Phase Change Thermal Diode Using Al2O3-Cu/Water Hybrid Nanofluids for Thermal Rectification Enhancement

2020 ◽  
Author(s):  
M. Y. Wong ◽  
C. Y. Tso ◽  
T. C. Ho
Keyword(s):  
Heat Transfer ◽  
Thermal Properties ◽  
Phase Change ◽  
Storage Systems ◽  
Thermal Storage ◽  
Solar Thermal ◽  
Working Fluid ◽  
Hybrid Nanofluid ◽  
Thermal Rectification ◽  
Hybrid Nanofluids

Abstract A thermal diode, a device to manipulate the heat flow in different directions, is useful in various thermal systems, such as solar thermal storage systems. It is noted that the performance of phase change thermal diodes shows the highest thermal rectification performances in the literature. The performances of the phase change thermal diode can be further improved by utilizing a working fluid with enhanced thermal properties. Since hybrid nanofluids are proven to have better thermal properties than the base fluid (i.e. water), in this study, a thermal diode using Al2O3-Cu/water hybrid nanofluid is fabricated and tested to investigate the feasibility of using hybrid nanofluid to enhance the performance of the thermal diode. The heat transfer and thermal rectification performances of the thermal diode using Al2O3-Cu/water hybrid nanofluid are compared experimentally, to a thermal diode using water. The effect of temperature on the heat transfer and thermal rectification performances of the thermal diode is also examined. The results indicate that the effective thermal conductivity in the forward direction and the diodicity of the thermal diode using Al2O3-Cu/water hybrid nanofluid are improved by 42.4% and 30.8%, respectively, compared to that of the thermal diode using water. The findings not only reveal a new direction for future research in enhancement of the thermal rectification performance of the phase change thermal diode but also provide an alternative research path for improving the performance of existing solar thermal storage systems.

Solar thermal storage systems using phase change materials

1988 ◽  
Vol 12 (3) ◽  
pp. 547-555 ◽  
Author(s):  
D. Buddhi ◽  
N. K. Bansal ◽  
R. L. Sawhney ◽  
M. S. Sodha
Keyword(s):  
Phase Change ◽  
Phase Change Materials ◽  
Storage Systems ◽  
Thermal Storage ◽  
Solar Thermal

scholarly journals Energetic and Exergetic Assessment of the Cooling Efficiency of Automobile Radiator Using Mono and Hybrid Nanofluids

2021 ◽  
Vol 39 (4) ◽  
pp. 1321-1327
Author(s):  
Khalid Faisal Sultan ◽  
Hosham salim Anead ◽  
Ameer Abed Jaddoa
Keyword(s):  
Heat Transfer ◽  
Fluid Velocity ◽  
Exergy Efficiency ◽  
Working Fluid ◽  
Hybrid Nanofluid ◽  
Exergy Destruction ◽  
Current Form ◽  
Nano Fluid ◽  
Hybrid Nanofluids ◽  
Primary Form

In this paper, for two separate half-breed Nano liquids, Ag (25nm) + refined water and Ag (50nm) + Zn (50nm)-refined water tentatively considered at the vehicle radiator, the execution of restricted convection. Four distinct cross-breed Nano liquid concentrations in the range of 2-6 vol %. The increase of half breed nanoparticles into the refined water as a base liquid was organized by percentage. Within the range of 20 l/min-60 l /min, the coolant flow rate is altered. Inside the warm trade, Crossover Nano coolants show colossal change compared to the refined water. Ag-refined water cross breed Nano liquid's warm exchange execution was found to be much better than Ag + Zn-refined water half breed Nano coolant. In addition, with the rise in the concentration of half breed nanoparticle and half breed Nano fluid velocity, the Nusselt number is found to expand. In the advancement of the warm exchange rate, Mono and hybrid nanofluid forms play a very important role in enhancing the heat transfer and refrigeration of car radiators. With an increase in concentration of half-breed nanoparticles for the primary form about 44 percent warm exchange transition, expansion of 6 vol percent crossover nanoparticles were achieved with the rate of warm exchange. In comparison to the current form of cross breed nanoparticles, with an expansion of 6 percent vol concentration, 22 percent extended. The exergy in flow, exergy destruction and exergy efficiency of mono nanofluid (Ag +Dw) are greater than hybrid nanofluid (Ag + Zn + Dw) and distilled water. The exergy inflow, exergy destruction, and exergy efficiency as the concentration of nanoparticles increases for the two forms of mono and hybrid nanofluid. The values parameters of the mono nanofluid (Ag + Dw) such as exergy in flow, exergy destruction and exergy efficiency at 6 vol% were 572 W, 460 W, 72% respectively while in hybrid nanofluids (Ag + Zn + Dw) were 420W, 282W, 51%. The use of mono and hybrid nanofluid as a working fluid results in higher efficiency of heat transfer, which promotes the performance of the car engine and decreases fuel consumption.

scholarly journals A novel empirical heat transfer model for a solar thermal storage process using phase change materials

Energy ◽  
2019 ◽  
Vol 168 ◽  
pp. 222-234 ◽  
Author(s):  
Yu Bie ◽  
Ming Li ◽  
Fei Chen ◽  
Grzegorz Królczyk ◽  
Lin Yang ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Phase Change ◽  
Phase Change Materials ◽  
Thermal Storage ◽  
Heat Transfer Model ◽  
Solar Thermal ◽  
Transfer Model ◽  
Storage Process

Experimental and numerical analysis on using CuO-Al2O3/water hybrid nanofluid in a U-type tubular heat exchanger

2020 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Emine Yağız Gürbüz ◽  
Halil İbrahim Variyenli ◽  
Adnan Sözen ◽  
Ataollah Khanlari ◽  
Mert Ökten
Keyword(s):  
Heat Transfer ◽  
Numerical Simulation ◽  
Thermal Performance ◽  
Single Type ◽  
Working Fluid ◽  
Hybrid Nanofluid ◽  
Tubular Heat Exchanger ◽  
Content Type ◽  
Hybrid Type ◽  
Hybrid Nanofluids

Purpose Heat exchangers (HEXs) are extensively used in many applications such as heating and cooling systems. To increase the thermal performance of HEXs, nano-sized particles could be added to the base working fluid which can improve the thermophysical properties of the fluid. In addition, further improvement in the thermal performance of nanofluids can be obtained by using two or more different nanoparticles which are known as hybrid nanofluids. This paper aims to improve the thermal efficiency of U-type tubular HEX (THEX) by using CuO-Al2O3/water hybrid nanofluid. Design/methodology/approach Numerical simulation has been used to model THEX with various configurations. Also, CuO-Al2O3/water hybrid nanofluid has been experimented in THEX in two various modes including parallel (PTHEX) and counter flow (CTHEX) regarding to the numerical findings. Hybrid nanofluids have been prepared in two particle concentrations and compared with CuO/water nanofluid at the same concentrations and also with water. Findings The numerical simulation results showed that adding fins and also using hybrid nanofluid can increase heat transfer rate in HEX. However, adding fins cannot be a good option in U-type THEX with lower diameter because it increases pressure drop notably. Experimental results of this work illustrated that using Al2O3-CuO/water hybrid nanofluid in the THEX improved thermal performance significantly. Maximum enhancement in overall heat transfer coefficient of THEX by using CuO-Al2O3/water nanofluid in 0.5% and 1% concentrations achieved as 9.5% and 12%, respectively. Originality/value The obtained findings of the study showed the positive effects of using hybrid type nanofluid in comparison with single type nanofluid. In this study, numerical and experimental analysis have been conducted to investigate the effect of using hybrid type nanofluid in U-type HEX. The obtained results exhibited successful utilization of CuO-Al2O3/water hybrid type nanofluid in HEX. Moreover, it was observed that thermal performance analysis of the nanofluids without any experiment can be done by using numerical method.

Numerical Model for Storage Systems Based on Phase-Change Materials

2011 ◽  
Author(s):  
Adriano Sciacovelli ◽  
Vittorio Verda ◽  
Francesco Colella
Keyword(s):  
Heat Transfer ◽  
Phase Change ◽  
Phase Change Materials ◽  
Storage Systems ◽  
Numerical Procedure ◽  
Thermal Storage ◽  
Operating Conditions ◽  
Heat Transfer Fluid ◽  
Inlet Temperature ◽  
Technical Problems

Phase-change materials (PCM) are particularly promising for thermal storage in various energy plants as solar plants, district heating, heat pumps, etc. mainly because of the possibility to reduce the volume of storage tanks, but also because the problems related with thermal stratification are considerably reduced. On the other hand, research is necessary in order to address technical problems, mainly related to the heat transfer in the medium, which needs to be enhanced in order to achieve reasonable charging and discharging processes. The present paper describes the application of computational fluid-dynamics (CFD) for the analysis of PCM thermal storage systems. The numerical analysis is directed at understanding the role of buoyancy-driven convection during constrained solidification and melting inside a shell-and-tube geometry. The 2D model is based on a finite-volume numerical procedure that adopts the enthalpy method to take in account the phase change phenomenon. The time-dependent simulations show the melting phase front and melting fraction of the PCM and incorporate the fluid flow in the liquid phase. The obtained temperature profiles are compared to a set of experimental data available in the literature. The results show that during the melting process natural convection within the PCM has non negligible effects on the behavior of the system. The numerical simulations of the solidification process show that the increasing solid fraction of the PCM inhibits the buoyancy in the remaining liquid portion of the phase-change-material. Furthermore, the paper discusses the effects on the phase-change processes of the main operating conditions, including inlet temperature and mass flow rate of the heat transfer fluid.

Energy Efficient Hybrid Nanofluids for Tubular Cooling Applications

2014 ◽  
Vol 592-594 ◽  
pp. 922-926 ◽  
Author(s):  
Devasenan Madhesh ◽  
S. Kalaiselvam
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Volume Concentration ◽  
Thermal Characteristics ◽  
Hybrid Nanofluid ◽  
Tubular Heat Exchanger ◽  
Overall Heat Transfer Coefficient ◽  
Flow Through ◽  
Hybrid Nanofluids

Analysis of heat transfer behaviour of hybrid nanofluid (HyNF) flow through the tubular heat exchanger was experimentally investigated. In this analysis the effects of thermal characteristics of forced convection, Nusselt number, Peclet number, and overall heat transfer coefficient were investigated.The nanofluid was prepared by dispersing the copper-titania hybrid nanocomposite (HyNC) in the water. The experiments were performed for various nanoparticle volume concentrations addition in the base fluid from the range of 0.1% to 1.0%. The experimental results show that the overall heat transfer coefficient was found to increases maximum by 30.4%, up to 0.7% volume concentration of HyNC.

scholarly journals Experimental Investigation on Stability, Viscosity, and Electrical Conductivity of Water-Based Hybrid Nanofluid of MWCNT-Fe2O3

Nanomaterials ◽  
2021 ◽  
Vol 11 (1) ◽  
pp. 136
Author(s):  
Solomon O. Giwa ◽  
Mohsen Sharifpur ◽  
Mohammad H. Ahmadi ◽  
S. M. Sohel Murshed ◽  
Josua P. Meyer
Keyword(s):  
Electrical Conductivity ◽  
Visual Inspection ◽  
Volume Concentration ◽  
Working Fluid ◽  
Hybrid Nanofluid ◽  
Multiwalled Carbon ◽  
Transmission Electron ◽  
Hybrid Nanofluids ◽  
Uv Visible ◽  
The Stability

The superiority of nanofluid over conventional working fluid has been well researched and proven. Newest on the horizon is the hybrid nanofluid currently being examined due to its improved thermal properties. This paper examined the viscosity and electrical conductivity of deionized water (DIW)-based multiwalled carbon nanotube (MWCNT)-Fe2O3 (20:80) nanofluids at temperatures and volume concentrations ranging from 15 °C to 55 °C and 0.1–1.5%, respectively. The morphology of the suspended hybrid nanofluids was characterized using a transmission electron microscope, and the stability was monitored using visual inspection, UV–visible, and viscosity-checking techniques. With the aid of a viscometer and electrical conductivity meter, the viscosity and electrical conductivity of the hybrid nanofluids were determined, respectively. The MWCNT-Fe2O3/DIW nanofluids were found to be stable and well suspended. Both the electrical conductivity and viscosity of the hybrid nanofluids were augmented with respect to increasing volume concentration. In contrast, the temperature rise was noticed to diminish the viscosity of the nanofluids, but it enhanced electrical conductivity. Maximum increments of 35.7% and 1676.4% were obtained for the viscosity and electrical conductivity of the hybrid nanofluids, respectively, when compared with the base fluid. The obtained results were observed to agree with previous studies in the literature. After fitting the obtained experimental data, high accuracy was achieved with the formulated correlations for estimating the electrical conductivity and viscosity. The examined hybrid nanofluid was noticed to possess a lesser viscosity in comparison with the mono-particle nanofluid of Fe2O3/water, which was good for engineering applications as the pumping power would be reduced.

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