Thermal Resistance Values Research Articles

Thermal Contact Resistance between Mold Steel and Additively Manufactured Insert for Designing Conformal Channels: An Experimental Study

The focus of this research is on thermal contact resistance between a mold and its insert, specifically inserts made by additive manufacturing (AM). Using a thermal steady-state system and varying contact pressures (0, 50, 75, and 100 bars), we present experimental results of the thermal contact resistance at the contact interface between steel A (1.2344), obtained from an extruded rod, and steel B (1.2709), produced by laser powder bed fusion. Thermal tests were performed for unbonded and bonded configurations. Results showed that increasing the contact pressure allows the system equilibrium to be reached at lower temperatures. Furthermore, thermal tests showed that in the transition zone of the bonded configuration, a well-defined resistance is not formed between the two steel samples as it occurs in the unbonded configuration. For the unbonded configuration, the thermal contact resistance values decrease with increasing applied contact pressure, improving the system’s heat transfer.

Investigating the Effect of Recycled Cotton Included Fabrics on the Thermal Behaviour by Using a Female Thermal Manikin

Abstract In recent years, with the increase in global awareness of environmental problems, the term “sustainability” became more important for apparel manufacturers and consumers. Therefore, recycling of wastes plays a significant role in environmental sustainability by converting the wastes into raw materials. This study focused on recycled cotton-included fabrics, to evaluate the effect of these fabrics on thermal comfort properties. In this context, first, the 45% recycled cotton/55% polyester blended yarns and 50% virgin cotton/50% blended yarns were obtained. Afterwards, single jersey and rib-structured fabrics were knitted using these yarns. The thermal comfort tests were performed on the fabrics and four long sleeve rounded neck shirts then were manufactured using these fabrics to test by the thermal manikin method. Results showed that the yarns including recycled cotton led to a decrease in the values in air permeability of the fabrics and in the effective clothing insulation of the garments. In contrast, it was observed that, including recycled cotton increased the thermal resistance values of the fabrics.

Investigation of the Thermal Comfort Properties of Masks Used during the COVID-19 Pandemic.

SARS-CoV-2, the causative agent of COVID-19, which was officially declared a pandemic by the World Health Organization (WHO) on 11 March 2020, is transmitted from person to person through respiratory droplets and close contact and can cause severe respiratory failure and pneumonia. Currently, while the worldwide COVID-19 pandemic is still ongoing and countries are taking strict precautions to protect populations against infection, the most effective precautions still seem to be social distancing and wearing a mask. The question of how effective masks were in the early stages of the COVID-19 pandemic has been widely discussed, both in public and scientific circles, and the protection of different mask types has been examined. This study aimed to examine the comfort conditions provided by the different mask types to the user during use. For this purpose, single-ply, double-ply, three-ply, cloth, FFP1, FFP2, and FFP3 masks with different standards were examined, with and without a valve. To conduct the experiments, the novel thermal head measurement system, developed within the scope of this study, was used specifically for mask comfort studies. Thanks to the developed measurement system, the thermal resistance and water vapor resistance values of different masks were measured, and their comfort conditions were evaluated. According to the findings, cloth masks provide a comfortable condition, with lower thermal resistance and water vapor resistance values than other masks. In addition, it was observed that surgical masks offer better thermal comfort conditions, although they have lower protection than FFP masks.

Thermal performance evaluation of two types of wall panels under dynamic weather conditions

Thermal performance of two types of wall panels were evaluated under dynamic weather conditions. The thermal performance of wall pane ls (61 x 61 cm) prepared in the laboratory with a 5.0 cm extruded polystyrene (XPS) board sandwiched between two 7.5 cm concrete layers and 5.0 cm layer of foam-mortar containing expanded polystyrene (EPS) beads sandwiched between two 7.5 cm concrete layers were evaluated simultaneously in a specially designed air conditioned test box. The thermal transmittance (U-value) and resistance (R-value) of the two wall samples were determined and compared. The thermal transmittance (air to air) of sandwiched XPS concrete and EPS beads foam-mortar concrete wall panel samples are 0.836 and 2.526 W/m2 K, respectively. The corresponding mean thermal resistance values (surface to surface) of the wall panels are 1.142 and 0.292 m2 K/W, respectively. Thermal performance indicates that the wall panel sample with the XPS insulation board sandwiched between concrete is much more effective than the wall panel sample made of foam-mortar containing EPS beads sandwiched between concrete. The results also indicate that the time lag between the maximum exterior surface temperature and the maximum heat transmission on the interior surface is about 4.5 hours for both samples.

Determining the influence of geometric factors and the type of heat carrier on the thermal resistance of miniature two-phase thermosyphons

This paper reports experimental data on the total thermal resistance of copper two-phase thermosiphons with internal diameters of 3 mm, 5 mm, and 9 mm, 700 mm long. Water, ethanol, methanol, and freon-113 were used as heat carriers. During the study, thermosiphons were located vertically. The length of the heating zone varied from 45 mm to 200 mm while the length of the condensation zone was constant and equaled 200 mm. The filling coefficient of thermosiphons varied from 0.3 to 2.0. Two series of experiments were conducted. The first series was distinguished by the fact that the filling coefficient of three thermosiphons with an internal diameter of 9 mm varied from 0.3 to 0.8 with the same length of the heating zone of 200 mm. The second series of experiments was carried out on thermosiphons with internal diameters of 3 mm and 5 mm. With the same amount of heat carrier, the length of the heating zone changed from 45 mm to 200 mm. As a result of research, it was determined that the total thermal resistance of thermosiphons is influenced by both their geometric factors (internal diameter and filling coefficient) and the type of heat carrier. The main factor that influenced the value of thermal resistance was also the transmitted heat flux. An increase in heat flow led to a significant decrease in thermal resistance. The maximum heat flux was determined with minimal thermal resistance. To calculate the value of the thermal resistance of thermosiphons, two dimensionless dependences were derived, which hold for two ranges of Reynolds numbers. For small Reynolds numbers (until 2000), which characterize the beginning of the action of vaporization centers and their gradual increase, the degree indicator was –0.8, and for larger Reynolds numbers, up to critical phenomena, the degree indicator was at the level of –0.3.

Data-driven numerical models for the prediction of the thermal resistance value of the Enclosed Airspaces (EAs) in building envelopes

ABSTRACT Enclosed airspaces (EAs) are a common component of different energy efficient technologies in building envelopes which have intrinsic adaptive behavior under various climatic conditions. The need for comprehensive accurate numerical models without restrictions for different applications still exists. Thus, for the first time, machine learning and regression-based techniques (Ordinary least squares Linear Regression (OLR), Support Vector Regression (SVR), Kernel Ridge Regression (KRR), k-Nearest Neighbors (kNN), r-Nearest Neighbors (rNN), and Artificial Neural Network (ANN)) were applied to develop precise models derived from the most credible experimental data with stochastic logic of testing and training in several runs. It was found that application of KRR, SVR, and ANN leads to the most desirable outcomes with highest R2 (0.97–0.99), and lowest errors, however OLR does not provide satisfactory results (R2 <0.6). Moreover, major deviations are observed for calculations by OLR, kNN, and rNN in horizontal EAs (thicknesses = 40mm) with downward heat flow direction.

Thermal resistance and bursting strength analysis of multilayer needle-punched bamboo/polyester nonwoven batt

This work aims to evaluate the potential of bamboo/polyester blended needle-punched nonwoven batts as thermal insulators. This research investigated the effects of physical properties on the thermal resistance and the bursting strength subjected to the different number of layers of the batt structure. Bamboo/polyester nonwoven batt was prepared by using a needle-punching technique. The nonwoven batt was made into single, two and three-layers structures termed as 1BP, 2BP and 3BP. Physical properties such as thickness, areal weight, density and porosity were determined to evaluate their relationship with thermal resistance and bursting strength. The properties of bamboo/polyester nonwoven batt were compared with that of polyester nonwoven batt commercially used as insulation layers in comforters. The thermal resistance and bursting strength were found to increase with the increased number of layers and were better than the commercial sample. The ranking shows that density and porosity have the most effect on thermal resistance and bursting strength, followed by areal weight and thickness. High and significant Pearson’s correlation coefficient and P-value indicated that density and porosity are the parameters that mainly influence the thermal resistance of the nonwoven batt. On the other hand, the number of layers was the most influential parameter for bursting strength. Based on the findings, 3BP nonwoven batts exhibited better thermal insulation performance and better strength with the value of 0.2932 m2 K/W and 3.78 kgf, respectively. In comparison, the commercial polyester nonwoven batt recorded a thermal resistance value of 0.2390 m2 K/W and bursting strength of 2.92 kgf.

(Invited, Digital Presentation) Thermal Conductance across Heterogeneously Integrated Interfaces for Thermal Management of Wide and Ultra-Wide Bandgap Electronics

Thermal management is important for wide and ultra-wide bandgap power electronics because overheating degrades device reliability and performance. High thermal conductivity substrates such as SiC and diamond facilitate heat dissipation of these devices while the thermal boundary resistance between devices and substrates accounts for a large portion of the total thermal resistance, which prevents devices from taking the full advantage of the high thermal conductivity of the substrates. Recently, heterogeneously integrated wide and ultra-wide bandgap semiconductor interfaces are found to have low thermal boundary resistances, which provides a new degree of freedom to design and fabricate thermally conductive interfaces for thermal management of related power devices. For example, GaN can be bonded with single crystal SiC or single crystal diamond directly at room temperature. β-Ga2O3 can be bonded with SiC with or without Al2O3 interfacial layers. Compared with growth, the bonded interfaces are not limited by lattice mismatch. Moreover, the room-temperature bonding process discussed in this talk can possibly eliminate the effects of thermal stress existed in high temperature growth or bonding techniques. Recent progresses in this sub-area will be discussed in this talk, especially thermal conductance across surface-activated bonded GaN and β-Ga2O3 interfaces measured by time-domain thermoreflectance (TDTR) and the effects of thermal boundary resistance values on device temperatures. Finally, the potential challenges will also be pointed out, for instance, high-throughput thermal measurements of buried interfaces, thermal property-structure relations of interfaces bonded under different conditions, theoretical understanding of interfacial thermal transport, and device demonstrations.

Диагностический контроль качества светодиодов по тепловым характеристикам

The results of measurements of the current dependences of the thermal resistance of the junction-case of LEDs of various types and manufacturers are presented. It is determined that the thermal resistance increases with increasing current, and for many samples there is a noticeable break in the current dependence of thermal resistance at currents close to the nominal one. It has been experimentally shown that the steepness of the current dependence of the junction-case thermal resistance can be used as a diagnostic parameter that makes it possible to estimate the degree of temperature distribution inhomogeneity. According to the results of tests of red low-power LEDs TLCR5800 under direct current for 8,000 h, a correlation was established between the magnitude of the power drop and the steepness of the current dependence of the junction-case thermal resistance: the correlation coefficient of these values ​​was 0.538. The relative change in thermal resistance during testing is strongly correlated with the absolute value of thermal resistance before testing: the correlation coefficient is -0.685. On the basis of the experimental results obtained, a method for quality control of LEDs was developed by the steepness of the current dependence of the thermal resistance of the junction-case. The developed methods for quality control of LEDs can be recommended for use at the input control of enterprises-manufacturers of LED products.

Flower Shaped Oscillating Heat Pipe at the thermosyphon condition: Performance at different rotational speeds, filling ratios, and heat supplies

The performance of a very effective and innovative thermal device based on Pulsating Heat Pipes (PHP) in a rotating system is studied and analysed in the paper. The appliance called a Flower Shaped Oscillating Heat Pipe (FSOHP) is developed for use in industrial sectors and is arranged in the specific shape of a flower so as to obtain homogeneous heat reception from technological processes. The capillaries, with an inner diameter of 2.7 mm, were filled and tested, with HFE−7000 as a working fluid. This fluid, according to a confinement criterion based on the Bond or Garimella numbers, places the device in the range of thermosyphon operation, the description and experimental verification of which is addressed in this paper. The influence of rotational speed (0–300 rpm), heat input (300–450 W), and filling ratio (40–90%) on the thermal performance has been studied as an experimental research. Current research shows that a low boiling point liquid such as HFE−7000 can be used as a working fluid in a rotating system, and the thermal resistance of the process is characterised by a value of almost 100% higher compared to water. The maximum value of the heat flux value achieved was equal to 22.1 kW/m2 for HFE−7000, while for water it was more than four times higher and equal to 98.4 kW/m2. It was also observed that by increasing the Filling Ratio (FR) by up to 80%, the thermal resistance decreases to the lowest value of 0.05 K/W in speed conditions such as above 200 rpm. Results have shown that with respect to dimensionless numbers, despite going beyond the scope of the confinement criterion, FSOHP achieves a low value of thermal resistance and temperature stabilisation with characteristics very similar to those that describe standard pulsating heat pipe solutions in a stationary system. Furthermore, in a rotating system, an increase in heating power improves the thermal efficiency of the device only for FR >70%, while in a stationary system, an increase in the power supply range studied is always associated with a decrease in thermal resistance, regardless of the FR.

Study of the Effect of Working Fluids on The Thermal Performance of A Horizontal Heat Pipe with Stainless Steel Wick

The present work aims to study the effects of working fluids on the thermal performance of the heat pipe with a wick and in a horizontal position. The experiments were conducted using a copper heat pipe with a 20.8 mm inner diameter, and the length of the evaporator, condenser, and the adiabatic regions were 300 mm, 350 mm, and 300 mm, respectively. The working fluids selected were water, Methanol, ethanol, and different binary mixtures (50: 50) %, (30: 70) %, (70: 30) % mixing ratios. The filling ratio was 50% of the evaporator volume for all working fluids, and the heat input values were 20, 30, 40, and 50 W. The results show that the heat pipe charged with Methanol has a thermal resistance of (0.85166oC/W), the lowest thermal resistance value. The lowest thermal resistance of using mixtures is (0.785 oC/W) for (50 % methanol: 50% ethanol). Both are achieved at 50 W heat input. Also, at 50 W heat input, the highest value of heat transfer coefficient when using water as a working fluid is (510.386 W/m2. oC), and for using a mixture (70 % water: 30% methanol) is (556.78 W/m2. oC).

INVESTIGATION OF THE HEAT PERFORMANCE OF THE HALF-BRIDGE DEVELOPMENT BOARD WITH GAN POWER DEVICES

GaN FET anahtarlar ufak paket boyutlarına sahip olması ve yüksek çalışma gerilim-akım değerlerini yüksek anahtarlama frekanslarında sağlayabilmesinden dolayı güç elektroniği çeviricilerinde yeni ufuklar açmıştır. Bu çalışma EPC firması tarafından üretilmiş olan küçük paket boyutlarındaki EPC2215 (VDS=200V, ID=32A, RDS(on)=8m) GaN FET anahtarların sonlu elemanlar yöntemi tabanlı ısıl modelinin elde edilmesini ile ilgilidir. JEDEC standartlarınca belirlenen deney talimatları kurulan benzetim modeline uygulanmıştır. Anahtarın jonksiyondan kılıfa, jonksiyondan dış ortama ve jonksiyondan devre kartına olan ısıl dirençleri benzetim modeli ile hesaplanmış ve firmanın veri föylerinde paylaştığı ısıl direnç değerleri ile karşılaştırılmıştır. Daha sonra yine aynı firmaya ait olan, EPC2215 anahtarları ile yapılan, EPC9099 yarım-köprü geliştirme kartının ısıl modellemesi yapılmıştır. Firma tarafından veri föyünde paylaşılan kayıp güç değerleri benzetim modeline uygulanmıştır. Benzetim sonucunda geliştirme kartının ısıl yönden zorlandığı bölgeler belirlenmiştir. Daha sonra benzetim ile elde edilen ısıl dağılım sonuçları ile deneysel termal kamera görüntüleri karşılaştırılmıştır.

The effect of thermal insulation of the lining on the heat exchange of rotating apparatuses

Rotary kilns are used in many industries to process bulk raw materials. In the building materials industry, rotary kilns are widely used for heat treatment. However, the fuel utilization factor in rotary kilns is extremely low. Thus, the bulk of cement clinker is fired in furnaces, the thermal efficiency of which does not exceed 55-60%. Therefore, the task of increasing the efficiency of such units is extremely relevant. In operating furnaces, heat losses to the environment only through the furnace body reach 20-25% of the total heat of combustion. In this case, one of the main factors determining the thermal efficiency of furnace operation is the value of thermal resistance of lining.&#x0D; The aim of the work is to study the evolution and temperature changes in the rotary kiln lining made of shaped refractory to reduce heat losses to the environment and improve the efficiency by increasing the thermal resistance of the lining. The increase in thermal resistance is achieved by changing the shape of the refractory by creating appropriate cells and introducing additional fibrous insulating material into them.&#x0D; A mathematical model and software have been developed and numerical calculations have been carried out to determine non-stationary temperature fields in the lining with a thermal insulating element and to substantiate the choice of an appropriate thermal insulating fibrous material.&#x0D; Analyzing the calculation results, it is possible to conclude about the expediency of using a lining with increased thermal resistance. The use of this technical solution makes it possible to reduce heat losses through the housing by 18-24%, to increase the amount of transferred material in the working zone by 1.5-8% due to the creation of an appropriate temperature field in the working volume, and to reduce the mass of the lining and the furnace as a whole. and increase the energy efficiency of the thermal unit.&#x0D; The presence of cells with additional thermal insulation contributes to the emergence of thermal pulsations having oscillatory character and affecting the intensification of heat and mass exchange processes, which in general contributes to the performance of the thermal unit.&#x0D; A significant advantage of this method is also the fact that increasing the energy efficiency of the furnace does not require additional fuel consumption, increasing the temperature or increasing the enthalpy of the combustion products.

Cooling Systems of Power Semiconductor Devices—A Review

In this paper, a detailed review of contemporary cooling systems of semiconductor devices is presented. The construction and the principles of operation of selected components of passive and active cooling systems, as well as selected computer tools supporting the design of such systems, are described. The dependences of thermal parameters calculated using these tools on selected factors characterizing the used cooling systems, e.g., the dimensions of their components, are presented and discussed. Additionally, some results of measurements illustrating the influence of selected parameters on the thermal resistance of power MOSFETs mounted in different cooling systems are shown. The properties of selected cooling systems are compared, and it is shown that by changing the type of cooling system, it is possible to reduce the thermal resistance value of a power MOSFET even 20 times. The presented considerations can make the process of designing cooling systems more effective.

Conjugate heat transfer in lattice frame materials based on novel unit cell topologies

This article presents conjugate heat transfer characteristics of strut-based sandwich-type configurations obtained through reticulation of unit cell topologies of Tetrakaidecahedron, Octet and Rhombic dodecahedron shapes (porosity ∼0.90) with water as working fluid. Tetrakaidecahedron lattice exhibited the highest overall heat transfer coefficient, followed by Octet and Rhombic dodecahedron, respectively. Pressure drop was the highest for Octet, followed by Rhombic dodecahedron, and Tetrakaidecahedron, respectively. Thickness of struts in contact with endwall played a dominant role in conjugate thermal exchange of sandwich configurations. For the investigated conditions, Tetrakaidecahedron-shape based lattice provided the least thermal resistance value at any given pumping power condition.

Effect of Wood Properties and Building Construction on Thermal Performance of Radiant Floor Heating Worldwide

Due to its relatively lower thermal conductivity, the suitability of wood is called into question when selecting the flooring material best suited to radiant heating systems. The European standard EN 1264 considers floorings with a thermal resistance over 0.15 m2 K/W to be out of scope. This belief was partially disproved in a previous article that studied wooden floors for Madrid’s climate. However, the effect of climate still needs to be addressed. The present study extends the previous research to worldwide climates and aimed to answer the following questions: (1) Do the lowest thermal conductivity woods present good thermal performance when used in radiant floors? (2) Should the flooring have a maximum thermal resistance value? (3) Is the standard thermal resistance limit of 0.15 m2 K/W objectively justified? And (4) Do the answers of the preceding questions depend on the climate and the construction characteristics? To answer these questions, 28 cities were selected according to the Köppen–Geiger climate classification. In each city, 216 different dwellings were simulated with 60 wood floorings and one of low thermal resistance as a reference, comprising a total of 368,928 cases. Thermal performance was evaluated in terms of three parameters: energy demand, thermal comfort, and start-up lag time. Consequently, the answers to the previous questions were: (1) The lowest thermal conductivity woods can be used efficiently worldwide in radiant floor heating systems with start-up lag times close to that of the reference flooring; (2) There is no limit value for thermal resistance for floorings that can be applied to all dwellings and climates; (3) No objective justification was found for establishing a thermal resistance limit for flooring of 0.15 m2 K/W; and (4) Climate and construction characteristics can play an important role in the correct selection of flooring properties, especially in severe winters and dwellings with the greatest outdoor-exposed envelope and the worst insulation.

Numerical study of heat losses of building walls containing reflective foils

In external building walls, air cavities are occasionally used to reduce heat losses. Closed air cavities improve the thermal resistance of building structures, especially when the inner surfaces of the cavities are covered with low-emissivity materials such as metalized foils. With these structures, the problem of accurate determination of radiative heat arises. In this contribution, radiative heat transfer is determined by the precise algebraic radiosity method, so far not applied in the field of thermal building technology. Radiative heat computed by the radiosity method has been coupled with convective heat evaluated by the correlation functions of the Nusselt numbers. The combined radiative-convective heat transfer through a sandwich wall containing an air cavity with metalized surfaces (aluminium foils) has been analysed. A computer program has been developed to quantify the real insulation effect of reflective aluminium foils. The sandwich building structure has been subjected to real one-month winter conditions as defined by official meteorological data valid for the city of Brno. The software is based on an iterative procedure that solves the combined radiative-convective steady heat transfers by means of one-day average temperatures and wind speeds. Various arrangements of foils in the cavity have been explored to achieve the maximum value of thermal resistance. The corresponding heat savings have been quantified. The best configuration of foils in the cavity has been found to ensure maximum thermal savings. The insulation system that uses foils has been compared to the system that uses mineral wool. The comparison was based on economic considerations.

Compact Thermal Modeling of Power Semiconductor Devices with the Influence of Atmospheric Pressure

The efficiency of the heat dissipation process generated in semiconductor devices depends on many factors, related both to the parameters of the cooling system and environmental factors. Regarding the latter factors, ambient temperature and volume in which the device operates are typically indicated as the most important. However, in the case of the operation of semiconductor devices in non-standard conditions, e.g., in stratospheric airships, the thermal parameters of the device are significantly affected by a low value of atmospheric pressure. This paper presents a compact thermal model of a semiconductor device, considering the effects of reduced atmospheric pressure along with its experimental verification under various cooling conditions, thus obtaining high compliance for computation and measurement results. The formulated model is dedicated to circuit-level simulations, and it enables computations of the junction temperature of the semiconductor device in a short time. It is also shown that lowering atmospheric pressure can double the value of the junction-ambient thermal resistance.

Thermal performances of a flat-plate pulsating heat pipe tested with water, aqueous mixtures and surfactants

An experimental study is reported about a copper closed-loop flat plate pulsating heat pipe tested in both horizontal and vertical -bottom heated mode- orientations and at two cold source temperatures (20 °C and 40 °C); several working fluids were tested after having modified of their surface tension compared to pure water, verified through dedicated sessile droplets test bench. After which, tests were performed using pure water, pure ethanol, binary aqueous mixtures (water/ethanol, water/butan-1-ol and water/butan-2-ol, the last two being self-rewetting fluids) and water/surfactant mixtures (Tween® 20 and Tween® 40) as working fluids. The thermal performances of the device tested in horizontal orientation were significantly better for the aqueous mixtures such as water/ethanol and water/butan-2-ol than for the others (with values of thermal resistances down to 63%, and 52%, respectively, lower than those of pure water at 20 °C cooling temperature). Concerning pure fluids, the device presents severe temperature and pressure instabilities. Water with surfactants also presents enormous instabilities, calling into question the interstitial influence of the tested surfactants in the hydraulic slug flow pattern occurring in horizontal inclination. The results in vertical orientation, although often studied in the literature, are less conclusive and more difficult to analyze given that surface tension effects are less influential compared to the gravity effects in the annular or bubbly flow patterns occurring in this operating mode. Finally, zeotropic mixtures with butan-2-ol and ethanol performing very similarly, and considering their identical surface tension, the expected rewetting effect of SRWF is not proven, and may not even explain improved FPPHP operation, which is rather assumed to be largely caused by enhanced wettability or increased (∂P/∂T)sat.

Calculation, simulation and fast estimation of thermal resistance of rotary voice coil actuators

Rotary voice coil actuator (RVCA) is mainly used for reciprocating drive of small inertia loads in a limited range of angle, which is widely used in aerospace and other fields. Thermal resistance is one of the most important parameters of RVCAs, which is directly related to the steady-state temperature rising and operation reliability. Because the thermal resistance cannot be measured directly, the analytical method is usually used to calculate the thermal resistance of the RVCA. However, due to the particularity of the thermal circuit calculation, the calculation is complicated and the result is not accurate. It is not conducive for engineering applications of this kind of actuator. In this paper, a series of rotary voice coil motor is selected as the research object. Through analytical calculation and thermal simulation, a more accurate thermal resistance calculation correction model and thermal resistance value of RVCAs are obtained, and the accuracy of the estimation results is verified by experiments. On this basis, the effective volume of the coil frame of the RVCA is selected as the variable, and the concise variation law of the series thermal resistance data is obtained. This paper provides a fast and accurate estimation method for the thermal resistance of RVCA, which has an important reference value for expanding the engineering applications of RVCAs.