Thermal Contact Resistance Research Articles

A robust lattice Boltzmann scheme for high-throughput predicting effective thermal conductivity of reinforced composites

Accurately predicting effective thermal conductivity is of great importance for the design and performance evaluation of emerging composites. In this paper, an efficient and implementation-friendly lattice Boltzmann (LB) scheme for predicting the effective thermal conductivity of 3D complex structures is proposed. The key innovation is that the optimum convergence parameter of the 3D thermal LB method is found, which enables the LB equation to converge to steady heat conduction equation with the fastest speed and without losing any accuracy. To deal with the thermal contact resistance between different components, an interface treatment scheme is derived. In comparison with the existing schemes, the present scheme enjoys several hundred times higher computational efficiency. By virtue of this LB scheme, the effective thermal conductivity of the reinforced composites with different dimensional fillers are systematically calculated, and a comprehensive machine learning model is developed. This work provides a powerful numerical tool for high-throughput simulations of the 3D representative volume elements with high thermal conductivity ratios and large grid numbers. It may facilitate the application of data-driven techniques in study of the thermal transport properties of emerging composite materials and structures.

Development of a fixed Langmuir probe system for newly installed tungsten monoblock lower divertors in KSTAR

A fixed Langmuir probe system for newly installed tungsten monoblock lower divertors in KSTAR is developed. The probe structure is designed to effectively cooled via divertor coolant using inclined contact surfaces between the probe components. The probe body is tapered, narrowing up towards the divertor surface to enhance thermal contact conductance through mechanical forces exerted by the probe-divertor assembly. The probe structure is designed for easy replacement of a probe tip in the event of its damage and to accommodate different shapes of the tip. Currently, all the installed probe tips have 16° of inclination, i.e., one-sided rooftop shape, with respect to the surrounding divertor surface protruding 1.0 mm from the divertor surface. An individual probe system occupies two mono-blocks along the direction of the coolant channel. A single divertor cassette can accommodate 52 probes having a nominal poloidal spatial resolution of 12 mm. In the newly installed KSTAR divertor system, a total of 104 probes are installed at two toroidal locations. Thermal analysis on the probe structure indicates that the one-sided rooftop-shaped probe tips can withstand a localized heat flux of 10 MW/m2 for 2 s and 5 MW/m2 for steady-state operation. Experiments with a probe-divertor mockup are conducted in a linear plasma device under a magnetic field (|B|<360 G) and steady-state plasmas of a density of the order of 1011 cm−3. Possible analysis models for the I–V characteristics are discussed with practical applications to the measured data from KSTAR.

Compliant composite elastomers via grafting short dangling chains for promoting thermal transport performance

AbstractThe multifunctional composite elastomers serve as thermal interface materials for heat dissipation in electronic devices when their thermal transport performance is enhanced. The common method for enhancement, continuously raising the thermal conductive filler loading only can improve thermal conductivity of composite elastomers but reduces compliance, resulting in elevated contact thermal resistance with solid surfaces, compromising thermal transport. To address this, we propose grafting short dangling chains onto the composite elastomer matrix to further promote compliance under a certain filler loading. Characterization results demonstrate that the grafted chains effectively reduce relaxation time, enabling faster deformation for the material under pressure. This approach enhances interfacial compatibility, widening the thermal transport path at contact interfaces to contact thermal resistance by 94% (from 17.8 to 1.07 mm2W/K), significantly improving overall thermal transport. Additionally, we discussed the feasibility of employing composite elastomers as thermal interface materials for efficient chip heat dissipation.Highlight The grafted dangling chains can promote the composite elastomers softness. The softness promotion can help reduce thermal contact resistance. A series of theories are employed to learn the mechanisms of the promotion. The resulting composite elastomers can be used as thermal interface materials.

Analysis of heat transfer coefficient and skid marks in a slab reheating furnace considering beam misalignment and contact heat conduction

Accurate analysis of slab heat transfer characteristics is crucial for optimal control of reheating furnaces. This paper established a half furnace model to describe the heat and mass transfer and slab step heating processes in a walking beam reheating furnace. The contact heat conduction and beams misalignment are fully considered. The distribution of total heat transfer coefficient and the effect of stepping strategies on skid mark severity are investigated. The results show that the contact thermal resistance accounts for 1/8 of the conductivity thermal resistance of skid buttons and welding pads and has a lighter effect on the skid marks. The misalignment of the water-cooled beams effectively eliminated the original skid marks and minimized the range of the new ones, but the new skid mark severity before discharge from the furnace remains at 121 °C. The total heat transfer coefficient showed a wave distribution on the slab bottom surface and varied in the range of about −0.72 to 1.71 due to the beam shielding. On the slab top surface, it followed a stepped distribution. Stepping while advancing in soaking zone effectively improve the new skid mark temperature and reduce the skid mark severity by 24 °C. Increasing the stepping number can also reduce the influence of skid marks on the temperature of slab end, thus improving the temperature uniformity of the slab head and tail.

Estimation of Multiple Contact Conductances in a Silicon-Indium-Silicon Stack

Abstract This report documents evaluation of simultaneous estimation of multiple interfacial heat transfer coefficients (HTCs) using transient measurements from an experiment designed for steady-state operation. The design of a mirror system for directing X-rays under cryogenic conditions requires knowledge of the interfacial HTC (contact conductance) between silicon and indium. An experimental apparatus was constructed to measure temperatures in a stack of five 7.62-mm thick pucks of silicon separated by 0.1-mm thick sheets of indium, which is operated under cryogenic temperatures in vacuum. Multiple pucks and interfaces are incorporated into the apparatus to allow evaluation of HTCs for surfaces of different roughness from a single experiment. Analysis of the sensitivity of each of the measured temperatures to each of the unknown HTCs reveals lack of linear independence of these sensitivities and suggests the recovery of the HTCs will be challenging. Artificially noised “data” were created from two different computational models by solving for temperatures and adding random Gaussian noise with a specified standard deviation. These data are subsequently analyzed using two different iterative parameter estimation methods: a Levenberg scheme and a Tikhonov iterative scheme. The required sensitivity matrix is computed using forward finite difference approximations. The results for the heat transfer coefficients for this model problem suggest that coefficients cannot be estimated independently, but the ratios relative to one of the unknowns can be recovered.

Understanding interfacial compounds induced by Ag diffusion on improving interface electrical contact resistivity between the Cu electrode and Bi2Te3 thin film

It has been reported that introducing Ag interlayer at the Cu/Bi2Te3 interface can achieve ultra-low electrical contact resistivity. However, there is no consensus on the influence of Ag diffusion induced by Ag interlayer on electrical contact. Thus, the impact of Ag diffusion on electrical contact conductivity for Cu/Ag/Bi2Te3 multilayers was investigated. The generation of interfacial compounds induced by Ag diffusion was analyzed and the contact resistivity was measured in Cu/Ag/Bi2Te3 multilayers with different Ag interlayer thickness before and after annealing. It was found that Ag diffusion induced interfacial compounds Cu4Ag3Te4 at the Cu/Ag interface before annealing, which could decrease contact resistivity to 3.728×10−12 Ω∙m2. After annealing, the relative amount of Cu4Ag3Te4 at the Cu/Ag interface slightly decreased, and the Ag2Te was found to appear at the Ag/Bi2Te3 interface, which could further decrease contact resistivity to 3.187×10−12 Ω∙m2. With Ag interlayer thickness increasing from 50 nm to 300 nm, the contact resistivity decreased from 3.726×10−10 Ω∙m2 to 3.728×10−12 Ω∙m2 before annealing because the relative amount of Cu4Ag3Te4 increased about 5 times, after annealing the contact resistivity further decreased by 10.27∼41.7 % because the relative amount of Ag2Te increased about 1.1 times. In addition, we had optimized the ultra-low contact resistivity test method by redesigning the structure of test samples and modifying the formula of contact resistivity to eliminate two errors. One is caused by Cu electrode short-circuit resistance due to the test current being short-circuited by the middle electrode between two test electrodes. The other is caused by the increased electrical resistance of Bi2Te3 thin film due to Te atom volatilization after annealing. The results showed that the errors of the test results were reduced by at least 21.50 %. Our work provides guidance for further optimizing electrical contact of thin-film thermoelectric devices.

Nonintrusive thermal contact conductance estimation in double-layered pipelines: A reciprocity functional method perspective

Thermal contact conductance (TCC) is a critical factor in various engineering applications involving heat transfer between solid surfaces. Accurate knowledge of TCC enables a more precise thermal system analysis, leading to improved efficiency, reduced energy consumption, and prevention of thermal damages. Moreover, TCC estimation can help to identify material discontinuities or failures. A recent tool for TCC estimation is the Reciprocity Functional Method (RFM) coupled with the Classical Integral Transform Technique (CITT). This method allows the solution of inverse boundary value problems without the need of iterative methods or intrusive measurements, making it valuable for nondestructive testing of interfacial flaws between solid materials. Furthermore, it enables the computation of TCCs using analytical expressions, resulting in a computationally fast procedure. The technique involves the solution of two auxiliary problems: one for the temperature discontinuity estimation, and the other for the interfacial heat flux estimation, both at the inaccessible interface between the two contacting materials. In this study, we applied the RFM and the CITT to estimate different types of TCCs, using a three-dimensional double-layer hollow cylinder geometry as a representative model, like double-layer pipelines used in the oil industry. Temperature measurements for solving the inverse problem were considered available on the outer surface of the pipe which, in the case of a real experiment, could be obtained via an infrared camera. The results demonstrated a good estimate for various analyzed test-cases, even when the measurements were contaminated with Gaussian noises.

Ultrahigh Thermal Conductivity of Epoxy/Ag Flakes/MXene@Ag Composites Achieved by In Situ Sintering of Silver Nanoparticles.

The growing use of high-power and integrated electronic devices has created a need for thermal conductive adhesives (TCAs) with high thermal conductivity (TC) to manage heat dissipation at the interface. However, TCAs are often limited by contact thermal resistance at the interface between materials. In this study, we synthesized MXene@Ag composites through a direct in situ reduction process. The Ag nanoparticles (Ag NPs) generated by the reduction of the MXene interlayer and surface formed effective thermally conductive pathways with Ag flakes within an epoxy resin matrix. Various characterization analyses revealed that adding MXene@Ag composites at a concentration of 3 wt % resulted in a remarkable TC of 40.80 W/(m·K). This value is 8.77 times higher than that achieved with Ag flakes and 7.9 times higher than with MXene filler alone. The improved TC is attributed to the sintering of the in situ reduced Ag NPs during the curing process, which formed a connection between MXene (a highly conductive material) and the Ag flakes, thereby reducing contact thermal resistance. This reduction in contact thermal resistance significantly enhanced the TC of the thermal interface materials (TIMs). This study presents a novel approach for developing materials with exceptionally high TC, opening new possibilities for the design and fabrication of advanced thermal management systems.

Detection of Defects by Identification of Thermal Contact Resistance

With technological development, the use of electronic components has become indispensable. These circuits that invade our daily lives are present in all kinds of applications and in all areas of active life. These components have become much miniaturized and still undergo very high powers that can cause a detachment between the layers, reflecting the delamination phenomenon that can be modeled by thermal contact resistances. The present work is a study of the thermal contact resistance estimation in multilayer electronic structures using an approach based on the Levenberg–Marquardt method. The first part of the contribution focuses on the study of the impact of the Levenberg–Marquardt algorithm’s damping factor on the identification of the thermal contact resistance, or more precisely, the impact of the decay rate. The results show that a judicious choice of this parameter ensures very good precision and good convergence of identification. The second part is devoted to the study of the impact of the measurement sensor’s position in the structure on the identification. The results obtained are satisfactory. The cost function converges to the expected minimum and ensures a good identification of the thermal contact resistance, whether it is identical or different at the contact interface.

Experimental, computational, and analytical investigation of cooktop thermosyphon heat transport device for its feasibility in indoor solar cooking system

Cooking is a key contributor to worldwide energy usage and subsequent greenhouse gas emissions. Given this, clean and green energy-based cooking technologies are being explored globally. Though many solar cooker designs are being researched, the social acceptance rate is low due to operational, financial, and accessibility aspects. Hence in the present study, an indoor solar cooking system has been proposed, which has a cooktop Thermosyphon heat transport device (THTD) as an integral part. It transports heat from the outdoor receiver to the indoor kitchen through natural circulation (buoyancy-driven flow) of a heat transfer fluid (HTF). For the first time, different aspects of cooktop THTD are explored through experimental, analytical, and computational approaches. Based on the recommendations from a previous study, the flat design of cooktop THTD was constructed and tested with Therminol-VP1 as the HTF for both steady-state and transient performance. The steady-state results predicted by analytical and computational models were in good agreement with the experimental outcome. The HTF flow in the system is unidirectional, except in the cooktop region, where a combination of radial flow maldistribution and localized recirculation loops are seen (from velcoty contours and vectors) due to a larger flow passage. However, such flow anomalies vanish once the flow gap is reduced. Further, the transient tests witnessed a longer time for boiling (41–68 min) one litre of water in the first trial, which was reduced to 18–27 min with subsequent refills. An important observation is the increment in boiling time with increase in hot leg length. The rise in HTF flow rate (due to increased center-line elevation) and subsequent reduction in the bulk average temperature of HTF in the THTD was the reason for it. Further, the cooktop THTD could cook 315 g of rice in 40–45 min against 35–40 min using an electric induction stove, which justifies the proposed system’s efficacy. The study also demonstrated the criticality of thermal contact resistance between the cooktop surface and the surface of the cooking vessel. Hence devising an efficient and practically viable method (other than thermal paste) is essential. Also, due diligence is required while selecting the HTF as viscous fluid leads to a poor transient performance due to reduced flow rate. Hence, the transient behavior (practically the boiling time) of cooktop THTD is a trade-off between the bulk average temperature of the HTF and its flow rate.

High-Performance Bioinspired Hierarchical Microgroove Wick for Ceramic Vapor Chambers Achieved by Nanosecond Pulsed Lasers.

Directly integrating ceramic vapor chambers into the insulating substrate of semiconductor power devices is an effective approach to solve the problem of heat dissipation. Microgrooves that could be machined directly on the shell plate without contact thermal resistance and mechanical dislocation offer exciting opportunities to achieve high-performance ceramic vapor chambers. In this study, a bioinspired hierarchical microgroove wick (BHMW) containing low ribs via one-step nanosecond pulsed laser processing was developed, as inspired by the Sarracenia trichome. The superwicking behavior of microgrooves with different structural parameters was investigated using capillary rise tests and droplet-spreading experiments. The BHMW exhibited excellent capillary performance and anisotropic hemiwicking performance. At a laser scanning spacing of 30 μm, the BHMW achieved a capillary wicking height of 114 mm within 20 s. The optimized BHMW demonstrated a capillary parameter (ΔPc·K) and an anisotropic hemiwicking ratio of 4.46 × 10-7 N and 11.93, respectively, which were 1182 and 946% higher than references, as achieved through nanosecond pulsed laser texturing under identical parameters. This work not only develops a high-performance hierarchical alumina microgroove wick structure but also outlines design guidelines for high-performance ceramic vapor chambers for thermal management in semiconductor power devices.

Integrated internal-external thermal modeling for packed pebble beds

In this study, an integrated external-internal thermal DEM model is introduced in a GPU environment. The external model considers contact conduction and radiation, exhibiting accuracy validated against effective thermal conductivity (ETC) under packed bed conditions. The effective radiation range for a mono-sized packed bed is determined to be 3.5rp, providing accurate predictions of ETC. The internal model integrates FDM-based discretization to solve heat generation, heat conduction and thermal expansion. The model well predicts the temperature gradient of a sphere with partial heat generation. Additionally, preliminary analysis is conducted on the postulated heat generation of packed beds under a complete coolant-loss condition. The results reveal that fission-induced expansion may impact local porosity variations exceeding 2.5%. It is also observed that internally homogeneous models may overestimate heat transfer in packed beds, critical for safety. The model's accuracy and feasibility are demonstrated, providing insights for future research.

Mastering thermal transport across carbon nanotube contacts through morphological control

Thermally conductive nanomaterials hold great promise for applications in thermal management. However, the interfaces between nanomaterials can significantly impede heat flow, and a comprehensive understanding of thermal transport across nanoscale contacts is highly desired. Here, by integrating a movable nano-manipulator within an electron microscope with a nanofabricated thermal sensor, we adjusted the contact positions, overlapping length, and crossing angles between two carbon nanotubes (CNTs) as desired, while concurrently measuring the thermal contact resistance (TCR) at the van der Waals junction. The TCR far surpassed that of the studied 6 μm-long CNTs, particularly in contacts affected by inevitable nanoscale surface contamination. The TCR per unit area exhibited significant variations across different contact morphologies, spanning two orders of magnitude even for identical pairs of samples, attributable to structural non-uniformity within the CNTs. This in-situ approach and the notable morphology effects can guide the control of heat at the nanoscale.

Ultrahigh thermal conductance of the point contact between amorphous nanowires

Amorphous interfaces/contacts are ubiquitous in numerous micro/nanoelectronic devices and functional composite materials. Traditionally, the thermal resistance of interfaces/contacts was believed to be the primary impediment to heat transport. However, in this study, through measuring thermal resistance between crystalline-amorphous core-shell Ge nanowires, we unveil an ultrahigh thermal conductance across the point contact between the amorphous shell of Ge nanowires with a room-temperature value of 892 MW/m2-K. This value surpasses the typical values observed in point contacts between crystalline nanowires/nanoribbons by one to three orders of magnitude and even exceeds that of epitaxial interfaces between well-lattice-matched materials. Molecular and lattice dynamic simulations further reveal that the observed ultrahigh thermal conductance is attributed to the broadened vibrational bandwidths within the amorphous contact, which facilitates the redistribution of phonon energy into a state conductive to more effective interfacial energy transmission, leading to an enhanced overlap of phonon modes and, consequently, a heightened thermal conductance.

Experiment-Validated multiphysics modeling, generalizable deep learning and interpretable global sensitivity analyses for thermoelectric generators

Despite extensive studies on thermoelectric materials in a thermoelectric generator (TEG), the inverse design of TEG operating conditions remains challenging. Recent efforts in deep learning of TEGs using artificial neural network (ANN) lack global sensitivity analyses and interpretation of the connection-weights, leading to unknown coupling between input parameters and errors in importance ranking. This work reports a deep learning framework for TEGs using generalizable ANN, interpretable local (LSA) and global sensitivity analyses (GSA). Sensitivity analyses are applied to determine how energy conversion efficiency (η) under the practical Neumann and Robin thermal boundary conditions is affected by TEG operating conditions, including hot-side heat flux (qh), cold-side convective heat transfer coefficient (hf), temperature of the cooling medium (Ta), load resistance (RL), electric contact resistance (Rc), and thermal contact resistance (Kc). First, multiphysics TEG simulation results based on 3D finite element method (FEM) are validated by our experimental measurements using a self-built TEG performance evaluation system. The partial derivative-based LSA is done on a 1D theoretical TEG model to obtain the trend in sensitivity factors. Then, an ANN model is trained and validated based on the FEM simulation results and applied to the GSA process, aiming at reducing the computational load. Variance-based GSA is applied on the ANN model to determine the importance ranking and reflect the coupling between input parameters. The variance-based GSA ranks the importance as qh>hf>RL>Ta≈Rc≈Kc, and reflects the coupling between qh and hf. Finally, to interpret the ANN and the hidden deep learning process, a method combining the connection-weights algorithm and neural interpretation diagram (NID) is proposed to extract the hidden information in the connection weights. The ANN model is proven generalizable towards larger ranges of operating conditions. This work provides a framework to design TEG operating conditions towards higher energy conversion efficiencies.

Interfacial thermal resistance between mechanically exfoliated nm-thick MoS2 and silicon from −60 °C to 50 °C based on ns-ET Raman technique

In the miniaturization and integration development of micro-devices, the large thermal contact resistance significantly affects the overall performance of micro-devices, which is influenced by both interfacial contact condition and material properties. However, the temperature dependence of interfacial thermal resistance of realistic materials remains unclear. In this work, the interfacial thermal resistance between nm-thick MoS2 nanosheets and Si substrate is measured by using the ns energy transport state-resolved Raman (ns ET-Raman) technique. By comparing the experimental data with finite difference numerical simulation, the real value of the interfacial thermal resistance is determined. By changing the ambient temperature from -60 °C to 50 °C, the interfacial thermal resistance against temperature curve is obtained. As the environmental temperature deviates from room temperature, a large increasement of the interfacial thermal resistance can be observed. As temperature goes back to room temperature, the unreversible interfacial thermal resistance indicates that the large thermal expansion mismatch deteriorates the contact situation. In the last, the interfacial thermal resistance evolution under varying environmental temperatures from both experiments and modeling results in literatures are compared and discussed to illustrate the effect of different interface formation methods. For epitaxial and CVD grown materials, the interfacial thermal resistance generally reduces with raising ambient temperature. While for mechanically exfoliated samples, the effect of thermal expansion mismatch and the resulting gaps dominate the interfacial thermal resistance, which leads to non-monotonous temperature dependency with a valley located at room temperature.

Thermal contact resistance on cylindrical flux channel with high contact ratio

This paper considers the resistance to the heat flow between two thick solids with a high contact ratio in a vacuum. Based on the least-action principle, we derive closed-form mathematical expressions for the temperature distribution and non-dimensional thermal contact resistance, both expressed as functions of the radii ratio. Furthermore, the thermal contact resistance is investigated as a function of contact pressure and microhardness. A comparison of the conventional and proposed methods reveals that the proposed method is more accurate for calculating the thermal contact resistance with a high contact ratio. In equipment with high contact pressure, such as electromagnetic launch, we compare armature melting models using different calculation methods for contact resistance. Small and all contact models were established based on the traditional and proposed methods, respectively. The melting morphology of the armature obtained from the all contact model is highly consistent with the experimental results. During the experiment, in areas where the armature did not melt, the small contact model incorrectly calculated the melting of the armature. The all contact model can describe the strong cooling effect of the rail on the armature, preventing the armature from melting. The all contact model obtained higher heat sources, contact thermal conductivity, and contact pressure in the melting region. Under the combined effect of the three factors, a deeper and more concentrated melting morphology was obtained. This morphology is more consistent with the experimental results.

Device engineering of Sb2X3 antimony chalcogenide for loss analysis and strategies for maximizing photovoltaic efficiency

Antimony chalcogenide (Sb2X3; X=S, Se) is reportedly stable in ambient open-air, abundant, and shows composition-dependent absorption tunability. We simulated the Sb2X3 device utilizing the reported optical and electrical properties to analyze the performance limiting factors and the extent of achievable performance. Initially, we benchmarked the simulated device with the experimental reported device. The VOC-temperature and VOC-illumination characterization of the benchmarked device revealed the contact issue responsible for the VOC deficit. The suboptimal device configuration is a major performance-limiting factor. Contact optimization and conduction band offset optimisation have improved efficiency to 14.86% and 20.45% in Sb2S3 and Sb2Se3, from their experimentally reported values of 7.5% and 9.2% respectively. The optimization of trap-assisted Shockley Read Hall (SRH) recombination in bulk and interface has improved efficiency to 19.43% and 26.13% in Sb2S3 and Sb2Se3, respectively. When extrinsic factors are optimised, such as resistance losses (series resistance as high as 2 Ωcm2 and shunt resistance as low as 1000 Ωcm2), efficiency increased to 20.03% and 26.82% for Sb2S3 and Sb2Se3, respectively. Finally, with ideal intrinsic recombination parameters (radiative and Auger recombination), efficiency improved to theoretical limits (corresponding to their band gap). The study highlights the possibility of immediate gain upon contact passivation in Sb2S3 and Sb2Se3.

Determination of optical properties of single crystal diamond substrates grown via welding-assisted microwave plasma enhanced chemical vapour deposition

Lab grown single crystal diamonds (SCDs) offer unrivalled hardness, a wide range of optical transparency, and supremely high thermal conductivity reliable materials to be a part of devices run at high frequency, temperature, and power. Effective synthesis techniques are essential in enhancing the potential applications of high-quality SCDs. This study aims to decrease the thermal contact resistance between diamond seeds and the molybdenum holder by utilizing welding material. Quality of grown diamond substrates (plates) were assessed by analysing optical properties through Raman, UV-Vis, and FT-IR spectroscopic methods. The findings revealed that the grown single-crystal diamonds have excellent transmittance (>70%) and absorption at 270 nm. Calculations also showed an average absorption coefficient of 1.1 cm−1, indicating the high quality of the grown SCDs with nitrogen impurities below 10 ppm. The absorption observed in the FTIR spectra, ranging from 1600 cm−1 to 2700 cm−1 with a peak at 2354.13 cm−1, is referred to as the “two phonon region,” which is a distinctive feature of the diamond phase.

Efficient boundary conditions identification in thermal simulation of the spindle system with reduced order model and differential evolution algorithm

The boundary conditions in thermal simulation of the spindle system are very complicated and the empirically calculated ones will usually result in a significant discrepancy between experiment and simulation. Thus, the optimal boundary conditions were identified by treating it as an inverse optimization problem in this paper. Moreover, to advance the optimization efficiency, a reduced order model is established to replace the time-consuming thermal simulation of the spindle system. By superposition of truncated eigenmodes and accurately predicted modal coefficients, the reduced order model can reconstruct the field very similar to thermal simulation. Experimental reconstruction of both the temperature field and thermal deformation field by the reduced order model demonstrated its at least 360 times speedup with 99.8 % accuracy compared to the actual thermal simulation. With the accurate reduced order model as a lightweight digital twin and using the differential evolution algorithm, three types of boundary conditions, i.e., the heat generation rates, the convective heat transfer coefficients and the thermal contact resistances, under the shaft rotation speed of 4,000r/min were identified within 11s. The maximum temperature simulation error was reduced from 85.6 % to 6.6 % and the thermal deformation simulation error was reduced from 60.9 % to 10.8 %.