Condensation heat transfer and pressure drop inside tubes with propane (R290) refrigerant. A review of experimental data and correlations

Condensation heat transfer and droplet departure characteristics under electric force with leaky dielectric assumption

Condensation heat transfer and pressure gradient behavior of low-GWP refrigerants R516A, R515B, and R513A in smooth and microfin tubes

This study numerically investigates the influence of square-wave inlet velocity pulsations on flow structure and heat transfer around a transverse circular cylinder, with particular emphasis on wall condensation behavior. The evolution of wake vortices and the distribution of the convective heat transfer coefficient on the cylinder surface are analyzed under both single-phase and two-phase flow conditions over a range of pulsation frequencies. The results indicate that inlet pulsations significantly modify the wake dynamics, leading to reduced vortex size and enhanced momentum and turbulence dissipation in single-phase flow, which in turn improves convective heat transfer downstream of the separation point. Under two-phase condensation conditions, similar wake modifications are observed, while additional small-scale vortical structures are generated within the condensate film due to interfacial shear, further enhancing local heat transfer. Overall, the findings demonstrate that appropriately tuned inlet pulsations can effectively enhance heat transfer performance for both single-phase and condensing flows around a circular cylinder.

A hydrophilic-hydrophobic silicon carbide/fluorine resin coating: Enhanced condensation heat transfer with robust corrosion and wear resistance for flue gas heat recovery

Study on condensing heat transfer characteristics of narrow-gap heat exchanger for flue gas in gas-fired boilers

Numerical simulation study on condensation heat transfer of plate heat exchangers with inner fins for new energy vehicles

Enhancement of condensation heat transfer on vertically oriented sintered copper powder surfaces: An experimental investigation

Efficient condensation is fundamental for high-performance passive two-phase heat transfer devices, such as grooved heat pipes, which are widely used in thermal management for electronic, automotive, aerospace and energy systems. Enhancing condensation heat transfer requires precise control of the condensate distribution and liquid drainage, which can be achieved through the optimization of fin geometry. This study investigates the condensation heat transfer over rectangular, trapezoidal and inverted trapezoidal fins under horizontal and vertical downflow conditions for four refrigerants (R134a, R245fa, R290 and R717) by means of three-dimensional steady-state CFD simulations using the volume-of-fluid (VOF) method. The fin surfaces, inspired by grooved wick heat pipes, are aimed at improving condensate removal and overall condensation heat transfer. The numerical model is validated through comparison with experimental data taken from the literature. Numerical results show that ammonia achieves the highest condensation heat transfer, due to its favorable thermophysical properties. In horizontal flow, inverted trapezoidal and rectangular fins yield up to 10% higher heat transfer than trapezoidal fins, with the inverted trapezoid promoting a more uniform condensate film. Vertical downflow enhances gravity-driven drainage, producing thinner, more stable films and up to 88% higher local heat flow rates in the grooves. These results provide insights into the coupled influence of geometry, working fluid, and flow conditions on condensation mechanisms, offering useful guidelines for the design and optimization of condensers in passive heat transfer devices.

Numerical study on the effects of flow direction on condensation heat transfer outside tubes

Numerical investigation on the condensation heat transfer characteristics in tube bundles of LNG intermediate fluid vaporizer

Experimental study and general correlation of condensation heat transfer for zeotropic mixture refrigerants in smooth and microfin tubes

Controllable droplet manipulation is essential for applications from biochemical analysis to soft robotics. Despite significant advances, existing methods struggle to achieve broadly tunable, asynchronous control of multiple droplets, limiting their efficiency in three-dimensional and dynamic environments. Here, we introduce a droplet ultrasonic tweezer (DUT), which leverages broadly tunable acoustic control to enable three-dimensional multi-droplet manipulation and enhance condensing surface renewal. The DUT generates a twin-trap acoustic field from a single phased-array focal point, allowing droplet coalescence and confinement at five specific trapping positions. Leveraging this capability, we demonstrate synchronous directional transport of three droplets and asynchronous control of their relative positions. Moreover, the DUT’s vertically extensible twin trap enables synchronous manipulation of droplets across double-layer surfaces. Beyond transport, programmable spatial modulation of the acoustic field enhances microdroplet coalescence and suppresses merged-droplet detachment, increasing the droplet detachment size and expanding the swept area for more effective surface renewal. Our results establish a robust paradigm for applications in optical surface self-cleaning, condensation heat transfer, and atmospheric water harvesting, offering a scalable solution for precise droplet control.

Sustainable dropwise condensation technology is crucial for applications in high-performance thermal management, energy conversion, and desalination. However, conventional condensation surfaces often suffer from low droplet departure efficiency and gravity dependence, limiting their practical application in advanced heat exchangers. Here, we report a dual-layer composite surface, composed of a slippery Janus copper mesh and a wedge-shaped microgrooved substrate (SJM-WM), which enables gravity-independent droplet departure via interfacial transport. This design spatially decouples vapor condensation on the upper Janus mesh and droplet transport in the lower substrate, leveraging synergistic wettability gradients and Laplace pressure-driven directional flow. By tailoring mesh pore size, the Laplace pressure and droplet coalescence dynamics are effectively regulated, achieving a small droplet departure diameter of 98 ± 2 μm, which is comparable to the bouncing-off behavior on superhydrophobic surfaces. The SJM-WM surface enhances condensation heat transfer by 23.1% and 102.4% compared to state-of-the-art hydrophobic-superhydrophilic wedge-grooved surfaces (HB-SHL) and hydrophobic copper mesh-wedged microgroove composite surfaces (HBM-WM), respectively. This work provides a promising strategy for advancing high-performance thermal management systems in power-dense electronics.

An efficient thermal management system (TMS) is essential for ensuring hybrid-electric aircraft (HEA) can handle the significant heat rejection required by electrified propulsion. This paper presents a system-level analysis of a compact P2PL TMS for a 1.4 MW battery generating a 70 kW heat load. A modular modeling method was used to size the key components, and then dynamic simulations were conducted under varying environmental conditions. The results indicate that a compact TMS weighing 22 kg can be developed, with a condenser heat transfer area of 26.20 m2 and operating with a refrigerant mass flow rate of 0.56 kg/s while maintaining low pump power consumption at 22 W. This system can successfully regulate a battery’s temperature so that it remains below 40 °C in both standard (15 °C) and cold (−20 °C) environments. Pressure analysis confirmed the system’s flexibility and its ability to control battery temperature between 27 °C and 38 °C by adjusting the working pressure (6–8 bar). Furthermore, under hot day conditions (40 °C), battery temperature can be maintained at 47.6 °C. Even under extreme conditions (50 °C), the TMS limits the temperature to 57.45 °C, ensuring it stays within the safe operating range.

There are many models in the literature for heat and mass transfer of vapor condensation in the presence of a non-condensable gas, but most models require the evaluation of three different heat transfer coefficients and input parameters that are usually unknowns and experimentally measured. In this paper, a condensing heat exchanger (CHE) with a new application was introduced for a turbofan aircraft to recover both heat and water and a novel methodology for the design of a CHE that evaluates directly the total heat transfer coefficient for the gas mixture was presented. Such a methodology locates the onset of condensation and does not require any experimental measurements. An air-cooled CHE was divided into 50 sections and the principles of thermodynamics, energy balance, and heat transfer were applied to evaluate the temperatures, properties, length of each section, and the local air and total gas heat transfer coefficients. The results showed that enhancing the overall heat transfer coefficient and reducing the CHE weight could be achieved with a less total pressure drop for the gas and airflows by increasing the air mass velocity at the same mass flow rates of the gas and air when compared with raising the gas velocity at the same mass flow rates of the gas and air.

Numerical Study on Condensation Flow and Heat Transfer of Hydrocarbon Mixtures in Inclined Tubes under Static and Swaying Conditions

In order to improve the condensation heat transfer performance of tubelines in cooling systems, a new type of large deformation heat transfer tube was proposed. Based on the theory of diffusion, the distributions of temperature, velocity, heat transfer coefficient, and species are presented to compare with smooth tubes. In addition, the effects of relevant parameters on thermo-hydraulic performance are discussed. The numerical results show that the distributions of temperature and velocity show a periodic distribution. The unique structure of the large deformation heat transfer tube disturbs the fluid flow near the wall. The boundary layer of air concentration is destroyed, resulting in heat transfer enhancement. Within the scope of this paper, the heat transfer coefficient and friction factor of the large deformation heat transfer tube are increased by 1.01–3.47 times and 1.05–7.13 times compared with the smooth tube. The heat transfer performance increases with the rising dimple depth and declining noncondensable gas content and dimple pitch.OPEN ACCESS Received: 25/06/2025 Accepted: 29/07/2025 Published: 23/01/2026

Numerical simulation of active enhancement of condensation heat transfer by pulsating flow in JAG-type corrugated plate heat exchangers

Enhancing the thermal performance of vapor compression refrigeration systems is crucial for developing energy-efficient and environmentally friendly cooling technologies. The present study investigates the application of magnetic field exposure to augment the condensation heat transfer coefficient in a refrigeration system operating with R404A refrigerant. The liquid line of the condenser having an inner diameter of 0.838 cm was subjected to magnetic treatment using two configurations: magnetic pairs and Halbach arrays with field strengths of 300 mT and 720 mT, respectively. Experiments were conducted under varying numbers of magnetizers (one to four), mean dryness fractions (0.5-0.6), and saturation temperatures (45°C and 50°C). Results show that the heat transfer coefficient is significantly influenced by magnetic configuration, saturation temperature, and mean dryness fraction. The effect of magnetic treatment was observed to be more significant at lower saturation temperatures and higher mean dryness fractions. Halbach arrays generally offer greater enhancement than magnetic pairs. However, this improvement was limited to a specific number of magnetizers in both configurations, beyond which the heat transfer coefficient deteriorated. For the current work, the limiting number of magnetizers was determined to be two for magnetic pairs and one for Halbach array. Under optimal conditions, the heat transfer coefficient is increased by 18.06% for Halbach arrays and by 9% for magnetic pairs. Additionally, CO<sub>2</sub> emissions were found to be lower with Halbach arrays compared to magnetic pairs. Emissions ranged from 2.56% to 4.24% for Halbach arrays and from 1.07% to 2.97% for magnetic pairs, across the use of one to four magnetizers.