scholarly journals Thermal Stability and Performance Testing of Oil-based CuO Nanofluids for Solar Thermal Applications

Energies ◽  
2020 ◽  
Vol 13 (4) ◽  
pp. 876 ◽  
Author(s):  
Moucun Yang ◽  
Sa Wang ◽  
Yuezhao Zhu ◽  
Robert A. Taylor ◽  
M.A. Moghimi ◽  
...  

For solar thermal systems, nanofluids have been proposed as working fluids due to their enhanced optical and thermal properties. However, nanoparticles may agglomerate over time, heating and thermal cycles. Even though pristine nanofluids have proven to enhance performance in low-temperature applications, it is still unclear if nanofluids can meet the reliability requirements of solar thermal applications. For this aim, the present study conducted experiments with several formulations of oil-based CuO nanofluids in terms of their maximum operational temperatures and their stabilities upon cyclic heating. In the samples tested, the maximum temperature ranged from 80 to 150 °C, and the number of heating cycles ranged from 5 to 45, with heating times between 5 to 60 min. The results showed that heating temperature, heating cycles, and heating time all exacerbated agglomeration of samples. Following these experiments, orthogonal experiments were designed to improve the preparation process and the resultant thermal-impulse stability. Thermal properties of these samples were characterized, and thermal performance in an “on-sun” linear Fresnel solar collector was measured. All tests revealed that thermal performance of a solar collecting system could be enhanced with nanofluids, but thermal stability still needs to be further improved for industrial applications.

2016 ◽  
Vol 3 (16) ◽  
pp. 1600248 ◽  
Author(s):  
Junhua Gao ◽  
Xiaoyu Wang ◽  
Bing Yang ◽  
Chengjun Tu ◽  
Lingyan Liang ◽  
...  

e-Polymers ◽  
2009 ◽  
Vol 9 (1) ◽  
Author(s):  
Marius Ciprian Rusu ◽  
Ionut Cameliu Ichim ◽  
Marcel Popa ◽  
Daniela Rusu ◽  
Mihai Rusu

AbstractBromine-containing methacrylate, 2-(2-bromoisobutyryloxy) ethyl methacrylate (BIEM), had been used in the formulation of acrylic radiopaque cements. The effect of this monomer incorporated into the liquid phase of acrylic bone cement (ABC), on the curing parameters, thermal properties, water absorption, density, compression tests and radiopacity was studied. A decrease of maximum temperature and an increase of the setting time were observed with the addition of the brominecontaining monomer in the radiolucent cement composition. Adding BIEM in radiolucent ABCs composition results in the decrease of glass transition temperature and increase in its thermal stability. The ABCs modified with bromine-containing comonomer are characterized by polymerization shrinkage lower than the radiolucent cement. Addition of bromine-containing comonomer in radiolucent ABC composition determines the increase of compressive strength. The ABCs modified with brominecontaining comonomer proved to be radiopaque.


2020 ◽  
Vol 15 (4) ◽  
pp. 629-636
Author(s):  
Lulu Safira ◽  
Nandy Putra ◽  
Titin Trisnadewi ◽  
Eny Kusrini ◽  
Teuku Meurah Indra Mahlia

Abstract This study aims to investigate the thermal properties of a phase change material (PCM) based on coconut oil for building energy storage applications. Coconut oil is classified as an organic PCM composed of fatty acids made from renewable feedstock. However, low thermal conductivity is one of the major drawbacks of organic PCMs that must be improved. Graphene could be an effective material to enhance the thermal performance of organic PCMs. In this study, coconut oil with a latent heat capacity of 114.6 J/g and a melting point of 17.38°C was used. PCMs were prepared by sonicating graphene into coconut oil, as a supporting material. The mass fractions of the prepared PCMs were 0, 0.1, 0.2, 0.3, 0.4 and 0.5. Thermal conductivity tests were performed using a KD2 thermal property analyser under different ambient temperatures of 5, 10, 15, 20 and 25°C simulated with a circulating thermostatic bath. The latent heat, melting point and freezing point were determined through differential scanning calorimetry, the thermal stability was determined using thermogravimetric analysis (TGA) and the morphology and chemical structure were examined using transmission electron microscopy and Fourier-transform infrared spectroscopy, respectively. The results of this study showed that graphene addition to coconut oil improved the thermal performance, with the highest improvement seen in a 0.3 wt% sample at 20°C. The latent heat decreased by 11% owing to molecular movements within the PCM. However, TGA revealed that the composite PCMs showed good thermal stability in ambient building temperature ranges.


Author(s):  
Donghyun Shin ◽  
Debjyoti Banerjee

Nanofluids are synthesized by doping solvents with nano-particles at minute concentrations (typically less than 1 percentage by volume). Experimental studies have shown that nano-particles can dramatically enhance thermal conductivity of various liquid solvents. This is also associated with enhancement of other transport properties (e.g., viscosity, specific heat, diffusivity, etc.). Hence, nanofluids are attractive materials for solar thermal applications. The objective of this study is to investigate the optimum performance of various nanofluids for solar thermal storage applications. Dimensional analyses and similitude techniques will be used to theoretically estimate the enhancement of transport properties of various nanofluids to predict their efficacy for solar thermal storage applications.


2016 ◽  
Vol 109 ◽  
pp. 901-905 ◽  
Author(s):  
Pramod Kandoth Madathil ◽  
Nagaraj Balagi ◽  
Priyanka Saha ◽  
Jitalaxmi Bharali ◽  
Peddy V.C. Rao ◽  
...  

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