Experimental investigation of solar water heater integrated with a nanocomposite phase change material

Energetic and exergetic approach
  • P. Manoj KumarEmail author
  • K. Mylsamy


This present work contributes to the improvement in thermal energy storage capacity of an all-glass evacuated tube solar water heater by integrating it with a phase change material (PCM) and with a nanocomposite phase change material (NCPCM). Paraffin wax as PCM and a nanocomposite of paraffin wax with 1.0 mass% SiO2 nanoparticles as NCPCM had been used during the experiments. The results were acquired through the real-time experimental measurements on the all-glass evacuated tube solar water heater integrated with built-in thermal energy storage, functioning under thermosyphonic flow. Three different cases, namely, without PCM, with PCM, and with NCPCM, were considered. The testing procedure involved the observation of total temperature variation in the tank water from 6.00 a.m. to 6.00 a.m. of next morning. Meanwhile, the water was completely renewed for every 12 h. The system performance was studied using energy efficiency, exergy efficiency, and temperature of hot water supply during the next morning, for all the three cases. The investigation exemplifies that the tank water temperature at 6.00 a.m. after one complete day of operation was notably improved to 37 °C and 39.6 °C, respectively, with PCM and NCPCM, whereas it was 33.1 °C for the case without PCM. The energy efficiencies for the three cases were found to be 58.74%, 69.62%, and 74.79%, respectively, and exergy efficiencies of the system were determined as 19.6%, 22.0%, and 24.6%, respectively, for without PCM, with PCM, and with NCPCM. Also, it was evidenced that the thermal conductivity of paraffin wax was considerably increased to 22.78% through the diffusion of SiO2 nanoparticles. Put together, this indicates that the incorporation of PCM and explicitly the dispersion of SiO2 nanoparticles in NCPCM had been significantly improved the thermal performance of the system.


PCM Nanocomposite PCM SiO2 nanoparticles Evacuated tube solar collector Energy efficiency Exergy efficiency 

List of symbols


Area of the collector (m2)


Specific heat of water (kJ kg−1 K−1)


Specific heat of PCM (kJ kg−1 K−1)


Melting mass fraction of PCM (%)


Exergy received by the collector (kJ)


Exergy of PCM (kJ)


Exergy of water (kJ)


Daily total solar radiation (kJ m−2)


Instantaneous solar radiation (Wm−2)


Beam radiations directly captured by the collector tubes per unit area (Wm−2)


Sky diffuse radiations directly captured by the collector tubes per unit area (Wm−2)


Sky diffuse radiation (Wm−2)


Number of evacuated tubes


Length of evacuated tube (m)


Diameter of evacuated tube (m)


Mass of water (kg)


Mass of PCM (kg)


Energy received by the collector (kJ)


Energy stored (kJ)


Energy stored in PCM (kJ)


Energy stored in water (kJ)


Ambient temperature (K)


Final PCM temperature (K)


Initial PCM temperature (K)


Final water temperature (K)


Initial water temperature (K)



Phase change material


Nanocomposite phase change material


Silicon dioxide


Aluminum nitride


Stainless steel


Percentage of mass







System body






Phase change material











Greek symbols


Energy efficiency (%)


Exergy efficiency (%)


Latent heat of PCM (kJ kg−1)


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Copyright information

© Akadémiai Kiadó, Budapest, Hungary 2018

Authors and Affiliations

  1. 1.Department of Mechanical EngineeringKPR Institute of Engineering and TechnologyCoimbatoreIndia
  2. 2.Department of Mechanical EngineeringDr.N.G.P. Institute of TechnologyCoimbatoreIndia

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