Thermal Zone Research Articles

Thermo-energetic simulation in openmodelica and energyplus: Test case from standard VDI 2078

In this work, the test case 1 of german standard VDI 2078 is used to compare the softwares OpenModelica and EnergyPlus. The mentioned standard provides calculation methods of thermal load and temperature and test cases for validation of thermal zones’ models. This case’s behavior was evaluated in both softwares, keeping the reference values provided by the standard. Pearson’s correlation coefficient calculated between the values obtained by OpenModelica and EnergyPlus for zone air temperature, operative temperature and thermal load for the thermal zone type M are, respectively, 0,98 (very strong correlation), 0,87 (strong correlation) and 0,99 (very strong correlation). Among the reasons for deviations in results from both programs are the calculation method of thermal resistances and capacitances and of radiative coefficient, as well as the treatment of zone’s internal mass.

Thyroid hormone manipulation influences development of endothermy and hatching in white leghorn chickens (Gallus gallus)

Chickens experience rapid change in their physiology and metabolism during hatching. We propose that thyroid hormones play a major role in regulating the developmental changes associated with attaining endothermy. To better understand the role thyroid hormones play in hatch timing and development of thermogenic capacity and metabolic rate we manipulated plasma thyroid hormone levels in chicken embryos beginning at 80% development (day 17 of a 21-day incubation) with either a single dose of triiodo-L-thyronine (T3) or the thyroperoxidase inhibitor methimazole (MMI). Manipulation of thyroid hormones altered the timing of hatching, accelerating hatching under hyperthyroid conditions, and prolonging hatching with hypothyroid conditions. Effect sizes comparisons of morphological variables between treatment groups revealed larger heart and body masses in hyperthyroid 1-day post hatch animals. Thyroid hormone manipulation influenced the thermal neutral zone for O2 consumption and body temperature during gradual cooling from 35 to 15 °C of externally pipped embryos and 1-day post hatch chicks. Hyperthyroid EP animals had a wider thermal neutral zone during cooling when compared to control animals. At the temperatures tested, the hypothyroid animals did not exhibit a thermal neutral zone. Similar differences between treatments in the breadth of the thermal neutral zone carried through to 1-day post hatch chickens. These findings suggest that thyroid manipulations influence the timing and development of the animal’s thermogenic response to cooling.

Behavior of molecular maturity parameters in overmature shales affected by diabase intrusion (Irati Formation, Paraná Basin – Brazil)

Molecular parameters based on saturated and aromatic compounds are important tools to access thermal maturation, but the behavior of these compounds is affected by different rates of heating. This study used samples from the Irati Formation, one of the most important source rocks in the Paraná Basin, to assess the behavior of commonly used maturation parameters in overmature rocks, in conditions of high heating rates. The Irati Formation belongs to an atypical hydrocarbon generation system. It was matured by heat of the magmatic intrusions related to volcanism of the Serra Geral Group. The main objective of this work is to evaluate how the heat of a diabase intrusion affected the distribution of the saturated and aromatic biomarker parameters, relating to the intrusive rock distance. For this purpose, eleven shale samples from the borehole CBM-002-ST-RS of the Santa Terezinha field were analyzed. The samples were located at a maximum distance of 46.4 m from a 35.32 m-thick diabase intrusion. For the better understanding of each parameter behavior, was established four different zones according to their trends: maturity correlation, equilibrium, reversal and high thermal stress. The maturity correlation zone is where the progression of the parameter's values are correlated to the increase in maturation towards the base of the profile. The saturated parameters, such as Ts/(Ts + Tm), M30/(M30 + H30) and C29Ts/(C29Ts + H29) marked the increase in maturation of the samples more distant from the intrusion, and the aromatic parameters, such as MPI-1, MPR, DMDBTR 2.4/1.4 and TA(I)/TA(I + II), show an increase in maturation at the intermediate-distance samples. The ratio of Tric/H30 marked the increase of maturation in the largest number of samples. The parameters that reach equilibrium in the beginning of oils window entered the profile already in the equilibrium zone, such as 20S/(20S + 20R), 22S/(22S + 22R) and ββ/(αα + ββ). Furthermore, most parameters presented a reversal zone after the equilibrium or the maturity correlation zone, where they showed an inverse pattern with increase in maturation value. Finally, all parameters presented a chaotic distribution in the samples closest to the intrusion (starting at an average distance of 11 m from the intrusion), this behavior characterize the high thermal stress zone.

Two-stage multi-step energy model calibration of the cooling systems of a large-space commercial building

Buildings play a major role in energy expenditure, representing 40% of Europe’s total energy consumption. It is estimated that heating, ventilation, and air conditioning systems consume between 50–60% of the total energy spent inside the building, thus corresponding to 20% of global worldwide energy consumption. Hence, there is a need to improve the accuracy of building thermal simulation and energy models that are essential in regulatory compliance calculations. In the present study, the authors empirically validate an optimization-based calibration methodology based on its application to a fully operational commercial building located in Pamplona, Navarre. The methodology used a white-box two-stage model in EnergyPlus, which combines a load profile object and a district cooling component to distribute the cooling load inside the building’s thermal zones. The study optimized the parameters and performance curves of different cooling system components using a second-generation non-sorting genetic algorithm in jEPlus software and 985 h of ten-minute time-step data. Finally, a multi-level benchmark is executed, which evaluates the electric energy consumption of the building’s heat pumps and the interior temperature of the different thermal zones for summer 2020 conditions. The assessment of the thermal and energy performance of the simulation model was conducted according to the requirements of the American Society of Heating, Refrigerating and Air-Conditioning Engineers, Guideline 14-2002, and the Chartered Institution of Building Services Engineers, Operation Performance Technical Memoranda 63.

Data-driven estimation of time-dependent solar gain coefficient in a two-zone building with synthetic occupants: Two B-splines integrated grey-box modeling approaches

Solar gains are a significant share of the heat input to the buildings’ interior energy balance. Therefore, it is important to estimate the dynamic details of solar gains precisely for predictive works, such as in model predictive control (MPC). Effective solutions to gauge the dynamic details of solar gains are still lacking. To fill this gap, a data-driven B-splines integrated grey-box modelling technique has been presented recently, and its potential to estimate dynamic solar gains based on the limited size of low-frequency on-site data has been demonstrated in a simplified one-zone building case, with a single level on/off heating input signal. Its robustness is examined in a two-zone building with heating inputs of synthetic occupants, in this study. Two thermal zones are established to mimic day and night zones in a test building, and corresponding synthetic occupancy profiles and thermostat systems have been implemented in each zone. This study shows that the B-spline integrated grey-box model is useful in this more realistic case considering the impacts of occupants, but demands more advanced modellings. Specifically, two updated solutions on B-splines integrated grey-box modelling are offered, although challenges in the model selection are noted, mainly attributed to the low statistical significance of solar gain, which had fortunately almost no impact on the effectiveness of the proposed techniques to characterize solar gain dynamics. The reported challenge could be further investigated in the future based on more case studies.

A quantitative evaluation model of outdoor dynamic thermal comfort and adaptation: A year-long longitudinal field study

The understanding of human outdoor thermal comfort demand and thermal adaptation contributes to sustainable urban design as well as city resilience in the context of human health and wellbeing. Humans' past thermal experience influence their outdoor thermal comfort. However, the quantitative relationship between the past thermal experience and outdoor thermal comfort is still not clear. This study aims to reveal quantitative relations of the impact of people's past thermal experience on adaptive thermal comfort and to develop a new outdoor adaptive thermal comfort model. A year-long longitudinal questionnaire survey along with a combination of outdoor thermal environment campaigns was carried out in Chongqing, China. It began on August 15, 2020, and finished on August 19, 2021. Through the analysis of 2240 valid responses to the questionnaire survey, the outdoor thermal adaptation characteristic and dynamic thermal comfort evaluation of the respondents were revealed. The results show that the quantified temperature of past outdoor thermal experience is the quadratic correlation with the thermal sensitivity coefficient and deviation constant, and the linear correlated with outdoor thermal demands. Based on the quantitative analysis, a new outdoor adaptive thermal comfort model has been developed as a function of the exponentially weighted sum of historical mean air temperature series (MeanTrm). The outdoor adaptive thermal comfort zones by 80% and 90% satisfactions thereby have been first drawn based on the Universal Thermal Climate Index (UTCI). The study developed a methodology for the evaluation of dynamic outdoor thermal comfort which can be used for different climate regions.

Thermal stress impaired expression of insulin-like growth factor binding proteins in pigs

This study aimed to investigate the correlation of IGFs, IGFBPs, and IGFBPRs of grower pigs with change in temperature humidity index (THI). THI was calculated to know the months of the year when pigs feel discomfort and samples of feed offered were analyzed to know the nutritional availability/deficit. The calculated average THI was above thermal comfort zone for seven months in a year. It was observed that crude protein (CP) and metabolizable energy (ME) availability to pigs were deficient. Gilts of two months age and similar body weight were randomly divided into two groups (n=6); viz. Con-fed animals (feed offered by the farmer) and For-fed animals (formulated feed supplement + Con-fed). The composition of formulated feed supplement was dried leaf of Moringa oleifera, soybean meal, rice mill waste, and mineral mixture. The plasma cortisol level increased in the experimental animals with accelerated THI as evidenced by the strong positive correlation of THI with HSP70 and HSP90. The level of leptin and ghrelin did not have significant relation with the expression level of HSPs in the present study, however, in the control animals, a low level of leptin was observed. The correlation between the growth factors and HSPs was not significant. During the season, where the THI was above the thermal comfort zone, the IGFBPR and IGFBP concentrations were non-significantly increased along with the increased THI.

Identification of climate change impact and thermal comfort zones in semi-arid regions of AP, India using LST and NDBI techniques

Andhra Pradesh, in southern India, frequently experiences warm summers and winters. However, the year-round greater relative humidity and the positioning of the summer hot spots are linked to actual weather heat exhaustion during the warmest months. Climate change is a significant—and frequently disregarded—factor in the relationship between climate and mortality. With the use of the Land Surface Temperature (LST) and Normalized Difference Built-up Index (NDBI), we sought to identify the climatic change in this research. Additionally, we attempted to identify the Thermal Comfort Zones (TCZs) in Andhra Pradesh, South India's semi-arid regions. Arc GIS and ERDAS Imagine were used to process the satellite data of Landsat 4–5 (TM & MSS), Landsat 7 ETM+, and Landsat 8 OLI for the development of LST and NDBI. The research was conducted for the past thirty years from 1990 to 2020. The resultant thermal comfort zones map was classified into four zones, Zone - I (Safe zone), Zone – II (Moderately safe zone), Zone – III (Risk Zone), and Zone -IV (Highly Risk Zone). The relation between the LST and NDBI is also revealed using correlation regression analysis in the study region. It has been noted that urban centre and high-density regions had greater LST than rural locations. The study finds that although this differs from one ecological zone to another and the distribution of LST intensity in the urban area depends on its changing LULC, various types of land cover within an urban region might impact the spatial pattern of urban LST. The main conclusions of this study might help policymakers understand the need of enabling more sustainable urban development in cities.

The current state of laser technologies in the field of functional coatings

Two main directions in the field of laser radiation application for functional coatings are considered - the application of coatings using purely laser study and the combination of laser and other technologies. The most popular technological lasers used in both directions are identified: gas molecular lasers, diode, fiber, and solid-state lasers. Methods of hardening heat treatment of parts using a laser beam both with and without melting of the material are considered. A method of introducing alloying components of metallic and non-metallic nature into the substrate material using laser technologies is presented. The methods of laser surfacing are given, where the surfacing material is fed into the zone of exposure to laser radiation both in the form of a powder mixture and in the form of a filler wire. Powder mixture is most commonly used as surfacing material, wire is less often used. Technologies of laser-assisted evaporation used in the creation of three-dimensional objects are considered. Hybrid technologies of coating deposition are presented - laser surfacing using a plasma arc and high-frequency heating. It was found out that two types of plasmatrons are used in laser-plasma surfacing - direct and indirect types of action. In addition to hybrid laser surfacing, the method of hybrid laser-assisted evaporation is considered - plasma sputtering, or LAAPS, accompanied by laser heating and allowing to obtain coatings with increased adhesion strength to the substrate surface. The main advantages (the ability to adjust the thickness of the deposited coating layers, reduction of the thermal impact zone) and disadvantages (occurrence of cold microcracks on the surface, formation of pores in the coating) in the application of coatings using laser radiation are considered. The prospects for the development of laser and laser-plasma technologies in the field of functional coatings are analyzed on the example of practical application. The development of these technologies in future is largely due to the elimination of their shortcomings, increasing the efficiency of interaction between laser and plasma technologies.

Household energy use response to extreme heat with a biophysical model of temperature regulation: An Arizona case study

Rising temperatures associated with climate change are impacting household energy use. Many of today’s industrial-technological-urban humans thermoregulate in the face of varying temperatures using extra-metabolic energy use for heating and cooling our indoor microclimates. Previously, household energy use as a function of temperature change over seasons and time has been described using a three-part model of thermoregulation, the Extra-Metabolic Scholander-Irving model (EMSI), where energy use is lowest in the thermal neutral zone around room temperature and increases in colder and hotter temperatures. However, the EMSI model has only been evaluated for moderately warm cities to date, covering only two parts of the three-part model and lacking evaluation of data for extremely hot temperatures. We show that household energy use in Arizona, a U.S. state that includes hot semi-arid environments, varies across topography, and increases in response to the hottest summer months–exemplifying the third part of the EMSI model. Additionally, household energy use is lowest in the spring and fall and increases in response to colder temperatures in the winter. This relationship has hysteresis related to differences in household income; service regions with lower-income households delay the onset of extra-metabolic energy use for cooling. We use this model to gain predictive insights into energy use demand due to ongoing warming in the context of the desert city of Yuma, Arizona, where a relatively small increase in mean temperatures of ~1.5°C since the Industrial Revolution produced a 20-day increase (6%) in cooling days annually. Our study expands the EMSI model of thermal regulation to the previously missing hot part of the model, thereby gaining insights into the unique challenges of sustaining extra-metabolic thermoregulation in the face of global warming.

Bioclimatic zoning for quails in the rain season in the state of Paraíba, Brazil

This work aimed to perform bioclimatic zoning based on the temperature and humidity index (THI) for quails from the 3rd to the 5th week of life during the rainy season in the state of Paraíba, Brazil, in order to identify the most suitable mesoregions among the Zona da Mata, Agreste, Borborema and Sertão for the breeding of these birds and to propose mitigating measures for the thermal comfort of the animals. The monthly air temperature and relative humidity data for calculating the THI were obtained from conventional meteorological stations of the National Meteorological Institute of the Brazilian federal government from 1961 to 2015, in turn making maps with the spatial distribution of the index. The index ranged from 71 to 76 in the various mesoregions of Paraíba, with Agreste being the best mesoregion for breeding quails from the 3rd to the 5th week of life, thus providing a thermal comfort zone for birds and only requiring a few corrective measures in their facilities, when necessary, followed by the Sertão, Zona da Mata and Borborema mesoregions.

Towards scalable physically consistent neural networks: An application to data-driven multi-zone thermal building models

With more and more data being collected, data-driven modeling methods have been gaining in popularity in recent years. While physically sound, classical gray-box models are often cumbersome to identify and scale, and their accuracy might be hindered by their limited expressiveness. On the other hand, classical black-box methods, typically relying on Neural Networks (NNs) nowadays, often achieve impressive performance, even at scale, by deriving statistical patterns from data. However, they remain completely oblivious to the underlying physical laws, which may lead to potentially catastrophic failures if decisions for real-world physical systems are based on them. Physically Consistent Neural Networks (PCNNs) were recently developed to address these aforementioned issues, ensuring physical consistency while still leveraging NNs to attain state-of-the-art accuracy, and applied to zone temperature modeling.In this work, we scale PCNNs to model the temperature dynamics of buildings with several connected thermal zones and propose a thorough comparison with classical gray-box and black-box methods. More precisely, we design three distinct PCNN extensions with different levels of information sharing between the modeled zones, thereby exemplifying the modularity and flexibility of the architecture, and formally prove their physical consistency. In the presented case study, PCNNs are shown to achieve state-of-the-art accuracy, even outperforming classical NN-based models despite their constrained structure. Our investigations furthermore provide a clear illustration of NNs achieving seemingly good performance while remaining completely physics-agnostic, which can be misleading in practice. While this performance comes at the cost of computational complexity, PCNNs on the other hand show accuracy improvements of 17–35% compared to all other physically consistent methods, paving the way for scalable physically consistent models with state-of-the-art performance.

Thermo-hydrological modeling of temperature variations in the spring waters of a headwater catchment (Strengbach critical zone Observatory–France)

This study is geared towards evaluating the hydrological information that can be extracted from spring water temperature variations in shallow and thin aquifers of headwater catchments. A series of temperature variations (from 2013 to 2017) in four spring water sources at the Strengbach Critical Zone Observatory (CZO) was analyzed and interpreted by relying upon a coupled two-dimensional unsaturated–saturated flow and heat transfer model specifically designed for the study. Temperature variations of spring waters at the Strengbach catchment obey a seasonal non-phased and attenuated cyclicity compared with temperature inputs from the air or very shallow waters in soils. Simulation results show that, within the shallow subsurface horizons, heat transfer is mainly controlled by thermal conduction and not by fluid flow. The results also emphasize that the depth and temperature value of the thermal invariance zone are key parameters to surface temperature attenuation patterns in the first meters beneath the surface. The average maximum porosity (or saturated water content) is another important parameter impacting heat transfers in the shallow subsurface. Stronger attenuations and delays of the thermal signal occur as the porosity increases. These different results indicate that temperature variations in the spring waters, especially the attenuation and phase shift of the signals compared with incoming air-surface water temperatures, do not bring information on hydrological transfers. In very shallow systems, characteristics, such as flow velocities and water residence times, cannot be inferred from temperature variations. Nevertheless, this study suggests that spring water temperature variations could become a way of identifying the usually poorly known saturated water content and its spatial variability at the catchment scale.

The radius of thermal influence of the chambers of underground structures of the cryolithozone

The subject of research is the underground structures of the cryolithozone (permafrost zones). The design of such structures, in particular the choice of space-planning solutions, methods and means of fastening rocks, unlike structures located not in frozen rocks, has a number of features and is associated with the need to take into account the zone of thermal influence of chambers operated with different thermal conditions constantly or periodically. For example, when changing the type of thermal regime in the chambers in cases of natural or man-made accidents and catastrophes. The purpose of the research was to determine the zone of thermal influence of a single chamber of an underground cryolithozone structure, depending on the type of fastening used (in the presence and absence of a thermal protective layer) and the duration of the operational period, using various calculation formulas. To achieve this goal, three types of formulas were studied that determine the dependence of the dimensionless radius of thermal influence of chambers on Fourier and Bio criteria. Multivariate calculations were performed using the formulas, which are presented in the form of 3D graphs. The analysis of the performed calculations showed that the calculations for all three formulas give similar results in a fairly wide range of changes in the initial parameters. Moreover, the formula, which does not take into account the influence of the Bio number on the radius of thermal influence, gives a certain calculated margin. In general, it is shown that the higher the value of the Bio number, the less its effect on the depth of the thermal influence zone of the underground chamber. Small values of the Bio number (up to 5-6) are typical for cameras that are fixed with sprayed concrete or have special heat-protective coatings.It is established that when choosing space-planning solutions for underground structures to assess the influence of the thermal factor, it is quite acceptable to use an approximate formula to estimate the radius of the thermal influence of a single chamber. The scientific novelty lies in establishing the scope of the studied formulas for predicting the radius of the zone of thermal influence of cameras with various types of fastening and thermal protection.

Projected expansion of hottest climate zones over Africa during the mid and late 21st century

Projected shifts in thermal climate zones over Africa during the mid and late 21st century are assessed by employing the Thornthwaite thermal classification applied to 40 CMIP6 global climate models under the SSP1-2.6, SSP2-4.5 and SSP5-8.5 forcing scenarios. The CMIP6 multimodel ensemble mean reproduces the observed pattern of thermal zones during the reference period, albeit with some discrepancies. The projections reveal a gradual expansion of the hottest thermal type consisting of a northward and southward displacement of torrid climate zones, with this effect intensifying as greenhouse gas (GHG) forcing increases and the time horizon moves from the mid to the end of the century. In particular, the Mediterranean region, almost all southern African countries, part of East Africa and most Madagascar predominantly warm in present-day conditions, are projected to face mostly hot climates in the mid—21st century and torrid by the end of the 21st century in the high-end forcing scenario. Generally, in the mid—21st century, torrid climates expand by up to ∼15%, 20% and 27% of total Africa’s land areas for the SSP1-2.6, SSP2-4.5 and SSP5-8.5, respectively, with these fractions increasing to ∼16%, 28% and 42% in the late 21st century. Therefore, at the end of the 21st century for the high-end GHG concentration scenario, the African continent will be covered by 81%–87% of torrid climate type, which will have enormous impacts on the sustainable development of African countries.

Summer weather perception and preferences in Powsin Culture Park (Warsaw, Poland)

Green areas situated inside the city play a very important role for many aspects. Among other, from the social point of view, they have a positive impact on the life of city habitants: directly improve well-being and health, reduce noise, provide opportunities for activity and recreation, improve the tourist attractiveness of the city, etc. The objective of this study was to assess thermal sensations and preferences of people staying outdoors for recreational purposes in the area of the city park during summer 2019, as well as to identify how bioclimate perceptions are modified by personal factors (physical and physiological). In order to determine the optimum thermal zone for recreation and urban tourism during the summer, the regression model for mean thermal preferences (MTPV) every 1 °C in PET value intervals was calculated, and according to this procedure, the preferable spectrum of thermal conditions for tourism and recreation in Warsaw which is related to the PET value range between 27.3 and 31.7 °C. All age groups indicated the highest frequency of neutral thermal sensation vote, which decreased with feeling more extreme thermal conditions. In the case of classification by the gender, the men more than the women indicated the thermal conditions as neutral, “slightly warm,” and “warm.” Studies have shown that women were more sensitive than men to extreme thermal sensations especially “hot” and men more often than women indicated greater acceptance for comfortable and warmer thermal conditions.

Hydrothermal alteration of surficial rocks at Los Humeros geothermal field, Mexico: a magnetic susceptibility approach

Utility of the geothermal surface manifestations (GSMs; thermal springs, geysers, fumaroles, and zones of hydrothermal alteration) in the studies related to the geothermal exploration is widely recognized. The identification of hydrothermally altered rocks and zones of alteration is very important because their presence indicates the type and size of the geothermal reservoir and existing thermal conditions. The use of traditional methods (i.e., geochemistry, mineralogy, and petrography) requires expensive equipment, time-consuming, and laborious sample preparation methods. Some of the rock magnetic parameters, like magnetic susceptibility (χlf) and percentage of frequency-dependent magnetic susceptibility (χfd%), are potential to become effective additional tools in identification of the hydrothermal rocks during the initial stages of geothermal exploration. Three chemical methods, Chemical Index of Alteration (CIA), loss-on-ignition (LOI), and the binary plot (CaO + Na2O + K2O) vs. (Fe2O3 + MnO + MgO), along with two rock magnetic methods, χlf and the binary plot (χlf vs. χfd%), are applied to nine intensively altered andesite reference rocks. All the five methods have correctly identified that 99 out of the total 350 studied rocks are altered. More altered rocks are distributed surrounding the several faults in the study area. Various faults (e.g., Los Humeros fault and the Loma Blanca fault) favor fluid flow and present strong hydrothermal alteration at the surface. However, there are no altered rocks on the surface region between the E-W trending Las Papas and Las Viboras faults. The presence of only the deeper fluid pathway toward the east in the surroundings of these two faults result into the almost absence of hydrothermal alteration along their strike at the surface. Consequently, there are not many altered rocks observed surroundings these two faults at the surface. These features suggest that the surface hydrothermal alteration at Los Humeros Geothermal Field (LHGF) is controlled by faults. χlf and χfd% are reliable, simple to measure, fast, cost-effective, and have the potential to become reliable additional tools for future exploration studies.

Real-Time Elastography versus Shear Wave Elastography on Evaluating the Timely Radiofrequency Ablation Effect of Rabbit Liver: A Preliminary Experimental Study

to evaluate and monitor the timely thermal ablation changes of rabbit liver by using two elastographic methods-real-time elastography (RTE) and shear wave elastography (SWE)-as compared to contrast-enhanced ultrasound (CEUS) and physical specimens. 20 ablation zones were created in the livers of 20 rabbits using radiofrequency ablation (RFA). After the ablation, RTE and SWE were used to measure the elastic properties of the twenty ablation zones. The consistency of efficacy evaluation for RTE and SWE measurements was analyzed using the Bland-Altman test. The areas of the thermal ablation zones were also measured and compared according to the images provided by RTE, SWE, CEUS, and gross physical specimen measurement. RTE and SWE could clearly display the shape of RFA ablation zones within one hour after the ablation. The average elasticity ratio for the ablation zone measured by RTE was 3.41 ± 0.67 (2.23-4.76); the average elasticity value measured by SWE was 50.7 ± 11.3 kPa (33.2-70.4 kPa). The mean areas of the ablation zones measured with RTE, SWE, gross specimen, and CEUS were 1.089 ± 0.199 cm2, 1.059 ± 0.201 cm2, 1.081 ± 0.201 cm2, and 3.091 ± 0.591 cm2, respectively. The Bland-Altman test showed that RTE and SWE have great consistency. Area measurements by CEUS were significantly larger than those of the other three methods (p < 0.05). RTE and SWE are both able to accurately confirm the range of ablation zones shortly after the ablation for rabbit livers.

Methodology for Modeling Multiple Non-Homogeneous Thermal Zones Using Lumped Parameters Technique and Graph Theory

Asymmetric thermal zones or even non-rectangular structures are common in residential buildings. These types of structures are not easy to model with specialized programs, and it is difficult to know the heat flows and the relationships between the different variables. This paper presents a methodology for modeling structures with multiple thermal zones using the graph theory arrangement. The methodology allows for generating a mathematical model using all the walls of each thermal zone. The modeling method uses the lumped parameter technique with a structure of two resistors and two capacitors for each thermal zone. The walls and internal surfaces of each zone define the thermal resistances, and the elements for the network structure are created by reducing resistances. The structure selected as a case study is similar to a residential apartment, which demonstrates the possibility of modeling complex and non-traditional structures. The accuracy of the generated mathematical model is verified by comparison with experimental data recorded in a scaled-down model. The reduced model is constructed using a 1:10 ratio with a real apartment. The proposed methodology is used to generate a graph arrangement adjusted to the case study, using the surfaces to build the mathematical model. The experimental data allowed to adjust the simulation results with errors in the range of 1.88% to 6.63% for different thermal zones. This methodology can be used to model different apartments, offices, or non-asymmetric structures and to analyze individual levels in buildings.

Transport mechanisms of hydrothermal convection in faulted tight sandstones

Abstract. Motivated by the unknown reasons for a kilometre-scale high-temperature overprint of 270–300 ∘C in a reservoir outcrop analogue (Piesberg quarry, northwestern Germany), numerical simulations are conducted to identify the transport mechanisms of the fault-related hydrothermal convection system. The system mainly consists of a main fault and a sandstone reservoir in which transfer faults are embedded. The results show that the buoyancy-driven convection in the main fault is the basic requirement for elevated temperatures in the reservoir. We studied the effects of permeability variations and lateral regional flow (LRF) mimicking the topographical conditions on the preferential fluid-flow pathways, dominant heat-transfer types, and mutual interactions among different convective and advective flow modes. The sensitivity analysis of permeability variations indicates that lateral convection in the sandstone and advection in the transfer faults can efficiently transport fluid and heat, thus causing elevated temperatures (≥269 ∘C) in the reservoir at a depth of 4.4 km compared to purely conduction-dominated heat transfer (≤250 ∘C). Higher-level lateral regional flow interacts with convection and advection and changes the dominant heat transfer from conduction to advection in the transfer faults for the low permeability cases of sandstone and main fault. Simulations with anisotropic permeabilities detailed the dependence of the onset of convection and advection in the reservoir on the spatial permeability distribution. The depth-dependent permeabilities of the main fault reduce the amount of energy transferred by buoyancy-driven convection. The increased heat and fluid flows resulting from the anisotropic main fault permeability provide the most realistic explanation for the thermal anomalies in the reservoir. Our numerical models can facilitate exploration and exploitation workflows to develop positive thermal anomaly zones as geothermal reservoirs. These preliminary results will stimulate further petroleum and geothermal studies of fully coupled thermo–hydro–mechanical–chemical processes in faulted tight sandstones.