aDepartment of Mechanical Engineering, Sri Venkateswara College of Engineering, Sri Perambudur–602 117, Tamil Nadu, India. E-mail: mgaja@svce.ac.in
bDepartment of Mechanical Engineering, SSN College of Engineering, OMR, Kalavakkam–603 110, Tamil Nadu, India. E-mail: nallusamyn@ssn.edu.in
Online published on 16 July, 2015.
Carbon nanofluids gain importance as heat transfer fluids due to their high thermal conductivity even with their presence in smaller fractions. This article investigates the influence of nanofluids as Heat Transfer Fluid (HTF) in Phase Change Material (PCM) based solar thermal energy storage system. The encapsulated cylindrical capsules contain the PCM, paraffin. The Thermal Energy Storage (TES) tank acts as a storage unit consisting of PCM capsules packed in three beds surrounded by water, which acts as Sensible Heat storage (SHS) material. The heat stored is a combination of sensible heat and latent heat. Carbon nanofluids transfer the heat received by solar Flat Plate Collector (FPC) from solar insolation to the TES tank. Carbon nanofluids of different concentration (0.1 per cent and 0.3 per cent by weight) were prepared with the Sodium Dodecyl Benzene Sulphonate (SDBS), as the surfactant and this mixture is sonicated to ensure proper mixing of nanofluid with water. Performance parameters such as charging time, instantaneous heat stored, cumulative heat stored and system efficiency are studied for various HTFs. The results show that there is considerable amount of reduction in charging time, around 26 per cent for carbon nanofluid of 0.1 per cent and 42 per cent for 0.3 per cent, and improvement of system efficiency around 42 per cent with reference to charging time when compared with the conventional HTF, water.
Solar energy, Thermal energy storage, Heat transfer fluid, Flat plate collector, Phase change material, Carbon nanofluids
