Effects of nanoparticle shape and size on the thermohydraulic performance of plate evaporator using hybrid nanofluids

Singh

Intl J of Energy Research

et al. 2021

Summary Thermal and pressure drop aspects of a minichannel heat sink have been investigated experimentally using distilled water as base fluid with alumina, graphene and alumina‐graphene hybrid composition at 0.01% volume concentration. The reasons to select alumina‐graphene as a potential nanomaterials combination for hybrid nanofluids are as: (i) thermal conductivity enhancement and (ii) to investigate the effect of morphology (shape and size of nanoparticles). Alumina (Al2O3) is oxide and has spherical shape whereas graphene is allotrope of carbon and has platelet shape. To examine the effect of different nanoparticles (in terms of shape, size and properties) dispersed hybrid nanofluid on hydrothermal bahaviour is an interesting study. Effects of Reynolds number (80‐450), flow rate (0.1‐0.5 L/min) and fluid inlet temperature (20‐40°C) are studied. The effects of uniform heat flux of 50 and 66.7 W/cm2 on hydrothermal behaviour of a minichannel are also examined. The increment in convective heat transfer coefficient (HTC) is 30.93% at 30°C with graphene/water composition nanofluid than water base fluid. A penalty of 23.82% has been observed in pressure drop with graphene/water nanofluid over base fluid. As inlet temperature increases, Nusselt number (Nu) increases while adverse effect is found in case of friction factor. Performance evaluation criteria (PEC) has been observed more than 1 for all nanofluids and hybrid nanofluids, which ensured that nanofluids act as a better electronic cooling agent than water. Al2O3 + graphene hybrid nanofluid delivers optimum comparison factor (HTC to pressure drop ratio) and lower entropy generation rate among used working fluids. Graphene/water nanofluid yields less comparison factor compared to other working fluids irrespective of high HTC. h/Δp is favourable for nanofluid of unlike particles of hybrid composition (in terms of particle size, properties and shape) as compared to mono nanofluid and hybrid nanofluid having similar particles.

“…The comparison factor, J , which is a ratio of HTC to ∆p , is used to investigate the combined effect of HTC and ∆p owing to the application of nanoparticles 48 . It is given by,

J = \frac{h}{normalΔ p}

…”

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Thermal and thermo‐hydraulic behaviour of alumina‐graphene hybrid nanofluid in minichannel heat sink: An experimental study

Singh

Intl J of Energy Research

et al. 2021

“…Therefore, by controlling the loading concentration of the nanoparticles, and hence the internal structure of the nanofluid, up to 45% of the solar irradiance can potentially be absorbed and converted into electrical and thermal energy (figure 4(b)). It is feasible to consider that, through further refinement of the particle geometries, flow rate conditions, and the collector architecture, higher collector performances could potentially be achieved [13,14,25,31,49]. However, such investigations are outside the scope of this current work.…”

Section: Solar Energy Conversion Performance Of Pvt System With Ag Nanofluidsmentioning

confidence: 96%

Evaluation of the potential of nanofluids containing different Ag nanoparticle size distributions for enhanced solar energy conversion in hybrid photovoltaic-thermal (PVT) applications

2022

Hybridising photovoltaic and photothermal technologies into a single system that can simultaneously deliver heat and power represents one of the leading strategies for generating clean energy at more affordable prices. In a hybrid photovoltaic-thermal (PVT) system, the capability to modulate the thermal and electrical power output is significantly influenced by the spectral properties of the heat transfer fluid utilised. In this study, we report on one of the first experimental evaluations of the capability of a multimodal silver nanofluid containing various particle shapes and particle sizes to selectively modulate the solar energy for PVT applications. The diverse set of particle properties led up to a 50.4% enhancement in the solar energy absorbed by the nanofluid over the 300 nm – 550 nm spectral region, where silicon is known to exhibit poor photovoltaic conversion performances. This improved substantially the absorption of solar energy, with an additional 18 – 129 W m-2 of thermal power being generated by the PVT system. Along with the advancements made in the thermal power output of the PVT system, a decrease of 4.7 – 36.6 W m-2 in the electrical power generated by the photovoltaic element was noted. Thus, for every ~11 W m-2 increase of thermal power achieved through the addition of the nanoparticles, a reduction of ~3 W m-2 in the ability to generate clean electricity was sustained by the PVT. Despite the energy trade-offs involved under the conditions of the nanofluid, the PVT system cumulatively harvested 405 W m-2 of solar energy, which amounts to a total conversion efficiency of 45%. Furthermore, the economics of the additional energy harvested through merging of the two systems was found to reach an enhancement of 77% under certain European conditions.

“…Albenese et al 12 revealed thermophysical relation correlating features of size, shape, surface charge, and chemical functionality and interpreted the change in flow attributes of nanofluid flow under mentioned attributes. Bhattad and Sarkar 13 probed the performance of thermohydraulic evaporators by analyzing morphometric characteristics of hybridized particles. Sarma and Pandit 14 deliberated free convective analysis of nanoliquid flow over an accelerated surface by using multi-shaped nanoparticles.…”

Section: Introductionmentioning

confidence: 99%

Significance of induced hybridized metallic and non-metallic nanoparticles in single-phase nano liquid flow between permeable disks by analyzing shape factor

Bilal

Shah

Ramzan

et al. 2022

Sci Rep

The current communication is designed by keeping in the mind high heat transfer capabilities of nanoliquids with the dispersion of diversified-natured nanoparticles in poorly conducting base liquids. Here, an amalgamation of metallic (Cu) and hybridization of metallic and non-metallic oxide (Cu-TiO2) nanoparticles to uplift thermophysical attributes of water is deliberated. The magnetically affected flow between rotating disks under the impact and permeability aspect is assumed. Empirical relations for effective dynamic viscosity, density, and heat capacitance to show mesmerizing features of obliged nanoparticles are also expressed. In addition, mathematical relations also depend on morphological factors like shape, size, and diameter of inducted nanoparticles. The mathematical formulation of the problem is conceded in the form of a system of ODEs after using similarity transformation on dimensional PDEs. Simulations of the complex coupled differential structure are solved by using a numerical approach by employing shooting and Runge–Kutta procedures jointly. The impact of flow concerning variables on associated distributions is revealed through tabular and graphical manner. Quantities of engineering interest associated with work like wall friction and thermal flux coefficients at walls of the disk are also calculated. It is deduced from an examination that the addition of metallic particles raises heat transfer more than non-metallic particles. A significant impression of magnetic field on shear stress is executed by hybrid nanoparticles along the surface of disks. In addition, elevation in Nusselt number and depreciation in skin friction coefficient is revealed against increasing magnitude of nanoparticle volume fraction. A positive trend in skin friction coefficient is manifested against the increasing magnitude of Reynold number. It is also observed that by increasing the size and shape of hybrid nanoparticles thermal conductivity and viscosity of the base fluid increases.