Thermal Carbon Research Articles

Comparison of microalgal hydrochar and pyrochar: production, physicochemical properties, and environmental application.

Microalgal biomass has been considered the third-generation biofuel production feedstock, but microalgae-derived biochar still needs to be thoroughly understood. This study aims to evaluate the production and physicochemical properties of microalgae-derived hydrochar produced by hydrothermal carbonization (HTC) process by comparison with pyrochar produced by dry thermal carbonization (DTC) process for environmental applications. Microalgal biochar was produced with commercially available Chlorella vulgaris microalgae using HTC and DTC processes under various temperature conditions. Pyrochar presented higher pH, ash contents, porosity, and surface area than hydrochar. Hydrochar gave more oxygen-containing functional groups on the surface and higher lead adsorption than pyrochar, making the microalgal hydrochar applicable in soil amendment and various environmental remediations. HTC could be an economically feasible thermochemical process for microalgal biochar production. It can produce hydrochar with high production yield from wet microalgae at low temperatures without a drying process.

Selection of the Utility Function of the Historic Building, Taking into Account Energy Efficiency

The energy efficiency of the building should be understood as the degree of preparation of the building to ensure the comfort of its use in accordance with its intended use with the lowest possible energy consumption of the building. The article presents an in-depth analysis of the possibility of changing the utility function of a historic building in such a way that ensures all aspects of comfort while meeting energy efficiency conditions. Combinatorics methods were used for this purpose. Four possible utility functions were proposed, including the reference state, i.e., the existing state. Five aspects of comfort were considered: thermal comfort, carbon footprint, energy efficiency, noise and vibration. For these five aspects of comfort, boundary conditions were adopted depending on the adopted building class. The selected utility function is therefore the result of comfort, energy efficiency and economic aspects. The purpose of the study was to verify whether the developed methodology for the selection of the utility function for historic buildings, based on combinatorial analyses, would allow the selection of the optimal function from the point of view of energy efficiency, user comfort and environmental impact. The methodology was tested on a historic building located in southern Poland. The new utility function for the analyzed building is to use the historic villa (or some part of it) as an Art Gallery.

Functional Activated Biocarbons Based on Biomass Waste for CO2 Capture and Heavy Metal Sorption.

Inexpensive porous activated biocarbons were prepared from biomass and agriculture waste following the method of thermal and hydrothermal carbonization and activation with superheated water vapor. The activated biocarbons were characterized by nitrogen adsorption-desorption at 77 K, SEM, XRD, Raman spectrometry, FTIR spectroscopy, determination of particle size, and elemental composition by XRF. The specific surface area was in the range of 240-709 m2/g, and the total pore volume was from 0.12 to 0.43 cm3/g. The percentage of microporosity in activated biocarbons was 89-92%. These activated biocarbons have been used for CO2 and heavy metal sorption. Activated biocarbons based on pine cones and birch prepared by thermal carbonization and activation with superheated water vapor had the highest ability to capture CO2 and amounted to 6.43 and 6.00 mmol/g at 273 K, as well as 4.57 and 4.22 mmol/g at 298 K, respectively. The best activated biocarbon was characterized by unchanged stability after 30 adsorption and desorption cycles. It was proved that the adsorption of CO2 depends on narrow micropores (<1 nm). Activated biocarbons have also been analyzed as effective adsorbents for removing Cu2+, Zn2+, Fe2+, Ni2+, Co2+, and Pb2+ ions from aqueous solutions. Activated biocarbons are effective adsorbents for the removal of lead and zinc ions from aqueous solutions.

Experimental study of the mechanical and thermal properties of metakaolin based geopolymer stabilized soil during low temperature curing

To address the challenges associated with significant thermal disturbance and carbon emissions resulting from the conventional stabilization of frozen soil using cement, geopolymer material is used to replace cement to stabilize frozen soil. The unconfined compressive strength (UCS) of the geopolymer stabilized soil was investigated in relation to the proportions of metakaolin (MK), calcium carbide slag (CCS), curing temperature, and curing age. Microscopic analysis was conducted to unveil the stabilized mechanism. The UCS, shear strength, thermal conductivity, hydration products and microstructure of geopolymer stabilized soil and cement soil were compared in parallel. A total of 240 experiments were conducted in this study. The outcomes indicate that the optimal content of MK and CCS is 10% and 6% respectively. The UCS of samples with the optimal content after 28d of curing at 20 °C, −2 °C, and − 10 °C are 3.783 MPa, 1.164 MPa, and 0.901 MPa respectively. The primary causes of the rise in UCS of the geopolymer stabilized soil are the production of amorphous calcium silicate hydrate and calcium aluminate hydrate gel as a result of the stimulation of MK based geopolymer with CCS. The UCS of the geopolymer stabilized soil decreases with a decrease in curing temperature. In frozen conditions, the expansion of ice crystals in the soil creates voids and promotes crack growth, leading to a decrease in the efficiency of geopolymerization reactions. After 28d of curing at room temperature and low temperature, the geopolymer stabilized soil with the optimal content exhibits higher UCS, failure strain, shear strength, cohesion, and internal friction angle compared to the cement soil. At all curing temperatures and ages, the geopolymer stabilized soil has a lower thermal conductivity than the cement soil. The geopolymer stabilized soil is less susceptible to low temperature curing than cement soil, demonstrating a larger amount of hydration products and a denser microstructure, according to experimental results from XRD and SEM. The results of this work offer a theoretical foundation for using geopolymer in place of cement to stabilize soils in permafrost regions.

Comfort, carbon emissions, and cost of building envelope and photovoltaic arrangement optimization through a two-stage model

The design of a high-performance building necessitates tradeoffs among multiple performance objectives, and many simulation-based optimization tools have been developed for this purpose. In practice, these tools are often constrained by excessive computational load and tight project deadlines. This study aimed to develop a holistic approach to rapidly identify optimal building design schemes. A novel two-stage model was developed as a surrogate to conventional physics-based models, which were then linked to multi-objective optimization algorithms, namely, NSGA-II, NSGA-III, and C-TAEA, in search of the Pareto optimal and best design schemes. The performance of the two-stage model was further enhanced by applying the least absolute shrinkage and selection operator (LASSO) and Neural Architecture Search methods and learning from the statistical layer. The above approach was tested in the design of an apartment building for seniors in Northern China such as thermal comfort, carbon, and cost. The optimal design achieved through the compromise optimum can significantly reduce thermal discomfort, life-cycle carbon emissions, and high levels of daylighting conditions. The design scheme was visualized using a geometrical remodel module. This study contributes methodologically to complex multi-objective building optimization problems with practical implications for design.

Performance of exhaust gas-natural gas reforming under simulated exhaust conditions from marine NG engine: An experimental and thermodynamic study

Stable and efficient hydrogen production through exhaust gas-natural gas reforming is crucial for the implementation of reformed exhaust gas-fuel recirculation (REGR) technology in marine LNG engines. The reforming reaction is controlled by the physicochemical characteristics of the catalyst and the initial conditions. Ni-based catalysts have been extensively studied for methane reforming at medium-high temperatures. However, there is limited research on the complex multiphase reforming process using Ni-based catalysts at low temperatures, variable gas flow velocity, multi-component, and high dilution exhaust conditions. Therefore, this study aimed to examine and evaluate the reforming characteristics of modified La–Ni/Ca–Al catalysts, as well as the differences in catalytic physicochemical properties before and after the reforming reaction under the simulated exhaust gas conditions. Characterization results of the catalyst samples demonstrated that the modified catalyst exhibited ideal activity in the low-temperature reforming process, along with good resistance to thermal sintering and carbon deposition. The relative content of CH4 to O2 (M/O ratio) and the temperature of feedstock were identified as critical parameters controlling the reforming reactions. To achieve efficient hydrogen production, the optimum M/O ratio should be within 1.5–2.5, which could guide the efficient operation of our developed reformer. The study determined the critical feedstock temperatures for methane oxidation, steam reforming, and dry reforming reactions activated in the reforming system to be approximately 300 °C, 400 °C, and 500 °C, respectively. These findings highlighted the promising potential of exhaust gas-natural gas reforming as a means to recover and utilize O2, H2O, CO2, and heat from the exhaust gas. The insights gained from this present investigation provide valuable guidance for the development of the REGR system.

Synergistic advancements in sewage-driven microbial fuel cells: novel carbon nanotube cathodes and biomass-derived anodes for efficient renewable energy generation and wastewater treatment

Microbial fuel cells (MFCs) offer a dual solution of generating electrical energy from organic pollutants-laden wastewater while treating it. This study focuses on enhancing MFC performance through innovative electrode design. Three-dimensional (3D) anodes, created from corncobs and mango seeds via controlled graphitization, achieved remarkable power densities. The newly developed electrode configurations were evaluated within sewage wastewater-driven MFCs without the introduction of external microorganisms or prior treatment of the wastewater. At 1,000°C and 1,100°C graphitization temperatures, corncob and mango seed anodes produced 1,963 and 2,171 mW/m2, respectively, nearly 20 times higher than conventional carbon cloth and paper anodes. An advanced cathode composed of an activated carbon-carbon nanotube composite was introduced, rivaling expensive platinum-based cathodes. By optimizing the thermal treatment temperature and carbon nanotube content of the proposed cathode, comparable or superior performance to standard Pt/C commercial cathodes was achieved. Specifically, MFCs assembled with corncob anode with the proposed and standard Pt/C cathodes reached power densities of 1,963.1 and 2,178.6 mW/m2, respectively. Similarly, when utilizing graphitized mango seeds at 1,100°C, power densities of 2,171 and 2,151 mW/m2 were achieved for the new and standard cathodes, respectively. Furthermore, in continuous operation with a flow rate of 2 L/h, impressive chemical oxygen demand (COD) removal rates of 77% and 85% were achieved with corncob and mango seed anodes, respectively. This work highlights the significance of electrode design for enhancing MFC efficiency in electricity generation and wastewater treatment.

Formation of tannic acid-calcium polymeric network in pore solution: Characterization and kinetics

This study investigates the changes of tannic acid (TA) at varying concentrations in cement pore solution. Interestingly, TA spontaneously forms nanosheet tannic acid-calcium polymeric networks (TA-Ca) by interacting with Ca2+. Spectral, thermal, ionic and organic carbon analyses determine the composition and structural characteristics of these networks and detail the formation mechanism. The networks are connected via hydrogen bonding, C–C coupling and complexation. Moreover, network composition, structure and formation are closely dependent on TA concentration. At low concentrations, crystalline coordination polymer networks form, following second-order kinetics (key factor: Ca2+ concentration). At high concentrations, amorphous C–C coupled polymer networks form, following first-order kinetics (key factor: catalytic oxidation of Ca2+). This study aims to elucidate the reaction and mechanism of TA in cement paste, providing a novel theoretical basis for applying renewable bio-admixtures in sustainable construction.

The source-load-storage coordination and optimal dispatch from the high proportion of distributed photovoltaic connected to power grids

With the rapid development of distributed PV, many distributed PV devices are connected to the power grid, which is essential to optimize the scheduling in the power grid containing a high proportion of distributed PV. In this paper, a new day-ahead optimal dispatching model of a power system combined with the high proportion of photovoltaic is established. The impact of time-of-use tariffs on customers and the regulation of electricity by energy storage plants are considered in the model. The main contribution of this paper is that providing a better solution for grids with a high proportion of distributed photovoltaic, reducing carbon emissions and improving photovoltaic consumption. A solution approach i.e., Wild horse optimizer (WHO) is employed to optimal dispatch. The results show that compared with the Particle swarm algorithm, using the Wild horse optimizer has saved 16% costs, reduced 28% in thermal power carbon emissions, and increased 24% in distributed PV utilization rates. Wild horse optimizer is a better optimal approach which can reduce distributed PV abandonment rates and decrease costs when applied to the optimal scheduling in the grid with high percentage of distributed photovoltaic.

Effect of graphene oxide nano-particles dispersed biodiesel on combustion, performance and emission characteristics of a diesel engine

Present study aims to investigate the impact of graphene oxide (GO) nano-particles as a fuel additive on the combustion, performance and emission characteristics of a compression ignition engine. The diesel and biodiesel fuels were blended with GO nano-particles at concentrations of 20, 40 and 60 ppm, resulting in the formation of fuel blends named B20GO20, B20GO40 and B20GO60, respectively. During the experiments, several parameters including cylinder pressure, heat release rate, brake-specific fuel consumption, brake thermal efficiency, carbon monoxide (CO), unburnt hydrocarbon, and nitrogen oxide (NOx) emissions were measured. The results showed that the addition of 40 ppm of GO led to a maximum reduction of 36.41% in CO emissions, 17.38% in HC emissions, and 12.56% in NOx emissions. Based on these findings, it can be concluded that biodiesel–diesel blends with GO nano-particles can be utilised as an alternative fuel in diesel engines without requiring significant engine modifications.

Enhancing flame retardancy of poly(lactic acid) with a novel fully biobased flame retardant synthesized from phytic acid and cytosine

AbstractIn order to reduce environmental pollution and improve material safety, biobased flame‐retardant polymers are gradually becoming a new trend. We synthesized a fully biobased flame retardant called PACY by reacting phytic acid (PA) and cytosine (CY) in water, and then mixed the flame retardant with biodegradable poly(lactic acid) (PLA) to obtain composites, characterizing the performance of the composites by microscopic morphology, thermal properties, flame‐retardant performance and so on. The test results showed that the PLA composite with 2 wt% PACY (PLA/2PACY) achieved UL‐94V‐1 and the PLA composite with 4 wt% PACY (PLA/4PACY) had a limiting oxygen index of 23.6%. Compared to pure PLA, PLA/4PACY had good flame retardancy with 12% less peak heat release and 19% less total heat release. Analysis of the flame‐retardant mechanism showed that PACY could promote the formation of a graphitized carbon layer after burning PLA, therefore enhancing the flame‐retardant properties of PLA. Through a thermal stability study, it was found that the temperature required for PACY mass loss of 5% was 275 °C and the residual weight reached 38% at 750 °C, which indicated high thermal stability and residual carbon rate. The addition of PACY also improved the thermal conductivity of PLA, with that of PLA/4PACY being 3.84 times higher than that of pure PLA. In addition, the tensile strength, flexural modulus, maximum force during impact and maximum energy received during fracture of PLA/4PACY increased by 3.3%, 8.1%, 29.2% and 17.5% respectively over pure PLA, effectively improving the mechanical properties of PLA. Overall, a fully biobased flame retardant was synthesized for improving the fire resistance of PLA degradable polymers. © 2023 Society of Industrial Chemistry.

Prediction and balanced allocation of thermal power carbon emissions from a provincial perspective of China.

Carbon control in the thermal power generation industry is crucial for achieving the overall carbon peak target. How to predict, evaluate, and balance the allocation of inter provincial carbon emissions has a significant impact on the decision-making of reasonable allocation of inter provincial carbon emissions in the target year. Therefore, this paper uses Monte Carlo-ARIMA-BP neural network and ZSG-DEA model to conduct temporal trend prediction and carbon emission quota allocation research. We propose the "intra provincial and inter provincial" framework for carbon emissions trading in thermal power plants, which aims to break through the barriers in carbon emission rights exchange among provinces. The conclusions are as follows: (1) the growth trend of carbon emissions from thermal power is gradually slowing down and is expected to peak before 2030. (2) Inner Mongolia, Jiangsu, and Shandong have high input-output efficiency, and are all the main output provinces for carbon emission quota allocation. After being adjusted using the ZSG-DEA model, they can still be at the forefront of efficiency. (3) The "intra provincial and inter provincial" framework for carbon emissions trading can effectively predict and allocate the carbon emission demand of each province from time and space dimensions, balance the carbon emission rights and interests of each province, and provide forward-looking planning suggestions for inter provincial carbon emission rights exchange.

Multimodal feedback systems for smart laser osteotomy: Depth control and tissue differentiation.

The study aimed to improve the safety and accuracy of laser osteotomy (bone surgery) by integrating optical feedback systems with an Er:YAG laser. Optical feedback consists of a real-time visual feedback system that monitors and controls the depth of laser-induced cuts and a tissue sensor differentiating tissue types based on their chemical composition. The developed multimodal feedback systems demonstrated the potential to enhance the safety and accuracy of laser surgery. The proposed method utilizes a laser-induced breakdown spectroscopy (LIBS) system and long-range Bessel-like beam optical coherence tomography (OCT) for tissue-specific laser surgery. The LIBS system detects tissue types by analyzing the plasma generated on the tissue by a nanosecond Nd:YAG laser, while OCT provides real-time monitoring and control of the laser-induced cut depth. The OCT system operates at a wavelength of 1288 ± 30 nm and has an A-scan rate of 104.17 kHz, enabling accurate depth control. Optical shutters are used to facilitate the integration of these multimodal feedback systems. The proposed system was tested on five specimens of pig femur bone to evaluate its functionality. Tissue differentiation and visual depth feedback were used to achieve high precision both on the surface and in-depth. The results showed successful real-time tissue differentiation and visualization without any visible thermal damage or carbonization. The accuracy of the tissue differentiation was evaluated, with a mean absolute error of 330.4 μm and a standard deviation of ±248.9 μm, indicating that bone ablation was typically stopped before reaching the bone marrow. The depth control of the laser cut had a mean accuracy of 65.9 μm with a standard deviation of ±45 μm, demonstrating the system's ability to achieve the pre-planned cutting depth. The integrated approach of combining an ablative laser, visual feedback (OCT), and tissue sensor (LIBS) has significant potential for enhancing minimally invasive surgery and warrants further investigation and development.

Optimization of CI Engine Performance and Emissions Using Alcohol–Biodiesel Blends: A Regression Analysis Approach

This research paper investigates the optimum engine operating parameters, namely engine load, palm biodiesel, and ethanol percentage, by using a regression analysis approach. The study was conducted on a single-cylinder, four-stroke diesel engine at varying engine loads and constant speed. A general full factorial design was established using Minitab software (Version 17) for three different input factors with their varying levels. The test results based on the regression model are used to optimize the engine load and percentages of palm biodiesel and ethanol in diesel–biodiesel–ethanol ternary blends. The analysis of variance (ANOVA) revealed a significant effect on performance and emission parameters for all three factors at a 95% confidence level. From the regression study, optimum brake thermal efficiency (BTE), nitrogen oxide (NOx), carbon monoxide (CO), and unburnt hydrocarbon (UHC) emissions were found to be 12.57%, 436.2 ppm, 0.03 vol.%, and 79.2 ppm, respectively, at 43.43% engine load, 11.06% palm biodiesel, and 5% ethanol share. The findings of this study can be used to optimize engine performance and emission characteristics. The regression analysis approach presented in this study can be used as a tool for future research on optimizing engine performance and emission parameters.

Performance optimization of a dual fuel engine with YSZ coating by Grey-Taguchi method

The performance and exhaust emissions of a dual-fuel (DF) coated engine are attempted to optimize by running with diesel and biogas. The impacts of performance indices like biogas flow rate (BGFR), engine load (EL), and compression ratio were varied to optimize the brake thermal efficiency, carbon monoxide (CO), and hydrocarbon (HC) emissions of the thermal barrier coated engine by the Grey-Taguchi technique. In the present research, the design of experiments (DOE) was constructed using an L9 orthogonal array based on the selected levels of input indices. Then, the observed results from the experiment were normalized by applying Grey relational analysis to get optimized thermal efficiency and engine exhaust characteristics by running with biogas. It was noticed that the ideal factor setting was found to be the biogas flow rate at 0.6 kg h−1, EL at 80 %, and compression ratio at 18:1.

Unfolding of Lignin Structure Using Size-Exclusion Fractionation.

The heterogeneous and recalcitrant structure of lignin hinders its practical application. Here, we describe how new approaches to lignin characterization can reveal structural details that could ultimately lead to its more efficient utilization. A suite of methods, which enabled mass balance closure, the evaluation of structural features, and an accurate molecular weight (MW) determination, were employed and revealed unexpected structural features of the five alkali lignin fractions obtained with preparative size-exclusion chromatography (SEC). A thermal carbon analysis (TCA) provided quantitative temperature profiles based on sequential carbon evolution, including the final oxidation of char. The TCA results, supported with thermal desorption/pyrolysis gas chromatography-mass spectrometry (TD-Py-GC-MS) and 31P NMR spectroscopy, revealed the unfolding of the lignin structure as a result of the SEC fractionation, due to the disruption of the interactions between the high- and low-MW components. The "unraveled" lignin revealed poorly accessible hydroxyl groups and showed an altered thermal behavior. The fractionated lignin produced significantly less char upon pyrolysis, 2 vs. 47%. It also featured a higher occurrence of low-MW thermal evolution products, particularly guaiacol carbonyls, and more than double the number of OH groups accessible for phosphitylation. These observations indicate pronounced alterations in the lignin intermolecular association following size-exclusion fractionation, which may be used for more efficient lignin processing in biorefineries.

Effect of oxygen enrichment on methane ignition

Oxygen-enriched combustion has attracted interest in the energy sector due to its increased thermal efficiency and low carbon capture cost compared to ‘air’ combustion. Experimental data on the ignition of oxygen-enriched mixtures are limited in literature. In this work, ignition delay times (IDTs) of various methane/oxygen mixtures diluted in argon/nitrogen were measured using a low- and a high-pressure shock tube over a temperature range of 1200 – 1700 K, three pressures of 1, 10, and 20 bar and an equivalence ratio range of 0.21 - 4. The oxygen mole fraction in the mixtures was varied from 19% (‘air’) to 90.5%, and dilution levels from 71% to zero. The reported IDTs were extracted from pressure and OH* emission profiles. To the best of our knowledge, this is the first comprehensive IDT study on the effect of oxygen enrichment on methane ignition. High-speed imaging experiments were performed to determine the possible presence of non-ideal ignition in these unconventional mixtures. The Bifurcation Damköhler number was found to be a good indicator of non-ideal ignition observed in some imaging experiments. Measured IDTs were compared with the predictions of AramcoMech 3.0 model as well as with GRIMech 3.0 and NUIGMech 1.1 for few cases. In general, AramcoMech 3.0 overestimated IDTs for the investigated methane mixtures. Brute force sensitivity analyses were conducted with AramcoMech 3.0 to identify reactions with a strong influence on IDT prediction for the investigated mixtures. Minor modifications were made to AramcoMech 3.0 resulting in improved predictions of ignition behavior in oxygen-enriched methane mixtures.

Continental Thermal Structure and Carbonate Storage of Subducted Sedimentary Origin Control on Different Increases in Atmospheric CO2 in Late Ediacaran and Jurassic

AbstractCarbon release during continental rifting is thought to regulate atmospheric CO2 levels. Supercontinent dispersal‐induced extensional tectonics is similar during the Late Ediacaran and Jurassic, while they exhibit different increases in atmospheric CO2 concentration. The underlying mechanism of distinct CO2 emissions remains to be understood. Here, we conduct petrological‐thermomechanical modeling to show that metamorphic decarbonation and melting of carbonates that are derived from subducted sediments are ubiquitous during continental extension. We find that the hotter lithosphere and deeper storage of these carbonates cause more significant amounts of rift‐related CO2 release through volcanoes and faults. They may cause ∼12%–77% larger decarbonation efficiency, providing an efficient driving mechanism for a ∼31% larger increase in atmospheric CO2 levels during the Late Ediacaran than throughout the Jurassic. The rapid eruption and deposition of recycled carbonatite volcanic ash may contribute to the production of Late Ediacaran marine carbonates with the largest negative δ13C (−12‰).

Straw bale construction towards nearly-zero energy building design with low carbon emission in northern China

With the aim of achieving carbon neutrality, bio-based construction is of increasing interest for decarbonization globally. Among the potential candidates, straw bale is promising due to its ready availability and energy efficiency benefits. However, thermal conductivities of straw bales can vary greatly due to construction details, which may lead to failures in meeting nearly-zero energy building (nZEB) design standards in real practice. In the context, this study applied thermal property and carbon emission assessment of full-size straw bale walls (SBWs) and construction of an experimental building in northern China. The results demonstrated that the thermal conductivities of different monitoring portions of the SBWs ranged from 0.067 to 0.088 W·m−1·K−1. This resulted in U-values (0.16 W·m−2·K−1) marginally higher than the lower limits of nZEB design, indicating the importance of addressing thermal bridging issues of SBWs. The SBWs without additional insulation layers therefore can satisfy nZEB design standards in the severe cold region after certain adjustments. Besides, when not accounting for carbon sequestration, SBWs generated the lowest emissions among the schemes in meeting U-value limits for nZEB design (at least 14.6% lower than those of timber walls), with increasing emission reductions as U-value limit decreased. The results indicated that SBW demonstrated effectiveness in carbon reductions with high thermal performance. The findings of the research can facilitate application of straw bales and development of clean construction and net-zero design in northern China.

Synthesis of highly thermal conductive carbon nanotubes on cellulose nanofiber film-loaded polyethylene glycol phase change material with flame retardancy by layered double hydroxide

The nitrogen-doped carbon nanotubes (CNTs) were obtained by using methyl orange as a soft template and high temperature treatment, on which the layered double hydroxide (LDH) was grown in situ by hydrothermal method, and finally mixed with the phase change materials (PCM) by vacuum filtration to obtain a series of novel composite films with great flame retardancy and thermal conductivity. The use of cellulose nanofiber (CNF), polyvinylpyrrolidone (PVP) and polyethylene glycol (PEG) as PCM increased the film-forming properties, and the CNTs could improve the thermal conductivity of composites, while reducing the agglomeration of LDH nanolayers and improving the flame retardancy of the composite films. The results showed that the LDH grown on the nanotubes had a typical hexagonal lamellar structure, and its uniform distribution was the fundamental reason for the flame retardancy of the films which was verified by defined combustion experiments, the shortest self-extinguishing time and the least unburned area were achieved at a mass ratio of 7.14 % of LDH material. The melt and crystallization enthalpies of the thermally conductive flame-retardant films were 74.65 J/g−1 and 74.82 J/g−1, and the thermal conductivity of the material was increased to 0.04129 W/(m·K) after the use of 2.5 % thermally conductive filler. It can reduce the temperature of LED by up to 5.9 °C during the LED opening process and up to 5.2 °C during the LED closing process.