Abstract

Current research on the thermal performance of Fresnel lens reflector (FLR)- based solar heat exchangers is being enriched by adopting a 0.3 % concentration of a hybrid nanofluid (carbon nanotube-CNT and copper oxide CuO) without and with different ratios of lithium nitride (LiNO3) and potassium nitride (KNO3) phase change materials (PCMs). During the investigation, 50:50, 70:30, and 80:20 ratios of LiNO3: KNO3 are used without hybrid nanocomposite under the flow rate of 4 LPM. Combined actions of hybrid nanofluid and varied ratios of organic and inorganic PCM on the thermal performance of FLR solar heat exchanger is investigated, and the presence of hybrid nanofluid and PCM compound showed the superior thermal characteristics with enhanced latent heat fusion behaviour. Moreover, the FLR solar heat exchanger system featured 0.3 % hybrid nanofluid with 80:20 LiNO3:KNO3 PCM ratio, demonstrated the optimum fluid outlet temperature of 81.9 degrees C, improved heat transfer rate of 1780.3 W, superior latent heat of fusion 480.3 J/kg, reduced pressure drop of 125.9 Pa, better charging and discharging time, and superior thermal efficiency of 68.3 %. It is the better choice for heat exchanger applications.