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Hybrid photovoltaic–thermal and solar thermal collectors with integrated phase change materials: toward sustainable greenhouse energy systems 集成相变材料的混合光电热和太阳能集热器:朝向可持续温室能源系统
IF 2.6 3区 工程技术 Q2 ENGINEERING, MECHANICAL Pub Date : 2026-01-31 DOI: 10.1016/j.ijheatfluidflow.2026.110268
Soroush Entezari , Meysam Khatibi , Mikhail Sorin
Greenhouses require substantial energy for heating, cooling, and electricity, yet current renewable solutions rarely provide all three simultaneously. Most existing systems supply either thermal or electrical output and lack integrated storage, creating mismatches between solar availability and greenhouse demand and reinforcing dependence on fossil fuels. This study addresses this problem by developing and analyzing a hybrid photovoltaic–thermal (PVT) and solar thermal (ST) collector system integrated with phase change materials (PCMs) for combined power generation and heat storage in greenhouse applications. A three-dimensional numerical model examines the effects of PCM type (RT21, RT31, RT35) and heat transfer fluid flow rate under typical summer conditions in Sherbrooke, Québec, Canada. Results indicate that low-melting PCMs (RT21) achieve rapid phase change before solar noon, offering early-day cooling but limited afternoon buffering. Conversely, higher-melting PCMs (RT31, RT35) extend heat absorption throughout peak irradiance, optimizing PV thermal regulation. Parametric analysis reveals that reduced HTF flow rates maximize PCM utilization and outlet temperatures, whereas higher flow rates prioritize electrical stability. Exergy results indicate a fundamental trade-off: RT21 maximizes daily-average thermal exergy through superior temperature gradients, while RT35 optimizes electrical exergy by maintaining lower cell temperatures. Increasing HTF flow rate enhances electrical exergy but reduces thermal exergy by lowering the temperature level of the delivered heat. A 100 m2 installation yields approximately 455 kWh/day of thermal energy and 35.5 kWh/day of electricity (July/August), satisfying nearly all thermal loads and 30–34% of electrical demand. This configuration achieves a significant mitigation of 77–78 kg CO2e/day, primarily through the displacement of carbon-intensive natural gas heating.
温室需要大量的能源来加热、冷却和发电,但目前的可再生能源解决方案很少能同时提供这三种能源。大多数现有系统要么提供热能输出,要么提供电能输出,缺乏综合存储,造成太阳能供应与温室气体需求之间的不匹配,并加强了对化石燃料的依赖。本研究通过开发和分析一种结合相变材料(PCMs)的混合光伏热(PVT)和太阳能热(ST)集热器系统,解决了这一问题,该系统可用于温室联合发电和蓄热应用。三维数值模型研究了在加拿大quemenbec Sherbrooke典型夏季条件下PCM类型(RT21, RT31, RT35)和传热流体流速的影响。结果表明,低熔点PCMs (RT21)在太阳正午之前实现了快速相变,提供了早期的冷却,但有限的下午缓冲。相反,高熔点pcm (RT31, RT35)在整个峰值辐照度中扩展热吸收,优化PV热调节。参数分析表明,降低HTF流量可使PCM利用率和出口温度最大化,而高流量则优先考虑电气稳定性。火用结果表明了一个基本的权衡:RT21通过优越的温度梯度最大化日平均热用,而RT35通过保持较低的电池温度来优化电能。增加HTF流量增加了电能,但通过降低传递热量的温度水平来减少热耗。一个100平方米的装置产生大约455千瓦时/天的热能和35.5千瓦时/天的电力(7月/ 8月),满足几乎所有的热负荷和30-34%的电力需求。这种配置主要通过取代碳密集型天然气供暖,实现了每天77-78千克二氧化碳当量的显著减排。
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引用次数: 0
Numerical modelling of heat and mass transfer during vapour condensation in porous media: Insights from neutron tomography 多孔介质中蒸汽凝结过程中传热传质的数值模拟:来自中子层析成像的见解
IF 2.6 3区 工程技术 Q2 ENGINEERING, MECHANICAL Pub Date : 2026-01-31 DOI: 10.1016/j.ijheatfluidflow.2026.110293
Arash Nemati , Philippe Séchet , Bratislav Lukić , Matthieu Briffaut
Moisture condensation in porous media influences heat and mass transport in natural and engineered systems, with implications for energy, environmental, and material applications. This study presents a new framework for analysing coupled heat and mass transfer during vapour condensation in porous materials. The Darcy-scale model, formulated under local thermal equilibrium, incorporates multiphase flow, phase change, and heat transport through standard capillary and permeability relationships. A finite-volume solver was implemented in OpenFOAM to couple heat and vapour transport via a temperature-dependent vapour saturation relationship. An analytical solution for the immobile case, where the condensed liquid remains stationary, defines an effective Péclet number that quantifies the competition between advective and diffusive transport of both heat and vapour. Together with the capillary number (relevant in mobile regimes), representing the balance between pressure and capillary forces, these parameters help classify the condensation regimes. Simulation results reveal that near the condensation front, water flux is driven by capillarity, while farther behind, pressure gradients from vapour injection dominate. Higher effective Péclet numbers yield sharper condensation fronts, while higher capillary numbers enhance liquid spreading near the front. Validation using time-resolved neutron tomography and prior numerical results confirms the ability of the model to capture key condensation mechanisms. The framework also extends to heterogeneous media with fractures, where condensation concentrates near the fracture and gradually diffuses into the surrounding matrix.
多孔介质中的水分凝结会影响自然和工程系统中的热量和质量传递,对能源、环境和材料应用产生影响。本研究提出了一种分析多孔材料蒸汽冷凝过程中耦合传热传质的新框架。darcy尺度模型是在局部热平衡下建立的,通过标准的毛细管和渗透率关系,结合了多相流、相变和热传递。在OpenFOAM中实现了一个有限体积求解器,通过温度依赖的蒸汽饱和度关系将热量和蒸汽传输耦合起来。对于凝固液体保持静止不动情况的解析解,定义了一个有效的psamclet数,该数量化了热和蒸汽的平流和扩散输送之间的竞争。这些参数与毛细管数(与流动状态有关)一起,代表压力和毛细管力之间的平衡,有助于对冷凝状态进行分类。模拟结果表明,在凝结锋附近,水通量由毛细作用驱动,而在凝结锋后面,蒸汽注入压力梯度占主导地位。较高的有效psamclet数产生更尖锐的冷凝锋,而较高的毛细数增强液体在锋附近的扩散。使用时间分辨中子层析成像和先前的数值结果验证了该模型捕获关键冷凝机制的能力。该框架也扩展到具有裂缝的非均质介质中,其中冷凝集中在裂缝附近,并逐渐扩散到周围的基质中。
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引用次数: 0
Numerical simulation of thermal counterflow in superfluid helium: converging/diverging, hyperbolic/elliptical, and forward/backward steps channels 超流氦热逆流的数值模拟:收敛/发散、双曲/椭圆和前/后阶通道
IF 2.6 3区 工程技术 Q2 ENGINEERING, MECHANICAL Pub Date : 2026-01-31 DOI: 10.1016/j.ijheatfluidflow.2026.110262
Hamid Yousefi, Hossein Afshin
In this study, the thermal counterflow of superfluid helium is numerically simulated within converging/diverging, hyperbolic/elliptic, and forward/backward step channels —all possessing identical length and volume— in order to gain deeper insight into how channel geometry influences heat transport, thereby supporting improved engineering and design of high-performance heat exchangers. Simulations were performed using the two-fluid model incorporating the Gorter-Mellink mutual friction formulation under varying ratios of maximum to minimum channel height. The newly developed Super-PIMPLE algorithm—previously proposed for coupling the momentum equations of the components with pressure—has also been employed here. Unlike many similar studies, common simplifications have been avoided, and the results have been validated through a four-stage verification process. Key performance indicators, including maximum temperature difference, thermal resistance, effective thermal conductivity, pressure drop, maximum Reynolds number, component velocity difference, and density ratio, were evaluated and compared across the different geometries. The results indicate that, in general, the straight channel yields the lowest thermal gradient (i.e., minimal thermal resistance and highest effective thermal conductivity). When low thermal resistance is prioritized, but a straight channel is not feasible, the elliptic geometry proves to be a more suitable choice. Furthermore, when the cross-section of the heat flux input is not aligned with the isothermal cross-section, it is preferable for the heat flux to be applied at the smaller cross-sectional area; in such cases, step geometries are more advantageous than nozzles/diffusers. The maximum temperature difference in the nozzle geometry is approximately 16.8 times greater, and in the elliptic channel, approximately 3.8 times greater than that of the straight channel. While all non-straight configurations generally exhibit higher pressure drop compared to the straight channel, a notable exception occurs in the hyperbolic geometry. In certain cases, due to the suppression of vortices and oscillatory flows, the pressure drop is reduced by about 64.9% compared to the straight channel. Overall, when minimizing pressure drop is the primary objective, the hyperbolic channel is preferable to the straight geometry. The highest component velocity difference and mutual friction were observed in the converging channel. In nozzle and backward-step geometries, the mean temperature is higher, and the normal fluid fraction is more dominant.
在本研究中,对具有相同长度和体积的收敛/发散、双曲/椭圆和前向/后向阶梯通道内的超流氦热逆流进行了数值模拟,以便更深入地了解通道几何形状如何影响热传递,从而支持改进高性能换热器的工程和设计。采用结合Gorter-Mellink相互摩擦公式的双流体模型,在不同的最大和最小通道高度比下进行了模拟。新开发的Super-PIMPLE算法——先前提出的用于耦合组件的动量方程与压力——也被用于这里。与许多类似的研究不同,避免了常见的简化,并且通过四个阶段的验证过程验证了结果。关键性能指标,包括最大温差、热阻、有效导热系数、压降、最大雷诺数、组件速度差和密度比,在不同的几何形状下进行了评估和比较。结果表明,一般来说,直线通道产生最低的热梯度(即最小的热阻和最高的有效导热系数)。当优先考虑低热阻,但直线通道不可行的情况下,椭圆几何被证明是更合适的选择。此外,当输入热流的截面与等温截面不对齐时,热流最好施加在较小的截面上;在这种情况下,阶跃几何比喷嘴/扩散器更有利。喷嘴几何形状的最大温差约为直线通道的16.8倍,椭圆通道的最大温差约为直线通道的3.8倍。与直通道相比,所有非直通道结构通常都表现出更高的压降,但在双曲几何结构中有一个明显的例外。在某些情况下,由于涡和振荡流的抑制,压降比直通道降低了约64.9%。总的来说,当最小化压降是主要目标时,双曲通道比直线通道更可取。在收敛通道中观察到最大的分量速度差和相互摩擦。在喷嘴和后退几何形状中,平均温度较高,正常流体分数占主导地位。
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引用次数: 0
A numerical study of a coupled heat transfer process with dual moving domains 双运动域耦合传热过程的数值研究
IF 2.6 3区 工程技术 Q2 ENGINEERING, MECHANICAL Pub Date : 2026-01-30 DOI: 10.1016/j.ijheatfluidflow.2026.110284
Jaya Joshi, Kalpana Kumari, Rajeev
The mathematical framework of the lyophilization (Freeze-drying) process belongs to the class of the Stefan problems. The broad applicability of the freeze-drying (FD) process in various industrial and pharmaceutical systems demands a detailed investigation of the process. It is observed that the influence of the size-dependent permeability remains unexplored in the scope of the FD process. This article presents a mathematical formulation of the FD process, incorporating the effects of vapor permeability as a function of the size of the region and molar diffusivity as a function of the molar concentration. The effect of the convective term arising from the moisture distribution of water vapor in the desorbed region is also explored. The mathematical formulation of the considered phase change process includes two continuously moving time-related interfaces. These moving interfaces bring major complexity to the problem. Therefore, a transformed form of Fibonacci wavelets is introduced to tackle the dual moving interfaces. The results show that the solution obtained from the proposed Fibonacci wavelet collocation method (FWCM) is sufficiently equal to the analytical solution. It is identified that the accuracy of the proposed method strengthens with an increasing degree of Fibonacci wavelets. The results demonstrate that the size-related vapor permeability increases the speed of the primary drying phase, whereas it slows down the secondary drying phase. This shows that the size dependent vapor permeability contributes to the higher kinetic energy of the particles in the primary drying region ζ1(τ)<z<ζ2(τ), whereas the particles in the desorption region 0<z<ζ1(τ) experience a loss in the phase change energy when the vapor permeability varies with the size of the region.
冻干过程的数学框架属于斯蒂芬问题的范畴。冷冻干燥(FD)工艺在各种工业和制药系统中的广泛适用性要求对该工艺进行详细的研究。可以观察到,在FD过程的范围内,尺寸相关渗透率的影响仍然未被探索。本文提出了一个FD过程的数学公式,结合了蒸汽渗透率作为区域大小的函数和摩尔扩散率作为摩尔浓度的函数的影响。本文还探讨了解吸区水汽湿度分布所引起的对流项的影响。所考虑的相变过程的数学公式包括两个连续移动的时间相关界面。这些移动的接口给问题带来了很大的复杂性。因此,引入了一种变换形式的斐波那契小波来处理双移动界面。结果表明,所提出的Fibonacci小波搭配法(FWCM)的解与解析解是充分相等的。结果表明,该方法的准确性随着斐波那契小波的增加而增强。结果表明,粒径相关的水蒸气渗透性增加了一次干燥阶段的速度,而减缓了二次干燥阶段的速度。这表明,蒸汽渗透率的大小决定了初级干燥区(ζ1(τ)<z<ζ2(τ))中颗粒的动能较高,而解吸区(0<z<ζ1(τ))中的颗粒在蒸汽渗透率随区域大小变化时,相变能会损失。
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引用次数: 0
A physics-informed neural network coupling framework for predicting heat and mass transfer characteristics of grains 预测晶粒传热传质特性的物理信息神经网络耦合框架
IF 2.6 3区 工程技术 Q2 ENGINEERING, MECHANICAL Pub Date : 2026-01-29 DOI: 10.1016/j.ijheatfluidflow.2026.110276
Hanru Liu , Tianqi Tang , Yurong He , Ming Zhai
Grain drying is a critical process in agricultural engineering, where optimizing drying efficiency and ensuring product quality depend on accurately understanding the internal temperature and moisture distribution. To obtain the dynamic evolution of internal microscopic information, this study developed a Physics-Informed Neural Network (PINN) coupling framework. By integrating the interaction between temperature and moisture, along with transfer learning, this framework can predict the spatiotemporal evolution of grain temperature and moisture under various drying conditions. The result shows that compared with purely data-driven neural networks (DNN), the PINN coupling framework with added physical constraints achieves lower prediction errors when applied to unknown data. Under the drying condition of 333.15 K, the prediction accuracy of particle temperature and humidity by PINN are improved by 62.4% and 55.3%, respectively, compared with DNN. Furthermore, incorporating transfer learning into the PINN framework significantly improves computational efficiency, enabling the model to adapt more effectively to varying drying conditions. The proposed computational framework offers an innovative approach to explore and predict the dynamic evolution of temperature and moisture in agricultural materials, providing a valuable tool for optimizing drying processes in agriculture and related applications.
粮食干燥是农业工程中的关键环节,优化干燥效率、保证产品质量取决于对粮食内部温度和水分分布的准确把握。为了获得内部微观信息的动态演化,本研究开发了一个物理信息神经网络(PINN)耦合框架。通过整合温度和水分的相互作用,结合迁移学习,该框架可以预测不同干燥条件下谷物温度和水分的时空演变。结果表明,与纯粹的数据驱动神经网络(DNN)相比,添加物理约束的PINN耦合框架在应用于未知数据时获得了更低的预测误差。在333.15 K干燥条件下,PINN对颗粒温度和湿度的预测精度比DNN分别提高了62.4%和55.3%。此外,将迁移学习纳入PINN框架可显著提高计算效率,使模型能够更有效地适应不同的干燥条件。提出的计算框架提供了一种创新的方法来探索和预测农业材料中温度和水分的动态演变,为优化农业和相关应用中的干燥过程提供了有价值的工具。
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引用次数: 0
Study on combined thermal protection performance of film cooling with silica aerogel 膜冷与硅胶气凝胶复合热防护性能研究
IF 2.6 3区 工程技术 Q2 ENGINEERING, MECHANICAL Pub Date : 2026-01-28 DOI: 10.1016/j.ijheatfluidflow.2026.110278
Fei He, Caiyi He, Shupeng Xie, Yatong Zhao, Juntao Xv, Mu Li, Tianle Feng
The thermal insulation capability and stability of thermal protection materials in high-temperature environments are critical to the aero-engine thermal protection. This study uses silica aerogel (SA) as thermal barrier coating (TBC) to investigate its combined thermal protection performance with film cooling. Firstly, thermal conductivity test shows SA can maintain a quite low conductivity value (0.018–0.034 W/(m K)) under a large temperature range, confirming its excellent insulation capability. Subsequently, experimental and numerical investigations were conducted on single film cooling, single SA passive cooling, and SA-film combined cooling under various operating conditions, and the active–passive combined thermal protection characteristics were systematically analyzed at different SA thickness and coolant blowing ratios. Results indicate that SA-film combined cooling exhibits excellent thermal protection capability, and the cooling efficiency at different zones is significantly enhanced. The combined cooling structure’s internal efficiency increases with SA thickness and blowing ratio, but excessive SA thickness impairs surface temperature uniformity and hot-side surface cooling efficiency. Non-uniform SA thickness can significantly reduce the counter-rotating vortex pair downstream of the film holes while enhancing the anti-counter-rotating vortex pair, and improve the active cooling efficiency. The SA-film combined cooling structure with graded increasing SA thickness maintains high cooling efficiency within the film plate while minimizing the coating surface temperature, achieving optimal comprehensive cooling effect.
热防护材料在高温环境下的隔热性能和稳定性是航空发动机热防护的关键。本研究以二氧化硅气凝胶(SA)作为热障涂层(TBC),研究其热防护与薄膜冷却的结合性能。首先,导热系数测试表明,SA在较大的温度范围内可以保持较低的导热系数值(0.018-0.034 W/(m K)),证实了其优异的保温性能。随后,对不同工况下的单膜冷却、单SA被动冷却和SA-膜复合冷却进行了实验和数值研究,系统分析了不同SA厚度和冷却剂吹气比下的主-被动复合热防护特性。结果表明,sa -膜复合冷却具有良好的热保护性能,不同区域的冷却效率均有显著提高。复合冷却结构的内部效率随SA厚度和吹风比的增加而增加,但SA厚度过大会影响表面温度均匀性和热侧表面冷却效率。非均匀SA厚度可以显著降低膜孔下游的反旋转涡对,同时增强反旋转涡对,提高主动冷却效率。分级增加SA厚度的SA-膜复合冷却结构,在保持膜板内部高冷却效率的同时,使涂层表面温度降到最低,达到最佳的综合冷却效果。
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引用次数: 0
Topology optimization of microchannel heat sinks with different Inlet-outlet Widths: 2D optimization and 3D numerical validation 不同进出口宽度微通道散热器拓扑优化:二维优化与三维数值验证
IF 2.6 3区 工程技术 Q2 ENGINEERING, MECHANICAL Pub Date : 2026-01-27 DOI: 10.1016/j.ijheatfluidflow.2026.110277
Xiao-Mei Jin, Ji-Kai Shao, Zeng-Yao Li
Although received considerable attention in microchannel heat sinks of thermal management systems, current topology optimizations have primarily concentrate on enhancing the thermohydraulic performance through internal channel redesign while maintaining fixed inlet and outlet configurations. In this study, the 2D topology optimization of microchannel heat sinks with different inlet and outlet widths is investigated based on the variable density method, with the aim of maximizing the total heat generation and minimizing the total power consumption. The influences of thermal objective weights and Reynolds numbers on topology optimization results are explored in detail. Meanwhile, the 3D numerical simulation is performed to validate the 2D optimized topology. It is demonstrated that the optimized Z-type flow arrangement microchannel heat sink with inlet and outlet both having half the width of the design domain can substantially enhance the thermohydraulic performance, and achieve a 46.4–62.2% reduction in pumping power with the lowest temperature of the bottom wall, compared to the conventional one.
尽管在热管理系统的微通道散热器中受到了相当大的关注,但目前的拓扑优化主要集中在通过重新设计内部通道来提高热水力性能,同时保持固定的入口和出口配置。本研究以总发热量最大化和总功耗最小化为目标,基于变密度方法,研究了不同进出口宽度微通道散热器的二维拓扑优化问题。详细探讨了热目标权值和雷诺数对拓扑优化结果的影响。同时,进行了三维数值仿真,验证了优化后的二维拓扑结构。结果表明,优化后的入口和出口宽度均为设计区域宽度的一半的z型流场微通道散热器,可以显著提高热液性能,在底壁温度最低的情况下,泵送功率比常规散热器降低46.4 ~ 62.2%。
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引用次数: 0
Numerical study of transmission-line icing based on Euler method and comparative analysis of multiple methods 基于欧拉法的输电在线结冰数值研究及多种方法对比分析
IF 2.6 3区 工程技术 Q2 ENGINEERING, MECHANICAL Pub Date : 2026-01-26 DOI: 10.1016/j.ijheatfluidflow.2026.110275
Wuyue Zang , Feng Xu , Zhongdong Duan , Jinping Ou
In this study, an icing model of a transmission line is established by using the secondary development of the Fluent user-defined scalar (UDS) transport equation. An Eulerian two-phase flow model is established by using the UDS transport equation framework to determine the impact of water droplets and the local water-droplet collection coefficient. As per the Messinger thermodynamic equilibrium principle, a user-defined function is developed to assess the icing amount on the microelements of the wire surface and convert it into the ice thickness. To verify the accuracy of the results, the calculation reference values, results, and procedures of the Lagrangian and Euler methods developed by using the discrete phase model are compared and analyzed. The two-dimensional three-dimensional results are compared to determine the relationship between the three-dimensional effect and particle size of the water droplets.
本文利用Fluent自定义标量传输方程(UDS)的二次开发,建立了输电线路结冰模型。利用UDS输运方程框架建立欧拉两相流模型,确定水滴的影响和局部水滴收集系数。根据Messinger热力学平衡原理,开发了一个自定义函数来评估金属丝表面微量元素的结冰量并将其转化为冰厚。为了验证结果的准确性,对离散相模型下拉格朗日法和欧拉法的计算参考值、计算结果和计算过程进行了比较分析。将二维三维结果进行对比,确定三维效果与水滴粒径的关系。
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引用次数: 0
Multi-objective optimization for maximizing thermohydraulic performance and minimizing entropy generation in finned-tube heat exchangers 翅片管换热器热水力性能最大化和熵产最小化的多目标优化
IF 2.6 3区 工程技术 Q2 ENGINEERING, MECHANICAL Pub Date : 2026-01-23 DOI: 10.1016/j.ijheatfluidflow.2026.110265
Luan Nguyen Thanh , An Quoc Hoang , Le Minh Nhut
This study addresses the impact of flat tube aspect ratio and inclined tube arrangement on the thermohydraulic properties and entropy generation in a finned-tube heat exchanger under air flow conditions with a low Reynolds number. Furthermore, this study determines the optimal parameters by maximizing thermohydraulic performance and minimizing entropy generation, aiming to provide valuable orientation for the efficient design of finned-tube heat exchangers using flat tubes for application in the air-cooled condensers of refrigeration and air-conditioning systems. The influence of Reynolds number (Re = 125 − 315), tube aspect ratio (ef = 0.4 − 0.6), and rotation angle (θ = 0 − 30ο) was considered. Multi-objective optimization was performed using Response Surface Methodology (RSM). The results indicated that the increase in the Reynolds number increased the heat transfer rate (HTR), pressure loss, and entropy generation. Increasing the tube aspect ratio increased pressure loss and entropy generation. The HTR and entropy generation change significantly when the tube arrangement is inclined. However, the variation trend depends on the value of the rotation angle and Reynolds number. The results of multi-objective optimization revealed the optimal parameters of Re = 125.9, ef = 0.4, and θ = 6.6ο. These optimal parameters yielded a THP of 1.249, increased the HTC by 11.91 %, and decreased the entropy generation by 2.54 % compared to the reference configuration.
本文研究了低雷诺数空气流动条件下,扁管长径比和斜管布置对翅片管换热器热工性能和熵产的影响。在此基础上,以最大化热工性能和最小化熵产为目标确定最优参数,为制冷空调系统风冷冷凝器中采用平板管的翅片管换热器的高效设计提供有价值的指导。考虑了雷诺数(Re = 125 ~ 315)、管长径比(ef = 0.4 ~ 0.6)和旋转角(θ = 0 ~ 30ο)的影响。采用响应面法(RSM)进行多目标优化。结果表明:雷诺数的增加增加了换热率、压力损失和熵产;增大管径比会增加压力损失和熵的产生。当管道布置倾斜时,热阻比和熵产变化显著。但其变化趋势取决于旋转角度和雷诺数的大小。多目标优化结果表明,最优参数Re = 125.9, ef = 0.4, θ = 6.6ο。与参考配置相比,优化后的THP为1.249,HTC提高了11.91%,熵产降低了2.54%。
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引用次数: 0
Swirl air jets for high heat transfer in solar collectors 用于太阳能集热器高传热的旋流射流
IF 2.6 3区 工程技术 Q2 ENGINEERING, MECHANICAL Pub Date : 2026-01-22 DOI: 10.1016/j.ijheatfluidflow.2026.110270
Nagendra Kumar, Satyender Singh, Sanjay Kumar, Ranchan Chauhan
In the present experimental work, an array of swirl air jets impinging on hot absorber plate is investigated to improve the heat transfer in solar air heater. Swirling nozzles are designed and 3D printed to obtain different velocity and diameter of the air swirls. Various geometrical parameters related to swirling nozzles, such as height of nozzle (30mmH50mm) and number of helix (0ξ4) for three different types of nozzles, i.e., smooth non-swirling (N1), with twisted tap helix (N2), and with twisted tap helix and central tube (N3). The nozzle, N3 presents a novel design that incorporates both smooth in the center and swirl (helix) configuration around to remove the heated zone that commonly left at the central region in swirl jet impingement. Thermal performance of solar air heater (SAH) for all three nozzles is analyzed and compared for the range of mass flow rate, i.e., 0.01kg/sṁ0.025kg/s. The results revealed high thermal performance for N3 which is obtained as 93% and about 40% high in comparison to non-swirling nozzle, N1. Hence, using nozzle, N3 about 9.5% enhancement is noticed in the thermal performance for the variation in H from 30 to 50 mm. The trends of thermohydraulic efficiency delineated the dominance of N3 over other nozzle designs at lower mass flow rate and obtained as 68%, when H = 50 mm and ξ = 2. However, this investigation presents a novel insight in terms of different nozzles design and way forward in the improvement of thermal performance of SAH utilizing mixed swirls and air jets.
在本实验中,研究了一组旋流射流冲击吸热板以改善太阳能空气加热器的传热。设计并3D打印了旋转喷嘴,以获得不同速度和直径的空气漩涡。旋流喷嘴的各种几何参数,如喷嘴高度(30mm≤H≤50mm)和螺旋数(0≤ξ≤4),分别适用于三种不同类型的喷嘴,即光滑非旋流喷嘴(N1)、带旋锥螺旋喷嘴(N2)和带旋锥螺旋和中心管喷嘴(N3)。N3喷嘴采用了一种新颖的设计,它结合了中心光滑和周围的漩涡(螺旋)结构,以消除漩涡射流撞击中通常留在中心区域的加热区。在0.01kg/s≤≤0.025kg/s的质量流量范围内,对三种喷嘴的太阳能空气加热器(SAH)的热性能进行了分析比较。结果表明,N3的热工性能比非旋转喷嘴N1高93%,约40%。因此,使用喷嘴,当H从30到50 mm变化时,N3在热性能上提高了约9.5%。当H = 50 mm, ξ = 2时,热工效率的变化趋势表明,N3在较低质量流量下优于其他喷嘴设计,达到68%。然而,本研究在不同喷嘴设计方面提出了新的见解,并在利用混合漩涡和空气射流改善SAH的热性能方面取得了进展。
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International Journal of Heat and Fluid Flow
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