Applied Thermal Engineering最新文献

{"title":"Combustion reconstruction strategy for ultra-low-load stability in a 1000 MW ultra-supercritical tangentially fired boiler","authors":"Yuanlu Li ,&nbsp;Xuejiao Liu ,&nbsp;Xi Chen ,&nbsp;Guanwen Zhou ,&nbsp;Hong Zhang ,&nbsp;Yonghua Gu ,&nbsp;Wenqi Zhong","doi":"10.1016/j.applthermaleng.2026.130877","DOIUrl":"10.1016/j.applthermaleng.2026.130877","url":null,"abstract":"<div><div>Coal-fired power plants are increasingly required to operate with high flexibility to accommodate renewable energy integration. However, stable combustion of supercritical large-scale units at ultra-low loads (e.g., &lt;20% rated load) is difficult because conventional air-staged strategies designed for emission reduction are incompatible with the weak aerodynamic field under low-momentum conditions. This study develops a combustion organization strategy focused on aerodynamic maintenance for a 1000 MW tangentially fired boiler operating at 20% load, based on an analysis of instability mechanisms and systematic parameter optimization. The results indicate that instability in the base air distribution is caused by an aerodynamic conflict between the over-fire air (OFA) and the main combustion flow, which prevents the formation of a stable tangential vortex and flame core. The proposed strategy addresses this through three modifications. The prerequisite is reversing the OFA to a co-rotating direction with sufficient velocity (≥33.5 m/s), this creates a unified macroscopic flow field and establishes an aerodynamic shield to isolate the core flame from upper furnace recirculation. To further enhance combustion stability, the flame is intensified by optimizing the main zone excess air ratio to 1.0, maximizing the heat release by balancing oxygen availability against flame cooling. Meanwhile, the integrity of tangential vortex is maintained by an optimal primary-to-secondary air mass ratio of 0.5 balances fuel jet penetration with swirl stability. This strategy offers a framework for constructing a stable combustion, offering guidance for the deep peak shaving operation of large-scale boilers.</div></div>","PeriodicalId":8201,"journal":{"name":"Applied Thermal Engineering","volume":"298 ","pages":"Article 130877"},"PeriodicalIF":6.9,"publicationDate":"2026-04-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147661317","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Heat transfer tuning-oriented optimization and screening of triply periodic minimal surface structure-phase change material composites","authors":"Kening Yan ,&nbsp;Junfei Liang ,&nbsp;Ranran Yu ,&nbsp;Tingting Zhou ,&nbsp;Yanhui Feng ,&nbsp;Lin Qiu","doi":"10.1016/j.applthermaleng.2026.130405","DOIUrl":"10.1016/j.applthermaleng.2026.130405","url":null,"abstract":"<div><div>Phase change materials (PCMs) are ideal candidates for thermal energy storage systems due to their high latent heat, small phase change temperature fluctuation and excellent thermal stability. However, low intrinsic thermal conductivity represents a critical limitation that severely restricts practical engineering applications. In this study, three triply periodic minimal surface (TPMS) configurations (Diamond, Primitive and Gyroid) were generated via the implicit function method. By adopting the numerical simulation method and taking solid-liquid interface evolution, temperature distribution, average convective heat transfer coefficient and total melting time as the key indices, the structural optimization of TPMS-PCM composite systems was conducted for TPMS configurations, porosity and pore gradients. The simulation results showed that the Diamond-type TPMS-PCM exhibited the optimal heat transfer performance, with its total melting time reduced by 8.7% and 3.8% vs. Gyroid and Primitive configurations, respectively. The positive pore gradient structure outperformed uniform and negative structures, with the average convective heat transfer coefficient enhanced by a maximum of 8.1%. Visual experiments indicated that pure paraffin had a total melting time of 2179 s, and TPMS-PCM exhibited a drastically enhanced melting rate due to the superior thermal conductivity of TPMS skeletons, with the Diamond-type TPMS-PCM achieving a total melting time of only 320 s, an 85.3% reduction relative to pure paraffin. Moreover, synergistic regulation of porosity and pore gradient further accelerated PCM melting, cutting the time to reach solid-liquid phase-change temperature by a maximum of 20.5%. The established TPMS thermal optimization method underpins porous PCM composite parameter optimization, guiding their engineering preparation and high-efficiency thermal management design.</div></div>","PeriodicalId":8201,"journal":{"name":"Applied Thermal Engineering","volume":"292 ","pages":"Article 130405"},"PeriodicalIF":6.9,"publicationDate":"2026-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147387203","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Predictive optimal dispatch for heterogeneous all-parallel chiller plant systems considering convex surrogate models and real-time operation constraints","authors":"Shanshuo Xing ,&nbsp;Zhiwei Li ,&nbsp;Zhe Wang ,&nbsp;Jili Zhang","doi":"10.1016/j.applthermaleng.2026.130344","DOIUrl":"10.1016/j.applthermaleng.2026.130344","url":null,"abstract":"<div><div>The increasing scale and operational complexity of heterogeneous all-parallel chiller plants pose significant challenges for real-time optimal operation, especially when equipment on/off constraints and load-side evolution are considered. This study proposes a predictive optimal dispatch framework for heterogeneous chiller plant systems that explicitly incorporates minimum up/down time (MU/DT) constraints and multi-step load-side prediction. Input convex neural networks (ICNNs) are used to build convex surrogate models for chillers, chilled-water pumps, condenser-water pumps and cooling towers. They are employed for balancing model fidelity and computational tractability and enhancing the convergence and robustness of continuous optimization. On this basis, a four-step XGBoost predictor is developed for load-side forecasting of cooling load and chilled water return temperature. A bi-level optimization scheme is then formulated. Wherein an upper-level depth-first search (DFS) with engineering-informed pruning and filtering determines feasible on/off sequences, and a lower-level gradient-based solver with ICNN surrogate models optimizes continuous variables. A case study on a hospital chiller plant demonstrates that the proposed method achieves an average energy-saving ratio of 7.92% compared with the baseline of a rule-based strategy. The results demonstrate a prevention of the frequent cycling and power spikes that are observed in static optimization. Pruning and filtering strategies reduce the number of equivalent sequences from 2⁴⁸ (exhaustive search) to 4–384, and each relaxed subproblem is solved in about 0.96 s. Robustness tests under three typical load conditions demonstrate highly concentrated optimal values without outliers, indicating strong reproducibility of the proposed method. Overall, the proposed method provides an effective reference for practical engineering applications of predictive dispatch in heterogeneous all-parallel chiller plants.</div></div>","PeriodicalId":8201,"journal":{"name":"Applied Thermal Engineering","volume":"292 ","pages":"Article 130344"},"PeriodicalIF":6.9,"publicationDate":"2026-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147387284","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Novel multi-condenser hybrid ground source heat pump system incorporated to vapour compressor refrigeration cycle with internal heat exchanger assessed with multi-objective genetic algorithm","authors":"Abu Hena Toslim,&nbsp;Nafisa Riza Chowdhury,&nbsp;Md. Hasan Ali","doi":"10.1016/j.applthermaleng.2026.130403","DOIUrl":"10.1016/j.applthermaleng.2026.130403","url":null,"abstract":"<div><div>Ground-source systems take advantage of the stability of the ground temperatures, allowing for performance levels higher than those of air-source systems. Nevertheless, in areas where cooling is the major requirement, the constant rejection of heat eventually depletes the ground's thermal capacity, gradually degrading the performance of ground-source systems. Internal heat exchangers also contribute to the problem by increasing the compressor's superheat, thereby accelerating the saturation of the ground. In addition, GSHPs suffer from thermal saturation during operation in hot climates. Therefore, there is a need for a heat-rejection system that minimizes heat transfer to the ground while maintaining GSHP performance. This study has proposed a multi-condenser vapour compression refrigeration system approach for solving the condenser load management problems in GSHPs using ground heat exchangers. The conventional GSHP has a reduced COP due to the integration of IHX. Furthermore, the VCR system integrated with the IHX has a greater load on the condenser. Therefore, three theoretical models are proposed and analyzed for the GSHP coupled with the GHE. The load management strategies for the GSHP are classified into air-assisted condenser (AAC) and ground heat exchanger-assisted condenser (GHEAC). Three models are developed for the GSHP coupled with the GHE. These include the baseline model coupled with the GHE, the conventional GSHP coupled with the IHX, and the conventional GSHP coupled with the GHE. The load management strategies for the GSHP are classified into air-assisted condenser (AAC) and ground heat exchanger-assisted condenser (GHEAC). The models are developed as permutations of the two condensers. The AAC model performs best under standard conditions, followed by the GHEAC model. For the AAC model, the amount of heat transferred to the ground is reduced by 63.44% relative to the baseline model. In addition, the exergy efficiency improves by 12.62%, while the COP decreases by 1.25%. In terms of COP, the baseline model performs best, followed by the model in which the ambient air is pre-cooled using the GHE before it is supplied to the condenser to cool the superheated refrigerant.</div></div>","PeriodicalId":8201,"journal":{"name":"Applied Thermal Engineering","volume":"292 ","pages":"Article 130403"},"PeriodicalIF":6.9,"publicationDate":"2026-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147386824","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Selection of high-performance phase change materials for enhanced building thermal management using hybrid multi-criteria decision-making","authors":"Anas Azhar ,&nbsp;Oumaima Imghoure ,&nbsp;Zohir Younsi ,&nbsp;Naoual Belouaggadia ,&nbsp;Nassim Sebaibi","doi":"10.1016/j.applthermaleng.2026.130393","DOIUrl":"10.1016/j.applthermaleng.2026.130393","url":null,"abstract":"<div><div>Phase change materials have attracted significant attention as highly effective and innovative solutions for thermal energy storage and temperature regulation. Due to their high latent heat capacity, PCMs can be incorporated into various applications to enhance thermal management, including walls, floors, bricks, gypsum, and insulation. However, selecting the most appropriate PCM remains a complex decision-making process due to the diversity of choices and multiple evaluation criteria.</div><div>The present research proposes a hybrid multi-criteria decision-making framework for the ranking and selection of optimal phase change materials for building applications. The evaluation criteria were weighted using a combination of objective and subjective methods. The final ranking of the alternatives was then determined using four multi-criteria decision-making techniques.</div><div>Sixteen PCMs with melting temperatures in the human comfort range (18–28 °C) were evaluated based on 16 criteria covering thermophysical, kinetic, economic, and environmental aspects. The results showed that A28 ranked first (260 kJ.kg⁻¹), followed by A26 (230 kJ.kg⁻¹) and PureTemp27 (202 kJ.kg⁻¹). The superior thermal behavior of these PCMs was further validated through building energy simulations in three different climate zones, highlighting their effectiveness in regulating temperature and enhancing thermal management.</div></div>","PeriodicalId":8201,"journal":{"name":"Applied Thermal Engineering","volume":"292 ","pages":"Article 130393"},"PeriodicalIF":6.9,"publicationDate":"2026-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147386825","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A techno-economic design framework and analysis for active solar heating systems in cold climates: A case study in Russia","authors":"Zahra Pezeshki ,&nbsp;Ildar Sultanguzin ,&nbsp;Yury V. Yavorovsky ,&nbsp;Eugene Krinitsky ,&nbsp;Glazov Vasily","doi":"10.1016/j.applthermaleng.2026.130311","DOIUrl":"10.1016/j.applthermaleng.2026.130311","url":null,"abstract":"<div><div>In this article, The viability of installing solar heating systems in Russia, in Ashukino, an urban locality (urban-type settlement) in Pushkinsky District of Moscow, is evaluated. Utilizing T*SOL software, the study examined a distinct solar collector system based on SK YaSolar and compared it with Apricus, Eraslan, and Thermital collectors. The SK YaSolar systems were selected based on their size, type of collector (flat plate or evacuated tube), and collector closed loop. Additionally, the effects of changing the hot water storage tank’s dimensions were examined. The goal is to find an techno-economical solution for a logical design that minimizes CO₂ emissions, lowers initial and ongoing costs, and maximizes energy efficiency. According to the analysis findings, for the case study, the electrical energy from solar for heating usage is 1029 kWh, of which 1024 kWh for a 500-liter domestic water tank and 5 kWh for 44-liter buffer tank and heating the space. To achieve long-term operational stability, the operational feasibility using the quantitative and qualitative data outputs of four collector systems, both closed-loop ETC and FPC, was done. Based on analyses, it was discovered that the larger gross surface and aperture area play an important role in meeting increasing energy demand; however, for smaller spaces with smaller water storage tanks, smaller collectors are more suitable, but small tanks, because they have higher standby losses per unit volume and reaches its maximum temperature faster, shutting off the collector, potentially does not allow the tank buffer to heat up and hence collects less solar energy. Based on findings from the geographical sensitivity analysis for various regions with different exposure level of solar radiation received in Russia, it is projected that from 0.002 to 0.069 million Ton of CO₂ emissions can be averted annually. So, solar heating systems provide a cost-effective and environmentally friendly energy solution by doing away with the requirement for an electrical water heater and saving a significant amount of energy.</div></div>","PeriodicalId":8201,"journal":{"name":"Applied Thermal Engineering","volume":"292 ","pages":"Article 130311"},"PeriodicalIF":6.9,"publicationDate":"2026-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147386855","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Optimization of spiral-baffle thermocline tanks under varying conditions in solar Kalina cycles","authors":"Kaiyuan Huang ,&nbsp;Junye Hua ,&nbsp;Baolian Niu ,&nbsp;Gui Li ,&nbsp;Xianan Zeng ,&nbsp;Xinmin Liu ,&nbsp;Hai Lan ,&nbsp;Keyi Sang ,&nbsp;Huiyan Liu","doi":"10.1016/j.applthermaleng.2026.130381","DOIUrl":"10.1016/j.applthermaleng.2026.130381","url":null,"abstract":"<div><div>The Kalina cycle, which is well suited for low- and medium-temperature heat sources, exhibits strong coupling potential with solar thermal power generation systems. Thermocline thermal energy storage tanks, owing to their simple structure and reliable operation, are widely used in solar thermal plants. In this study, a spiral baffle is introduced into an inclined thermocline storage tank with the aim of improving thermal stratification behavior through geometric and operating parameter adjustment. Transient three-dimensional numerical simulations are conducted to investigate the combined effects of height-to-diameter ratio and incline angle, as well as operating conditions including inlet molten salt temperature, on the charging and discharging characteristics. Within the investigated parameter ranges, the results indicate that favourable discharging performance occurs when the inclination angle is between 10° and 20° and the height-to-diameter ratio is between 3.2 and 3.4, with a maximum simulated discharging efficiency of 93.36%. Increasing inlet temperature tends to destabilize the flow field, and relatively better performance is observed within a moderate temperature range. When the inlet temperature is between 473 K and 573 K, the simulated charging and discharging efficiencies reach 93.0% and 92.8%, respectively. In addition, numerical comparison with a conventional storage tank under the same modeling assumptions suggests that the spiral-baffle configuration can shorten the charging and discharging durations by 37.1% and 35.5%, respectively, and increase the discharging efficiency from 88.37% to 90.84%. These findings reflect trends observed within the present numerical framework and parameter space, rather than general optimization results.</div></div>","PeriodicalId":8201,"journal":{"name":"Applied Thermal Engineering","volume":"292 ","pages":"Article 130381"},"PeriodicalIF":6.9,"publicationDate":"2026-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147386890","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A thermodynamics-based turbocharger matching method for large-displacement methanol engines considering in-cylinder air state and exhaust composition","authors":"Xianyu Jia ,&nbsp;Yongfeng Liu ,&nbsp;Lifeng Ma ,&nbsp;Qisheng Zhang ,&nbsp;Xiqing Zhang","doi":"10.1016/j.applthermaleng.2026.130180","DOIUrl":"10.1016/j.applthermaleng.2026.130180","url":null,"abstract":"<div><div>Methanol has attracted increasing attention for internal combustion engines due to its clean combustion characteristics and carbon-neutral potential. Most existing methanol engines are converted from natural gas or diesel engines. However, their performance is constrained by methanol's low heating value and lean-burn characteristics, which demand a larger intake air mass under high-power conditions. This challenge is further complicated by the high water content and relatively low temperature of the exhaust gas, which hinder efficient exhaust energy recovery. Consequently, turbochargers originally matched for fossil-fuel engines often fall short in meeting the needs of methanol engines, making dedicated re-matching of the turbocharging system necessary. In this study, a thermodynamics-based turbocharger matching method is proposed to improve engine performance by accounting for the in-cylinder air state and the effects of exhaust composition, thereby achieving thermodynamic synergistic matching among the engine, compressor, and turbine. The method was validated experimentally across a range of engine speeds and throttle openings, with the deviation between the measured and calculated values remaining within 5%. Finally, a well-matched turbocharger for a 14.5 L methanol engine is selected according to the method, achieving a maximum power of 481.82 kW and a maximum torque of 2880.17 N·m, representing improvements of 23.52% and 9.20%, respectively, compared with the original turbocharger. The proposed method directly determines key turbocharger performance parameters for given engine targets, enabling rapid turbocharger–engine matching and accelerating methanol engine development.</div></div>","PeriodicalId":8201,"journal":{"name":"Applied Thermal Engineering","volume":"292 ","pages":"Article 130180"},"PeriodicalIF":6.9,"publicationDate":"2026-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147386941","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Gyroid-based PCM-water compact heat exchangers","authors":"Federico Torri ,&nbsp;Fabio Berni ,&nbsp;Youssef Aider ,&nbsp;Prashant Singh","doi":"10.1016/j.applthermaleng.2026.130352","DOIUrl":"10.1016/j.applthermaleng.2026.130352","url":null,"abstract":"<div><div>Triply periodic minimal surface structures are investigated in heat exchanger configuration with phase change material and water as participating media. Gyroid-based monolith heat exchangers are additively manufactured via selective laser melting AlSi10Mg at three different porosities of 0.7, 0.75 and 0.8. Transient heat transfer experiments are conducted for a wide range of water flow rates to understand the effect of porosity and water flow conditions on the phase change material solidification. Besides experimental characterization, a computational fluid dynamics methodology is proposed to investigate the performance of the tested exchangers and is validated against experiments. This study shows that the lowest-porosity structure provides the best thermal performance in terms of total time required for phase change material solidification, with a reduction of nearly 40% compared to the highest porosity one. This performance is the result of higher convective heat transfer coefficient and effective thermal conductivity due to higher metal content. The highest-porosity specimen exhibits greater latent heat storage capability and lower water pressure drop, reducing the required pumping power to 40% of that associated with the lowest porosity structure. The total solidification time is found to be less sensitive to water flow rate for a given Gyroid porosity. In comparison with a conventional offset strip fins topology, the Gyroid structure exhibits higher performance evaluation criterion, thus offering higher global thermo-hydraulic efficiency.</div></div>","PeriodicalId":8201,"journal":{"name":"Applied Thermal Engineering","volume":"292 ","pages":"Article 130352"},"PeriodicalIF":6.9,"publicationDate":"2026-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147386944","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Vertical-finned microchannel heat exchangers: Fin geometry effects on thermal–hydraulic performance under dry and frosting conditions","authors":"Yuzhao Luo ,&nbsp;Meng Lu ,&nbsp;Chen Zheng ,&nbsp;Jiedong Ye ,&nbsp;Jianxun Huang ,&nbsp;Kewei Shi ,&nbsp;Feng Li ,&nbsp;Bao Yue ,&nbsp;Bin Luo","doi":"10.1016/j.applthermaleng.2026.130473","DOIUrl":"10.1016/j.applthermaleng.2026.130473","url":null,"abstract":"<div><div>Optimizing fin geometry is crucial for mitigating frost-related degradation of vertical-finned microchannel heat exchangers (VMHXs) in air-source heat pumps, yet trade-offs between dry, frosting, and drainage performance remain unclear. This study experimentally compares wavy/louvered fins (1.3<!--> <!-->mm/1.5<!--> <!-->mm spacings) under standard dry (35/24 °C) and frosting (2/1 °C) conditions. At Re<span><math><mo>≈</mo></math></span>568 (dry), louvered fins enhance Colburn <span><math><mi>j</mi></math></span>-factor by 54.9% but double the friction factor, with 1.5<!--> <!-->mm spacing showing higher thermo-hydraulic efficiency (PEC) than 1.3<!--> <!-->mm. Under frosting (484<!--> <!-->m³ <!-->h⁻¹), louvered fins achieve higher peak heat transfer (520.5<!--> <!-->W vs. 500.7<!--> <!-->W) but accumulate twice the total frost mass by cycle end, leading to faster performance decay. Wavy fins (1.3<!--> <!-->mm) exhibit superior frost resilience, 45% shorter drainage time (107.4 s vs. 195.9 s), and 24% lower water retention. All tested configurations feature a hydrophilic coating and identical core dimensions. A climate-adaptive guideline is proposed: wavy fins (1.3<!--> <!-->mm) for high-humidity/frost-prone regions, louvered fins (1.5<!--> <!-->mm) for dry climates, and hybrid fins for mixed conditions. This work provides practical insights for optimizing VMHX energy efficiency and operational stability in next-generation HVAC systems.</div></div>","PeriodicalId":8201,"journal":{"name":"Applied Thermal Engineering","volume":"292 ","pages":"Article 130473"},"PeriodicalIF":6.9,"publicationDate":"2026-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147387017","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}