The suitability of lithium-ion battery thermal management strategies (TMSs) varies substantially across operating conditions and engineering constraints, limiting the effectiveness of single-metric or fixed-weight evaluation methods. This study develops a scenario-adaptive framework integrating the Analytic Hierarchy Process and Fuzzy Comprehensive Evaluation (AHP-FCE). The framework comprises four primary criteria (technical performance, economic viability, environmental safety, and sustainability) and 15 secondary indicators, with scenario-specific weights and evaluation boundaries established for energy storage systems (ESS), electric supercars (ESC), and electric propulsion ships (EPS). Among the evaluated candidates, single-phase immersion cooling, two-phase immersion cooling, and single-phase cold-plate cooling rank first for ESS, ESC, and EPS, with adaptability scores of 0.894, 0.930, and 0.885, respectively, highlighting the scenario dependence of TMS selection. Robustness analyses confirm the overall stability of these recommendations, although the ESC ranking is more sensitive to the weighting method. An external techno-economic benchmark further supports the engineering plausibility of the ESS recommendation. The proposed framework provides a transparent and interpretable quantitative basis for preliminary TMS screening and scenario-specific engineering decision-making.
The thermal reliability of polymer gears operating under dry-running conditions is governed by the interaction between friction-induced heat generation, conductive heat dissipation, and localized thermal accumulation. However, the relationship between intrinsic thermal transport and component-level thermal reliability remains insufficiently understood. In this study, the transient thermal behavior of polyoxymethylene (POM) gears reinforced with carbon black (CB) and nano-calcium carbonate (NCC) was investigated through an integrated experimental–numerical approach. Thermal conductivity, specific heat capacity, transient temperature evolution, cooling behavior, wear, and surface degradation were experimentally characterized, while three-dimensional finite element simulations were used to analyze localized temperature fields and heat-transfer pathways. A cooling-stage-based validation strategy was introduced to evaluate the component-level cooling response under controlled conditions while excluding active friction-induced heating. Furthermore, localized heat-flux analysis, thermal hotspot localization, cooling-time-constant evaluation, and a Heat-Flow Intensity (HFI) index were employed to quantitatively characterize internal heat transport within the gear tooth, while a normalized Thermo-Tribological Performance Index (TTPI) was developed to provide a unified comparative assessment of thermal transport, cycle-normalized wear performance, and service durability. Thermal conductivity increased from 0.29 to 0.449 W m⁻1 K⁻1 with increasing nanofiller loading, leading to faster cooling and enhanced heat transport. However, the highest thermal conductivity did not provide the best thermal reliability because excessive nanoparticle loading was associated with increased friction-induced heating and surface degradation. Instead, the POM/CB/3NCC composite exhibited the best overall performance, combining efficient heat dissipation, reduced operating temperature, superior wear resistance, and the longest service life. The proposed framework, together with the HFI and TTPI indices, provides quantitative comparative tools for evaluating internal heat transport and integrated thermo-tribological performance of polymer nanocomposite gears and offers a potentially transferable basis for the thermal and tribological design of polymer transmission components.
Waste tire rubber has low density, high elasticity, and excellent fatigue resistance. When mixed with sand, it forms a sustainable composite geomaterial in which thermal conductivity (TC) governs thermal performance. This study systematically investigated the TC of rubber-sand composite geomaterials (RSCG) with varying rubber particle sizes, rubber contents, water contents, and dry densities using the transient thermal probe method. Scanning electron microscopy (SEM) was also used to examine heat-transfer pathways and thermal-resistance mechanisms. Results show that TC decreases rapidly at low rubber contents and then more gradually with further rubber addition, whereas TC increases monotonically with dry density. Water content generally increases TC, but its effect weakens at higher rubber contents. Fine rubber particles (40 mesh) more effectively fill pores and reduce direct sand-sand contacts, causing a pronounced TC decrease at relatively low rubber contents. In contrast, coarse rubber particles (20 mesh) form more heterogeneous pore structures, allowing water-induced TC enhancement to remain pronounced over a broader rubber-content range. Where an identifiable turning point was observed, the critical water contents for both particle-size systems were mainly 8%-9%. A Wiener-bounds-based four-phase TC model considering rubber, river sand, water, and air was developed and showed significantly better predictive accuracy than the Kersten and Gangadhara models. The findings support TC prediction, mixture optimization, and engineering applications of RSCG.
Non-uniform temperature fields can trigger thermally induced flows, generating radiometric force and radiometric torque on the solid structure. Thus, rotational motion occurs. The non-equilibrium gas flows of the microbeam with equilateral triangle fin surfaces immersed in the circular cold chamber are numerically investigated based on direct simulation Monte Carlo (DSMC) method. Here, one side of the equilateral triangle fin is cold, and the other side is hot. The characteristics of torque applied to the microbeam are analyzed for different configurations. Moreover, the output power and thermal efficiency performance are evaluated with the system as a heat engine model. It is demonstrated that the radiometric torque is a bell-shaped function of Knudsen number (Kn), reaching the peak value at around Kn∼0.1. The radiometric torque is almost a linear function of temperature difference, increasing monotonically with the temperature difference. However, the radiometric torque is inversely proportional to the chamber size, with a non-linear dependence. Moreover, the total torque is a linear function of rotational speed, monotonically decreasing with the rotational speed, which reveals its potential application for rotating machines. In addition, the dependence of output power on the rotational speed exhibits a parabolic profile. Both the maximum output power and the corresponding thermal efficiency have a non-linear dependence on Kn, and reach the peak values of ∼ 0.43 mW and ∼ 0.36 %, at Kn∼0.2 and Kn∼0.5, respectively.
This study investigated the pyrolysis of waste cooking oil sludge (WCOS) and its co-pyrolysis with polypropylene (PP) and high-density polyethylene (HDPE) at 500 °C in a continuous double-screw reactor to evaluate product yields, oil quality, energy recovery, and preliminary economic performance. The novelty of this work lies in evaluating WCOS with individual polyolefin co-feedstocks under the same continuous operating conditions, together with an integrated assessment of product distribution, liquid-fuel characteristics, energy performance, and preliminary process economics. At a 50:50 blend ratio, co-pyrolysis with PP increased the pyrolysis oil yield from 46.0 wt% for WCOS alone to 71.0 wt%, while HDPE increased it to 64.0 wt%, with pyrochar yields reduced to approximately 2.2–2.3 wt%. GC–MS and FTIR analyses showed that plastic addition produced hydrocarbon-rich oils dominated by alkanes and alkenes, with a marked reduction in oxygenated compounds. The co-pyrolysis oils also exhibited high heating values (44–45 MJ kg−1), low water contents, and favorable density and viscosity, indicating improved fuel properties and potential for stationary thermal applications. The fraction of feedstock energy recovered in the pyrolysis oil increased from 73.9% for WCOS alone to 88.3% and 80.7% for WCOS–PP and WCOS–HDPE, respectively. A preliminary economic assessment further suggested shorter payback periods for the co-pyrolysis systems. Overall, WCOS–plastic co-pyrolysis shows potential for integrated waste valorization and fuel-oriented product recovery.
