We report a substantial enhancement mechanism by optimizing the morphological parameters of sintered Cu/Ni alloy surfaces. An increase in the nucleation sites density of the sintered surfaces by controlling the average surface roughness, porosity, particle diameter, and coating thickness yields a substantial augmentation in pool boiling of a highly wetting liquid. For instance, increasing surface roughness

The results of experimental studies on heat transfer and pressure drop with forced convection of air and liquid ethylene glycol in internally finned tubes are presented. The tubes with inte-gral fins were machined of an aluminium alloy by extrusion, the fins were straight along the tube or helically twisted, and their tips almost reached the tube axis. Depending on process parameters, the heat transfer

Stable and reliable energy supply units are important components of micro-power wireless monitoring systems intended for alpine regions. In this work, a phase change material (PCM)–based solar thermoelectric energy-harvesting device was proposed, and a corresponding coupled heat transfer numerical model was built. The spatial and temporal thermal distribution and output power characteristics of the

Boiling heat transfer is widely used in many practical applications due to significantly high heat transfer coefficients (HTC) associated with it. Several surface modification techniques are known to further improve the heat transfer performance. Applications such as cooling of 3D electronic stacks and portable electronic devices demand nucleate boiling in narrow gaps and often with inclined surfaces

The present experimental research was carried out to study the heat transfer and friction factor characteristics of a zinc oxide (ZnO)/water/ethylene glycol-based nanofluid in a square duct. The square duct surface was roughened by an inclined rib attached to the underside of the plate. The various geometrical parameters and their ranges involved in the present experimental analysis were the following:

The role of pore geometry (pore diameter dp and pore pitch Pp) on pore/subtunnel surfaces was investigated using the refrigerant R-123, and the results are compared with those of R-134a. Nine samples had 0.1 ≤ dp ≤ 0.3 mm and 0.75 ≤ Pp ≤ 3.0 mm. The trend of heat transfer coefficients was approximately the same as that of R-134a. It increased as the pore size increased and pore pitch decreased. The

A numerical simulation of fluid structure interaction effects on vortex dynamics and heat transfer was performed in a rectangular channel with two plates mounted symmetrically across from one another on two channel walls. The two plates can both be rigid (configuration 1), plate 1 can be flexible while plate 2 is rigid (configuration 2), or both can be flexible (configuration 3). The vorticity and

Twisted tape has been widely used in industry and heat transfer enhancement. However, most research is focused on the single-phase flow induced by the tape; the flow characteristics in the gas-liquid two-phase flow induced by the tape are largely unexplored. In this work, vortex motion and decay characteristics in a gas-liquid two-phase swirl flow induced by a short twisted tape were studied by numerical

The thermophysical properties of working fluids play a significant role in determining the performance of heat exchangers. These properties can be customized by mixing nanoparticles of different types and different volume concentrations in the working fluid. The effect of three different nanofluids, viz., the suspensions of single-component Fe3O4 and SiC nanoparticles, and the hybrid mixture of Fe3O4

The present experimental work is a comprehensive study of heat transfer and flow field characteristics inside a rectangular duct integrated with ribs of variable cross sections on the bottom wall. Four kinds of rib configurations, i.e., square (Case 1), pentagonal (Case 2), trapezium (Case 3), and truncated prismatic (Case 4), were deployed in the cooling passage to improve the thermal performance

The thermal performance of wavy channels with different phase shifts (φ = 0° and 180°) introduced between the top and bottom conducting walls was experimentally investigated using a typical Mach-Zehnder interferometer. The experiments were performed on compact plane and wavy channels (with varying phase shifts and similar hydraulic diameters) in deionized water (Pr = 6.13) for a range of Reynolds numbers

In the present paper, a proposal for enhancement of flow boiling is made by developing tubes with discrete internal structures inside the tube. Experiments have been conducted with R407C refrigerant. Heat flux from 5 to 12.5 kWm-2 and mass flux from 40 to 200 kgm-2s-1 has been considered an experimental range in an in-house setup. The heat transfer characteristics of the newly developed tube with an

Boiling heat transfer with pure fluids deteriorates significantly under downward-facing heater (−1g) and in narrow gaps/confined spaces where surface tension dominates over buoyancy. The addition of amphiphilic additives such as surfactants and ionic liquids in water is well known to enhance boiling heat transfer under the downward-facing heater. However, the potential of amphiphilic additives to enhance

During the free-surface circular water jet impingement cooling of a heated surface (250°C-900°C), rewetting is an important phenomenon that can be directly correlated with the measured surface temperature history and heat flux distribution. In the present work, an experimental study of water jet impingement cooling is done on a heated horizontal SS-304 plate of dimension 78 × 78 × 13 mm3 instrumented

This issue of the Journal of Enhanced Heat Transfer [JEH(T)] contains a collection of six extended papers from the 25th National and 3rd International ISHMT-ASTFE Heat and Mass Transfer Conference (IHMTC 2019).

In the present study, thermohydraulic characteristics of heat sinks with short micro pin fin (height of fin shorter than the total height of heat sink) of different shapes (square and elliptical) and different arrangements (interrupted and staggered) are studied, considering deionized water as the coolant. Experiments are conducted on silicon heat sink fabricated using wet etching. The pressure drop

Polymers are usually known for their low thermal conductivity. However, the demand in industries for polymers with high thermal conductivity has increasingly grown due to their low density, low cost, flexibility, and good environmental resistance compared with conventional substances of high thermal conductivity. Composites filled with high thermal conductivity nanofillers will increase thermal conductivity

Thermoelectric generators (TEGs) have attracted increasing interest due to their ability to directly convert heat to electricity. However, relatively low conversion efficiency limits their broad applications in the future. One of the crucial factors affecting TEG performance is thermal contact resistance (TCR). In particular, TCR matching at the interfaces of p- and n-type thermoelements strongly affects

Device miniaturization and complex work load due to rapid growth in technologies have imposed great challenges in aspects of thermal management to prevent overheating. Nanofluids are emerging as thermal solutions due to their enhanced thermal properties. Recently, graphene oxide (GO) nanofluids (NFs) has been studied and found to have high thermal conductivity. However, their potential in microchannel

From an energy saving viewpoint, full melting of phase change material in thermal storage systems should be achieved. Constrained ice melting with natural convection inside a horizontal H-shaped capsule with adiabatic curved sidewalls is not completed because energy input from hot surfaces overheats the liquid phase on top while stable thermal stratification on bottom persists. Although 90° inclination

The heat transfer characteristics of gravity heat pipes (GHPs) with internal helical microfins (IHMs) were investigated experimentally, in comparison with smooth GHPs. The influence of different IHM arrangements on the GHPs was obtained. Four types of GHPs were designed and fabricated: GH-PIHM1 (GHP with IHM arranged only in the condenser section); GHPIHM2 (GHP with IHM arranged in both the condenser