Publication: Corrigendum to �A review on the performance of nanoparticles suspended with refrigerants and lubricating oils in refrigeration systems� [Renewable and Sustainable Energy Reviews, 15 (1), 2011, pp. 310�323](S1364032110002704)(10.1016/j.rser.2010.08.018)
Date
2018
Authors
Saidur R.
Kazi S.N.
Hossain M.S.
Rahman M.M.
Mohammed H.A.
Journal Title
Journal ISSN
Volume Title
Publisher
Elsevier Ltd
Abstract
The authors regret that they have inadvertently published this paper with parts that appear close to some materials we had included in some of our other review research (new reference [A] below). This other review was submitted for publication at about the same time and was not referenced in this review. However, the technical content and focus of these review papers are much different. The other review [A] focused on different applications of nanofluids, and this review examines nanolubricants and nanorefrigerants with specific applications in refrigeration systems. The portions that are similar do not affect the major technical review contents or the different technical review scopes�and are mainly background and supporting materials in this review. We did not intend to have an issue with similarity�and we apologize for any inconvenience this has caused the readers and the journal. In order to ensure that this similarity is addressed, we are providing the following changes to this review: The authors provide the following revision to heading 1.0 Introduction, first and second paragraphs (because this written material is very important as originally written to this review we have provided it in quotation marks): �Nanofluids are new class of heat transfer fluids where nano-sized particles (1�100 nm) of metals or metal oxides are suspended in base-fluids to improve the heat transfer performance in various applications. One unique feature of the nanofluid is that its thermal conductivity is higher than the base-fluids due to nano-sized suspended solid particles into the base-fluids. There is more heat transfer surface between fluid and particles due to high specific surface area of nanofluids. Brownian motion made the better dispersion stability of nanofluids. Low pumping power is required due to heat transfer intensification of nanofluids. Less tendency of particle clogging in the flow channel for the nanofluids and system can me made compact or miniaturized for this reason. Properties can be adjusted or fined tuned with the concentrations of nano-particles to suit specific applications [A])� Heading 3.0 Thermal conductivity of nanofluids, first, second, third and fourth paragraph to be replaced with Thermal conductivity is an important parameter that plays a great role for heat transfer performance improvement for various applications in refrigeration and air conditioning systems. Eastman et al. [24] reported 40% improvement of 0.3% copper nanoparticles with ethylene glycol nanofluids compared to base-fluids. Liu et al. [6] reported 23.8% improvement in thermal conductivity with 0.1% of copper nanoparticles with base-fluids. Hwang et al. [25] explained that thermal conductivity improvement of nanofluids is significantly influenced by thermal conductivity of nanoparticles and base-fluid. However, surface to volume ratio of nanoparticles found to be a dominant factor for the thermal conductivity improvement according to Yoo et al. [26]. About 150% thermal conductivity improvement was reported by Choi et al. [27] for poly oil with MWCNT with 1% volume fraction. However, Yang [28] reported 200% improvement of thermal conductivity for the same oil but with 0.35% MWCNT. Jana et al. [29] reported 70% thermal conductivity improvement for cu nanoparticles in water with 0.3% concentration. About 75% thermal conductivity improvement was reported by Kang et al. [30] for ethylene glycol with 1.2% diamond nanoparticles. However, there are findings on the thermal conductivity in the literature that shows anomalous results [31�34]. Thermal conductivity is influenced by pH, addition of surfactant, stability of nanofluids, temperature, volume fraction, size, shape of nano-particles as well [11,35�38]. These are also explained in Figs. 5 and 6 [A]. Higher cooling rates, decreased pumping power needs, smaller and lighter cooling systems, reduced inventory of heat transfer fluids, reduced friction coefficients, and improved wear resistance are the resulting benefits of improved thermal conductivities of various nanofluids used in different applications. These made nanofluids highly potential as refrigerants, coolants, lubricants, hydraulic and cutting fluids. Heading 11, Challenges of nanofluids to be replaced with Since 1993, huge amount of interesting research works on the thermos-physical, rheological, chemical, and optical properties of nanofluids/nano-refrigerants were reported in the literature. Along with these properties, many applications of nanofluids were also reported in the literature. However, there are number of challenges that need to be overcome. Those are listed below: Heading 11.1 Long term stability to be replaced with Long term stability of nanofluids is one of the important requirements for the various applications as reported in the literatures. However, this is one of the major challenges as they aggregate due to van der wall forces. Addition of surfactant, surface modification of nanoparticles, application of strong force on the clusters of suspended particles have been found to improve this characteristics of nanofluids. However, excessive amount of surfactant is detrimental for the thermos-physical, rheological, chemical properties of nanofluids and should be used with great care and control [81,84,87�88,90]. Time is an important factor that also influence dispersion behaviour of nanofluids as shown in Figs. 17 and 18 [A]. Eastman et al. [24] reported better thermal conductivity for the fresh nanofluids compared to the nanofluids stored for 2 months. Lee and Mudawar [77] also reported similar trend for the Al2O3 nanofluids. Heading 11.2 Higher viscosity to be replaced with Viscosity of water based nanofluids found to be increased with the higher concentration of nanoparticles. This raises the pressure drop across the cooling channel. Therefore, large volume of nanofluids in heat exchangers with nanofluids is not a good option according to Lin et al. [65]. Vassallo et al. [20] reported that concentration of CNTs should be less than 0.2% to avoid rapid increase in viscosity. Heading 11.3 Lower specific heat to be replaced with Praveen et al. [76] mentioned that some of the nanofluids has lower specific heat compared to base-fluids. This is undesirable for some specific applications as specific heat capacity should be higher to remove more heat. Heading 11.4 Thermal conductivity model to be replaced with Hamilton-Crosser, Yu-Choi and Xue models cannot predict thermal conductivity of CNTs accurately as mean deviation is quite high [11]. Heading 11.5 High cost of nanofluids to be replaced with Nanofluids or nanoparticles are produced either by one or two step methods which are expensive methods. High cost of nanofluids preparation is one of the challenges for various applications of nanofluids [77,79]. Heading 11.6 Difficulties in production process to be replaced with Reduction reactions or ion exchange take place during the production of nanoparticles by one or two step methods. Base-fluids also contain other ions and reaction products which are difficult to separate from the fluids. Nanoparticles tend to agglomerate with larger particles during the manufacturing process and this consequently limits the benefits of high surface area of nanoparticles. To avoid this, some additives can be added. However, this may lead to some unacceptable level of impurities in the prepared nanofluids. Along with these issues, synthesis, characterization, thermos-physical properties, heat and mass transfer issues need to be taken care as well [92�93]. New reference [A] Saidur R, Leong KY, Mohammad HA. A review on applications and challenges of nanofluids. Renew Sustain Energy Rev, 15; 2011, 1646�1668. Again, the authors would like to apologise for any inconvenience caused by these required corrections. We appreciate the opportunity to clarify this situation. DOI of original article: <https://doi.org/10.1016/j.rser.2010.08.018> � 2018