Exothermic Phase Research Articles

Acoustic frequency-based method for high-speed aircraft combustion analysis and hybrid artificial intelligence diagnostics

In the paper, a method of high-speed continuous combustion monitoring for jet aircrafts, based on acoustic data processing, is proposed. As part of the research, acoustic signals corresponding to the specific phases of the combustible mixture formation and its combustion were separated. They were assigned to the generated process energy value. In the result, parametric functions were obtained in multidimensional spaces of states and processes. Parameters and acoustic characteristics in the amplitude, frequency and JTFA domains constituted information about particular symptoms in the jet engine, thanks to which reference waveforms of signals and forms for specific malfunctions were mapped. The above graphic characteristics have been parameterized to determine their diagnostic reliability factors.The method is verified by empirical signals obtained from turbojet propulsion system in time and power dependent conditions. Appropriate exothermic combustion phases were assigned for the determined acoustic spectra, taking into account the obtained power. Then, representative diagnostic parameters transformed in the process values domain were calculated. Finally, monitoring functions and algorithms of combustion efficiency with determination of malfunctions sources (at dynamic conditions) are proposed.As a result, it is possible to identify first outbreaks of design and process failures during fuel injection and combustion in aircrafts, taking into account artificial intelligence methods. The obtained results indicate it is possible to adapt the acoustic characteristics of the spectra and their discrete representatives, for appropriate states and failures, to detect first dangerous symptoms in the aircraft during flight conditions (supporting OBD with the acoustic adaptive diagnostic procedures).

Periodic open cellular structures (POCS) as catalyst support for intensified heat transport in the partial oxidation of methanol to formaldehyde

Heat transport in catalytic reactors is one of the most important factors in reactor design, especially for highly endo- or exothermic reactions. The limited thermal conductivity of randomly packed beds can be significantly improved when alternative catalyst supports are used. A new generation thereof are periodic open cellular structures (POCS), which are used in this study as catalyst support for the partial oxidation of methanol to formaldehyde, an exothermic gas phase reaction. A comparison to traditional packed bed reactors revealed that a POCS made of the highly conductive alloy AlSi10Mg can significantly reduce the hot-spot temperature, allowing almost isothermal operation at optimal reaction conditions. The improved temperature control allows for operation with higher methanol inlet concentrations and wall temperatures as compared to the commercial process. The beneficial heat transport properties of POCS were used to conduct isothermal kinetic measurements at elevated temperature. Based on these findings and the design freedom of additive manufacturing, an optimized cellular structure was designed and fabricated, which improved the heat transport especially in the critical inlet section of the reactor.

In situ Raman spectroscopy study of the oxidative polymerization of aniline in media of different acidity

In situ Raman spectroscopy was used for the first time to study the reaction intermediates/products of the oxidative polymerization of aniline to polyaniline (PANI) with peroxydisulfate in aqueous solutions of different initial acidity. Raman spectra were recorded for the drops of reaction mixture taken at various reaction times. Five reaction systems with different pH of the monomer solution (pHmon), leading to 1-D nanostructured PANIs (pHmon =5.8, 4.6 and 4.5) and granular PANIs (pHmon= 3.4 and 1.0) were explored. Spectral characteristics of different reaction phases - athermal, exothermic and post-propagation were identified and correlated with the proposed mechanisms of aniline polymerization and nanostructures formation. For the nanostructured PANIs, the athermal phase was characterized by pronounced strengthening of the δ(N−H)/ν(CN)Q band at 1510–1520 cm−1, while the characteristic of the second exothermic phase was the strengthening of the ν(C∼C)B/ν(C∼C)Phz band at c.a. 1636 cm−1 which becomes stronger than the ν(CC)Q/ν(C∼C)SQ band at c.a. 1590 cm–1. For granular PANIs, the band at 1590 cm–1 was stronger than that at 1630 cm–1 for all reaction phases. For all reaction systems, characteristic feature of the post-propagation phase was strengthening of the ν(C∼N+•) band at 1330–1340 cm−1 due to delocalized polarons. For granular PANIs, the band associated with phenazine-like units at c.a. 1415 cm−1 disappeared after the exothermic phase, while for nanostructured PANIs it was seen until the end of the reaction. The obtained results are expected to be useful in further investigations of the intermediates/products and mechanisms of polymerizations of other aromatic amines.

Mechanical and electrochemical properties of porous NiTi intermetallics synthesized via rapid thermal explosion

In this paper, porous NiTi intermetallic was synthesized via a modified thermal explosion (TE) method, utilizing Ni (74 μm, 38 μm, 5 μm, 100–200 nm) and Al element powders as raw material. The exothermic behavior and phase transition of porous NiTi intermetallic compounds were studied. The results showed that with the refinement of Ni particle size, the heat release decreased, and the Ti-74 μm sample was the product of two eutectic reactions. Their mechanical properties were verified by the Vickers hardness tester and universal testing machine, and the corrosion behavior of porous NiTi intermetallic compounds in phosphate-buffered saline (PBS) solution was studied by electrochemical tests. Among them, Ti-5 μm exhibits the most homogeneous microstructure and favorable mechanical properties, which has a porosity of 31.7 % and a compressive strength of 321.71 MPa. However, corrosion resistance is sacrificed due to the high open porosity. This study holds great promise for precise control microstructural characteristics and optimization of mechanical and electrochemical properties of porous NiTi intermetallics.

ZrB2–MoSi2 ceramics: Kinetics of compaction during hot pressing in СО environment, phase interactions at interfaces and static fatigue

Ceramics in the ZrB2–MoSi2 system pass through different stages during hot pressing in CO-CO2 environment. The first stage follows a smooth parabolic curve up to 1600 °C, then, a sharp compaction to full density occurs by transient liquid-phase sintering in the 1610–1850 °C temperature range. Ceramics sintered in this range have the primary compounds, ZrB2 and MoSi2, disappeared and new phases, such as (ZrB2)SS, SiC, B4C and ZrC, formed. The high sintering rate are associated to exothermic phase transformations, which significantly increase the temperature in the diffusion zones. In the 1850–2150 °C range, complete homogenization of the solid solution based on ZrB2 occurs and the sintering curve follows that typical of solid-state densification, i.e. increases continuously and slowly. Materials sintered at 1370–1850 °C have matrix grain size around 0.6–1.8 µm, while those sintered at 1940–2150 °C have grain size around 8–10 µm. Hot compression tests showed that the ZrB2-MoSi2 ceramic sintered at 1870 °C had the highest creep resistance compared with a ZrB2-SiC baseline.

Sustainable assessment of an integrated energy system coupled with solar thermochemical cycle

The energy transition globally makes the development of carbon-free and low-carbon fuels obligatory as these fuels cannot only be utilized as energy carriers but also for long-term energy storage. This paper presents the energy, technoeconomic, and environmental assessment of a new hybrid renewable energy integrated system with a novel concept of the thermochemical cycle for methanol production. For this purpose, a thermochemical cycle based on CeO2/Ce2O3 oxides is integrated with the methanol synthesis system. It consists of two chemical steps: (1) oxygen carrier reduction step where metal oxide reduction Ce (IV) to Ce (III) (endothermic phase) is performed employing renewable thermal energy and chemical energy originated from ultra-high concentrated photovoltaics and fossil methane respectively and (2) waste gas dissociation step where oxidation of Ce(III) takes place with dissociation of water and carbon dioxide (exothermic phase) and resulting syngas is converted to methanol. Plant design and simulation are performed in ASPEN plus commercial software. MATLAB was employed for the programming of thermal data to perform pinch analysis. The technical feasibility of the second step was investigated comprehensively in terms of temperature, input molar ratio and the potential operating conditions that were identified (TOXI = 900 °C and H2O/CO2 = 3.7) based on methanol production performance. Overall energy efficiency, solar-to-fuel efficiency and thermal efficiency are calculated to be 77.2%, 38% and 44.1% respectively. The findings of the environmental analysis show that carbon utilization of 20.85%, carbon storage of 79.14%, carbon capture of 100% and carbon avoidance of 19.6% are achieved. Economic analysis shows that the net project capital expenditure (CAPEX) and operating expenditure (OPEX) are estimated to be $186.49M and $218.67M. It was found that the best-case scenario of natural gas (NG) price is 40$/MWh, where the breakeven point is achieved during the 5th year of the project lifetime.

Polyurethane Exothermic Polymerization and Phase Change Material Thermal Delay Matching: An Approach to Reducing Fire Risks in Mining Polymer Materials

Polyurethane Exothermic Polymerization and Phase Change Material Thermal Delay Matching: An Approach to Reducing Fire Risks in Mining Polymer Materials

Microencapsulated binary eutectic phase change materials with high energy storage capabilities for asphalt binders

Octanoic acid (OA) and tetradecane (TD) underwent mixing and the eutectic method to improve the energy storage capacities of phase change materials (PCMs) that were reduced by microencapsulation. A microencapsulated phase change material (MPCM) was synthesized by using nano-TiO2 and polyvinyl alcohol reinforced melamine formaldehyde resin as the wall and wrapping materials of OA–TD. The chemical composition, morphological structure, thermal properties, and thermal stability of the MPCM were analyzed. Additionally, the effects of microcapsules on asphalt properties and the ability to regulate asphalt temperature were investigated. The results showed that neither eutectic nor microencapsulated encapsulation produced new characteristic peaks. The MPCMs were transparent spheres with particle sizes of 1–50 μm and good formability. Compared with OA and TD, the enthalpy values of the exothermic phase transition process of OA–TD increased by 67.6% and 10.7%, respectively, and the phase transition temperature ranges increased by 53.5% and 26.7%, respectively. The exothermic enthalpy of the formed MPCM is 140.61 J/g, which provides latent heat and good thermal stability when mixed with asphalt. Temperature regulation tests demonstrated that MPCM effectively reduced the cooling rate and peak temperature of asphalt. The addition of MPCM to asphalt resulted in a decrease in penetration and ductility, but an increase in softening point. At high temperatures, MPCM enhanced the apparent viscosity, composite modulus, and rutting factor of asphalt, thereby improving its high-temperature deformation resistance.

Mechanical activation time of 6B2O3–13Al powder mixture vs. structure and phase composition of SHS products

The paper discusses the time of mechanical activation of the 6B2O3–13Al powder mixture affecting the self-propagating high-temperature synthesis (SHS), exothermic reaction temperature, structure, and phase composition of synthesis products. It is found that the time increase of the mechanical activation up to 180 min leads to a reduction in the average size of aluminum and boron trioxide particles down to 4.8 and 3.5 μm, respectively. Aluminum particles with boron trioxide inclusions are observed on the particle surface and inside their structure. Changes in the particle size and structure in the initial mixture components modify the SHS reaction front from chaotic to by layers. The structure of SHS products consists of the alumina layer (63–68 wt%) with aluminum dodecaboride (AlB12) particles (32–37 wt%) distributed under this layer. After 10 and 60 min of mechanical activation, acicular and elongated AlB12 particles appear in products synthesized from the 6B2O3–13Al powder mixture. Based on the data obtained, the SHS with subsequent mechanical activation is proposed for the fabrication of the Al2O3/AlB12 nanocomposite from the 6B2O3–13Al powder mixture. It is shown that after washing grinded SHS products with hydrochloric acid solution, the synthesized powder contains 100 wt% AlB12.

Synergistically enhanced structural, thermal and interfacial stability of K0.45MnO2 via tailoring the local structure for high-energy and high-power potassium-ion batteries

Mn-based layered oxides are widely considered as cost-effective cathodes for K-ion batteries (KIBs), whereas the local lattice distortion induced by the Jahn-Teller effect of Mn3+ usually results in limited capacity and unsatisfactory cycling lives. Herein, a new P3-type K0.45Mn0.9Al0.1O2 material is designed via riveting electrochemical inactive Al3+ in the octahedral Mn3+ sites, which is experimentally proved to play a key role in suppressing misfit dislocations at the atomic scale, enlarging the spacing of K+ layers, relieving exothermic phase transition at elevated temperature and helping to form a stable and uniform cathode electrolyte interphase (CEI) layer synergistically. Thanks to these inherent merits, K0.45Mn0.9Al0.1O2 delivers a high specific capacity of 152 mAh/g at 20 mA g−1 and excellent cyclic performance with capacity retention of 67 % over 1000 cycles, much superior to K0.45MnO2. Impressively, the full battery achieves a high energy (291 Wh kg−1) and power (843 W kg−1) densities over state-of-the-art layered cathodes for KIBs. This study not only provides a facile and effective strategy to jointly enhance the structural, thermal and interfacial stability of Mn-based layered cathodes, but also the underlying mechanism revealed here sheds light on designing novel cathodes via tailoring the local structural environments.

Subpixel Analysis of Primary and Secondary Infrared Emitters with Nighttime VIIRS Data

Biomass burning is a coupled exothermic/endothermic system that transfers carbon in several forms to the atmosphere, ultimately leaving mineral ash. The exothermic phases include flaming and smoldering, which produce the heat that drives the endothermic processes. The endothermic components include pre-heating and pyrolysis, which produce the fuel consumed by flaming and smoldering. These components can be broadly distinguished from each other based on temperature. For several years, we have researched the subpixel analysis of two temperature phases present in fire pixels detected in nighttime VIIRS data. Here, we present the flaming subtractive method, with which we have successfully derived temperatures and source areas for two infrared (IR) emitters and a cooler background. This is developed as an add-on to the existing VIIRS nightfire algorithm version 3 (VNF v.3) which uses Planck curve fitting to calculate temperatures and source areas for a single IR emitter and background. The flaming subtractive method works with data collected in four spectral ranges: near-infrared (NIR), short-wave infrared (SWIR), mid-wave infrared (MWIR) and long-wave infrared (LWIR). With sunlight eliminated, the NIR and SWIR radiances can be fully attributed to the primary IR emitter. The analysis begins with Planck curve modeling for the primary emitter based on the NIR and SWIR radiances, yielding temperature, source area and primary emitter radiances in all spectral bands. The primary emitter radiances are subtracted from each spectral band and then the residual radiance is analyzed for a secondary IR emitter and the background. Spurious results are obtained in pixels lacking a discernable secondary emitter. These misfit pixels revert back to the single IR emitter analysis of VNF v.3. In tests run for two California megafires, we found that the primary emitters straddle the temperature ranges for flaming and smoldering, the exothermic portions of biomass burning, which are apparently commingled on the ground. The secondary emitter temperatures span 350–750 K, corresponding to pre-heating and slow pyrolysis. The natural gas flare test case had few numbers of successful secondary emitter retrievals and a wide range of secondary emitter temperatures. The flaming subtractive analysis is the key addition to VNF version 4, which will commence production later in 2021. In 2022, we will seek validation of the VNF v.4 from nighttime Landsat and other data sources.

Repeatability and Reproducibility Study of Organic Material (Musa AAB Simmonds) in the Measurement of Enthalpy and Transition Temperature

To establish repeatability and reproducibility parameters in the enthalpy values obtained in a differential scanning calorimeter, DSC Q2000, the endothermic and exothermic phase changes of Musa AAB Simmonds (Plantain). Were used peel samples were analyzed in a temperature range between -50 °C and 500 °C; with heating rates between 2 °C/min and 10 °C/min, in an N 2 atmosphere, and mass values of 3.0 mg, 6.0 mg and 9.0 mg. For variability analysis, a completely randomized experimental design with factorial structure, to model the effect of sample mass and heating rate on the enthalpies associated with three anomalies presented by the organic material studied. In the analysis of variance, it was found that, although the factors Mass (mg) and Rate (°C/min), influence the uncertainty, there is no dependence between them when it comes to the peak temperature variables. The analysis of enthalpy with respect to mass (mg) showed that there are no differences between the masses at significance levels greater than 0.20, attributable to the fact that the enthalpy measurement is made for first order phase transitions, i.e., the enthalpies correspond to latent heats which are constant for the same material.

Effects of strain rate on strain-induced martensite nucleation and growth in 301LN metastable austenitic steel

The effects of strain rate on strain-induced α′-martensite nucleation and growth were analyzed in this work. Tension tests were performed at room temperature at strain rates of 2×10−4 s−1 and 0.5 s−1 using small polished specimens that fit inside a scanning electron microscope. The specimens were deformed incrementally, and microstructural evolution was tracked carefully at a specific location on the specimen surface. This approach allows the analysis not only of the spatial but also of the temporal evolution of the α′-martensite. Optical microscopy images and electron backscatter diffraction (EBSD) measurements were taken for each plastic deformation increment. The size and number of α′-martensite particles were evaluated from the EBSD images, whereas local microlevel strains were obtained using Digital Image Correlation (DIC). According to the results, the number of nucleation sites for α′-martensite does not seem to be affected much by the strain rate. However, there is a notable strain rate effect on how the transformation proceeds in the neighborhood of freshly formed α′-martensite particles. At a low strain rate, repeated nucleation and coalescence leads to the notable growth of α′-martensite particles, whereas at a high strain rate, once nucleated α′-martensite particles remain as small isolated islands that do not markedly grow with further plastic strain. This phenomenon can be attributed to local microstructure-level heating caused by plastic deformation and exothermic phase transformation. This reduces the local growth rate of the α′-martensite particles in the vicinity of the above-mentioned islands, thus leading to a lower bulk transformation rate at higher strain rates.

Polymorphism in early development: The account of MBQ-167

With McCrone’s famous statement in mind, we set out to investigate the polymorphic behavior of a small-molecule dual inhibitor of Rac and Cdc42, currently undergoing preclinical trials. Herein, we report the existence of two polymorphs for 9-ethyl-3-(5-phenyl-1H-1,2,3-triazol-3-yl)-9H-carbazole (MBQ-167). These were characterized by differential scanning calorimetry, thermogravimetric analysis, Raman and Infrared spectroscopy, as well as powder and single crystal X-ray diffraction. The results obtained from the thermal analysis revealed that MBQ-167 form II undergoes an exothermic phase transition to form I, making this the thermodynamically stable form. An examination of the Burger-Ramberger rules for assigning thermodynamic relationships in polymorphic pairs indicate that this system is monotropic. The structure elucidation reveals that these forms crystallize in the orthorhombic (Pbca) and monoclinic (P21/n) space groups. A conformational analysis shows that the metastable form (form II) presents the most planar conformation along the significant torsion angles identified. Hirshfeld surface analysis confirms that van der Waals contacts are the primary interactions and only subtle differences in short contacts help differentiate each form. These findings support the notion that polymorphism is prevalent in organic molecules and that one should invest time and money probing possible polymorphs, particularly in early development as in the case of MBQ-167.

Preparation and characterization of phase-change energy storage nonwoven fabric

In this work, a phase-change energy storage nonwoven fabric was made of polyurethane phase-change material (PUPCM) by a non-woven melt-blown machine. Polyethylene glycol 2000 was used as the phase transition unit and diphenyl-methane-diisocyanate as the hard segment to prepare PUPCM. Thermal stability of the PUPCM was evaluated through thermal stability analysis. The performance of pristine PUPCM was determined by Fourier transform infrared spectroscopy and differential scanning calorimetry to analyze the spinning technology of spinning temperature and the stretching process. Phase-change energy storage nonwoven fabric (413.22 g/m2) was prepared, and the morphology, solid–solid exothermic phase transition, mechanical properties, and the structures were characterized. The enthalpy of solid–solid exothermic phase transition reached 60.17 mJ/mg (peaked at 23.14°C). The enthalpy of solid–solid endothermic phase transition reached 67.09 mJ/mg (peaked at 34.34°C). The strength and elongation of phase-change energy storage nonwoven fabric were found suitable for garments and tent fabrics.

Experimental study on heat storage and exothermic characteristics of spherical high temperature fixed composite phase change materials

ABSTRACT In this study, Al-Si/fly ash spherical high temperature shaped composite phase change material (heat storage ball) was made, and an experimental device for heat storage and release characteristics of the heat storage ball was designed and built. The experiment verified that the accuracy of the device met the requirements. The surface and center temperature of four heat storage spheres with different heating/cooling rates and different pressing processes were measured and their heat storage and release characteristics were analyzed. The results show that the heating/cooling rate is higher, the heat storage/release rate is higher, the temperature difference between the surface layer and the center of the heat storage sphere is greater, the heat transfer resistance is greater, and the heat storage/release efficiency is lower. The heating/cooling rate and the diameter of the regenerative ball had little influence on the temperature at the melting/solidification starting point, but had great influence on the temperature at the melting/solidification ending point of the regenerative ball. The phase transition temperature range of Al-Si alloy was expanded, the heating rate was higher, the melting termination point temperature was higher. Higher grade heat energy was needed for heating and heat storage, it increased the requirement of heat source. The end temperature of solidification of cooling rate 6°C/min and 9°C/min was lower than 500°C, it exceeded the lower limit of high-temperature heat storage/exothermic temperature, and the utilization of high-temperature heat energy could not be realized. For high-temperature heat storage/release, the 15 diameter heat storage ball was prepared by the process (1), phase change latent heat was high and heat storage was ample. When the heating/cooling rate was 3°C/min, the phase change temperature range of Al-Si alloy was relatively reasonable, the heat storage phase change temperature was 567.0 ~ 599.9°C, and the exothermic phase change temperature was 542.4 ~ 504.7°C, it met the requirements of high-temperature heat storage/release.

Effects of Strain Rate on the Strain Induced Martensite Nucleation and Growth in 301LN Metastable Austenitic Steel

The effects of strain rate on the strain induced α’-martensite nucleation and growth were analysed in this work. Tension tests were performed at room temperature at strain rates of 2×10-4 s-1 and 0.5 s -1 using small polished specimens, which fit inside a scanning electron microscope. The specimens were deformed incrementally, and microstructural evolution was tracked carefully at the same location. This approach allows analysing not only the spatial but also the temporal evolution of the α’-martensite. Optical microscopy images and electron backscatter diffraction (EBSD) measurements were taken for each plastic deformation increment. The size and number of α’-martensite particles were evaluated from the EBSD images, whereas the local microlevel plastic strains were obtained with Digital Image Correlation (DIC). According to the results, the number of nucleation sites for α’-martensite does not seem to be affected much by the strain rate. However, there is a notable strain rate effect on how the transformation proceeds in the neighbourhood of freshly formed α’-martensite particles. At low strain rate, repeated nucleation and coalescence leads to notable growth of the α’-martensite particles, whereas at high strain rate, once nucleated α’-martensite particles remain as small isolated islands which do not markedly grow with further plastic strain. This phenomenon can be attributed to local microstructure level heating caused by plastic deformation and the exothermic phase transformation. This reduces the local growth rate of the α’-martensite particles in the vicinity of the above-mentioned islands, thus leading to a lower bulk transformation rate at higher strain rates.

Development of a technology of isothermal annealing with the use of the forging heat for chromium‑molybdenum steel

The article discusses the results of investigations performed during a thermo-mechanical treatment of forgings made of chromium‑molybdenum 42CrMo4 grade steel. The treatment was realized during a regular series production. The forging process was combined with a heat treatment carried out directly after forging on a specially adapted station. Such a production technology will make it possible to eliminate the step of repeated heating of the forgings. On the example of an element of a steering gear, it was demonstrated how it is possible to perform an isothermal annealing process starting from the temperature at which the trimming of the forgings ends. During the cooling of the forgings, it is enough to maintain the temperature at the proper level in order for the exothermal phase transformation of austenite into pearlite to take place. The test results show that, with the properly selected temperature of isothermal annealing, it is possible to obtain an equilibrial ferritic-pearlitic structure in the required hardness scope. Introducing such a solution into the industrial practice would allow savings more than 80% of the energy used for the heat treatment of forging in this case.

Maximum mass of hybrid star formed via shock-induced phase transition in cold neutron stars

ABSTRACT This paper studies the maximum mass limit of the hybrid star formed after the shock-induced phase transition of a cold neutron star. By employing hadronic and quark equation of state that satisfies the current mass bound, we use combustion adiabat conditions to find such a limit. The combustion adiabat condition results in a local or a global maximum pressure at an intermediate density range. The maximum pressure corresponds to a local or global maximum mass for the phase transformed hybrid star. The phase transition is usually exothermic if we have a local maximum mass. The criteria for exothermic or endothermic phase transition depend on whether the quark pressure/energy ratios to nuclear pressure/energy are smaller or greater than 1. We find that exothermic phase transition in a cold neutron star usually results in hybrid stars whose mass is smaller than a parent neutron star. The phase transition is endothermic for a global maximum pressure; thereby, one gets a global maximum mass. Hybrid stars much massive than phase transformed local maximum mass can be formed, provided there is some external energy source during the phase transition process. However, for some cases, even massive hybrid stars can form with exothermic phase transition for equations of state having global maximum pressure.

Controls on the present-day dynamic topography predicted from mantle flow models since 410 Ma

SUMMARYMantle convection induces dynamic topography, the lithosphere's surface deflections driven by the vertical stresses from sublithospheric mantle convection. Dynamic topography has important influences on a range of geophysical and geological observations. Here, we studied controls on the Earth's dynamic topography through 3-D spherical models of mantle convection, which use reconstructed past 410 Myr global plate motion history as time-dependent surface mechanical boundary condition. The numerical model assumes the extended-Boussinesq approximation and includes strongly depth- and temperature-dependent viscosity and phase changes in the mantle. Our results show that removing the chemical layer above the core–mantle boundary (CMB) and including depth-dependent thermal expansivity have both a limited influence on the predicted present-day dynamic topography. Considering phase transitions in our models increases the predicted amplitude of dynamic topography, which is mainly influenced by the 410 km exothermic phase transition. The predicted dynamic topography is very sensitive to shallow temperature-induced lateral viscosity variations (LVVs) and Rayleigh number. The preservation of LVVs significantly increases the negative dynamic topography at subduction zones. A decrease (or increase) of Rayleigh number increases (or decreases) the predicted present-day dynamic topography considerably. The dynamic topography predicted from the model considering LVVs and with a Rayleigh number of 6 × 108 is most compatible with residual topography models. This Rayleigh number is consistent with the convective vigor of the Earth as supported by generating more realistic lower mantle structure, slab sinking rate and surface and CMB heat fluxes. The evolution of the surface heat flux pattern is similar to the long-term eustatic sea level change. Before the formation of Pangea, large negative dynamic topography formed between the plate convergence region of Gondwana and Laurussia. The predicted dynamic topography similar to that of present-day has already emerged by about 262 Ma. Powers for degrees 1–3 dynamic topography at 337 and 104 Ma which correspond to times of higher plate velocities and higher surface heat fluxes are larger.