. 2020 Aug 24;135:110254. doi: 10.1016/j.rser.2020.110254

Table 11.

Comparison of nanoparticles associated with the thermal properties and key findings.

Nanoparticle type	Researcher	Base fluid	Particle size (nm)	Temperature (°C)	Volume fraction (vol. %)	Mass flux rate (kg/s·m²)	Mass flow rate (L/min)	Key findings
Al₂O₃	Ghaderian and Sidik [81]	Distilled water	40	30	0.03 and 0.06	N/A	0.33, 0.67 and 1.0	• The maximum thermal efficiency achieves 58.65% when the concentration reaches 0.06 vol%. • Result confirmed that Al₂O₃ nanofluid contributes to enhancing the heat transfer rate and system performance.
	Tong et al. [82]	Water	20	30	0.5,1 and1.5	0.047	N/A	• The highest efficiency could achieve 77.5% when the 1.0% concentration of Al₂O₃ nanofluid is adopted, which is 21.9% higher compared to water. • The system exergy efficiency based- 1.0 vol% Al₂O₃ nanofluid is improved by 56.9% compared to water.
	Sardarabadi et al. [97]	Water	32	30	0.2	N/A	0.67	• The thermal output of the PV/T based-Al₂O₃ could enhance 8.12% in comparison with that of the PVT/water. • The electrical output of the PV/T based-Al₂O₃ could improve 5.5% compared with conventional PV array. • Using Al₂O₃ nanofluid as working fluidcontributes to decreasing the system exergy loss and entropy production.
	Eidan et al. [98]	Acetone	20	30	0.25 and 0.5	N/A	0.017 and 0.033	• The system thermal efficiency based-Al₂O₃ could enhance 18% and 30% for different concentrations of 0.25% and 0.5%, respectively. • Higher concentration (0.5%) Al₂O₃ nanlofluid provides a greater performance in comparison with the lower concentration one (0.25%).
	Mercan and Yurddaş [99]	Water	30	30, 45 and 60	1, 3 and 5	0.025, 0.05 and 0.07	N/A	• The heat transfer rate improves when the nanoparticles ratio grows. • The system thermal output based-Al₂O₃ increased by 4.13% for the 24-tube collector.
	Al-Waeli et al. [100]	Water	30–60	25	0.5, 1, 2, 3 and 4	N/A	N/A	• The Al₂O₃ nanofluid has more stability than CuO nanofluid.
CuO	Tong et al. [82]	Water	40	30	0.1, 0.3, 0.5 and 0.7	0.047	N/A	• The CuO nanofluid could achieve the maximum efficiency of 73.9%, which is 16.2% higher than water. • The system exergy efficiency based- 0.5 vol % CuO nanofluid is enhanced by 49.6% compared to water.
	Ghaderian J et al. [83]	Distilled water	30–50	40	0.03 and 0.06	N/A	0.33 and 1.0	• The mean outlet fluid tempertaure could be increased by 14% for 0.03 vol % concentration of CuO nanofluids in comparison with water. • The system performance is individually improved by 51.4% and 41.9% for 0.06 vol % and 0.03. Vol. % concentrations.
	Qu et al. [84]	Water	200–1350	30	0.25, 0.15, 0.05, 0.025 and 0.01	N/A	N/A	• The outlet temperature is improved by 9.2 °C in comparison with water when the concentration of 0.25 vol %, CuO nanofluid is adopted in the system.
	Eidan et al. [98]	Acetone	25	30	0.25 and 0.5	N/A	0.017 and 0.033	• The system thermal efficiency based-CuO could enhance 16.7% and 28% for different concentrations of 0.25% and 0.5%, respectively. • Higher concentration (0.5%) CuO nanlofluid could provide a greater performance in comparison with the lower concentration one (0.25%).
	Mercan and Yurddaş [99]	Water	30	30, 45 and 60	1, 3 and 5	0.025, 0.05 and 0.07	N/A	• The heat transfer rate improves when the nanoparticles ratio grows. • The thermal output of the PV/T based-CuO nanlofluid could increase by 6.8% for the 24-tube collector.
	Al-Waeli et al. [100]	De-ionized Water	35–45	25	0.5, 1, 2, 3 and 4	N/A	N/A	• The CuO has greater thermal conductivity than Al₂O₃.
CuO-MWCNT	Qu et al. [84]	Water	200–1350	60–80	0.0015	N/A	N/A	• The maximum temperature could be improved by 14.1 °C when the hybrid CuO-MWCNT nanofluids is adopted. • Results indicated that the hybrid CuO-MWCNT nanofluids is a potential method to boost the system efficiency.
SiC	Al-Waeli et al. [85]	Water	40–60	20	1, 1.5, 2, 3 and 4	N/A	40.11	• The power efficiency of SiC nanofluid could enhance by 24.1% in comparison with conventional PV array. • The system heat efficiency of SiC nanofluid could improve by 100.19%. • The overall system effectiveness based SiC nanofluid has a greater efficiency of around 88.9% than the separate PV panel.
SiC	Al-Waeli et al. [100]	Water	45–65	25	0.5, 1, 2, 3 and 4	N/A	N/A	• Results found that the SiC has the highest thermal conductivity and the best stability in comparison with CuO and Al₂O_3. • SiC nanofluid could enhance the system performance more than the CuO and Al₂O_3.
Ag	Aberoumand et al. [88]	Water	50	40 and 80	2 and 4	0.034, 0.064 and 0.116	N/A	• The electricity output and efficiency based-Ag nanofluid at the concentration of 4 vol % have an improvement ranging from 8% to 10% and 14%, respectively, compared to water. • The exergy efficiency of the system based-Ag nanofluid has a 50% enhancement in comparison with pure water.
Ag–CoSO4	Han et al. [89]	Water/Ag	29–65	10	0.4	N/A	N/A	• Ag/CoSO₄ nanofluid could generate higher UV absorption and visible wavelengths compared to water.
MgO	Dehaj and Mohiabadi [90]	Deionized water	30	25	0.014 and 0.032	N/A	5, 8, 11 and 14	• The system efficiency with MgO nanofluid is higher compared with ones with water. • System performance improves with the growth in the concentration of the nanofluid.
CeO₂	Sharafeldin and Gróf [91]	Water	25	30	0.015, 0.025 and 0.035	0.013, 0.015 and 0.017	N/A	• The higher concentration of CeO₂ nanofluid could give higher temperature difference. • The maximum growth of heat obtained is higher by 42.3% compared with water. • The growth of the concentration of CeO₂ could boost the outlet temperature and system efficiency, however it also adds the coefficient of thermal loss. • The system best performance is found when the 0.025 vol % concentration is adopted.
WO₃	Sharafeldin and Gróf [92]	Water	90	30	0.014, 0.028 and 0.042	0.013, 0.015 and 0.017	N/A	• The system thermal-optical efficiency could achieve 72.83% and increase by 19.3% in comparison with water. • The maximum heat obtained is improved by 23% when the WO₃ nanoparticles is added in the system.
Ti₂O₃	Ebaid et al. [93]	Deionized water	80	20–60	0.2	N/A	0.5–5	• The overall PV/T system exergy efficiencies for the ZnO, Al₂O₃, TiO₂ and water are individually increased by15.45%, 18.27%, 15.93% and 12.34%. • Results revealed that Ti₂O₃ nanofluids could decrease the exergy loss and entropy production because of their heat transfer improvement in PV/T system.
Ti₂O₃	Sardarabadi et al. [97]	Water	30	30	0.01, 0.05 and 0.1	0.002, 0.012 and 0.0024	N/A	• Al₂O₃ nanofluid has a better performance compared with TiO₂ nanofluid. • In terms of electrical output and efficiency, TiO₂ nanofluid gives better performance in comparison with Al₂O₃ nanofluid.
ZrO₂	Sarafraz et al. [55]	Acetone	20	10–90	0.025, 0.05, 0.075 and 0.1	N/A	N/A	• The ZrO₂–C₃H₆O nanofluid could decrease the thermal resistance. • The ZrO₂–C₃H₆O nanofluid could improve the heat transfer coefficient of the evaporator section.
Graphene	Sarafraz and Safaei [94]	Methanol	123–424	5–75	0.025, 0.05, 0.075 and 0.1	N/A	3	• The thermal efficiency reaches the maximum value of 0.95 at 0.1 wt%. • The system thermal efficiency increases with the mass concentrations of the graphene nanofluid.
Carbon	Sarafraz et al. [96]	Acetone	50	3–80	0.025, 0.05, 0.075 and 0.1	N/A	1, 2 and 3	• The maximum thermal efficiency is about 70% for the pure acetone, while the carbon-acetone nanofluid has an enhancement in the thermal efficiency which could achieve about 90% for 0.025 wt% and 0.1 wt%.