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21 pages, 10772 KB

Open AccessArticle

Structured Design Methodology for Compact Plate Heat Exchangers

by Md Zishan Akhter, Mohammad Faisal, Ahmed Shaaban, Kamil Jaworczak and Philip Hart

Energies 2026, 19(4), 914; https://doi.org/10.3390/en19040914 - 10 Feb 2026

Viewed by 624

Abstract

The increasing demand for compact and high-performance thermal management systems in the industrial and energy sectors has renewed interest in plate-type heat exchangers for high heat-flux dissipation. These exchangers offer high surface-area-to-volume ratios, modular architecture, and scalable construction, making them suitable for applications [...] Read more.

The increasing demand for compact and high-performance thermal management systems in the industrial and energy sectors has renewed interest in plate-type heat exchangers for high heat-flux dissipation. These exchangers offer high surface-area-to-volume ratios, modular architecture, and scalable construction, making them suitable for applications requiring advanced cooling within restricted space. This study presents a structured thermo-hydraulic design framework for compact plate heat exchangers operating under fixed wall-temperature boundary conditions. The framework integrates geometric scaling, surface-morphology variation, and multi-parameter performance evaluation to assess the balance between convective enhancement and hydraulic losses. Water at 25 °C serves as the working fluid due to its favorable thermophysical properties and economic viability. A constant wall temperature of 100 °C is applied as a fixed boundary condition to provide a consistent thermal driving potential for comparing different geometries in a range of industrially relevant operating regimes. Three primary design variables are examined: (i) a baseline flat-plate configuration used to establish the fundamental flow–thermal response; (ii) systematic variation of inter-plate spacing to characterize the hydraulic–thermal tradeoff; and (iii) surface-morphology variation using chevron and sinusoidal corrugations to enhance convection through secondary flow generation and boundary-layer modulation. The key performance metrics include wall heat flux, overall heat-transfer coefficient, thermal resistance, and pressure-drop penalty. These indicators are evaluated to identify configurations that are thermally effective and hydraulically feasible. The results show that an inter-plate spacing of 7 mm provides a favorable balance between confinement and convective enhancement under the present operating conditions. Sinusoidal corrugations yield the most favorable thermo-hydraulic performance (PEC

\approx 1.30

) while maintaining low frictional losses. The proposed framework provides a transferable physics-based methodology for comparative assessment and early-stage design of compact heat exchangers under fixed pumping-power constraints. The approach is broadly applicable to renewable-energy systems and compact thermal management in industrial applications. Full article

(This article belongs to the Special Issue Heat Transfer and Fluid Flows for Industry Applications)

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19 pages, 4115 KB

Open AccessArticle

Research on Transformer Hot-Spot Temperature Inversion Method Under Three-Phase Unbalanced Conditions

by Mingming Xu, Bowen Shang, Ning Zhou, Wei Wang, Xuan Dong, Yunbo Li and Jiangjun Ruan

Energies 2025, 18(16), 4422; https://doi.org/10.3390/en18164422 - 19 Aug 2025

Viewed by 1210

Abstract

When a transformer operates under three-phase unbalanced conditions, the location of the winding hot-spot temperature (HST) is no longer fixed on a certain phase. Taking an S13-M-100 kVA/10 kV transformer as the research object, this paper proposes a streamline inversion method for inverting [...] Read more.

When a transformer operates under three-phase unbalanced conditions, the location of the winding hot-spot temperature (HST) is no longer fixed on a certain phase. Taking an S13-M-100 kVA/10 kV transformer as the research object, this paper proposes a streamline inversion method for inverting the winding HST based on the analysis of oil flow morphology. The study employs the finite volume method for coupled calculations of a transformer’s thermal fluid field and combines a support vector regression (SVR) model for the HST inversion. An orthogonal experimental method is used to construct the training and testing sample sets, and the grid search method is utilized to optimize the parameters of the SVR model. In response to variations in hot-spot locations under three-phase unbalanced conditions, representative streamlines are reasonably selected, and a genetic algorithm-based dimensionality reduction optimization is performed on the feature quantities. The research results indicate that the established inversion model exhibits high inversion accuracy under three-phase unbalanced conditions, with a maximum temperature difference of 3.71 K, and the robustness check verifies the stability of the model. Full article

(This article belongs to the Special Issue Heat Transfer and Fluid Flows for Industry Applications)

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19 pages, 3482 KB

Open AccessArticle

Development and Performance Evaluation of Central Pipe for Middle-Deep Geothermal Heat Pump Systems

by Xiong Zhang, Ziyan Zhao, Zhengrong Guan, Jiaojiao Lv and Lu Cui

Energies 2025, 18(14), 3713; https://doi.org/10.3390/en18143713 - 14 Jul 2025

Viewed by 1056

Abstract

In this study, the optimal design of the central pipe in a middle-deep geothermal heat pump (MD-GHP) system is studied using the response surface method to improve the system’s coefficient of performance (COP) and operational reliability. Firstly, a model describing the energy transfer [...] Read more.

In this study, the optimal design of the central pipe in a middle-deep geothermal heat pump (MD-GHP) system is studied using the response surface method to improve the system’s coefficient of performance (COP) and operational reliability. Firstly, a model describing the energy transfer and conversion mechanisms of the MD-GHP system, incorporating unsteady heat transfer in the central pipe, is established and validated using field test data. Secondly, taking the inner diameter, wall thickness, and effective thermal conductivity of the central pipe as design variables, the effects of these parameters on the COP of a 2700 m deep MD-GHP system are analyzed and optimized via the response surface method. The resulting optimal parameters are as follows: an inner diameter of 88 mm, a wall thickness of 14 mm, and an effective thermal conductivity of 0.2 W/(m·K). Based on these results, a composite central pipe composed of high-density polyethylene (HDPE), silica aerogels, and glass fiber tape is designed and fabricated. The developed pipe achieves an effective thermal conductivity of 0.13 W/(m·K) and an axial tensile force of 29,000 N at 105 °C. Compared with conventional PE and vacuum-insulated pipes, the composite central pipe improves the COP by 11% and 7%, respectively. This study proposes an optimization-based design approach for central pipe configuration in MD-GHP systems and presents a new composite pipe with enhanced thermal insulation and mechanical performance. Full article

(This article belongs to the Special Issue Heat Transfer and Fluid Flows for Industry Applications)

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14 pages, 2432 KB

Open AccessArticle

Charge Reduction and Performance Analysis of a Heat Pump Water Heater Using R290 as a Refrigerant—A Field Study

by Ahmed Elatar, Joseph Rendall, Jian Sun, Jamieson Brechtl and Kashif Nawaz

Energies 2025, 18(14), 3661; https://doi.org/10.3390/en18143661 - 10 Jul 2025

Viewed by 2112

Abstract

Heat pump water heaters (HPWHs) are a proven technology for water heating that has been commercialized. The adoption of HPWHs for domestic and commercial water heating is growing rapidly because of their superior performance compared with alternative water heating methods. Whereas most existing [...] Read more.

Heat pump water heaters (HPWHs) are a proven technology for water heating that has been commercialized. The adoption of HPWHs for domestic and commercial water heating is growing rapidly because of their superior performance compared with alternative water heating methods. Whereas most existing systems use R-134a as a working refrigerant, R290 has gained major attention owing to its superior thermodynamic properties. The goal of the current study is to assess the performance of residential HPWH with R290 as a direct refrigerant replacement for R134a. Two units of a 50 gal HPWH were used in this experimental study. A baseline unit contained R134a refrigerant, and a prototype unit contained R290 refrigerant. The prototype unit was developed through the modification of a commercially available HPWH unit to achieve a low charge of R290 refrigerant. Another major modification was the replacement of the baseline compressor with a compressor designed for R290. Tests were conducted in a field environment (a research and demonstration house) using programmed drawn profiles daily. The prototype that reduced the charge by 43–47% provided displayed performance comparable to the baseline unit regarding first-hour rating (FHR) and the uniform energy factor (UEF). Full article

(This article belongs to the Special Issue Heat Transfer and Fluid Flows for Industry Applications)

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11 pages, 8517 KB

Open AccessArticle

Analysis of Water Injection and Heat Recovery Potential of Abandoned Oil Wells Transformed into Geothermal Wells in Northern Shaanxi

by Huagui Yu, Shi Liu, Yanyan Pang, Peng Wang and Qian Gao

Energies 2025, 18(3), 551; https://doi.org/10.3390/en18030551 - 24 Jan 2025

Cited by 1 | Viewed by 1290

Abstract

The Chang 2 bottom water reservoir area in the western part of northern Shaanxi constitutes one of the key oil-producing regions within the Ordos Basin. A principal reservoir here is the Triassic Yanchang Formation’s Chang 2 reservoir, which is characterized by favorable physical [...] Read more.

The Chang 2 bottom water reservoir area in the western part of northern Shaanxi constitutes one of the key oil-producing regions within the Ordos Basin. A principal reservoir here is the Triassic Yanchang Formation’s Chang 2 reservoir, which is characterized by favorable physical properties, dynamic edge and bottom water activity, and a high geothermal gradient. This study employs the STARS module of the CMG reservoir numerical simulation software to model water intake and heat recovery processes in the target region. It analyzes the heat recovery rate and efficiency of three water production methods—direct water extraction, four-injection–one-production, and one-injection–four-production—under varying injection pressures. The results indicate that direct water extraction from the bottom water reservoir is challenging. However, the annual heat recovery per well for the four-injection–one-production and one-injection–four-production methods equates to a standard coal production ranging between 190 and 420 tons, suggesting that there is significant potential for water injection and heat recovery in the Chang 2 reservoir in the western part of northern Shaanxi. Full article

(This article belongs to the Special Issue Heat Transfer and Fluid Flows for Industry Applications)

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21 pages, 9853 KB

Open AccessArticle

Numerical Study on Heat Transfer Efficiency and Inter-Layer Stress of Microchannel Heat Sinks with Different Geometries

by Fangqi Liu, Lei Jia, Jiaxin Zhang, Zhendong Yang, Yanni Wei, Nannan Zhang and Zhenlin Lu

Energies 2024, 17(20), 5076; https://doi.org/10.3390/en17205076 - 12 Oct 2024

Cited by 2 | Viewed by 2417

Abstract

As electronics become more powerful and compact, laminated microchannel heat sinks (MCHSs) are essential for handling high heat flux. This study aims to optimize the MCHS design for improved heat dissipation and structural strength. An orthogonal experiment was established with the average surface [...] Read more.

As electronics become more powerful and compact, laminated microchannel heat sinks (MCHSs) are essential for handling high heat flux. This study aims to optimize the MCHS design for improved heat dissipation and structural strength. An orthogonal experiment was established with the average surface temperature of the heat source as the evaluation metric, and the optimal structure was determined through simulation. Finally, cooling uniformity, fluidity, and performance evaluation criterion (PEC) analyses were carried out on the optimal structure. It was determined that the optimal combination was the triangular cavity microchannel (MCTC), with a microchannel width of 0.5 mm, a microchannel distribution density of 60%, and the presence of surface undulation on the microchannels. The result shows that the optimal structure’s peak inter-layer stress is just 34.8% of its longitudinal tensile strength. Compared to the traditional parallel straight microchannel (MCPS), this structure boasts an 8.6 K decrease in the average surface temperature and a temperature variation along specific paths that is only 9.9% of that in traditional designs. Moreover, the optimal design cuts the velocity loss at the microchannel entrance from 75% to 59%. Thus, this research successfully develops an effective optimization strategy for MCHSs. Full article

(This article belongs to the Special Issue Heat Transfer and Fluid Flows for Industry Applications)

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15 pages, 4571 KB

Open AccessArticle

Study on Leakage and Diffusion Behavior of Liquid CO₂ Vessel in CCES

by Lin Gao, Jinlong Wang, Song Wu, Xuan Liu, Binfei Zhu and Yuguang Fan

Energies 2024, 17(15), 3613; https://doi.org/10.3390/en17153613 - 23 Jul 2024

Viewed by 1528

Abstract

Numerical simulations of the leakage and diffusion behavior of liquid CO₂ vessels and security analyses were conducted in this paper, based on a CO₂ compression energy storage system. With isentropic choking model, the leakage of vessels under specific conditions was numerically [...] Read more.

Numerical simulations of the leakage and diffusion behavior of liquid CO₂ vessels and security analyses were conducted in this paper, based on a CO₂ compression energy storage system. With isentropic choking model, the leakage of vessels under specific conditions was numerically simulated. The influence of different wind speeds on leakage in near-zone field was studied. Meanwhile, the diffusion characteristics of CO₂ under three different influencing factors were investigated with the UDM (Unified Dispersion Model) diffusion model, and the diffusion ranges of certain concentrations were detected in the far-zone field. The results show that the low-temperature zone of the 50 mm leak aperture can reach 0.74 m downwind, and basically does not change with wind speed. In the leakage direction, the maximum damage zone of high-speed flow can reach 7.70 m. For the far-zone field, the diffusion area and downwind distance of a dangerous concentration decrease with the increasing of wind speed, and the hazardous area of the low concentration is greatly affected. Based on specific conditions, the maximum diffusion area is 78.46 m² at 1 m/s wind speed, and the dangerous range reaches 36.32 m downwind. The larger the leakage aperture, the faster the growth trend of the low concentration area under the same conditions. As the equivalent radius of the leakage aperture is less than 50 mm, the maximum diffusion area is proportional to the cubic of the leakage aperture radius. The higher the height of the leakage source, the smaller the concentration range at 1.5 m, which is the average human breathing height. The overall cloud moves upward, meaning that the ground risk decreases. When the leakage aperture is 50 mm and the wind speed is 1 m/s, the maximum cloud diffusion range is 857.35 m² at the leakage height of 2 m, and the dangerous range reaches 109.53 m downwind, where the maximum concentration is 14.65%. Full article

(This article belongs to the Special Issue Heat Transfer and Fluid Flows for Industry Applications)

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Review

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26 pages, 3750 KB

Open AccessReview

Research Progress on Heat Transfer of Herringbone Plate Heat Exchangers Under Single-Phase/Two-Phase Flow

by Junhui Song, Li Lei, Naixiang Zhou and Jingzhi Zhang

Energies 2026, 19(1), 249; https://doi.org/10.3390/en19010249 - 2 Jan 2026

Cited by 1 | Viewed by 1149

Abstract

Against the backdrop of the “dual carbon” strategy, enhancing energy utilization efficiency and promoting low-carbon urban heating have become key directions for energy system transformation. Due to the compact structure, high heat transfer efficiency, and strong adaptability, herringbone plate heat exchangers have emerged [...] Read more.

Against the backdrop of the “dual carbon” strategy, enhancing energy utilization efficiency and promoting low-carbon urban heating have become key directions for energy system transformation. Due to the compact structure, high heat transfer efficiency, and strong adaptability, herringbone plate heat exchangers have emerged as critical intermediate heat exchange equipment in long-distance heating systems. This paper reviews research on the heat transfer performance of herringbone plate heat exchangers, systematically examining fluid flow patterns within plate heat exchangers and the mechanisms influencing thermohydraulic performance under single-phase and two-phase flow conditions, along with recent advancements. First, factors affecting fluid flow within herringbone corrugated plates are introduced. Subsequently, recent experimental and numerical simulation advancements under single-phase and two-phase conditions are presented, along with corresponding performance correlation equations. In contrast, two-phase heat transfer mechanisms are more complex, with relatively insufficient research and a lack of universally applicable theoretical models and performance correlations. This paper argues that future efforts should focus on strengthening research into two-phase flow heat transfer mechanisms and developing more universal and predictive performance models to support the efficient application of plate heat exchangers in low-carbon heating and industrial energy conservation. Full article

(This article belongs to the Special Issue Heat Transfer and Fluid Flows for Industry Applications)

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