quartz, alteration of Na-rich feldspar to kaolinite, replacement of plagioclase with albite and precipitation of muscovite, depending on the sandstone. These processes are not expected to significantly deteriorate the physical properties of the reservoir. However, for the Bunter Sandstone Formation, flushed with Ca-depleted brine, a significant portion of the cementing calcite dissolved. In the reservoir, this may ultimately reduce the mechanical strength of the geological formation. Thus, this study suggests that heat storage in geothermal reservoirs can be technically feasible in typical and extensive Danish geothermal sandstone reservoirs. However, in reservoirs containing calcium carbonate, means for avoiding calcium carbonate precipitation during heat storage should be chosen with caution to minimise possible reservoir damaging side effects.</p>

Process-Based Decomposition of the Decadal Climate Difference between 2002–13 and 1984–95

2017 ◽  
Vol 30 (12) ◽  
pp. 4373-4393 ◽  
Author(s):  
Xiaoming Hu ◽  
Yana Li ◽  
Song Yang ◽  
Yi Deng ◽  
Ming Cai
Keyword(s):  
Radiative Transfer ◽  
Heat Storage ◽  
Decomposition Analysis ◽  
Arctic Region ◽  
The Arctic ◽  
Radiative Transfer Model ◽  
Transfer Model ◽  
Model Calculations ◽  
Surface Warming ◽  
Decadal Climate

This study examines at the process level the climate difference between 2002–13 and 1984–95 in ERA-Interim. A linearized radiative transfer model is used to calculate the temperature change such that its thermal radiative cooling would balance the energy flux perturbation associated with the change of an individual process, without regard to what causes the change of the process in the first place. The global mean error of the offline radiative transfer model calculations is 0.09 K, which corresponds to the upper limit of the uncertainties from a single term in the decomposition analysis. The process-based decomposition indicates that the direct effect of the increase of CO2 (0.15 K) is the largest contributor to the global warming between the two periods (about 0.27 K). The second and third largest contributors are the cloud feedback (0.14 K) and the combined effect of the oceanic heat storage and evaporation terms (0.11 K), respectively. The largest warming associated with the oceanic heat storage term is found in the tropical Pacific and Indian Oceans, with relatively weaker warming over the tropical Atlantic Ocean. The increase in atmospheric moisture adds another 0.1 K to the global surface warming, but the enhancement in tropical convections acts to reduce the surface warming by 0.17 K. The ice-albedo and atmospheric dynamical feedbacks are the two leading factors responsible for the Arctic polar warming amplification (PWA). The increase of atmospheric water vapor over the Arctic region also contributes substantially to the Arctic PWA pattern.

Experimental determination of parameters in models of indoor air temperature response to reduction in supplied energy

2016 ◽  
Vol 40 (4) ◽  
pp. 346-371 ◽  
Author(s):  
Bernard Zawada
Keyword(s):  
Time Constant ◽  
Heat Storage ◽  
Temperature Drop ◽  
Temperature Response ◽  
Second Order ◽  
Order Model ◽  
Indoor Temperature ◽  
Integration Model ◽  
Model Calculations ◽  
Average Value

To diminish peaks of energy power demand in buildings, we need to determine parameters in transmittance models that describe indoor temperature response to changes in heating. This article discusses first- and second-order models as well as an integration model. Calculations deal with indoor temperature drop in the range to −2 K following the heating power reduction for a period of 4–6 h. The second-order model was found to be the most accurate in showing the decrease in temperature. The calculated values of parameters vary within wide ranges, with significant differences occurring even with values obtained in consecutive measurement series. It was shown that the use of averaged values produce large result errors in the predictions of indoor temperature changes. This renders an offline method useless and promotes an online method. The average value of the time constant in the first-order model correlates well with the value of the time constant calculated as a ratio of the heat storage mass to the room heat loss coefficient. This is true if we take into account exclusively this part of the building partition layer that contributes to the heat storage.

Effects of Ambipolar Diffusion on Prominence Thread Models

1994 ◽  
Vol 144 ◽  
pp. 315-321 ◽  
Author(s):  
M. G. Rovira ◽  
J. M. Fontenla ◽  
J.-C. Vial ◽  
P. Gouttebroze
Keyword(s):  
Energy Balance ◽  
Transition Region ◽  
Ambipolar Diffusion ◽  
Line Profiles ◽  
Balance Equations ◽  
Model Calculations ◽  
Partial Frequency ◽  
Frequency Redistribution ◽  
Partial Frequency Redistribution ◽  
Theoretical Structure

AbstractWe have improved previous model calculations of the prominence-corona transition region including the effect of the ambipolar diffusion in the statistical equilibrium and energy balance equations. We show its influence on the different parameters that characterize the resulting prominence theoretical structure. We take into account the effect of the partial frequency redistribution (PRD) in the line profiles and total intensities calculations.

Electron microscopy of niobium and tantalum hydrides

1978 ◽  
Vol 36 (1) ◽  
pp. 644-645
Author(s):  
T. Schober
Keyword(s):  
Electron Microscopy ◽  
Heat Storage ◽  
Measurement Techniques ◽  
Metal Hydrides ◽  
Detailed Understanding ◽  
Storage Devices ◽  
Unit Cells ◽  
Endothermic Reactions ◽  
Hydrogen Reactions ◽  
New Phase

Nb, Ta and V are prototype substances for the study of the endothermic reactions of H with metals. Such metal-hydrogen reactions have gained increased importance due to the application of metal-hydrides in hydrogen- und heat storage devices. Electron microscopy and diffraction were demonstrated to be excellent methods in the study of hydride morphologies and structures (1). - Figures 1 and 2 show the NbH and TaH phase diagrams (2,3,4). EM techniques have contributed substantially to the elucidation of the structures and domain configurations of phases β, ζ and ε (1,4). Precision length measurement techniques of distances in reciprocal space (5) recently led to a detailed understanding of the distortions of the unit cells of phases ζ and ε (4). In the same work (4) the existence of the new phase η was shown. It is stable near -68 °C. The sequence of transitions is thus below 70 %.

Influence of stable iodine on the uptake of the thyroid – model vs. experiment

2001 ◽  
Vol 40 (01) ◽  
pp. 31-37 ◽  
Author(s):  
U. Wellner ◽  
E. Voth ◽  
H. Schicha ◽  
K. Weber
Keyword(s):  
Time Course ◽  
Compartment Model ◽  
The Body ◽  
Iodine Uptake ◽  
Model Calculations ◽  
Physiological Conditions ◽  
Iodine Supply ◽  
Predicted Values ◽  
The Individual ◽  
Stable Iodine

Summary Aim: The influence of physiological and pharmacological amounts of iodine on the uptake of radioiodine in the thyroid was examined in a 4-compartment model. This model allows equations to be derived describing the distribution of tracer iodine as a function of time. The aim of the study was to compare the predictions of the model with experimental data. Methods: Five euthyroid persons received stable iodine (200 μg, 10 mg). 1-123-uptake into the thyroid was measured with the Nal (Tl)-detector of a body counter under physiological conditions and after application of each dose of additional iodine. Actual measurements and predicted values were compared, taking into account the individual iodine supply as estimated from the thyroid uptake under physiological conditions and data from the literature. Results: Thyroid iodine uptake decreased from 80% under physiological conditions to 50% in individuals with very low iodine supply (15 μg/d) (n = 2). The uptake calculated from the model was 36%. Iodine uptake into the thyroid did not decrease in individuals with typical iodine supply, i.e. for Cologne 65-85 μg/d (n = 3). After application of 10 mg of stable iodine, uptake into the thyroid decreased in all individuals to about 5%, in accordance with the model calculations. Conclusion: Comparison of theoretical predictions with the measured values demonstrated that the model tested is well suited for describing the time course of iodine distribution and uptake within the body. It can now be used to study aspects of iodine metabolism relevant to the pharmacological administration of iodine which cannot be investigated experimentally in humans for ethical and technical reasons.

Latent heat storage for hot beverages

2019 ◽  
Vol 13 (3) ◽  
pp. 5653-5664
Author(s):  
M. S. M. Al-Jethelah ◽  
H. S. Dheyab ◽  
S. Khudhayer ◽  
T. K. Ibrahim ◽  
A. T. Al-Sammarraie
Keyword(s):  
Latent Heat ◽  
Food Industry ◽  
Heat Storage ◽  
Food Storage ◽  
Thermal Engineering ◽  
Engineering Applications ◽  
Latent Heat Storage ◽  
The Impact ◽  
Encapsulated Phase Change Material ◽  
Change Material

Latent heat storage has shown a great potential in many engineering applications. The utilization of latent heat storage has been extended from small scales to large scales of thermal engineering applications. In food industry, latent heat has been applied in food storage. Another potential application of latent heat storage is to maintain hot beverages at a reasonable drinking temperature for longer periods. In the present work, a numerical calculation was performed to investigate the impact of utilizing encapsulated phase change material PCM on the temperature of hot beverage. The PCM was encapsulated in rings inside the cup. The results showed that the encapsulated PCM reduced the coffee temperature to an acceptable temperature in shorter time. In addition, the PCM maintained the hot beverage temperature at an acceptable drinking temperature for rational time.

Sign in / Sign up

Export Citation Format

Share Document