Three‐dimensional computational comparison of mini‐pinned heat sinks using different nanofluids: Part two—energy and exergy characteristics

Abstract

The energy and exergy characteristics of 3D-pinned heat sink (HS) designs have been computationally compared as the second part of a three-part investigation. Different pin profiles, such as circular, square, triangular, strip and elliptic pins, and without pin HS are conducted with three different types of nanofluids-Al 2 O 3 -water, SiO 2 -water, and CuO-water for laminar forced convection. The concentrations of nanofluids vary from 0 to 5 vol% with different Reynolds numbers ranging between 100 and 1000. The finite volume method employing the SIMPLE algorithm for a computational solution is applied to solve the Navier-Stokes and energy equations. Four criterions studies are explained-energy efficiency, exergy loss, and exergy efficiency of HSs with pressure drop. The results showed that the highest energy and exergy efficiencies are nearly 76% and 57%, respectively, for elliptic-pinned HSs using pure water, while about 82% and 62% using 5 vol% of SiO 2 -water nanofluids. Besides, the elliptic-pinned HSs have a favorable reduction in the exergy loss, nearly 17% using 5 vol% of SiO 2 -water nanofluids. Subsequently, the elliptic-pinned HS is recommended to apply with pure water considering the development in pressure drop required. However, the elliptic-pinned HSs could be employed with 5 vol% of SiO 2 -water nanofluids regardless of the development in pressure drop required for thermal energy dissipation applications with more exergy efficiency and reduction of exergy loss. K E Y W O R D Sdifferent nanofluids, different pinned heat sinks, energy and exergy characteristics, exergy loss, thermal energy enhancement

Experimental investigation of forced convective heat transfer and fluid flow in a mini heat pipe with rectangular micro grooves

“…They flowed water in a microchannel created in silicon chips and the maximum value of a heat flux they were able to reach was 790w/cm 2 without any change in phase with a pressure drop of 1.94 bar. Amer et al [9] discovered that the number of Nusselt depends on the Reynolds number in laminar microchannels flow [10]. This was observed clearly from their simulation with the use of microchannels inside diameters ranging from 3 to 81μm.…”

“…Different positions are selected at a fixed temperature of heat sink T sf = 35°C. Figure (10) demonstrates the diversity of thermal resistance versus heat loads, For thermal input power larger than 40 W, the (R th ) of the flat mini heat pipe is almost the same for all the positions taking into account the uncertainties of the thermal resistance, but for heat load lower than 40W, the flat mini heat pipe is sensitive to any change in direction. In fact, the position of thermosyphon displays the lowest thermal resistance, while the position of anti-gravity displays the highest one.…”

Numerical Study on the Effect of Using CuO-Water Nanofluid as a Heat Transfer Fluid on the Performance of the Parabolic Trough Solar Collector

“…Luz Black Chrome Selective coating was used in this study. Emissivity of the Selective coating (𝜀 3 ) is calculated based on the temperature of the coating layer with the equation below [25]: 𝜀 3 = 0.0005333 (𝑇 3 + 273.15) -0.0856 (16) The equation used for the conduction across the wall of the absorber is used for the conduction through the glass envelope. The thermal conductivity of the glass cover is assumed to be constant with a value of 1.04 𝑊 𝑚.𝐾 (Pyrex glass) [26].…”

“…ρ, Cp, K and μ are the density, specific heat capacity, thermal conductivity and dynamic viscosity respectively. Table 3 lists CuO thermo physical properties [12,25].…”

Numerical investigation of hydrothermal performance over perforated conical pin heat sinks

“…In addition, perforating the fins provides an improvement in terms of heat transfer is nearly 20%-30%, a decrease in pressure drop is up to 25%, and a reduction in heat sink mass is over 6%. Al-Damook et al 8,9 concluded that the pins containing five holes containing Nu are 11% larger than the cases of solid pins. These benefits arise due to not only the increased surface area but also heat transfer enhancement near perforation through the formation of localized air jets.…”