Review on aqueous graphene nanoplatelet Nanofluids: Preparation, Stability, thermophysical Properties, and applications in heat exchangers and solar thermal collectors
- Publisher:
- PERGAMON-ELSEVIER SCIENCE LTD
- Publication Type:
- Journal Article
- Citation:
- Applied Thermal Engineering, 2022, 210
- Issue Date:
- 2022-06-25
Closed Access
| Filename | Description | Size | |||
|---|---|---|---|---|---|
| Review on aqueous graphene nanoplatelet Nanofluids Preparation, Stability, thermophysical Properties, and applications in heat exchangers and solar thermal collectors.pdf | Published version | 2.9 MB |
Copyright Clearance Process
- Recently Added
- In Progress
- Closed Access
This item is closed access and not available.
Nanofluids of graphene nanoplatelets (GNP) have superior thermal performance characteristics and good stability, are relatively affordable, and can easily be prepared by the two-step method. This review performs an in-depth analysis of the preparation, stability, and thermophysical properties of GNP nanofluids, and their applications in heat exchangers, solar thermal collectors, and heat pipes. This study analyses in detail the performance improvements achieved with pristine, covalent functionalised, and non-covalent functionalised GNP nanofluids compared to water. Covalent functionalisation was found to be superior to non-covalent functionalisation in terms of stability and heat transfer coefficients. Functionalisation by electrophilic addition and free-radical grafting were found to be more environmentally friendly compared to acid treatment. In terms of convective heat transfer coefficient, pristine GNP outperformed functionalised GNP, but both types showed large improvements compared to water. It was found that stability and heat transfer performance improved as particle size was decreased, while thermal conduction and convection coefficients increased with nanofluid concentration and temperature. Thermal conductivity improvements of over 30% were found for both pristine and covalently functionalised GNP nanofluids at 0.1 wt% concentration. A maximum convection heat transfer coefficient increase of 200% was achieved using 0.1 wt% pristine GNP nanofluid. By comparison, a maximum improvement of 119% was achieved using covalently functionalised GNP. The convective heat transfer enhancement seemed to increase with decreasing tube diameter. In flat plate solar collector applications, efficiency improvements over 20% were obtained for covalently functionalised GNP nanofluids at 0.1 wt%, while an efficiency improvement of over 65% was obtained using pristine GNP in an evacuated tube solar collector. Applications in cooling, heat pipes, and direct absorption solar collectors were also reviewed. From this study, it could be inferred that GNP nanofluids are a viable alternative working fluid. Further research is needed to optimise their performance.
Please use this identifier to cite or link to this item: