Investigating the yield improvement of modified passive solar still using nanoparticle coatings and nanoparticle-enhanced phase change materials

Figures & data

Table 1. Thermophysical properties of the CuO nanoparticle.

Chemical composition	Density	Thermal conductivity	Specific heat	Size
CuO	6320 kg/m^3	76.5 W/m K	42.36 J/mol K	12–14 nm

Table 2. Thermophysical properties of paraffin wax and CuO-mixed Paraffin Wax (Nano-PCM).

Properties	Paraffin wax	Nano-PCM
Melting temperature (°C)	58	56
Latent heat of fusion (kJ/kg °C)	180	168
Thermal conductivity (W/m K)	0.2	0.335
Specific heat capacity (J/kg K)	2100	2000
Density (kg/m^3)	840	894
Tsolidus/Tliquidus (K)	321/335	321/335

Figure 1. Experimental set-up of the conventional and modified pyramid solar still.

Table 3. Accuracy and error for various measuring instruments.

Instrument	Model	Range	Accuracy	Error
Thermocouple	K-type thermocouple	0–100°C	±0.1°C	0.4%
Thermometer	Digital thermometer	0–100°C	±0.1°C	0.4%
Distilled collection	Borosilicate glass	±5 ml	0–1000 ml	1%

Figure 2. Variation of the solar radiation and ambient temperature.

Figure 3. Hourly variations of absorber plate temperature with CPSS and MPSS.

Figure 4. Variations of water temperatures with CPSS and MPSS.

Figure 5. Variations of glass cover temperatures with CPSS and MPSS.

Figure 6. Hourly variations of PCM temperatures with MPSS.

Figure 7. Comparison of the daily cumulative yield for CPSS and MPSS.

Figure 8. Daily average thermal efficiency of CPSS and MPSS.

Figure 9. Daily average exergy efficiency of a solar still with CPSS and MPSS.

Table 4. Daily average yield, thermal and exergy efficiency of CPSS and MPSS.

S. No	Case study	CPSS	MPSS
1.	Daily average cumulative yield	2.95 L/m^2/day	5.73 L/m^2/day
2.	Improvement in distillate yield	–	94.2%
3.	Average daily thermal efficiency	43.90%	63.72%
4.	Improvement in daily thermal efficiency	–	45.1%
5.	Average daily exergy efficiency	2.2%	3.7%
6.	Improvement in daily exergy efficiency	–	68.2%

Table 5. Comparison of the present work with earlier research works.

Authors	Type of solar still	Type of study	Thermal efficiency (%)	Yield (l/m^2 day)	Incorporated modifications
Kianifar, Zeinali Heris, and Mahian (2012)	Pyramid solar still	Experimental	–	3.14	Small fan and water depth
Sharshir, Elkadeem, and Meng (2020)	Pyramid solar still	Experimental	60.5	5.0	v-corrugated, wick materials, nanocoating
Present work	Pyramid solar still	Experimental	63.72	5.73	v-corrugated, CuO nano-coated, NPCM and internal reflectors

Table 6. Water quality analysis of saline and distilled water.

S/No	Name of the test	Actual test result for		WHO requirement limits
		Saline water	Distilled water
1.	Potential of Hydrogen (PH) value	9.73	6.76	6.5–8.5
2.	Electrical conductivity (EC) (mS)	3.17	0.391	0.5
3.	Total dissolved solids (TDS) (ppt)	2.06	0.254	0.5
4.	Fluoride (F) (mg/L)	0.294	0.02	0.05
5.	Turbidity (NTU)	6.79	4.48	5
6.	Taste	Saline	None	Agreeable

Kianifar, A., S. Zeinali Heris, and O. Mahian. 2012. “Exergy and Economic Analysis of a Pyramid-Shaped Solar Water Purification System: Active and Passive Cases.” Energy 38 (1): 31–36. doi:10.1016/j.energy.2011.12.046

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Sharshir, S. W., M. R. Elkadeem, and A. Meng. 2020. “Performance Enhancement of Pyramid Solar Distiller Using Nanofluid Integrated With v-Corrugated Absorber and Wick: An Experimental Study.” Applied Thermal Engineering 168: 114848. doi:10.1016/j.applthermaleng.2019.114848

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