摘要
针对高温高湿工业环境中红外热像仪的热防护需求,文中提出一种融合被动隔热与主动对流换热的热防护结构。通过采用低热导率聚四氟乙烯作为外壳材料,结合优化设计的圆形散流器(导叶角度θ=55°、扩散圆直径D1=40 mm、导叶长度L=10 mm),显著增强结构内部对流换热性能。基于计算流体力学模拟(CFD)与实验验证,优化后结构对流传热系数提升至78.07 W·m^(-2)·K^(-1),热像仪表面最高温度由42.6℃降至33.75℃,并提升了温度分布均匀性。模拟了在夏季最高气温38℃条件下,热像仪温度稳定于42.35℃,满足多种室温条件下的运行要求。实验结果与数值模拟结果有较高的一致性,二者最大相对误差为5.92%。研究结果表明,该结构通过协同优化材料热特性与流场分布,有效解决了高温密闭环境中光学仪器的热防护难题,为红外热像仪在高温工业场景的应用提供了重要技术支持,同时也为类似设备的热防护设计提供了借鉴思路。
Objective Thermal protection for infrared cameras is critical for maintaining their stability under complex operating conditions,such as high temperatures and high humidity.The elevated temperatures and humidity during the drying process pose significant challenges to the camera’s performance and lifespan,potentially causing deformation of the imaging window,damage to electronic components,and a loss of temperature measurement accuracy.To address these issues effectively,a thermal shield that combines thermal insulation with active cooling is essential to maintain the camera’s operating temperature within its acceptable range(10℃to 50℃).This thermal protection device must provide efficient heat dissipation,reliable sealing,and compact design.However,conventional thermal protection methods relying solely on insulation or basic cooling are insufficient to meet the demands of such complex conditions.Therefore,this study proposes a thermal protection device for infrared thermal imager that integrates passive insulation with active cooling,enabling adaptation to hightemperature,high-humidity environments while optimizing the camera’s temperature measurement performance and operational stability.Methods A thermal protection structure for an infrared thermal imager is proposed(Fig.3).The design integrates passive thermal insulation using a PTFE housing and active heat transfer optimization with a diffuser installed at the cooling air inlet(Fig.4).Numerical simulations were performed to determine the optimal structural parameters of the diffuser(Fig.5).The flow and heat transfer processes within the structure were analyzed using computational fluid dynamics(CFD),with the Realizable k-εturbulence model selected as the computational approach.Grid-independence validation(Fig.6)was conducted to ensure that the numerical simulation results were unaffected by the grid density.In order to verify the validity of the numerical simulation results,experimental tests were carried out within the high temperature drying process section(Fig.14).Results and Discussions The guide vane angle was increased from 35°to 55°,significantly improving convective heat transfer efficiency and optimizing temperature distribution(Fig.7).The cooling effect was optimal at 55°,where the average temperature of the thermal imaging camera was 36.55℃,and the maximum temperature was 36.7℃(Fig.8).When the horizontal diffusion circle diameter D1=40 mm,the average temperature of the infrared thermal imager was further reduced to a minimum of 33.65℃(Fig.10),and the convective heat transfer coefficient reached a maximum value of 78.07 W·m^(−2)·K^(−1)(Table 5),achieving optimal airflow distribution and temperature uniformity.Under fixed guide vane angle and diffusion circle diameter conditions,the guide vane length L=10 mm,resulted in the lowest infrared thermal imager temperatures,with an average temperature of 33.65℃and a maximum temperature of 33.75℃(Fig.12).At this length,the convective heat transfer coefficient also reached its maximum value of 78.07 W·m^(−2)·K^(−1)(Tab.6),indicating optimal airflow disturbance and heat transfer efficiency.However,excessive guide vane length reduced cooling performance and caused a temperature rebound.The temperature of the cooling air varies with seasonal weather,requiring a higher flow rate to enhance convective heat transfer in hot conditions.At an air inlet temperature of 38℃,increasing the flow rate from 40 m/s to 140 m/s reduced the average temperature of the camera from nearly 50℃to 42.35℃(Fig.13),meeting its operational requirements.The influence of the thermal gradient on heat conduction was analyzed,with the calculated results presented in Tab.7.The maximum deformation observed was 0.11 mm,and the peak thermal stress reached 5.52 MPa,both within acceptable limits.Numerical simulations were conducted under the same boundary conditions as the experiments,and the results from both approaches were compared.Figure 15 illustrates the comparative analysis between experimental data and numerical simulation outcomes under varying air inlet temperatures.The findings indicate a high degree of correlation between the numerical simulations and experimental measurements,with the maximum relative error for peak temperatures at measurement points being 5.72%,and for average temperatures,5.92%.Conclusions A forced convection heat transfer protection structure was designed by integrating passive heat insulation and active convection technologies.The passive design utilizes low thermal conductivity materials to form a shell structure,minimizing heat transfer in high-temperature environments.For active cooling,highpressure gas is introduced as a cooling source,with a circular diffuser and optimized air inlet structure enhancing convective heat transfer efficiency.Both numerical simulations and experimental tests confirm that the proposed structure can reliably protect infrared thermal imager in ambient temperatures up to 130°C.The optimized design achieves uniform cooling gas distribution,lowering the maximum camera temperature from 42.6℃ to 33.75℃—a 20.78% reduction.Under extreme room temperatures of 38℃,increasing the air inlet velocity to 140 m/s reduces the camera temperature to 42.35℃,meeting operational requirements.This study provides a valuable reference for addressing thermal protection challenges of optical instruments in industrial hightemperature scenarios.The experimental validation ultimately confirmed the effectiveness of the thermal protection structure,with the experimental results demonstrating excellent agreement with the numerical simulation outcomes.
作者
席志远
施海亮
曹家升
孙熊伟
王先华
王济乐
XI Zhiyuan;SHI Hailiang;CAO Jiasheng;SUN Xiongwei;WANG Xianhua;WANG Jile(Institutes of Physical Science and Information Technology,Anhui University,Hefei 230601,China;Key Laboratory of Optical Calibration and Characterization,Anhui Institute of Optics and Fine Mechanics,Hefei Institutes of Physical Science,Chinese Academy of Sciences,Hefei 230031,China;Zhanjiang Cigarette Factory,China Tobacco Guangdong Industrial Company Limited,Zhanjiang 524033,China)
出处
《红外与激光工程》
北大核心
2025年第7期110-121,共12页
Infrared and Laser Engineering
基金
喷雾粒径与烟片加料均匀性量化关联分析研究项目(E43Y0J23)。
关键词
热防护
红外热像仪
散流器
强迫空气对流换热
thermal protection
infrared thermal imager
diffusers
forced air convection heat transfer
