Equilibrium Zone Research Articles

The Effect of Joint Damage on a Coal Wall and the Influence of Joints on the Abutment Pressure on a Fully Mechanised Working Face with Large Mining Height

Coal wall spalling is regarded as a key technical problem influencing safe and efficient mining of large-mining-height working faces while the distribution of abutment pressure within the limit equilibrium zone (LEZ) influences coal wall spalling within a large-mining-height working face. This research attempted to explore the distribution characteristics of abutment pressure within the LEZ in a large-mining-height working face. For this purpose, the influences of the orientation of joints on mechanical characteristics of coal with joints and on the distribution of abutment pressure within the LEZ in the large-mining-height working face were analysed by theoretical analysis and numerical simulation. Research results show that the damage variable of coal with joints first rises, then decreases, and finally increases with increasing dip angle of the joints; as the azimuth of the joints increases, the damage variable first declines, then increases; the damage variable gradually declines with increasing joint spacing; an increase in the dip angle of joints corresponds to first reduction, then growth, and a final decrease of the abutment pressure at the same position in front of the coal walls; on certain conditions, the abutment pressure at the same position within the LEZ first rises, then declines as the azimuth of joints increases; with the growth of the joint spacing, the abutment pressure at the same position within the LEZ rises. The dip angle and azimuth of joints marginally affect the abutment pressure within the LEZ.

Relationship between advancing abutment pressure and deformation of surrounding rock in a roadway: a case study in Helin coal mine in China

The determination of propulsive abutment pressure and deformation characteristics of roadway surrounding rock mass in top-coal caving mining is of great significance for further research on mining stress, roadway support and equipment selection. This paper adopts the method of combining theoretical analysis and field test, taking Helin coal mine j7401 working face as the research object. The relationship between abutment support pressure and roadway surrounding rock mass deformation is revealed by monitoring the stress of transportation and ventilation roadway and observing the deformation of mining roadway. The main conclusions are as follows: when the distance between top-coal caving mining and borehole is about 65 m, the borehole stress begins to exceed the original rock stress, and the peak of the abutment pressure is 15–22 m in front of the working face, ranging from 33 to 39 MPa, which is 3.2–3.8 times the original rock stress. The intersection of propulsive abutment pressure curve and original rock stress curve is located at 8.1 m in front of the working face, the boundary of roadway rapid deformation stage and deceleration deformation stage is 8.9 m ahead of the working face, the distance between the two stages is 0.8 m, and the peak position of propulsive abutment pressure is 19.8 m. The boundary of roadway decelerative deformation stage and stationary small deformation stage is 20.1 m, and the distance between the two stages is 0.3 m. The boundary between the fracture zone and the limit equilibrium zone is the intersection of the propulsive abutment pressure curve and the original rock stress curve. The plastic zone is constituted by the damage zone and the limit equilibrium zone, and the boundary between the plastic zone and the elastic zone is located at the peak of the propulsive abutment pressure. The above study results provide a basis for roadway support and efficient coal mining.

Influence of the Coal Seam Strength on the Boundary of a Top Coal Limit Equilibrium Zone in a Fully Mechanized Top Coal Caving Stope

Influence of the Coal Seam Strength on the Boundary of a Top Coal Limit Equilibrium Zone in a Fully Mechanized Top Coal Caving Stope

Characteristics of morphodynamic conditions in the shallows of Puck Bay (southern Baltic Sea)

Abstract Puck Bay is an unusual and thus interesting coastal water region, as it combines two different environments – a lagoon and the sea. They differ from each other in their seabed morphology, salinity, dynamics and water exchange. Their common elements are the extensive shallows and the vicinity of the Hel Peninsula. The shallows of Puck Bay have developed at various stages of its evolution, which began several thousand years ago and continues to this day. They have been shaped by varying morphogenetic factors resulting from changes in sea level and accompanying evolution phases of sand barriers, e.g. washover fans, as well as the intensity and directions of sediment transport. At present, the shallows cover more than 35% of the seabed area and are influenced by hydrodynamic factors and availability of sediments. The study area was divided into five fields, taking into account morphological and genetic criteria as well as recent hydrodynamic conditions. This study provides an updated map with classification and distribution of surface sediments and describes grain size parameters for sediment samples collected in the selected fields. Based on a comprehensive assessment of grain size parameters, lithodynamic equilibrium zones were determined and areas of sediment deposition and redeposition were identified.

A thermal nonequilibrium model to natural convection inside non‐Darcy porous layer surrounded by horizontal heated plates with periodic boundary temperatures

AbstractThis article displays a numerical investigation on natural convection within non‐Darcy porous layer surrounded by two horizontal surfaces having sinusoidal temperature profiles with difference in phase and wave number. The Darcy–Brinkman–Forchheimer model and local thermal nonequilibrium condition have been employed. Simulations have been performed for wide ranges of inertia coefficient (10–4 ≤ Fs/Pr* ≤ 10–2), thermal conductivity ratio (0.1 ≤ K r ≤ 100), phase difference (0 ≤ β ≤ π), modified Rayleigh number (200 ≤ Ra* ≤ 1000), wavelength (3 ≤ k ≤ 12), and nondimensional heat transfer coefficient (0.1 ≤ H ≤ 100). Results demonstrate that Nusselt number highly relies on Fs/Pr*, K r, β, Ra*, and k as compared to H. A considerable enhancement in fluid, solid, and overall Nusselt numbers has been observed with diminishing Fs/Pr* and β and increasing k, K r, and H. The raising in β has a significant impact on Nu for smaller k and this effect is almost ignored when k > 12. The increase in Ra*, K r, β, and H and decrease in Fs/Pr* and k acts to reduce the severity of nonequilibrium zone and increase the size of thermal equilibrium zone. The influence of H on nonequilibrium area is more evident than K r.

CO2 capture using activated carbon synthesized from date stone: breakthrough, equilibrium, and mass-transfer zone

Global warming and climate changes are the ultimate consequences of increased CO2 volume in the air. Physical activation was used to prepare high-throughput activated carbon from a low-cost date stone. The adsorption performance of activated carbon using fixed bed for CO2 separation was studied. The reliance of temperature, flow rate, and initial CO2 concentration levels on breakthrough behaviour was analysed. The adsorption response was explored in terms of breakthrough and saturation points, adsorption capacity, temperature profiles, utilization factor, and length of mass-transfer zone. Increased temperatures lead to vary the breakthrough periods notably. The vastly steep breakthrough curves reveal satisfactory utilization of bed capacity. LMTZ is varied positively with increased feed rates and temperatures. The high utilization factor of 0.9738 with 1.66 mmol/g CO2 uptake was acquired at 298 K and 0.25 bars. The findings recommend that the carbon prepared from date stone is encouraging to capture CO2 from CO2/N2 mixture.

Study on the basic properties and mechanism of waste sludge solidified by magnesium phosphate cement containing different active magnesium oxide

Magnesium phosphate cement (MPC) containing different active magnesium oxides was used to solidify waste sludge. The fluidity, setting time, unconfined compressive strength, water resistance, shrinkage deformation, spontaneous imbibition, water absorption, thermal conductivity, leachate and particle shape and arrangement of the solidified body were studied and evaluated. Results showed that MPC can be used as a fast sludge curing agent. When the ratio of dead burnt magnesia to light burnt magnesia was 3:7, the strength was the highest. This suggested that appropriately reducing the reaction rate can quantitatively adjust struvite crystals and increase strength. The retarder reduced the reaction rate and increased the strength, which indirectly indicated that the strength was affected by the rate of formation of hydration products. The shrinkage mainly came from the dry shrinkage induced by the evaporation of water, the conversion of free water in the reaction into the bound water in the crystal, and the shrinkage induced by the heat released by the acid-base neutralization reaction. The unsaturated imbibition was mainly divided into the rapid imbibition stage, the unsteady imbibition stage and the equilibrium zone. Imbibition indexes have a linear relationship with the square root of time. For spontaneous imbibition height: the arrangement of regular hexagonal particles ≤ triangular arrangement < spherical arrangement. The equivalent diameters of different particle shapes and the corresponding pore shape correction factors were derived. This study provided a scientific basis for the feasibility of solidified waste sludge as a slope protection, landfill and sustainable green building material.

Experimental Research on Adsorption Kinetic Characteristics of CH4, CO2, and N2 in Coal from Junggar Basin, China, at Different Temperatures

The adsorption kinetic characteristics of CH4, CO2, and N2 in coal provide crucial information for increasing coal seam gas recovery. In this study, isothermal adsorption kinetics experiments were conducted using automatic high-pressure gas adsorption analyzer to reveal differences in adsorption kinetic characteristics of CH4, CO2, and N2 in coal. The research shows that, before reaching adsorption equilibrium, the adsorption ratio of CO2 was higher than that of N2 while that of CH4 was the smallest. The initial adsorption rates of CO2, CH4, and N2 were 1998, 205, and 76 cm3 g−1 h−1, respectively. The order of decreasing gas adsorption rate with respect to the fluctuation zone was CO2 → N2 → CH4. Before reaching adsorption equilibrium, the gas adsorption ratio at high temperature was higher than that at low temperature. The adsorption rates (Rt) of gas were divided into a rapid decay zone (Rt > 0.1 Qe/h), slow decay zone (0.01 Qe/h < Rt < 0.1 Qe/h), and an adsorption equilibrium zone (|Rt| < 0.01 Qe/h). Among the pseudo-first-order kinetic equation, the Fickian diffusion model and the dynamic diffusion model, the latter can best describe the adsorption kinetic process of coal. This work is expected to improve the theoretical basis of enhancing coal seam gas recovery and enrich the theory of gas adsorption in coal.

Study on the Instability Mechanism and Control Measures of a Roadway in a Mine with Retained Coal Pillars and Close Coal Seams

The deformation and instability of roadway surrounding rock reflect the processes of energy accumulation and release. To reveal the instability of roadway surrounding rock, based on the engineering geological conditions of a certain mine, this paper established a nonuniform superimposed stress model of a coal pillar, starting from the energy accumulation and release of the surrounding rock of the floor roadway after coal pillar failure. The essence of the deformation of the lower roadway was revealed, and the following conclusions were drawn: (1) The elastic strain energy accumulated in the lower roadway roof and upper coal pillar is related to not only the physical properties of the coal seam but also the distance between the coal pillar and surrounding rock, the caving height and shape, the burial depth, and the retained pillar width. (2) The elastic strain energy accumulated in the lower roadway roof and the upper coal pillar induced large displacements of the roadway due to the energy release during excavation. (3) It is proposed that the “stress relief degree” and failure morphology are used to identify zones in the rock and coal, and the two zoning modes have a high consistency. (4) The stress distribution in a narrow coal pillar should be calculated in segments. (5) Based on the zoning and energy release characteristics, the following control factors are suggested regarding the coal pillar width and roadway layout: (a) for the coal pillar, avoid the overlap or intersection of the peak values in the limit equilibrium zone and ensure a sufficient elastic zone; (b) arrange the roadway in shear slip Zone B‐2 or the moderate pressure relief Zone B‐2 to reduce the accumulation of elastic strain energy in the surrounding rock.

Stress Analysis of Negative Coal Pillar Gob-Side Entry and Its Principle of Preventing Rock Burst

Gob-side entry is an area where it is difficult to prevent and control the frequent occurrence of rock burst. Based on “Longwall Mining with Split-level Gateways” (LMSG), this paper puts forward the technology of preventing rock burst by a new gob-side entry (NCPG). The abutment pressure distribution of LMSG shows that the stress peak of solid coal is lower than the conventional panel, and the width of the limit equilibrium zone is also reduced by a small percentage. After the narrow coal pillar gob-side entry has been excavated, the peak stress in solid coal increases, and the width of the limit equilibrium zone decreases, so the practical stress concentration increases. However, the NCPG located in areas of lower stress. The peak stress in solid coal of the NCPG does not increase, but the width of the limit equilibrium zone increases, so the practical stress concentration decreases. NCPC makes the concentrated stress transfer into the deep coal body and plays the role of pressure avoidance. Compared with the narrow coal pillar gob-side entry, the NCPG reduces the energy stored in coal and rock masses and increases the energy consumption. It has significantly improved the regionality, initiative, safety, and timeliness of rock burst prevention in deep high-stress coal seam mining.

CO2 sorption from a mixture of N2/CO2 using an activated carbon and silica gel: equilibrium, breakthrough and mass transfer zone

&lt;p&gt;The temperature, feed rate, length of mass transfer zone, utilization factor and partial pressure are the parameters considered for fixed bed sorption of CO2 from N2/CO2 mixture. The breakthrough time relies strongly on the temperature and feed rate. The prolonged breakthrough and saturation times have been realized for AC. The response curves of AC are vastly steep signifying the maximal utilization of bed capacity at the breakpoint. In general, the length of MTZ increases with raised temperature and feed flow rate. The capacity utilization factor reduces with raised temperature and feed flow rate. A utilization factor of 0.919 was determined for AC. The maximal capacity for CO2 reduces significantly with an increased temperature. The maximal capacities of 32.99 gm CO2/Kg was determined at a temperature of 298 K for AC. The capacity improves considerably with CO2 partial pressure and AC exhibited higher adsorption capacity compared to SG. The capacity improves considerably with increased feed rates and maximal capacity of 39.14 g CO2/Kg adsorbent was determined for AC at the feed rate of 8.33 x10-3 m3/sec. Owing to higher sorption capacity and utilization factor, the AC may be used for economical separation of CO2 from N2/CO2 mixture&lt;/p&gt;&#x0D;

Nucleation and growth of cholesteric collagen tactoids: A time-series statistical analysis based on integration of direct numerical simulation (DNS) and long short-term memory recurrent neural network (LSTM-RNN)

HypothesisLiquid-crystalline phase separation by nucleation and growth (NG) is a crucial step in the formation of collagen-based biomaterials. However, the fundamental mechanisms are not completely understood for chiral lyotropic colloidal mesogens such as collagen. MethodologyTo capture the dynamics of NG under a quenching process into the biphasic equilibrium zone, we use direct numerical simulation based on the time-dependent Ginzburg-Landau model allowing minimization of the total free energy comprised of five key contributions: phase separation (Flory-Huggins), ordering (Landau-de Gennes), chiral orientational elasticity (Frank-Oseen-Mermin), interfacial and coupling effects. LSTM-RNN is applied as a surrogate model to greatly enrich the results. Significant correlations are established using Symbolic Regression. FindingsWe quantify the NG boundaries existing in the collagen phase diagram that has recently been developed and validated by our thermodynamic model (Khadem and Rey, 2019 [1]). We characterize the three NG stages (induction, nucleation, and coarsening) in terms of tactoids’ shape, morphology, growth laws, and population across the NG zone. Wide-range generic correlations are developed, revealing the quench depth dependence of NG characteristics and connecting the sequential NG stages. We confirm experimental observations on time-dependent growth law exponent changes from an initial n≈0.5 for the mass transfer limited regime to n≈1 for the volume-driven phase ordering regime upon increasing quench depth during the nucleation period and having exclusively a value of n≈0.5 for the coarsening period regardless of quench depth. We lastly uncover the underlying physics behind the NG phenomena.

Adsorption behavior of molecular sieve 3 Å and silica gel for CO2 separation: equilibrium, breakthrough and mass transfer zone

In this study, two types of adsorbents, Molecular sieve 3 A and Silica gel 8–20 mesh were used for CO2 separation from CO2/N2 mixture in a fixed bed column. The impact of the temperature, superficial velocity and CO2 partial pressure on the breakthrough behavior, adsorption capacity and mass transfer zone has been thoroughly investigated. The breakpoint time declined with increased temperature, and maximal breakthrough period of 870 s was attained at a temperature of 30 °C using molecular sieve 3 A, which is significantly higher than that obtained for Silica gel 8–20 mesh. Furthermore, the width of the mass transfer zone (MTZ) increases with reduced bed temperatures, which signifies the extent of utilization of bed capacity at the breakpoint. The breakpoint time increases with reduced superficial velocity, and the prolonged breakthrough time was achieved at a minimal superficial velocity of 0.026 m/s for MS 3 A. The adsorption capacity reduced considerably with elevated temperature, and the maximal adsorption capacity of 903.8 mmol CO2/Kg adsorbent was determined at a temperature of 30 °C for MS 3 A. The capacity increases considerably with increased feed superficial velocity, and the capacities of 792 mmol CO2/Kg and 152.9 mmol/Kg adsorbent were achieved for MS 3 A and SG 8–20 mesh, respectively, at a constant superficial velocity of 0.042 m/s. The capacity increases considerably with increased partial pressure of the CO2, and an adsorption capacity of 894.7 mmol CO2/Kg adsorbent was acquired with an equilibrium partial pressure of 0.4 bars utilizing MS 3 A. An adsorption capacity of 167.84 mmol/Kg adsorbent was evaluated at a partial pressure of 0.40 bars by controlling the temperature at 30 °C for SG 8–20 mesh. Owing to its remarkably higher capacity, the MS 3 A adsorbent can be economically utilized for separation of CO2 from CO2/N2 mixture.

Investigation of the flow characteristics with one-line emergent canopy patches in open channel

Experiments are performed on channels with emergent one-line porous canopy patches distributed along the channel sidewalls in which flow dynamics and turbulent structures are analyzed. The evolution of the transverse distribution of the mean streamwise velocity and Reynolds stress profiles in specific transverse sections with downstream distance suggests that a fully equilibrated zone is reached beyond an adjustment distance, and the adjustment distance needed for vegetation with high solid volume fractions is short. The flow field can be divided into three main different regions based on the transverse distribution of the mean streamwise velocity and Reynolds stress in the equilibrium zone: a boundary-affected region, an analog mixing layer, and a uniform region in a non-vegetated area. The analog mixing layer exhibits a two-layer structure governed by local coherent vortices. The dominant frequencies of the vortices at the interface are determined through spectral analysis and proven to correspond to a patch scale. The development of the shear layer, the analysis of the frequencies and scales of the vortices, and the experiment on flow visualization indicate that von-Karman vortices continue to form downstream despite the interference of the sidewall and the special one-line distribution pattern of patches. Quadrant analysis is adopted to illustrate the lateral momentum exchange caused by different motions. Results show that ejections and sweeps are the main contributions to Reynolds stress in the analog mixing layer. Different signs of Reynolds stress in the boundary-affected region and the analog mixing layer can also be explained through quadrant analysis.

Modern globalization: development of glocalization and fragmentation of the world economy

PurposeThe purpose of the article is to analyze the contradictory trends in the development of the modern world economic system. The relevance of the topic is due to the multifaceted and ambiguous nature of regionalization, glocalization and fragmentation tendencies formed as the most important trends in the crisis of globalism.Design/methodology/approachBased on the classical methods of historical and functional analysis, system approach and comparative studies, the authors realized the research potential of modern methodological tools, alternative forecasting methods and comparative modeling, as well as special methods of economic globalistics and global political economy. Heuristic possibilities of the methodological–theoretical concept of glocalization of international economic relations are used.FindingsNew directions and opportunities for attaining regional and global geo-economic leadership are revealed and demonstrated. It is justified that glocalization does not lead to economic isolation in previously known historical forms but to priority realization of the interests of local economic entities included in the processes of globalization and subordinated to its patterns. Glocalization causes an increase in the role of local factors in the global development of the society, in particular of the global economy.Originality/valueIt is established that the so-called equilibrium zones (enjoying the advantages of an intermediary role in the interrelationships of large areas of the world economy, which are headed by geo-economic leaders) possess the potential for novelty in the dynamics of a globalizing economy. The article predicts the formation of a multidimensional and multilevel geo-economic multipolarity due to the reshaping of the global system of leadership in the world economy and due to the contradictory competitive relationships of its main centers.

Еколого-порівняльний аналіз добових змін вегетативного балансу в організмі

Еколого-порівняльний аналіз добових змін вегетативного балансу в організмі

Performance study of activated carbon and silica gel for sorption of CO2 from a mixture of N2/CO2: equilibrium, breakthrough and mass transfer zone

Performance study of activated carbon and silica gel for sorption of CO2 from a mixture of N2/CO2: equilibrium, breakthrough and mass transfer zone

Spatial Characteristics Reveal the Reactive Transport of Radium Isotopes (224Ra, 223Ra, and 228Ra) in an Intertidal Aquifer

AbstractThis study presents high‐resolution two‐dimensional distributions of radium isotopes in the shallow intertidal aquifer of Tolo Harbor, Hong Kong, illustrating the importance of salinity, groundwater residence time, and tidal flushing and mixing in controlling radium behavior in the system. The activities of radium isotopes are low in the fresh groundwater zone with activities increasing in the transition zone (1 &lt; salinity &lt; 25) due to desorption of radium from sediment surface coatings. In the high salinity zone (salinity &gt; 25), the activities of radium isotopes increase with depth due to tidal flushing and mixing of the recirculating seawater in the shallow aquifer as well as increasing residence time with depth. The dissolved radium isotopes are identified to be in disequilibrium in shallow intertidal aquifer based on radium isotopic ratios and observed depletion of dissolved radium isotopes compared to the theoretical mixing line between the equilibrium activity and fresh groundwater. The influence of continuous tidal flushing of the shallow intertidal aquifer on radium is revealed, and shallow sediments are observed to have less total exchangeable radium isotopes than deeper in the aquifer. A new one‐dimensional reactive transport model that considers a depth‐dependent production rate is applied to simulate the vertical distribution of radium isotopes in the intertidal aquifer as seawater infiltrates the beach. Using least squares fitting of the model to field data, the vertical infiltration seepage velocity is estimated to be ~0.5 m/day, and the dimensionless adsorption partition coefficient of radium isotopes (K) is 350. This agrees well with K values (202–365) calculated using an adsorption/desorption model as well as measured values (266 in February and 205 in April). Based on the spatial distribution of radium isotopes and flow patterns in the intertidal aquifer, groundwater in Ra disequilibrium zone is recommended as the endmember for tide‐ or wave‐driven submarine groundwater discharge (SGD) that has shallow flow paths, and groundwater in Ra equilibrium zone is recommended as endmember for seasonally driven or density‐driven SGD that has deep flow paths.

Numerical Simulation of Mandible Bone Remodeling under Tooth Loading: A Parametric Study

Bone adapts to the change of mechanical stimulus by bone remodeling activities. A number of numerical algorithms have been developed to model the adaptive bone remodeling under mechanical loads for orthopedic and dental applications. This paper examines the effects of several model parameters on the computed apparent bone density in mandible under normal chewing and biting forces. The density change rate was based on the strain energy density per unit mass. The algorithms used in this study containing an equilibrium zone (lazy zone) and saturated values of density change rate provides certain stability to result in convergence without discontinuous checkerboard patterns. The parametric study shows that when different boundary conditions were applied, the bone density distributions at convergence were very different, except in the vicinity of the applied loads. Compared with the effects of boundary conditions, the models are less sensitive to the choice of initial density values. Several models starting from different initial density values resulted in similar but not exactly the same bone density distribution at convergence. The results also show that higher reference value of mechanical stimulus resulted in lower average bone density at convergence. Moreover, the width of equilibrium zone did not substantially affect the average density at convergence. However, with increasing width, the areas with the highest and the lowest bone density areas were all reduced. The limitations of the models and challenges for future work were discussed for the better agreement between the computed results and the in vivo data.

Clinopyroxene–Liquid Equilibria and Geothermobarometry in Natural and Experimental Tholeiites: the 2014–2015 Holuhraun Eruption, Iceland

Abstract Clinopyroxene–liquid geothermobarometry is a widely used tool for estimating the conditions under which mafic magmas are stored before they erupt. However, redox variability, sector zoning and disequilibrium crystallization present major challenges to the robust estimation of magma storage conditions. Moreover, most recent studies seeking to address these challenges have focused on clinopyroxenes from alkalic systems and are thus of limited use for understanding clinopyroxenes from the tholeiitic systems that dominate global magma budgets. Here we combine observations on natural clinopyroxenes from the 2014–2015 Holuhraun lava in Iceland with observations on experimental clinopyroxenes synthesized during high-pressure, high-temperature experiments on the same lava in order to investigate clinopyroxene–liquid equilibria in tholeiitic systems and optimize of geothermobarometric strategies. Natural clinopyroxenes from the 2014–2015 Holuhraun lava are sector zoned, with {1-11} hourglass sectors being enriched in the enstatite–ferrosillite component at the expense of all other components with respect to {hk0} prism sectors. In contrast with observations on clinopyroxenes from alkalic systems, sector zoning in clinopyroxenes from the 2014–2015 Holuhraun lava is characterized by differences in Ca and Na contents as well as in Ti and Al contents. The products of crystallization experiments performed at 100–600 MPa and 1140–1220 °C on a powdered starting glass at two sets of melt H2O content–oxygen fugacity conditions (∼0·1 wt % H2O and close to the graphite-oxygen redox buffer, and 0·5–1·0 wt % H2O and approximately one and half log units above the quartz–fayalite–magnetite redox buffer) demonstrate that clinopyroxene crystals from nominally equilibrium experiments can preserve strongly disequilibrium compositions. The compositional systematics of experimental clinopyroxenes are consistent with the presence of sector zoning. Furthermore, the magnitude of compositional variability increases with decreasing melt H2O content and increasing deviations of experimental temperatures below clinopyroxene liquidus temperatures (i.e. degrees of undercooling sensu lato), indicating that kinetic processes play a key role in controlling clinopyroxene compositions, even under notionally equilibrium conditions. Few published analyses of experimental clinopyroxene crystals may thus represent truly equilibrium compositions. Stoichiometric calculations on natural and experimental clinopyroxenes show that Fe3+ is a major constituent of clinopyroxenes from tholeiitic magmas under naturally relevant oxygen fugacity conditions. They also show that Fe3+ is most likely incorporated as Ca- and Al- bearing Ca–Fe-Tschermak’s component rather than Na-bearing aegirine component at oxygen fugacities up to one and a half log units above the quartz–fayalite–magnetite buffer. Elevated oxygen fugacities are thus less likely to compromise clinopyroxene–liquid geothermobarometry than previously thought. Guided by our experimental results, we combined published descriptions of clinopyroxene–liquid equilibria with geothermobarometric equations to develop an internally consistent and widely applicable method for performing geothermobarometry on tholeiitic magmas that does not require equilibrium zones to be selected a priori. Applying this method to natural clinopyroxene crystals from the 2014–2015 Holuhraun lava that formed under low but variable degrees of undercooling (perhaps 25 °C or less) returns values in excellent agreement with those from independent methods (232 ± 86 MPa, 1161 ± 11 °C). Robust estimates of magma storage conditions can thus be obtained by performing clinopyroxene–liquid geothermobarometry on tholeiitic magmas when disequilibrium is suitably accounted for.