LAUSR

The current study presents a numerical analysis of the heat transfer and the pressure drop quantification of Al 2 O 3 –R718-based nanorefrigerant flow through a circular tube of a flooded evaporator chiller. R718 (water) is one of the most widely used secondary refrigerants in HVAC applications. The flow Reynolds number through a chiller tube of a typical 325 TR capacity water chiller is between 13,000 and 33,000. Therefore, the nanorefrigerant flow was simulated at Reynolds number (Re) varying between 13,000 and 33,000 for three distinct particle volume fractions ( ϕ ): 0.25%, 0.5% and 1.0%. The temperature variation in the computational domain was between 278 and 288 K. Therefore, temperature-dependent thermophysical property values were utilised in the present study in order to get more reliable results. It was found that the surface heat flux is higher for Al 2 O 3 –R718 nanorefrigerants in comparison with that of water. The average surface heat flux increases with increase in particle volume fraction, but the pumping power also elevates with particle volume fraction. The turbulence in the nanorefrigerant flow was also analysed and discussed. Furthermore, the entropy generation analysis revealed that the entropy generation rate for Al 2 O 3 –R718 nanorefrigerants was lower in comparison with that of pure R718. The overall performance of the nanorefrigerant was analysed using two different thermal performance parameters, and it was found that the thermal performance parameter was higher than 1 for all the flow scenarios investigated in the current simulation.