Journal Description
Thermo
Thermo
is an international, peer-reviewed, open access journal on all aspects of thermal sciences, including key features on thermodynamics, statistical mechanics, kinetic theory and satellite areas, published quarterly online by MDPI.
- Open Access— free for readers, with article processing charges (APC) paid by authors or their institutions.
- High Visibility: indexed within ESCI (Web of Science), Scopus, EBSCO, and other databases.
- Journal Rank: JCR - Q2 (Thermodynamics)
- Rapid Publication: manuscripts are peer-reviewed and a first decision is provided to authors approximately 26.1 days after submission; acceptance to publication is undertaken in 3.5 days (median values for papers published in this journal in the second half of 2025).
- Recognition of Reviewers: APC discount vouchers, optional signed peer review, and reviewer names published annually in the journal.
- Thermo is a companion journal of Entropy.
Impact Factor:
2.3 (2024);
5-Year Impact Factor:
2.3 (2024)
Latest Articles
Thermoeconomic Analysis of a Cryogenic Power Plant for the Conversion of LNG Cold Energy into Electricity
Thermo 2026, 6(2), 46; https://doi.org/10.3390/thermo6020046 (registering DOI) - 15 Jun 2026
Abstract
This paper investigates the energy recovery potential of LNG cold energy using cryogenic binary cycles. The thermoeconomic performance of single-, two- and three-stage Organic Rankine Cycle (ORC) configurations across different working fluids and LNG regasification capacities has been evaluated. The analysis shows that
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This paper investigates the energy recovery potential of LNG cold energy using cryogenic binary cycles. The thermoeconomic performance of single-, two- and three-stage Organic Rankine Cycle (ORC) configurations across different working fluids and LNG regasification capacities has been evaluated. The analysis shows that ORC-based LNG cold energy power units achieve specific net power outputs of 45–55 kW/(kgLNG/s) for single-stage, 74–83 kW/(kgLNG/s) for two-stage, and 79–88 kW/(kgLNG/s) for three-stage configurations. The corresponding net energy efficiencies are 6.6–7.5%, 10.1–11.2% and 10.8–12.0%, respectively, while the exergy efficiencies are 15.9–17.6%, 22.9–25.3%, and 24.3–26.8%, respectively. Two-stage systems achieve the lowest costs: a levelized cost of electricity (LCOE) of 80–105 €/MWh and a specific investment cost (SIC) of 6000–8300 €/kW. For most of the evaluated working fluids, the power gain from a third stage does not justify the increase in equipment costs. Among the evaluated working fluids, R32, R41 and R161 achieve the best economic performance, while carbonyl sulfide (COS), R32 and R161 achieve the best thermodynamic performance. The highest net power, 12.5 MW, is achieved with COS, whereas the lowest LCOE (80 €/MWh) and SIC (6000 €/kW) are obtained with R32, all for an LNG regasification capacity of 700,000 Sm3/h.
Full article
Open AccessArticle
Steady-State Feasibility of a Phase Change Material-Based Defrosting System and Energy Storage Management Strategies
by
Adrian Chiriac, Horatiu Pop, Valentin Apostol, Claudia Ionita and Daniel Taban
Thermo 2026, 6(2), 45; https://doi.org/10.3390/thermo6020045 - 11 Jun 2026
Abstract
The present work proposes a phase change material-based defrosting system (PCM-DS) for vapor compression refrigeration systems (VCRSs). The primary objective is to determine the optimal PCM mass and refrigerant mass flow rate required to melt 1 kg of accumulated evaporator ice. A steady-state
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The present work proposes a phase change material-based defrosting system (PCM-DS) for vapor compression refrigeration systems (VCRSs). The primary objective is to determine the optimal PCM mass and refrigerant mass flow rate required to melt 1 kg of accumulated evaporator ice. A steady-state macroscopic thermodynamic model, governed by global energy balances and driven by experimental boundary conditions, evaluates the VCRS in both cooling and defrosting operating modes. The PCM-DS is not installed on the experimental setup. The latter is used to obtain experimental data to be used as inputs in the steady-state model. Among the three candidates investigated (OM42, OM46, OM48), OM42 was selected for minimizing system mass and volume constraints. Results demonstrate that integrating the PCM-DS induces only a 3% reduction in the theoretical coefficient of performance (COP) compared with a 5.6% reduction in the case of using the electric heater defrosting (EHD). The core innovation of this work involves proposing and evaluating three distinct energy storage management strategies: unique superheating, unique bypass, and intermittent bypass. The results show that the highest COP is obtained for unique superheating (2.93), followed by unique bypass (2.82) and intermittent bypass (2.81). The work conducted proves the theoretical feasibility of such PCM-DS.
Full article
Open AccessArticle
Heat Transfer Enhancement in the Presence of a Resonant Impinging Jet
by
Michel Matar, Bilal El Zohbi, Ali Hammoud, Marwan Alkheir, Kamel Abed-Meraim, Bilal Taher, Anas Sakout and Hassan H. Assoum
Thermo 2026, 6(2), 44; https://doi.org/10.3390/thermo6020044 - 10 Jun 2026
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This study investigates the coupling between flow dynamics, acoustic response, and convective heat transfer in a rectangular impinging jet striking on a heated slotted plate at two closely spaced Reynolds numbers (Re = 3550 and Re = 3750). Velocity fields were obtained using
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This study investigates the coupling between flow dynamics, acoustic response, and convective heat transfer in a rectangular impinging jet striking on a heated slotted plate at two closely spaced Reynolds numbers (Re = 3550 and Re = 3750). Velocity fields were obtained using Particle Image Velocimetry (PIV), and coherent structures were analyzed using Proper Orthogonal Decomposition (POD) while acoustic measurements were used to characterize the tonal behavior. Infrared thermography was employed to determine local and mean Stanton numbers. The mean Stanton number increased by 6.6% when the Reynolds number increased from Re = 3550 to Re = 3750, while the sound pressure level decreased from 78 dB to 71 dB. At Re = 3550, the acoustic spectrum exhibited multi-tone behavior associated with distributed modal energy. In contrast, at Re = 3750, a single dominant frequency governed the flow dynamics. The energy of the first POD mode nearly doubled when passing from Re = 3550 to Re = 3750. The cross-correlation coefficients between the first POD mode and the acoustic field increase from 0.76 to 0.93 when changing from Re = 3550 to Re = 3750. These findings show that the dominant vortex mode which contains nearly 20% of the fluctuating energy (for Re = 3750), significant influences the energy transfer from the dynamic field to the acoustic field resulting in a strong noise reduction. Simultaneously, convective heat transfer increases, highlighting the key role of coherent flow organization on both acoustic and thermal behavior of the system.
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Open AccessArticle
Thermal Analysis of a Turbulent Ventilated Cavity with Internal Heat Generation
by
Armando Piña-Ortiz, Jesús Fernando Hinojosa, Pablo Sosa-Flores, Ricardo Arturo Pérez-Enciso, Resty Levy Durán and Adolfo Vázquez-Ruiz
Thermo 2026, 6(2), 43; https://doi.org/10.3390/thermo6020043 - 9 Jun 2026
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This work investigates heat transfer experimentally and numerically within a ventilated cavity, both with and without an internal heat source, simulating a room with a person at the interior at 1:3 scale. This setup has applications in building energy systems, cooling of electronic
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This work investigates heat transfer experimentally and numerically within a ventilated cavity, both with and without an internal heat source, simulating a room with a person at the interior at 1:3 scale. This setup has applications in building energy systems, cooling of electronic equipment, solar energy collectors, etc. The experimental configuration consists of a cube in which the left vertical wall is subjected to a uniform heat flux, and the opposing wall is maintained at a constant temperature. A rectangular parallelepiped heat source was placed inside. The remaining walls are thermally insulated, and air is the thermal fluid. Air enters and exits through square ports on the top surface. Experimental temperature profiles were recorded at multiple depths and heights. Corresponding numerical results for temperature fields, flow patterns, turbulent viscosity, and turbulent kinetic energy were generated using the Ansys Fluent 18 CFD software, with six turbulence models assessed against experimental data under steady-state conditions. A key finding is that the Nusselt number and the convective heat transfer coefficients (average) for the hot wall remain negligibly affected by the incorporation or status (on/off) of a heat source at the interior of the cavity, the biggest temperature difference (experimental vs numerical) corresponds to the rkε model with 6.2% when there is no thermal source in the cavity and the lowest difference for the average convective heat transfer coefficient is with the rslrso model with 5.2%.
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Open AccessFeature PaperArticle
Integrated Cryogenic Separation and Energy Valorization of Flue Gas: Thermodynamic Analysis of a Process Line for CO2 and N2 Liquefaction with CO2-Based Power Recovery
by
Orlando Corigliano and Angelo Algieri
Thermo 2026, 6(2), 42; https://doi.org/10.3390/thermo6020042 - 2 Jun 2026
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This work presents the thermodynamic design and performance assessment of an integrated process line for the separation, liquefaction, storage, and valorization of carbon dioxide (CO2) and nitrogen (N2) from flue gas streams. The proposed system aims to combine carbon
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This work presents the thermodynamic design and performance assessment of an integrated process line for the separation, liquefaction, storage, and valorization of carbon dioxide (CO2) and nitrogen (N2) from flue gas streams. The proposed system aims to combine carbon capture with cryogenic energy storage by exploiting the thermophysical properties of the main flue gas constituents. A representative flue gas derived from complete methane combustion (9.5% CO2, 71.5% N2, and 19% H2O by volume) is considered as the feed stream. The process is developed and simulated in DWSIM v9.0.5, adopting a steady-state mass and energy balance framework coupled with rigorous thermodynamic modeling of phase equilibria and unit operations. The plant configuration is based on sequential cooling, compression, and expansion stages, enabling the selective condensation of H2O, CO2, and N2 at different temperature levels. The system integrates heat exchangers, compressors, pumps, turboexpanders, phase separators, and cryogenic storage tanks, while a portion of the liquefied CO2 is reused as an energy carrier through vaporization and expansion in a dedicated turbine. The results demonstrate that the process achieves a CO2 capture ratio of 81.7%, with a specific electric consumption (SEC) of 10.44 kWh/kgCO2 and 1.71 kWh/kgN2. The overall net electric demand is 1.29 kWh/kg of treated flue gas, while the round-trip efficiency (ηRT,CO2) is 18.6%. A significant amount of energy can further be recovered from the “waste” exhaust water stream (12.94 kgL-H2O/kgflue-gas, at 91 °C and 1.2 bar) up to 800 Wh/kgflue-gas, improving the performance of the entire process (SECCO2: 3.86 kWh/kgCO2, ηRT,CO2: 69.8%). The study confirms the thermodynamic feasibility of the proposed configuration and identifies nitrogen liquefaction as the dominant energy-intensive step. Future optimization efforts should therefore focus on reducing exergy destruction in the deep cryogenic section through improved heat integration, enhanced cold-energy recovery, optimized compression–expansion staging, and reduced pressure losses.
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Open AccessArticle
Coupled Irreversibilities and Asymmetric Dissipation in Liquid-State Thermocells
by
Xiongxiong Wu, Zhimin Yang and Yanning Yang
Thermo 2026, 6(2), 41; https://doi.org/10.3390/thermo6020041 - 1 Jun 2026
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Liquid-state thermocells (LTCs) are emerging electrochemical heat engines for harvesting low-grade thermal energy across small temperature differences. Their practical performance is jointly limited by internal dissipation associated with ionic and electrochemical transport, as well as by external irreversibility arising from finite thermal coupling
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Liquid-state thermocells (LTCs) are emerging electrochemical heat engines for harvesting low-grade thermal energy across small temperature differences. Their practical performance is jointly limited by internal dissipation associated with ionic and electrochemical transport, as well as by external irreversibility arising from finite thermal coupling to the heat source and sink. In this work, a finite-rate thermodynamic framework is developed for LTCs subject to coupled internal and external irreversibilities. The model combines effective thermoelectrochemical transport, a phenomenological asymmetric Joule-heat partition parameter motivated by electrode and interfacial heat effects, and non-ideal thermal contacts, thereby enabling analytical optimization of power output in four representative configurations. Closed-form expressions are derived for the maximum power and the efficiency at maximum power (EMP), together with the admissible operating domain and an equivalent-circuit interpretation. The results show that the thermal impedance ratio governs a transition between externally limited and internally limited regimes. In the externally dominated limit, all configurations recover the Curzon–Ahlborn efficiency, whereas in the internally dominated limit, the asymptotic EMP depends on the side receiving irreversible heat release. When both dominant irreversibilities are located on the hot side, the highest EMP is achieved, while the opposite configuration yields the lowest EMP. These findings provide a thermodynamic benchmark for the LTC architecture and clarify how thermal contact asymmetry and internal heat release pathways should be coordinated to enhance performance in low-grade heat recovery.
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Open AccessFeature PaperArticle
Enhancing Battery Available Operating Time (BAOT) via a Passive Series-PCM and Optimized Finned Structures
by
Nicola Bianco, Rosa Francesca De Masi, Andrea Fragnito, Marcello Iasiello, Vittorio Orlanducci and Francesco Piccirillo
Thermo 2026, 6(2), 40; https://doi.org/10.3390/thermo6020040 - 31 May 2026
Abstract
Keeping the battery temperature below a reasonable limit of 50 °C is a primary objective of battery thermal management systems (BTMSs). Accordingly, the battery available operating time (BAOT) can be defined as the time required for the battery maximum temperature to reach 50
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Keeping the battery temperature below a reasonable limit of 50 °C is a primary objective of battery thermal management systems (BTMSs). Accordingly, the battery available operating time (BAOT) can be defined as the time required for the battery maximum temperature to reach 50 °C, which could be adopted as a key indicator for safe and efficient operation. BAOT can be improved through different BTMS configurations. This work focuses on passive solutions, aiming to increase BAOT without requiring pumping power. The study numerically investigates the combined use of phase change materials (PCMs) and fins to evaluate their effectiveness in terms of time percentage improvement (TPI). A preliminary analysis is conducted to assess the need for PCMs and fins at three discharge rates, namely 1C, 3C, and 5C. The results indicate that PCMs are required under all operating conditions, while the use of fins is not always advantageous; in particular, at 1C, fins lead to a reduction in BAOT. The analysis then focuses on the 3C and 5C cases, where topology-optimized fins are employed to dump temperatures under these stress conditions. Three fin arc lengths (ψfin) and eight diffusion coefficients (Rf) are examined. The optimized fin configurations increase BAOT, achieving maximum TPIs of 10.61% and 7.69% for the 3C and 5C cases, respectively, both corresponding to ψfin = 2.75 mm and Rf = 0.10 mm. At 5C, BAOT is limited to only a few seconds; therefore, configurations with PCMs arranged in series are also analyzed using different combinations of four selected PCMs. When coupled with optimized fins, the PCM-in-series solutions yield further improvements, with maximum TPIs of 22.92% for 3C and 62.50% for 5C compared to the single-PCM configuration coupled with optimized fins. The results also show that the optimal diffusion coefficient and PCM arrangement strongly depend on the discharge rate.
Full article
(This article belongs to the Special Issue Design, Simulation and Optimization of Bio-Inspired Thermal Systems)
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Open AccessArticle
Effect of Vanadium Microalloying on the Mechanical and Microstructural Behavior of Moroccan Reinforcing Steels for Seismic Applications
by
Jihane El Hamzaoui, Bennaceur Ouaki and Ahmed Faih
Thermo 2026, 6(2), 39; https://doi.org/10.3390/thermo6020039 - 29 May 2026
Abstract
Seismic-resistant reinforcing steels play a key role in structures subjected to earthquake loading, requiring an optimal balance between strength, ductility, and weldability. Microalloying with vanadium (V), niobium (Nb), and titanium (Ti) is widely used to improve these properties through precipitation strengthening and grain
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Seismic-resistant reinforcing steels play a key role in structures subjected to earthquake loading, requiring an optimal balance between strength, ductility, and weldability. Microalloying with vanadium (V), niobium (Nb), and titanium (Ti) is widely used to improve these properties through precipitation strengthening and grain refinement. This work aims to contribute to the development of seismic-resistant reinforcing steels for the Moroccan construction sector. A literature review identified key international requirements, including a tensile-to-yield strength ratio (Rm/Re) of 1.15–1.35 and a total elongation at maximum force (Agt ≥ 7%). In parallel, Moroccan reinforcing bars were mechanically and microstructurally characterized. A conventional steel containing 0.65 wt.% Mn and no vanadium was used as a reference. This steel exhibited limited strain-hardening capacity, with Rm/Re ratios between 1.12 and 1.15. To improve this behavior, steels containing 1.1 wt.% Mn with different vanadium additions were investigated. Preliminary results indicate that vanadium microalloying improves mechanical performance through combined precipitation strengthening and ferrite grain refinement. The increase in strength is likely associated with fine V(C,N) precipitates formed during cooling, while ferrite grain refinement appears to contribute to maintaining ductility. This synergistic effect results in a more favorable strength–ductility balance, supporting the development of seismic-resistant reinforcing steels for structural applications.
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(This article belongs to the Special Issue Thermal Science and Metallurgy)
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Open AccessArticle
Estimation and Analysis of Power Generation Potential from Municipal Solid Waste in Dire Dawa City Using the Rankine Cycle
by
Aleazar Abraham Wollebo, Gedyon Fikade Alemu, Venkata Ramayya Ancha and A. Johnson Santhosh
Thermo 2026, 6(2), 38; https://doi.org/10.3390/thermo6020038 - 28 May 2026
Abstract
The transition toward renewable energy sources has become a critical global objective. For developing nations facing the dual challenges of inefficient waste management and limited energy access, waste-to-energy (WTE) technologies offer a transformative solution to mitigate environmental concerns while enhancing power grid stability.
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The transition toward renewable energy sources has become a critical global objective. For developing nations facing the dual challenges of inefficient waste management and limited energy access, waste-to-energy (WTE) technologies offer a transformative solution to mitigate environmental concerns while enhancing power grid stability. This paper presents a detailed performance analysis of a proposed WTE thermal power plant for Dire Dawa City, Ethiopia, utilizing municipal solid waste (MSW) as a sustainable feedstock. The primary objective of this study is to estimate the power generation potential of the city’s MSW through thermal incineration integrated with a Rankine Vapor Cycle. Field data collection reveals that Dire Dawa City produces an average of 237.2 tons of waste daily, with a per capita generation rate of 0.49 kg. Laboratory characterization indicates that the waste possesses high energy potential, featuring an average calorific value of 18.20 MJ/kg (18.20 × 103 kJ/kg), a volatile matter content of 73.50%, and fixed carbon at 19.18%. Thermodynamic modeling and energy-flow simulations demonstrate that the facility can achieve a power output ranging from 7.64 MW to 22.80 MW, providing a nearly constant total energy yield of approximately 183,360 kWh per day. These results confirm that Dire Dawa City’s waste stream is a potent strategic resource for renewable energy. Ultimately, this research provides a technical roadmap for stakeholders, facilitating informed investment decisions and resource planning to ensure the successful implementation of sustainable thermal energy infrastructure in the region.
Full article
(This article belongs to the Special Issue Thermodynamic Analysis and Optimization of Energy Systems)
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Open AccessArticle
Performance Evaluation of Indirect Solar Fryer System for Baking Application
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Mesele Hayelom Hailu, Mulu Bayray Kahsay, Asfafaw Haileselassie Tesfay, Znabu Mehari Gebrezgi and Ole Jorgen Nydal
Thermo 2026, 6(2), 37; https://doi.org/10.3390/thermo6020037 - 21 May 2026
Abstract
This study presents an experimental performance evaluation of an oil-based indirect solar fryer system designed for injera baking. The system consists of a receiver vessel, a closed-loop delivery and return pipe network, and a 60 cm diameter aluminum baking plate with spiral grooves
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This study presents an experimental performance evaluation of an oil-based indirect solar fryer system designed for injera baking. The system consists of a receiver vessel, a closed-loop delivery and return pipe network, and a 60 cm diameter aluminum baking plate with spiral grooves on its bottom surface. Heat transfer oil circulates within the closed loop to transfer thermal energy from the receiver to the baking plate. The system was experimentally investigated under controlled electrical heating conditions using input power levels of 1.0, 1.3, 1.6, 1.75, 2.0, and 2.4 kW, representing equivalent solar thermal input scenarios with varying intensity. The results confirmed the technical feasibility of the system for injera baking across all tested conditions, with performance strongly dependent on input power. At higher input levels (≥2.0 kW), faster heating and shorter baking cycles of approximately 2.5–3 min were achieved; however, increased oil temperatures and thermal instability were observed due to limited heat redistribution within the fixed low-flow circulation system. At lower input levels (≤1.3 kW), the system remained thermally stable but exhibited long initial heating times (up to approximately 85 min) and reduced operational efficiency, limiting its practical applicability. The most balanced performance was observed at intermediate input power levels of 1.6–1.75 kW, where the system achieved approximately 45–60 min initial heating time, stable temperature behavior during operation, and consistent baking cycles of about 3 min with 1 min reheating time. This range provided an optimal compromise between thermal efficiency, operational stability, and energy utilization under the present configuration. Overall, the study demonstrates that the indirect solar fryer system is a promising alternative for energy-efficient injera baking; however, performance is strongly influenced by thermal input and circulation conditions, highlighting the need for further optimization and validation under real solar operating environments.
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(This article belongs to the Topic Clean Energy Technologies and Assessment, 2nd Edition)
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Open AccessFeature PaperArticle
Experimental Investigation of a Miniature Refrigeration System Using R134a and a Low GWP Blend R515B
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Juan Carlos Silva-Romero, José Luis Rodríguez-Muñoz, Francisco Noé Demesa-López, Donato Hernández-Fusilier, Vicente Pérez-García and Juan Manuel Belman-Flores
Thermo 2026, 6(2), 36; https://doi.org/10.3390/thermo6020036 - 19 May 2026
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Miniature vapor compression refrigeration systems are gaining increasing relevance in cutting-edge applications such as drone docking station cooling, electric vehicle battery thermal management, portable medical and diagnostic devices, compact beverage dispensers, field-mounted telecom cabinet cooling, as well as the already established fields of
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Miniature vapor compression refrigeration systems are gaining increasing relevance in cutting-edge applications such as drone docking station cooling, electric vehicle battery thermal management, portable medical and diagnostic devices, compact beverage dispensers, field-mounted telecom cabinet cooling, as well as the already established fields of electronics and personal cooling. These systems offer a promising pathway to localized and mobile cooling solutions. When coupled with the implementation of alternative low-GWP refrigerants that match or even enhance system performance, the result is a more efficient, environmentally responsible, and potentially sustainable refrigeration technology. Therefore, this study experimentally evaluates the performance of R515B as a low-GWP drop-in replacement for R134a in a miniature vapor compression refrigeration system. Key parameters were analyzed to determine the most suitable operating conditions, resulting in a capillary length of 1.25 m, refrigerant charge of 110 g, compressor speed of 4500 rpm, and high condenser fan speed, under which R515B achieved a COP of 5.16 and a cooling capacity of 252.20 W, representing improvements of 38% and 6.5%, respectively, compared to R134a. These results confirm the viability of R515B as an efficient, environmentally friendly alternative for miniature small-scale vapor compression systems.
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Open AccessFeature PaperArticle
Coupling Project-Based Learning with a Heat Exchanger Test Bench: Pedagogical Methodology, Design and Technical Capabilities
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Andrés Hernández, Alanis Zeoli and Samuel Gendebien
Thermo 2026, 6(2), 35; https://doi.org/10.3390/thermo6020035 - 13 May 2026
Abstract
Bridging the gap between theoretical heat exchanger analysis and physical intuition remains a persistent challenge in engineering education, particularly when students are confronted with real-system effects such as pressure losses, measurement uncertainty, and deviations from simplified models. This work addresses this challenge through
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Bridging the gap between theoretical heat exchanger analysis and physical intuition remains a persistent challenge in engineering education, particularly when students are confronted with real-system effects such as pressure losses, measurement uncertainty, and deviations from simplified models. This work addresses this challenge through the coupled development of a pedagogical framework and an experimental platform. A modular heat exchanger test bench was conceived, designed, and constructed by graduate students within a structured project-based learning environment, in which competitive and cooperative phases were combined to emulate real engineering practice. This approach positions the test bench not only as a laboratory tool, but as the outcome of an active learning process that integrates system design, instrumentation, and modeling. The resulting platform enables the comparative study of multiple heat exchanger technologies—including three water-to-water heat exchangers (plate, shell-and-tube, and double-pipe) and one air-to-water fin-and-tube heat exchanger—under parallel, counterflow, and crossflow arrangements across a wide range of operating conditions. Comprehensive instrumentation (temperature, flow rate, and pressure measurements) supports rigorous energy balance analysis, effectiveness evaluation, and hydraulic performance assessment. Beyond undergraduate experimentation, the test bench provides a framework for advanced learning objectives, including uncertainty propagation, -NTU analysis, model development, and experimental validation. The confrontation between model predictions and experimental data, including observed discrepancies, is shown to play a central role in developing critical engineering judgment. The proposed approach demonstrates how the integration of project-based learning with a reconfigurable experimental platform can create a sustainable and scalable environment for heat transfer education.
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(This article belongs to the Collection Thermodynamics Education Collection: Methods and Results)
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Open AccessArticle
Laminar Heat Transfer Enhancement in a Rectangular Channel Using Rectangular Wing Vortex Generators with Triangular Tips: 3D Numerical Analysis
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Assadour Khanjian, Ibrahim S. Resen, Ali Al Shaer, Youssef Ezzeddine, Mahdi Awada, Ahmed Mohsin Alsayah, Jalal Faraj and Mahmoud Khaled
Thermo 2026, 6(2), 34; https://doi.org/10.3390/thermo6020034 - 12 May 2026
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Creating secondary flows that encourage fluid interchange between hot and cold regions is frequently necessary to improve convective heat transfer in compact channels. A well-known passive method for enhancing mixing and boosting thermal performance in laminar regimes is the use of vortex generators
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Creating secondary flows that encourage fluid interchange between hot and cold regions is frequently necessary to improve convective heat transfer in compact channels. A well-known passive method for enhancing mixing and boosting thermal performance in laminar regimes is the use of vortex generators (VGs), which create streamwise and transverse vortices. Laminar forced convection in a rectangular channel with rectangular wing vortex generators with triangular tips is investigated numerically in this work. The primary goal is to assess the impact of the number of tips per wing on pressure drop and heat transfer enhancement at a fixed angle of attack (α). This study examines a single row of rectangular wing vortex generators (VGs) with triangular tips and systematically evaluates how variations in tip number influence not only the global Nusselt number and friction factor but also the three-dimensional vortex structure distribution along the channel. This approach contrasts with many previous studies that primarily focus on global performance indices or on classical delta-type VGs. ANSYS Fluent’s finite volume method is used to solve three-dimensional stable, laminar, incompressible flow and heat transfer. Two Reynolds numbers, Re = 456 and Re = 911, are simulated for different triangular-tip configurations at a fixed angle of attack of α = 30°. To connect flow structures to heat transfer behavior, area-averaged Nusselt numbers and friction factors are calculated for each case, and vortex cores and their spatial locations are examined. The findings demonstrate that heat transfer improvement is directly and significantly impacted by the VG tip arrangement. The trade-off between heat gains and pressure losses is highlighted by the fact that some tip configurations produce stronger, more persistent vortices and higher Nusselt numbers at the expense of an increased friction factor. The conclusions are limited to laminar flow conditions at α = 30°, Reynolds numbers of 456 and 911, and the investigated one-, two-, and three-tip configurations.
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Open AccessArticle
Experimental Study on Dynamic Thermal Response Characteristics in a Microchannel Evaporator
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Yangfan Zhong, Zhijie Gong, Taocheng Zhao, Chengcheng Fan and Chaoqun Shen
Thermo 2026, 6(2), 33; https://doi.org/10.3390/thermo6020033 - 2 May 2026
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As the heat flux of electronic devices continues to increase, conventional air cooling and single-phase liquid cooling technologies are increasingly constrained by heat transfer limits and pumping power consumption. However, systematic investigations on the coupling between microchannel evaporators and the overall dynamic response
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As the heat flux of electronic devices continues to increase, conventional air cooling and single-phase liquid cooling technologies are increasingly constrained by heat transfer limits and pumping power consumption. However, systematic investigations on the coupling between microchannel evaporators and the overall dynamic response of MPTL systems remain limited. To address this issue, a visualization experimental platform for the microchannel MPTL was developed, and flow boiling experiments were conducted under varying heat fluxes and circulating flow rates. Key parameters including wall temperature, fluid temperature, pressure drop, and flow patterns were measured to characterize the thermal–hydraulic behavior of the system. The results show that the wall temperature increases stepwise with increasing heat flux, reaching a critical heat flux of 814.2 W/cm2 at a mass flux of 105.6 kg/(m2·s), where heat transfer deterioration occurs. During this transition, inlet temperature oscillations with an average amplitude of 8 °C were observed due to vapor backflow. With decreasing circulating flow rate, the flow pattern evolved sequentially from single-phase flow to bubbly, slug, churn, annular, and reverse annular flow, accompanied by a shift in the dominant heat transfer mechanism from forced convection to nucleate boiling and convective evaporation. The best heat transfer performance occurred under annular flow conditions at an outlet vapor quality of 0.4–0.5. These findings provide useful guidance for the design and operation optimization of microchannel MPTL systems in high-heat-flux electronic cooling applications.
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Open AccessReview
A Critical Review of Multi-Energy Microgrids and Urban Air Mobility
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Yujie Yuan, Chun Sing Lai, Loi Lei Lai and Zhuoli Zhao
Thermo 2026, 6(2), 32; https://doi.org/10.3390/thermo6020032 - 2 May 2026
Abstract
This paper offers a critical review of cutting-edge research on multi-energy microgrids (MEMs), with a novel exploration of their potential role in supporting urban air mobility (UAM), specifically electric vertical takeoff and landing (eVTOL) aircraft. While extensive research has focused on improving the
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This paper offers a critical review of cutting-edge research on multi-energy microgrids (MEMs), with a novel exploration of their potential role in supporting urban air mobility (UAM), specifically electric vertical takeoff and landing (eVTOL) aircraft. While extensive research has focused on improving the economic performance and emission reductions of MEMs, particularly in the context of electric vehicle (EV) charging, there remains a significant gap in understanding how microgrids can support the decarbonization of UAM. The paper examines the opportunities and challenges of integrating microgrids with UAM operations, highlighting the need for more research to optimize energy management systems that balance renewable energy use with the growing demand for aerial transport. Thermal energy storage systems are emphasized as a critical component for addressing transportation energy needs, offering a promising solution to reduce carbon emissions while enhancing system efficiency. This review aims to provide new insights into how the coupling of microgrids and UAM can contribute to the development of economically and environmentally sustainable smart cities.
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(This article belongs to the Special Issue Thermal Energy Modeling in Microgrids)
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Open AccessArticle
Calorimetric, Thermogravimetric, and Theoretical Study of Norharmane, Harmane, and Harmine: Insights into the Energetics of β-Carbolines
by
Ana Ivette Delgado-Moreno, Raúl Ricardo Quiñonez-López, María de Jesús Palacios-Sánchez, Oscar Guillermo Zúñiga-González, Francisco Javier Moscoso-Sánchez, Eulogio Orozco-Guareño and Jesús Baudelio Campos-García
Thermo 2026, 6(2), 31; https://doi.org/10.3390/thermo6020031 - 30 Apr 2026
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The thermochemical properties of Norharmane, Harmane, and Harmine were investigated using DSC, combustion calorimetry, thermogravimetry, and G3B3 computational methods. DSC measurements enabled accurate determination of melting temperatures and fusion enthalpies. Complementary IR, NMR, and HPLC analyses performed for Harmine indicate that partial degradation
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The thermochemical properties of Norharmane, Harmane, and Harmine were investigated using DSC, combustion calorimetry, thermogravimetry, and G3B3 computational methods. DSC measurements enabled accurate determination of melting temperatures and fusion enthalpies. Complementary IR, NMR, and HPLC analyses performed for Harmine indicate that partial degradation occurs during the melting process, becoming more evident at higher temperatures (above ~330 °C). The standard enthalpies of formation in the solid state were 159.6 kJ·mol−1 (Norharmane), 80.5 kJ·mol−1 (Harmane), and −47.0 kJ·mol−1 (Harmine). Using sublimation enthalpies derived from TGA, the gas-phase formation enthalpies were established as 282.7, 186.0, and 87.4 kJ·mol−1, respectively. Homodesmotic G3B3 calculations showed excellent agreement with experimental data, with absolute deviations below 1.5 kJ·mol−1. The combined results reveal a consistent thermodynamic stability trend in both phases: Harmine > Harmane > Norharmane.
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Open AccessArticle
A Low-Order Thermodynamic Chamber Model for Multiphase Compressible Flow in a Profiled-Rotor Rotary Compressor
by
Mihaela Constantin, Antonios Detzortzis and Cătălina Dobre
Thermo 2026, 6(2), 30; https://doi.org/10.3390/thermo6020030 - 26 Apr 2026
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This study presents a combined numerical and experimental investigation of transient multiphase compressible flow inside a profiled-rotor rotary volumetric compressor. While most existing studies rely on high-fidelity CFD approaches, a low-order thermodynamic chamber-based model implemented in MATLAB Release 2023a is proposed to predict
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This study presents a combined numerical and experimental investigation of transient multiphase compressible flow inside a profiled-rotor rotary volumetric compressor. While most existing studies rely on high-fidelity CFD approaches, a low-order thermodynamic chamber-based model implemented in MATLAB Release 2023a is proposed to predict the temporal evolution of pressure, temperature, and vapor volume fraction during the compression cycle. The model is based on mass and energy conservation applied to variable-volume control chambers and incorporates a simplified cavitation criterion derived from local pressure relative to saturation vapor pressure. An open-loop experimental test bench was developed to measure air mass flow rate, suction and discharge pressures, temperatures, torque, and shaft power under controlled operating conditions. These measurements are used to validate the numerical predictions. The results show good agreement between measured and simulated pressure levels and global performance indicators, with deviations quantified using mean absolute percentage error values remaining below 5% over the investigated operating range. The numerical analysis further reveals the occurrence of localized low-pressure zones during the suction phase, indicating incipient cavitation or microbubble formation at specific rotor positions. The proposed modeling approach provides a computationally efficient alternative to full CFD simulations and enables rapid parametric analysis of rotor geometry and operating conditions. The cavitation formulation does not aim to resolve detailed bubble dynamics or erosion mechanisms, but rather to identify cavitation tendency based on thermodynamic pressure thresholds.
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Open AccessArticle
A Charge Transport Closure Model for Plasma-Assisted Laminar Diffusion Flames
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Sharif Md. Yousuf Bhuiyan, Md. Kamrul Hasan and Rajib Mahamud
Thermo 2026, 6(2), 29; https://doi.org/10.3390/thermo6020029 - 24 Apr 2026
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Electrohydrodynamic effects can significantly alter transport processes in reacting flows, even when the plasma is weakly ionized. However, predictive modeling of such plasma–flame interactions remains challenging due to the multiscale coupling among charge transport, fluid motion, and chemical kinetics. This study presents a
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Electrohydrodynamic effects can significantly alter transport processes in reacting flows, even when the plasma is weakly ionized. However, predictive modeling of such plasma–flame interactions remains challenging due to the multiscale coupling among charge transport, fluid motion, and chemical kinetics. This study presents a charge-transport closure model to investigate electrohydrodynamic influences on laminar non-premixed flames. A two-dimensional computational framework in cylindrical coordinates is used to simulate plasma-assisted methane–air diffusion flames under weak electric-field conditions representative of practical combustion environments. To represent plasma–flow coupling in a computationally feasible yet physically consistent manner, a charge-transport formulation based on the drift–diffusion approximation is employed. The model solves transport equations for representative positive and negative charge carriers coupled with Poisson’s equation for the electric potential to obtain a self-consistent electric field. This formulation assumes a weakly ionized regime for low-temperature plasma-assisted combustion, in which neutral species dominate the mass and momentum transport, while ionization chemistry is simplified and charge transport primarily influences the flow through electrohydrodynamic body forces and Joule heating. Assuming a weak electric field, the steady flamelet model is applied, in which plasma effects primarily influence scalar transport and local thermal balance rather than inducing significant bulk ionization dynamics. The governing equations are discretized using a high-order compact finite-difference scheme that provides improved resolution of steep gradients in temperature, species concentration, and space-charge density near thin reaction zones. The canonical laminar flame model configuration was validated using the established laminar methane–air diffusion flame benchmark, and steady-state spatial profiles of key transport properties were evaluated. Two-dimensional analysis identified the discharge coupling location as an important factor. The application of discharge in the fuel-air mixing region leads to a clear restructuring of the flame. When the discharge is activated, electrohydrodynamic forcing and ion-driven momentum transfer produce a highly localized, columnar flame with sharp gradients and a confined reaction zone. Compared with the baseline case, the plasma-assisted flame localizes the OH-rich reaction zone, confines the high-temperature region into a narrow column, and enhances downstream H2O formation.
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Open AccessArticle
Planning Waste-to-Energy-Coupled AI Data Centers Through Grade-Matched Cooling and Corridor Screening
by
Qi He, Chunyu Qu and Wenjie Zuo
Thermo 2026, 6(2), 28; https://doi.org/10.3390/thermo6020028 - 20 Apr 2026
Cited by 6
Abstract
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AI data-center (DC) growth is increasingly constrained by limited deliverable electricity, interconnection capacity, and cooling demand. This study develops a boundary-consistent screening framework for waste-to-energy (WtE)-coupled AI DC cooling, treating cooling as an energy service that can be supplied through grade matching rather
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AI data-center (DC) growth is increasingly constrained by limited deliverable electricity, interconnection capacity, and cooling demand. This study develops a boundary-consistent screening framework for waste-to-energy (WtE)-coupled AI DC cooling, treating cooling as an energy service that can be supplied through grade matching rather than solely through electricity-driven mechanical chilling. The framework translates plant-side exportable heat into corridor-level planning objects by explicitly accounting for thermal attenuation, absorption-based conversion, and parasitic electricity associated with delivery and auxiliaries. Three results structure the analysis. First, a reference-case energy-service ledger shows how a representative regulated WtE plant with municipal solid-waste throughput of 1500 t/day and lower heating value of 10 MJ/kg yields ~78.1 MWth of exportable driving heat and, at a 20 km corridor, ~53.0 MWcool of delivered cooling and ~8.0 MWe of net avoided cooling electricity after parasitic debiting. Second, the coupled system is governed by operating regimes, not a single efficiency score. Under the baseline package, full thermal coverage is maintained up to ~20.9 km, the stricter quality-adjusted criterion remains positive to ~22.9 km, and the electricity–relief criterion remains positive to ~44.7 km. Third, deployment-scale translation for a 1 GW IT campus ( , m) implies a net grid relief of ~116.9–264.4 MW across scenario packages, while the required WtE footprint ranges from roughly three to 148 equivalent representative plants, or about 0.6–40 full-load-equivalent plants at a 25% displacement target. The contribution is a siting-ready planning framework that identifies when WtE-coupled cooling remains corridor-feasible, when it becomes hybrid and marginal, and when infrastructure scale rather than thermodynamic benefit becomes the binding constraint. It is intended as a screening tool for planning and comparison, not as a project-specific hydraulic or plant-cycle design.
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Open AccessFeature PaperArticle
Analysis of Conductive Heat Transfer and Moisture Diffusion Through the Insulated Wall of a Refrigerated Warehouse
by
Laurențiu Mihail Constantin, Lavinia Grosu, Tiberiu Catalina, Adalia Andreea Percembli (Chelmuș), Daniel Taban, Claudia Ioniță and Alexandru Dobrovicescu
Thermo 2026, 6(2), 27; https://doi.org/10.3390/thermo6020027 - 18 Apr 2026
Abstract
This study investigates steady-state conductive heat transfer and water-vapor diffusion through the external wall of a refrigerated warehouse with a specified load-bearing wall assembly. The formal analogy between heat conduction and mass diffusion is stated and used to establish a practical calculation framework
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This study investigates steady-state conductive heat transfer and water-vapor diffusion through the external wall of a refrigerated warehouse with a specified load-bearing wall assembly. The formal analogy between heat conduction and mass diffusion is stated and used to establish a practical calculation framework for estimating heat and moisture ingress through multilayer cold-store walls. Calculation routines are presented to determine the temperature field and the corresponding water-vapor saturation and partial-pressure distributions across (and within) the insulation layer, enabling the identification of regions prone to interstitial condensation. The analysis highlights the roles of (i) the vapor diffusion resistance of the vapor barrier layer, (ii) the thermal resistance of the insulation, and (iii) key outdoor boundary conditions in governing condensation risk. Increasing insulation thermal resistance reduces external heat gains; however, it may also increase the likelihood of condensation in layers close to the cold side by lowering local temperatures and saturation pressures. Among external parameters, outdoor relative humidity exerts the strongest influence on interstitial condensation risk. For the investigated wall assembly, increasing outdoor relative humidity by 50% shifts the condensation onset location within the insulation toward mid-thickness. The effects of vapor barrier diffusion resistance, insulation thermal resistance, and changes in outdoor conditions (relative humidity, temperature, and wind speed) are reported in tabulated form and illustrated through pressure–position and temperature–position profiles.
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(This article belongs to the Special Issue Heat and Mass Transfer in Nanoporous Media)
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