Elsevier

Energy Conversion and Management

Volume 155, 1 January 2018, Pages 32-41
Energy Conversion and Management

Experimental investigation of flat plate solar collector using CeO2-water nanofluid

https://doi.org/10.1016/j.enconman.2017.10.070Get rights and content

Highlights

  • CeO2-water nanofluid was prepared using two step method.

  • Stability of CeO2-water nanofluid was achieved.

  • Effect of different volume fraction of nanofluid on solar collector thermal efficiency was studied.

  • The study made at different mass flux rates.

  • The efficiency of solar collectors increased by 10.74%.

Abstract

Using nanofluids in thermal energy devices, such as flat-plate solar collectors, is gradually making progress, and getting awareness in the scientific community. Experiments were performed to study the effect of using CeO2-water on the efficiency of flat-plate solar collector by three different volume fractions of CeO2 nanoparticles of 0.0167%, 0.0333% and 0.0666%, while the mean particle dimension was kept constant at 25 nm. An ultrasonic process was used for maintaining the stability of the CO2-water nanofluid. The working fluid mass flux rates were 0.015, 0.018 and 0.019 kg/s m2. The experiments were carried out in Budapest, Hungary on the latitude of 47°28′N and longitude of 19°03′E. Higher collector efficiency was achieved when using CeO2-water nanofluid compared to results achieved with water application. Based on present data, the efficiency of the collector is directly proportional with the mass flux rate and with the volume fraction in the ranges of the present study. Experiments indicate that the highest rise in efficiency of the collector at zero value of [(Ti – Ta)/GT] is 10.74%, for volume fraction (φ) 0.066%, and for mass flux rate of 0.019 kg/s m2 compared to water.

Introduction

In the past few years, scientists raised general attention to nanoparticles with less than 100 nm in size. It was found out that the tiny particles hold by fluids and make a remarkable change or even the properties of fluids. Based on this fact, it was observed that a lot of nano-scale materials added to fluids changed their thermal properties, as well as the performance of thermal devices. Solar collectors are one of these devices which take advantage of the observed properties of nanofluid. In this part, when getting a focus view on using nanofluid as the working fluid in flat-plate types of solar collectors, will be presented. Table 1 shows different experimental investigation of performance of flat plate solar collector when using nanofluid as a working fluid.

Although all above studies didn’t modify the conventional solar collector design, other researchers made some modification in the design of solar collector such as Faizal et al. [24] who used numerical methods to design a smaller solar collector that can produce the same desired output temperature as the bigger one. From his study, it was found that by applying nanofluid the cost of solar collector, embodied energy and CO2 emissions were reduced. Colangelo et al. [25] modified the design of the flat-plate collector by rearranging bottom and top headers to reduce the sedimentation of the clusters of nanoparticles, and, in this way, they were able to apply high nanoparticle concentration for the first time ever. Sekhar et al. [26] investigated convective heat transfer analysis for a horizontal circular pipe with Al2O3 nanofluids at different volume concentrations in mixed laminar flow range.

Based on Latest review studies [28], [29], [30], [31], [32], [33], [34], [35] no research had been done to detect the effect of CeO2-water nanofluid on the efficiency of a flat-plate collector although it had good thermal properties as Tiwari et al. [27] found. Also, CeO2 nanoparticles has several benefits like:

  • It has good availability and easy to prepare

  • it’s price isn’t high so it has a good economic potential

  • the stability of it with water is high comparing to other nanoparticles

  • No toxicity or flammability was observed when it was using so it environmental friendly.

This paper is focusing on studying the performance of a flat-plate collector using CeO2-water nanofluid as working fluid instead of using distilled water. Also, making a stable CeO2-water nanofluid using ultrasonic technique is an aim for this work. On other side, examine to what extent the thermal performance is affected by adding CeO2 nanoparticles and using different mass flux rate is deeply studied in this paper. A detailed discussion about the effect of environmental parameters like ambient temperature and solar radiation is held in presented work by using the reduced temperature parameter, [(Ti–Ta)/GT], as independent variable in several figures.

Section snippets

Methodology

This section is presented in two parts. The first part deals with nanofluid preparation and the second part describes the set-up that has been used for experiments on the flat plate solar collector.

Testing method

In the current study, ASHRAE Standard 93-2003 [36] was the basis to investigate the thermal performance of the solar collector. The purpose of this standard is to introduce test methods to detect thermal performance of solar collectors that use single-phase fluids without significant internal energy storage. According to ASHRAE Standard 93-2003 [36] solar collector should examine at 0.02 kg/s m2 or at recommended flow rate as manufacturer. Therefore, we use these mass flux rate of 0.015, 0.018,

Uncertainty analysis

Uncertainty analysis is an important task in experimental studies since it shows the accuracy of measurements. In this part, the aim is to determine the value of uncertainty in efficiency of solar collector. Based on Eq. (4), the uncertainty in efficiency depends on mass flow rate, heat capacity, inlet and outlet temperature of working fluid, surface area of the solar collector, and solar radiation.

The uncertainty of temperature data is determined by the precision of Pt-100 sensors (in our

Stability of nanofluid

Ultrasonic is used to break up agglomeration and to promote the dispersion of nanoparticles into base fluids to get more stable nanofluid as Mahbubul et al. [40] reported. Ultrasonic techniques have a significant effect on the surface and the structure of nanoparticles, and grant long-term, stable and well-dispersed nanofluids, and better particle breakdown. After several experiments for CeO2-water Nanofluid, we found that higher concentration gave less stability so we choose these

Thermal performance

The enhancement in thermal properties of fluids when using nanoparticles was examined and confirmed in several papers like [37], [39], [41], [42], [43], [44], [45]. Among these paper and also the presented paper a deeply discussion was made to show the reason of thermal effect of adding nanoparticles to water.

The results presented in this paper are focused in studying the effect of adding CeO2 Nanoparticles on water. The dissociation is divided to two main parts, firstly study the pure water,

Conclusions

A study was performed experimentally to determine the efficiency curves of a flat-plate solar collector with using nanofluid of CeO2-water as working fluid. The stability of CeO2-water nanofluid was weak. Three different volume fractions of 0.0167%, 0.0333%, and 0.0666% were tested at three mass flux rates, including 0.015, 0.018, and 0.019 kg/s m2. The experiments and results elucidated that using CeO2-water nanofluid increased the efficiency of the solar collector more efficiently than using

Acknowledgment

The authors would like to thank Professor István Csontos and Dr. Enikő Krisch for their help and support. The authors would like to thank the “Egyptian Ministry of Higher Education” (MOHE) for the invaluable professional promotion of the Stipendium Hungaricum scholarship provided for the PhD studies carried out in Hungary.

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