Present Heat Flow Research Articles

Regional assessment of the ultra-deep geothermal (UDG) reservoir quality and potential of the Dinantian Zeeland Formation, the Netherlands

Abstract Dinantian carbonates in the NW European Carboniferous Basin (NWECB) in the Netherlands form a target for ultra-deep geothermal (UDG) exploration. The NWECB was a deep water area with shallow water attached carbonate systems in the southwestern Netherlands and isolated carbonate platforms nucleated on horsts in the northern part of the Netherlands. Carbonate platforms in the SW Netherlands contain intra-Dinantian, sub-Namurian and sub-Cretaceous karst systems with irregular cavities, enlarged fracture systems and collapse breccias with relict porosity. Isolated carbonate platforms in the northern Netherlands were not affected by sub-Namurian or sub-Cretaceous karst but contain petrophysical anomalies interpreted as intra-Dinantian karst or fracture systems. The matrix reservoir quality of Dinantian limestones is generally poor but has been improved by a phase of regional dolomitization that affects the lower parts of both isolated and attached carbonate platforms. Dolomitization took place during burial and was associated either with late Carboniferous to early Permian burial or a thermal event during the middle to late Jurassic. Additional reservoir quality is present in a system of hydrofractures in late Tournaisian ramp carbonates in the SW Netherlands that post-date dolomitization; the fracture system may have formed during late Jurassic basin inversion. Present heat flow indicates that two isolated carbonate platforms in the northern Netherlands are buried to sufficient depth to be considered as potential UDG exploration targets. Attached carbonate systems in the SW Netherlands are too shallow to have been heated to the temperature required for industrial applications or for generating electricity from geothermal energy.

Present geothermal field of the Santos Basin, Brazil

The Santos Basin, located in the southeastern waters of Brazil, is a passive continental margin basin with the most abundant deepwater petroleum resources in the world discovered to date. However, few studies have been conducted on the present geothermal fields of the Santos Basin, which severely restricts the oil and gas resource evaluation of the basin. This study first utilizes 35 temperature data from 16 post-salt drilling wells and 370 temperature data from 31 pre-salt drilling wells to calculate the post-salt and pre-salt geothermal gradients and terrestrial heat flows in the Santos Basin. Then, the basin simulation software BasinMod 1D is used to quantitatively evaluate the impacts of salt rock sedimentation on the present geothermal fields and the maturity of pre-salt hydrocarbon source rocks. The results demonstrate that the present post-salt geothermal gradient in the Santos Basin is 2.20–3.97 °C/100 m, with an average value of 2.99 °C /100 m, and the post-salt terrestrial heat flow is 54.00–97.32 mW/m2, with an average value of 73.36 mW/m2, while the present pre-salt geothermal gradient is 2.21–2.95 °C/100 m, with an average value of 2.53 °C/100 m, and the pre-salt terrestrial heat flow is 61.85–82.59 mW/m2, with an average value of 70.69 mW/m2. These values are characteristic of a low-temperature geothermal field in a zone with a stable structure. The sedimentation of the salt rock causes a decrease in the temperature of the pre-salt strata, which inhibits pre-salt hydrocarbon source rock maturity, with an inhibition rate of up to 1.32%. The inhibition degree decreases with increasing salt rock thickness. At the same time, the salt rock thickness is positively correlated with the present surface heat flow. The unique distribution of the salt rock and related salt structures lead to present terrestrial heat flow differences among different structural units in the basin. This study is of great significance for evaluating and exploring the pre-salt oil and gas resources in the Santos Basin.

Contribution to Active Thermal Protection Research—Part 1 Analysis of Energy Functions by Parametric Study

The thermal energy consumption for heating objects is one of the main parameters deciding their technical and structural solution. Reducing energy consumption is realized in various ways. The most used method is passive thermal protection, that is, increasing the thermal insulation parameters of the envelope constructions and optimizing the operation of the technical equipment of the buildings. There are also methods of active thermal protection to reduce heat leakage through non-transparent parts of the building envelope. Active thermal protection (ATP) is a dynamic process that applies primarily to building structures with integrated energetically active elements that fulfill one or more functions in mutually exclusive operating modes of energy systems and heat sources, such as thermal barriers (TB), large-scale heating/cooling, long-term heat/cool storage, capturing solar energy, and energy from the surroundings or even recovering heat in the cold season or cold in the warm season and other combinations. The research area focuses on analyzing active thermal protection’s energy potential. The methodology is based on a parametric study of dynamic thermal resistance (DTR), and heat flows to the interior and exterior from ATP for the investigated envelope of the experimental house EB2020 made of aerated concrete blocks. Such constructions generally show a consistently high DTR of 11.8 to 30.8 ((m2·K)/W) at a low mean heat transfer temperature of 10 to 16 °C, corresponding to the thermal insulation of 300 to 1000 mm. In the case of ATP storage heating with an average temperature of the heat-carrying substance of 30 °C, the heat flow into the interior of the investigated structure would be only 2.31 W/m2. Therefore, they are only suitable for a thermal barrier and heat/cold accumulation. Based on the synthesis and induction of analogical forms of the results of previous research into recommendations for the design of individual energy functions of ATP for perimeter structures of buildings, we present heat flows to the interior/exterior when changing the material of the layers towards the interior from ATP and describe possible variants of the development of building structures with integrated energetically active elements.

High Heat Flow Anomaly Within the St Paul Fracture Zone: Heat Advection and/or Inherent Thermal Structure?

AbstractHeat flow across oceanic transform faults (TFs) and fracture zones (FZs) has rarely been studied in detail, despite these features representing distinct thermal boundaries within the oceanic lithosphere. Here, we present heat flow measurements across the St Paul fracture zone (SPFZ) in the equatorial Atlantic Ocean, from 48 Ma crust in the south to 71 Ma in the north. To the north of the FZ we find a basal heat flow of 63 mWm−2, and to the south a basal heat flow of 79 mWm−2, both in agreement with plate cooling models. However, within the SPFZ we find a heat flow of 83 mWm−2, greater than the values of the adjacent crust and 10–15 mWm−2 higher than predicted from conductive cooling models, suggesting that the thermal structure of the FZ has been modified. Evidence from seismic and sub‐bottom profiler data indicate recent active deformation within the SPFZ, potentially driven by lithospheric flexure across the FZ or temporal changes in TF configuration. We propose that this deformation may enable fluid circulation and heat advection within the basement, creating the seafloor heat flow anomaly within the FZ. These findings suggest that FZs may remain important zones predisposed to host deformation and fluid flow in the oceanic lithosphere, despite not being active plate boundaries.

The role of geotectonic setting on the heat flow distribution of southern South America

SUMMARYThe surface heat flow of southern South America was examined based on an updated database containing 1113 locations. Accordingly, this study presents the most accurate heat flow map of the southern portion of the continent (south of 16°30′S latitude), covering areas that previously presented limited information. The main anomalies show a strong spatial correlation with geothermal zones and with the most up-to-date lithospheric thickness maps. The blanketing effect produced by the sedimentary basins reduce the surface heat flow up to 27 mW m–2 over the thickest basins. The study region was separated into four large areas and their connection to tectonic processes analysed. The Central Andes present high heat flow zones related to a thick radiogenic crust, volcanic activity, and a hot asthenospheric wedge. In the Pampean flat-slab region, the low heat flow coincides mostly with the horizontal projection of the Juan Fernández aseismic ridge and not with a wide region as previously thought. Furthermore, a close relationship between the subduction of the ridges at different angles and a cold upper-plate lithosphere is suggested. Besides active regions of arc magmatism and a thin lithosphere, we propose that a hot upper-plate upwelling beneath the Patagonian Platform is also contributing to the high heat flow in the area. The foreland region exhibits a low heat flow coinciding with a thick cratonic lithosphere, and local high heat flow values in suture zones possibly triggered by ancient delamination beneath these regions.

1D modelling of the NW Sab'atayn Basin Upper Jurassic source rocks, Yemen: Implications for hydrocarbon generation and thermal maturity

Sab'atayn Basin is considered to be the most petroliferous Mesozoic basin in Yemen, although exploration efforts in the northwestern part of the basin are unproven due to scant drilling activities. In this work one‐dimensional (1D) basin modelling was used to examine the hydrocarbon generation and expulsion history of the Upper Jurassic source rocks using PetroMod2012.2 software. The geo‐history modelling was applied for the studied wells, and it shows that some stratigraphic units are missing, which adversely affect the tectonics, sedimentary subsidence, burial history, hydrocarbon maturation, and generation. There is a major period of subsidence that occurred in the Upper Jurassic and is manifest in the Kamaran‐01 well. In addition, a second major uplift occurred in the Miocene and had a discernible effect on heat flow distribution as well as burial histories. Reverse heat flow is observed in the Saba‐01 well, where the present heat flow is greater than the palaeo‐heat flow. The beginning of petroleum generation in the Meem and Lam members (Madbi Formation) source units has been predicted to occur during the Late Jurassic, and subsequently occurred in the Lower Cretaceous. Peak expulsion of hydrocarbons from the Meem Member occurred in the Eocene and late Oligocene, while expulsion modelling performed on the Lam Member asserts that it has not reached the phase of oil expulsion.

Present Heat Flow and Paleo‐Geothermal Anomalies in the Southern Golan Heights, Israel

AbstractWhile present heat flow (HF) throughout Israel and the Dead Sea Transform (DST) area is considered low, a thermal anomaly exists near the Yarmuk valley at the southern tip of the Golan Heights. New temperature measurements in the southern Golan Heights show that the distribution of the thermal anomaly is significantly wider than previously thought. The new data conforms to either a local and shallow magmatic chamber, which is in thermal steady state with the surrounding rocks, or to a transient heat front associated with localized Pleistocene magmatic intrusions in the Yarmuk. An alternative mechanism suggests that the present HF intensity is higher than the HF value calculated based on the apparent borehole temperatures due to heat removal by deep aquifer flow. A paleothermal analysis was performed using high‐resolution organic matter maturation profiles on the Late Cretaceous source rocks, across the southern Golan basin. The maturation data show remarkably similar values throughout the basin, indicating that a single thermal event led to the source rock maturation. Constraints given by geological considerations have associated the paleothermal event with Pliocene volcanic eruptions, which has allowed the calculation of the basin paleo‐heat flows, and indicated on a basin wide heat source, such as a crustal heat source. The paleothermal event is sharply bounded by a DST branching fault. This observation is suggested to be related to either strike‐slip movement associated with the DST or to heat removal and modulation by a deep hydrological system.

Distribution of Present Heat Flow in the Phu Khanh Basin, Offshore Vietnam

This study aims to determine the distribution of present heat flow in the Phu Khanh basin from shallow water to deep water throughout the basin. The results from 42 present heat flow data points extracted from the global heat flow database by Goutorbe et al. (2011) indicated that there is an uneven distribution of the present heat flow in the research area. Heat flow accumulation in uplift structures in the north-west direction (78 - 86 mW/m2) of the Phu Khanh basin is usually higher than in trenches or deep depressions in the south-east direction of the basin (58 - 72 mW/m2). This is due to the sediment layer up to more than 10,000m thick in the deep water of the Phu Khanh basin. As a result, heat flow values in deep water are significantly lower than in shallow water of the Phu Khanh basin. The thick sediment layer acts as an insulator that prevents heat flow from escaping to the surface. The mean values of present heat flow calculated from wells TH - 1X and CMT - 1X are 85.60 mW/m2 and 83.20 mW/m2 respectively. These values are relatively consistent with the predicted results from Kriging 42 data points extracted from the global heat flow data set in the study of Goutorbe et al. (2011). The high present heat flow values can be explained by the fact that the Phu Khanh basin is still experiencing thermal subsidence because of its relatively young age (approximately 35 million years). This basin has not yet regained its thermal equilibrium value after the Early Oligocene - Miocene extension stage, so the present heat flow value is still high in this basin.

Heat Flow Data in an Area of the Eastern Southern Basin and Range in Arizona Contribute to an Analysis of Neogene Lithosphere Thinning Greater than 100 Km

Abstract Heat flow data and thermochronologic derived paleotemperature gradient data are examined to calculate heat flow ~25 Ma and, at present, for a southern Basin and Range location north of Tucson, Arizona. An increase in the surface heat flow is estimated from ~25 Ma to the present; changing from ~47 to ~83 mW m-2. Steady-state conduction temperature vs. depth profiles provide estimates of lithosphere thicknesses both for the present and for ~25 Ma. Different heat transfer models for present heat flow predict present LAB depth that agrees with seismic studies. From these temperature profiles, lithosphere thinning from ~184 km to ~70 km is suggested during the Neogene. Mantle lithosphere thinning caused by thermal phenomena is likely a fundamental driving force for southern Basin and Range extension. Because the mantle lithosphere has likely thinned much more than the crust, it is shown that additional vertical advection, such as an asthenosphere plume, delaminating part of the mantle lithosphere, convection cells, and rising magmas along conduits, add to the vertical advection component of upper mantle lithosphere extension. Interestingly, values of heat flow 25 Ma, lithosphere thicknesses 25 Ma, and Neogene lithosphere thinning are somewhat similar for the Four Corners area of the Colorado Plateau and the southern Basin and Range, even though Neogene tectonic development was quite different, i.e., no Neogene extension in the Colorado Plateau vs. ~57% in the southern Basin and Range. Neogene lithosphere thinning phenomena are likely different in the two regions.

Optimization of the lumped parameter thermal model for hard-cased li-ion batteries

Abstract Li-ion batteries are widely employed for electric vehicles. Real-time prediction of the internal battery temperature is crucial for accurate battery management system control. This paper intends to optimize the lumped parameter thermal model so that it is able to precisely present heat flow distribution and achieve broad applicability for online battery temperature estimation. Three lumped parameter thermal models for hard-cased Li-ion batteries are proposed, including the two-state lumped thermal model (2STM), five-state lumped thermal model (5STM), and improved five-state lumped thermal model (5STM+). The 5STM+ considers the heat transfers between the surface states of the 5STM. The model parameters are identified through solving linear equations and nonlinear curves fitting in the least square sense based on experimental data. Model applicability is confirmed by the evaluation of calculation accuracy under seven possible application situations. It is found that 2STM and 5STM behave excellently with uniform boundary conditions, but lead to significant discrepancy for local liquid cooling scenarios. 5STM+ provides high calculation accuracy under all proposed situations, covering natural convection, forced air convection, regional liquid cooling as well as localized heating. Meanwhile, the calculation time consumption is only a millisecond level. It is practical for online battery internal temperature estimation.

Formation of detrital clay grain coats by dewatering of deep-water sands and significance for reservoir quality

ABSTRACTWell-developed detrital clay grain coats are observed in deep-marine sandstones of the Upper Cretaceous Springar Formation of the Vøring Basin in the Norwegian Sea. The detrital clay coats form thin and compact rims on individual sand grains and meniscus-shaped bridges between grains. These well-developed coats are found in high-density turbidites and proximal hybrid event beds with common to pervasive dewatering structures deposited in proximity to the base of a syndepositionally active basin high. Here, in one exploration well, detrital clay grain coats are common throughout a sandstone package 100 m thick. High-density turbidites and proximal and distal hybrid event beds drilled in mid- to distal-fan settings unaffected by seismically resolved seafloor topography show common dewatering features, but have only scattered detrital clay coats confined to individual dewatering pipes or dish structures. Hence, we propose that intense sediment dewatering has the potential to form detrital clay coats in deep-marine sandstones by a combination of elutriation and reorganization of clays during fluid escape from sediment bodies with pore fluid pressures significantly higher than the hydrostatic pressure. In submarine fan systems, deposition of sediment with coeval trapping of large volumes of interstitial pore fluid is most likely to occur where gravity flows undergo rapid deceleration in response to an abrupt decrease in confinement or gradient. Such environments include the channel–lobe transition and settings in proximity to seabed topography.The investigated sandstones are quartz arenites and subarkoses, with minor to moderate volumes of quartz cement (up to 6%). However, strongly to completely quartz-cemented intergranular pore space is observed where detrital clay coats or matrix does not cover quartz grains in the deepest part of the studied formation. Modeling of quartz cementation predicts that most intergranular macroporosity in the lower part of the Springar Formation would be quartz cemented if the sandstones were free of detrital clays. Based on our observations and modeling results we propose that intense sediment dewatering has the potential to form detrital clay coats, which can be important for retaining porosity in deeply buried sandstones and in basins with high present or past heat flow.

Thermal evolution of the Northern Cordillera Volcanic Province: implication for heat flow in remnant back-arc regions

ABSTRACT Active and remnant back-arc regions do not follow a typical conductive lithosphere cooling model, but instead have an apparent two-stage cooling, defined by a high heat flow back-arc region during subduction and a second post-subduction heating event that extends elevated heat flow for several 10s million years. Numerical one-stage cooling models have not reproduced observed heat flow anomalies in active subduction zones using physically realistic parameters and require a secondary post-subduction heating mechanism. Here, an extension driven-volcanism model is developed to examine extension driven heating and volcanism as a mechanism to produce a prolonged thermal anomaly within back-arc lithosphere. This model is tested using the recorded thermal evolution of the Northern Cordillera Volcanic Province (NCVP), a Neogene-Quaternary alkaline volcanic province located in the remnant back-arc region of the Pacific-North American subduction zone in British Columbia, Canada. A single steady-state lithosphere geotherm does not intersect all previously published temperature estimates, suggesting previous data record the thermal evolution of the NCVP. Calculated geotherms at equilibrium with the minimum and maximum MELTS temperatures predict an increase in reduced mantle heat flow (Qm ) from 43 to 72 mW/m2 and lithosphere thinning from a depth of 87 to 48 km. The newly developed extension-volcanism model reproduced the calculated pre- and post-volcanism thermal regimes for the NCVP and supports that extension within the remnant back-arc could produce the present heat flow anomaly and volcanism. The model most readily produces volcanism when Qm is ~45–65 mW/m2, a typical range for back-arcs. Back-arc regions are prime locations for limited volcanism because their warmer thermal regime minimizes tectonic stress requirements to produce volcanism. Additionally, two-stage cooling of back-arcs can be explained with a time-dependent extension-volcanism thermal feedback mechanism that is possible because of the subduction driven pre-heating of back-arc regions.

Accurate meso-scale simulation of mixed convective heat transfer in a porous media for a vented square with hot elliptic obstacle: An LBM approach

In the present study, heat and fluid flow of water in a vented cavity with elliptical hot obstacle is numerically investigated using Lattice Boltzmann Method (LBM). This flow is assumed to be laminar, 2D and incompressible. The main purpose in this work is to investigate the effect of utilizing porous medium on mixed convective heat transfer in an obstructed vented cavity. The simulations are performed for Richardson number of 0.1, 1 and 10, porosity of 0.5, 0.7 and 0.9, and solid-to-fluid conductivity ratios of 10, 33.3, 66.7 and 100. The results are presented by streamlines, temperature contours, and Nusselt number curves. Results show that by increasing Richardson number, due to the dominance of natural convective heat transfer compared with that of the forced case, the heat penetration in fluid layers in all areas of the cavity is increased. Moreover, as the Richardson number increases, due to limitation of forced heat transfer, the temperature gradients in the cavity rise and the growth of thermal boundary layer becomes significant. This behavior has an undesirable effect on heat transfer of hot obstacle especially around the cavity outlet and right side of the obstacle. By decreasing the cavity porosity, the areas around the hot obstacle will experience higher heat penetration into the fluid and consequently the heat transfer is reduced. In this study, the highest Nusselt number is obtained for Richardson number of Ri=0.1 and porosity of Po=0.5 and the increase in Richardson number and porosity coefficient results in reduced Nusselt number in all areas around the hot obstacle. The porosity changes have more significant effect on heat transfer in smaller Richardson numbers. This results in Nusselt number higher about 79% in best condition at conductivity ratio of 33.33 (Ri=0.1) while it changes the Nusselt number about 17.4% at conductivity ratio of 10 (Ri=10).

Analysis of heat and fluid flow between parallel plates by inserting triangular cross-section rods in the cross-stream plane

In the present research, heat and fluid flow between the parallel plates has been investigated in the presence of the forward triangular cross-section rods. The rods are located at different non-dimensional axial distances such as S/Lh = 1/3, 1/4, and 1/5. In addition, the rods are distributed at two rows having vertical non-dimensional gap spaces of G/H = 0, 0.1, and 0.2. Computations have been performed numerically by means of the finite volume approach at various Reynolds numbers in the range from 400 to 1000 based on the channel mean velocity and its hydraulic diameter. Several quantitative and qualitative results are presented in the present study. It is found that all parameters under consideration such as S/Lh, G/H, and Re have considerable effects on the flow behavior and heat transfer rate of the advanced channel. In other words, decreasing S/Lh (or increasing the number of rods) as well as increasing the Reynolds number upgrades the channel heat transfer performance, generally. However, the maximum heat transfer enhancements occur in the case of G/H = 0.1 at each S/Lh and Re. The maximum heat transfer enhancement of the advanced channel with respect to the conventional parallel plate is obtained with 64.8% under Re = 1000, G/H = 0.1, and S/Lh = 1/5. Moreover, values of the pressure drop penalty and goodness factor have been presented accordingly for all cases under consideration.

Present Terrestrial Heat Flow Measurements of the Geothermal Fields in the Chagan Sag of the Yingen‐Ejinaqi Basin, Inner Mongolia, China

Owing to the lack of terrestrial heat flow data, studying lithospheric thermal structure and geodynamics of the Yingen‐Ejinaqi Basin in Inner Mongolia is limited. In this paper, the terrestrial heat flow of the Chagan sag in the Yingen‐Ejinaqi Basin were calculated by 193 system steady‐state temperature measurements of 4 wells, and newly measuring 62 rock thermal conductivity and 20 heat production rate data on basis of the original 107 rock thermal conductivity and 70 heat production data. The results show that the average thermal conductivity and heat production rate are 2.11±0.28 W/(m·K) and 2.42±0.25 μW/m3 in the Lower Cretaceous of the Chagan sag. The average geothermal gradient from the Lower Suhongtu 2 Formation to the Suhongtu 1 Formation is 37.6 °C/km, and that of the Bayingebi 2 Formation is 27.4 °C/km. Meanwhile, the average terrestrial heat flow in the Chagan sag is 70.6 mW/m2. On the above results, it is clear that there is an obvious negative correlation between the thermal conductivity of the stratum and its geothermal gradient. Moreover, it reveals that there is a geothermal state between tectonically stable and active areas. This work may provide geothermal parameters for further research of lithospheric thermal structure and geodynamics in the Chagan sag.

Burial and thermal evolution of coal-bearing strata and its mechanisms in the southern North China Basin since the late Paleozoic

During the interaction between the South China plate and the North China plate, the southern North China Basin (SNCB) underwent a strong tectonic thermal evolution in the early Mesozoic. Recently, burial history reconstruction and thermal maturity simulation of coal-bearing strata from the Late Carboniferous to the present were carried out in the SNCB. Rock-Eval pyrolysis (12 samples), vitrinite reflectance (60 samples), apatite fission track (AFT) analysis (17 samples), and PetroMod 1D were performed on wells located in the SNCB. Geothermal gradients were found to range between 30.3 and 36.4 °C/km, averaging 31.0 °C/km, and present heat flow was found to vary between 51 and 58, averaging 55 mW/m2. The paleo heat flow model with higher heat flow peaks of 86 mW/m2 during the first rifting phase resulted in the best fit between the calculated and the observed vitrinite reflectance and bottom hole temperatures in the modeling. Using this model of thermal maturity history combined with AFT analysis, we analyze the main hydrocarbon generation stages and discuss the coupling relationship of thermal maturity history with tectonic evolution. The results indicate that tectonic activities restrict the thermal maturity evolution of source rocks to a large extent by controlling the geotemperature. The thermal history demonstrates that two phases of heating (315–163 Ma, 83–38 Ma, depositing) happened to the source rocks, separated by two cooling (163–83 Ma, 38–23 Ma, uplifting) events. The maturity history indicates that the process of hydrocarbon generation can be divided into three stages in the SNCB (315–163 Ma, thermal genesis gas generation stage; 163–83 Ma, gas reservoir destruction stage; 83–0 Ma, secondary biogas generation stage). Hydrocarbon generation started as early as 198 Ma with a peak at 162 Ma, and expulsion started at around 195 Ma. The Taiyuan and Shanxi formations' source rocks reached a high maturity (1.0% < Ro < 1.3%) with a greater potential for hydrocarbon generation, and the Xiashihezi formation is mid-mature (0.7% < Ro < 1.0%) with limited hydrocarbon generation potential at the present day.

Finite Difference Simulation of MHD Radiative Flow of a Nanofluid past a Stretching Sheet with Stability Analysis

In the present study, unsteady heat and mass nanofluid flow past a stretching sheet with the effect of thermal radiation and magnetic field was carried out. To obtain non-similar equation, the boundary layer governing equations including continuity, momentum, energy and concentration balance were non-dimensionalized by usual transformation. The non-similar approach was employed, which depends on the dimensionless parameters such as Magnetic parameter (M), Radiation parameter (R), Prandtl number (Pr), Eckert number (Ec) Lewis number (Le), Brownian motion parameter (Nb), Thermophoresis parameter (Nt), Local Reynolds number (Re) and velocity parameter (b/a). The temperature and concentration distributions are found affected by these dimensionless parameters. The obtained equations have been solved by explicit finite difference method (EFDM). A theoretical model of the stability and convergence to describe the aspects of the finite difference scheme was developed in this study. This analysis makes the EFDM approach more accurate and able to provide the convergence criteria of the method (Pr ≥ 0.375 and Le ≥ 0.25). The temperature and concentration profiles are discussed for the different values of the dimensionless parameters by considering different time steps. The present computational investigation finds applications in the area of magnetic nanomaterials processing.

Effect of Freeze Dryer Design on Heat Transfer Variability Investigated Using a 3D Mathematical Model

During the freeze-drying process, vials located at the border of the shelf usually present higher heat flow rates that result in higher product temperatures than vials in the center. This phenomenon, referred to as edge vial effect, can lead to product quality variability within the same batch of vials and between batches at different scales. Our objective was to investigate the effect of various freeze dryer design features on heat transfer variability. A 3D mathematical model previously developed in COMSOL Multiphysics and experimentally validated was used to simulate the heat transfer of a set of vials located at the edge and in the center of the shelf. The design features considered included the vials loading configurations, the thermal characteristics, and some relevant dimensions of the drying chamber geometry. The presence of the rail in the loading configuration and the value of the shelf emissivity strongly impacted the heat flow rates received by the vials. Conversely, the heat transfer was not significantly influenced by modifications of the thermal conductivity of the rail, the emissivity of the walls, or the geometry of the drying chamber. The model developed turned out to be a powerful tool for cycle development and scale-up.

Present temperature field and Cenozoic thermal history in the Dongpu depression, Bohai Bay Basin, North China

The Dongpu depression is located in the southern Bohai Bay Basin, North China, and it has abundant oil and gas reserves. There has been no systematic documentation of this depression's temperature field and thermal history. In this article, the present geothermal gradient and heat flow were calculated for 68 wells on the basis of 892 formation-testing data from 523 wells. Moreover, the Cenozoic thermal history was reconstructed using 466 vitrinite reflectance data from 105 wells. The results show that the Dongpu depression is characterized by a medium-temperature field between stable and active tectonic areas, with an average geothermal gradient of 34.8 °C/km and an average heat flow of 66.8 mW/m2. The temperature field in the Dongpu depression is significantly controlled by the Changyuan, Huanghe, and Lanliao basement faults and thin lithosphere thickness. The geothermal gradient twice experienced high peaks. One peak was during the Shahejie 3 Formation depositional period, ranging from 45 °C/km to 48 °C/km, and the second peak was in the middle and late of the Dongying Formation depositional period, ranging from 39 °C/km to 40 °C/km, revealing that the Dongpu depression experienced two strong tectonic rifts during the geothermal gradient high peak periods. The geothermal gradient began to decrease from the Neogene, and the geothermal gradient is 31–34 °C/km at the present day. In addition, these results reveal that source rock thermal evolution is controlled by the paleo temperature field of the Dongying Formation depositional period in the Dongpu depression. This study may provide a geothermal basis for deep oil and gas resource evaluation in the Dongpu depression.

Cenozoic development of southwestern Malay Basin: new insights from subsidence analysis and thermal history

Subsidence and thermal history analysis are carried out in order to investigate the Cenozoic basin development of the southwestern (Tenggol Arch and basinal side) part of the Malay basin. Structurally, the southwestern part consists of normal faults and horst and graben geometry. Tectonic subsidence curves show that the basinal side is more active than the Tenggol Arch due to movement along normal faults. Cenozoic development initiated with the deposition of sedimentary Units M & L (Oligocene) and the activation of the Tenggol fault on the basinal side. Several periods of accelerated and slow subsidence are observed during the Oligocene to Middle Miocene that could be associated with changes in regional stresses caused by pulsating plate movement. The Malay Basin experienced inversion throughout the Middle to Late Miocene related to mantle induced slab avalanche effect, causing relatively higher tectonic subsidence rates on the Tenggol Arch compared to the basinal side, suggesting that the Tenggol Arch is less affected by inversion than the basinal side. After a period (Late Miocene) of non-deposition, the basin was reactivated (Pliocene to recent) due to thermal relaxation with thick sedimentation. Paleo heat flows estimated utilizing a novel technique introduced in this study and present day heat flow calibrated using BHT data further supports our results, in that increase in heat flow is related to rapid tectonic subsidence. An anomalously high heat pulse affected the basin during inversion and could be the cause of meta-sediment formation whereas present heat flows, although high compared to average basins, shows decreasing trend from the inversion period.