The thermodynamic relations of exergy efficiency, exergy destruction, thermal and friction entropy generation, Bejan number, and collector efficiency was evaluated experimentally by considering water-based nanodiamond nanofluids circulating in the flat plate collector (FPC) at different particle loadings (ϕ = 0.2% to ϕ = 1.0%) and Reynolds number (5000 – 13000). Additionally, heat transfer, pumping

Proven to have superior mechanical and thermal properties, graphene has the potential to enhance the boiling heat transfer performance as a coating material. As defective graphene is inevitably produced together with pristine graphene, however, it is more practical to examine the impact of defective graphene. In the current work, a molecular dynamics simulation was adopted to investigate water pool

Nanofluids have the solid-fluid interface which affects their thermal properties during heat transfer processes. In this study, nanolayer and thermal interfacial resistance (TIR) at the solid-fluid interface are discussed to determine their role in the enhancement of thermal conductivity of Al2O3-CO2 nanofluid. The current work focuses on molecular dynamics (MD) simulations to study the TIR and nanolayer

In order to improve the performance of Air Cooled Condensers and reduce power plants' water dependence, air-side heat transfer and pressure-drop experiments were performed with various modifications to heat transfer surfaces. Experiments were conducted in an open wind tunnel with a free stream velocity of 0.35-20 m/s and five different heat exchanger configurations, namely, a bare tube and tubes with

Performance characteristics of a car radiator with new radiator coolants of ternary hybrid nanofluid of 0.1% vol.fraction (Al2O3-CuO-TiO2/water) and water is experimentally investigated. Waste heat from the mentioned radiator coolants has been treated as the preheating intake air for a single-cylinder diesel engine, and the performance was evaluated and compared. Furthermore, the numerical analyses

This study presented a two-dimensional heat transfer analysis of the light-emitting-diodes equipment’s heat sink module under forced convection theoretically. The metal materials of the base and fins in the heat sink included Cu, Al, Al alloy, Mg, Zn, Fe, constantan and stainless steel. The point-matching and series truncation methods were used to solve the heat transfer problem. Due to the complexity

This paper discusses the conjoint effect of circular fin turbulators and alumina (Al2O3) nanofluid on the thermal performance of a helically wound coil-in-shell heat exchanger used for waste heat recovery. An experiment was conducted using three different coils: two with circular fin turbulators brazed to the annular coil surface at 45° and 90° orientations and one plain coil without a fin. The coil

The Pulsating Heat Pipe (PHP) is more and more popularity for the increasing demand of heat dissipation. This work proposed the novel structure with connected-path to achieve the purpose of split-flow of working fluids. Furtherly, it numerically studied the thermal performance of PHP with different structures. For the first, the geometric model was established in ANSYS Workbench and the VOF model was

The present study proposed some novel designs that can surpass the most widely used louver fin geometry for air-cooling applications. Innovative fin types such as ring fins, circular disk fins, and hexagonal disk fins are numerically modeled and compared with a louver fin-and-flat tube heat exchanger in terms of thermal resistance in the same pumping power. Flow visualization is also carried out by

The present study reports a substantial enhancement mechanism by optimizing the morphological parameters of sintered Cu/Ni alloy surfaces. An increase in the nucleation site densities of sintered surfaces by controlling the average surface roughness, porosity, particle diameter, and coating thickness yielded substantial augmentation in pool boiling of a highly wetting liquid. For instance, increasing

The results of experimental studies on heat transfer and pressure drop during forced convection of air and liquid ethylene glycol in pipes with inner fins are presented. Tubes with integrated fins were made by extrusion from an aluminum alloy; the fins were straight or twisted spirally along the tube and their tips almost reached the tube axis. Depending on the process parameters, the heat transfer

Stable and reliable energy supply units are important components of micropower 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 temporal thermal distribution and output power characteristics of the device were

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:

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

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