Effects of nanoparticle-enhanced phase change material (NPCM) on solar still productivity

This paper investigates the effects of nanoparticle-enhanced phase change material (NPCM) on solar still operation and performance. Technical and economic aspects were considered, to show an advance on earlier works using virgin phase-change materials (PCM). Three types of nanoparticle (TiO2, CuO and GO) were impregnated individually at 0.3 weight% in paraffin to form NPCM-1, NPCM-2 and NPCM-3 respectively. Experiments were conducted with four solar stills (SS) each of 0.5 m2 area using respectively paraffin (SSPCM), paraffin-TiO2 (SSNPCM-1), paraffin-CuO (SSNPCM-2) and paraffin-GO (SSNPCM-3). There was observed an increase in thermal conductivity and a reduction in melting and solidification temperatures, with NPCM compared to PCM. The effects of NPCM on water temperature, storage temperature, hourly and annual productivity were determined. SSPCM, SSNPCM-1, SSNPCM-2 and SSNPCM-3 yielded 3.92, 4.94, 5.28 and 3.66 l/m2/day respectively, corresponding to 26 and 35% increases in productivity of SSNPCM-1 and 2 respectively over SSPCM. Economic analysis showed cost per liter (CPL) of water of $0.035,$0.028, $0.026 and$0.13 for SSPCM, SSNPCM-1, 2 and 3 respectively. Considering the advantages in productivity and CPL, SSNPCM-2 can be recommended as the best solar still compared to SSPCM, SSNPCM-1 and 3, providing clean water at less than half the cost of bottled water in India

Solar stills:a comprehensive review of designs, performance and material advances

The demand for fresh water production is growing day by day with the increase in world population and with industrial growth. Use of desalination technology is increasing to meet this demand. Among desalination technologies, solar stills require low maintenance and are readily affordable; however their productivity is limited. This paper aims to give a detailed review about the various types of solar stills, covering passive and active designs, single- and multi-effect types, and the various modifications for improved productivity including reflectors, heat storage, fins, collectors, condensers, and mechanisms for enhancing heat and mass transfer. Photovoltaic-thermal and greenhouse type solar stills are also covered. Material advances in the area of phase change materials and nanocomposites are very promising to enhance further performance; future research should be carried out in these and other areas for the greater uptake of solar still technology

Nanoparticles Enhanced Phase Change Material (NPCM) as Heat Storage in Solar Still Application for Productivity Enhancement

Whereas other researchers used various active and passive techniques to improve the productivity of solar still, this paper uses nanoparticles impregnated in phase change material (NPCM) for productivity enhancement. The solar still is fabricated individually with phase change material (PCM) and NPCM and analyzed both experimentally and theoretically. It is found that the solar still with PCM yielded 1.96 kg/0.5m2 whereas the solar still with NPCM yielded 2.64 kg/0.5m2. There was 35% improvement in productivity observed in solar still with NPCM as against solar still with PCM. The experimental results were validated with the predicted results and the discrepancy was found to be ±10%. Hence it is concluded that NPCM has better potential than PCM for solar still application

Techno-economic analysis of solar stills using integrated fuzzy analytical hierarchy process and data envelopment analysis

Desalination using solar stills is an ancient economic method for water desalination. Over the years, research and development in the area of solar still has resulted in increased distillate yield by means of integration of PCM (phase change material), photo-voltaic thermal (PVT), etc with the still. Nano-PCM is an upcoming technology which modifies the thermal performance of PCM. The aim of this research is to analyze the efficiency of 20 solar stills including nano-PCM based solar stills considering various input and output criteria using integrated fuzzy analytical hierarchy process (AHP) and data envelopment analysis (DEA). The efficiency derived here is relative with regard to the parameters and stills considered in this study. The result infers that, even though the productivity of stepped solar still with sun tracking system was high, but when techno-economic aspects were considered it is not among the top solar stills. The analysis indicated pyramid type solar still, single slope solar still with PVT, solar still with NPCM (paraffin + copper oxide), solar still with NPCM (paraffin + titanium dioxide) and solar still with PCM (paraffin) occupies the top five positions with relative efficiency of 100, 100, 88.47, 88.46 and 76.93% respectively

Low mass fraction impregnation with graphene oxide (GO) enhances thermo-physical properties of paraffin for heat storage applications

Whereas previous researchers analyzed the thermal behavior of paraffin waxes impregnated with graphene oxide nanoparticles (P-GONP) at high mass fraction ( > 1%), this paper analyzes behavior and stability at only 0.3% mass fraction. GONP was prepared by Hummer’s method. The morphology was studied using scanning electron microscope (SEM), transmission electron microscope (TEM), X-Ray diffraction (XRD) and Fourier Transformation-Infrared (FT-IR) Spectrometer and the thermal properties were measured using laser flash analyser (LFA), differential scanning calorimetry (DSC), thermo-gravimetric analysis (TGA) and thermal cycling. LFA showed a 101.2% and 94.5% increase in the thermal conductivity of P-GONP compared to pure paraffin (P) in solid and liquid state respectively. Melting and solidifying temperatures and latent heat were found to be 63.5, 59 °C & 102 kJ/kg and 57.5, 56 °C & 64.7 kJ/kg for P and P-GONP respectively. Thermal cycling over 4000 cycles showed that P-GONP was 27% more stable than P. The latent heat was 64.7 kJ/kg, a 36.5% deterioration compared to virgin paraffin. Compared against higher mass fraction impregnation, lower mass fraction P-GONP was found to have almost equivalent thermo-physical properties (namely thermal conductivity, melting and solidifying characteristics, thermo-chemical stability and reliability) while providing considerable cost saving

Microscopic characteristics of biodiesel – Graphene oxide nanoparticle blends and their Utilisation in a compression ignition engine

Use of nano-additives in biofuels is an important research and development topic for achieving optimum engine performance with reduced emissions. In this study, rice bran oil was converted into biodiesel and graphene oxide (GO) nanoparticles were infused into biodiesel-diesel blends. Two blends containing (i) 5% biodiesel, 95% diesel and 30 ppm GO (B5D95GO30) and (ii) 15% biodiesel, 85% diesel and 30 ppm GO (B15D85GO30) were prepared. The fuel properties like heating value, kinematic viscosity, cetane number, etc. of the nanoadditives–biodiesel-diesel blends (NBDB) were measured. Effects of injection timing (IT) on the performance, combustion and emission characteristics were studied. It was observed that both B15D85GO30 and B5D95GO30 blends at IT23° gave up to 13.5% reduction in specific fuel consumption. Compared to diesel, the brake thermal efficiency was increased by 7.62% for B15D85GO30 at IT23° and IT25°. An increase in IT from 23° to 25° deteriorated the indicated thermal efficiency by 6.68% for B15D85GO30. At maximum load condition, the peak heat release rates of NBDB were found to be lower than the pure diesel at both IT. The CO, CO2 & NOx emissions were reduced by 2–8%. The study concluded that B15D85GO30 at IT23° gave optimum results in terms of performance, combustion and emission characteristics