Application of nanofluid and coiled tubes are two passive methods for increasing the heat transfer. In the present study, the turbulent flows of water and nanofluid in coiled tubes heat exchanger were numerically studied. CuO-water nanofluid containing 1 vol% copper oxide nanoparticles was used and single-phase approach was considered for nanofluid flow. The effect of different geometrical para...

helical coil heat exchangers are widely used in industrial applications ranging fromcryogenic processes, air-conditioning, and nuclear reactors to waste heat recovery due totheir compact size and high heat transfer coefficient. in this kind of heat exchangers, flowand heat transfer are complicated. this paper reports a numerical investigation of theinfluence of different parameters such as coil...

Pipes are widely used in many industrial and mechanical applications and devices. Although there are many different constructions according to the specific application and device, these can show helical pattern, such as spiral pipes, wire-reinforced pipes/shells, spring-suspension, and so on. Theoretical modelling of wave propagation provides a prediction about the dynamic behavior, and it is f...

Even though two-phase heat transfer of refrigerants in minichannel sinks has been studied extensively, there is still a demand for improvements overall thermal performance miniature exchangers. Experimental investigation and sophisticated calculations with respect to devices are needed. In this work, time-dependent experimental study subcooled boiling was carried out FC-72 flow sink, comprising...

In this paper, the cooling performance of water-cooled heat sinks for heat dissipation from electronic components is investigated numerically. Computational Fluid Dynamics (CFD) simulations are carried out to study the rectangular and circular cross-sectional shaped heat sinks. The sectional geometry of channels affects the flow and heat transfer characteristics of minichannel heat sinks. T...

Ab = heat-sink-base surface area Ac = cross-sectional area of the fin Cp = specific heat of the air EI = Elenbaas number g = gravity H = fin height h = heat transfer coefficient around fin ka = thermal conductivity of the air kh = thermal conductivity of the heat sink L = fin length N = total number of fins of the heat sink P = plate-air parameter Pe = perimeter of the fin pf = fin pitch qb = h...

The effect of flow instabilities on flow boiling heat transfer in microchannels is investigated using water as the working fluid. The experimental test section has six parallel rectangular microchannels with each having a cross sectional area of 1054 × 197 microns. Flow restrictors are introduced at the inlet of each microchannel to stabilize the flow boiling process and avoid the backflow phen...

The aim of this paper is to enhance thermal performance of a microchannel heat sink by using nanoencapsulated phase change material (NEPCM) slurry as a cooling fluid instead of pure fluid. A threedimensional model of a circular channel using water slurry of NEPCM was developed. The results show a significant reduction in the mean fluid temperature along the channel and heat sink wall temperatu...

Flow boiling in small hydraulic diameter channels is becoming increasingly important in many diverse applications. The previous studies addressing the effects of the channel size on the flow patterns, and heat transfer and pressure drop performance are reviewed in the present paper. The fundamental questions related to the presence of nucleate boiling and characteristics of flow boiling in micr...