Experimental Study of Convective Heat Transfer of Cu/Water Nanofluid in Different Flow Regimes

Abstract

Nanofluid has been defined as conventional fluid with suspended particles at nano size normally less than 100 nm at least one dimension and lots of prior studies have demonstrated that nanofluid played much higher convective heat transfer efficiency than its base fluid. The present work focuses on the forced heat transfer characteristics of water based copper (Cu) nanofluid with different volume concentrations under different flow regimes (300 < Re <= 16000). The convective heat transfer coefficient is increased both in laminar and turbulent flow as increasing the concentration. Especially in laminar flow, the heat transfer coefficient of Cu/water nanofluid increases two times around Re = 2000 comparing with that of base fluid water, and average increases by 62% at 1 v% concentration. The enhancement rate increases dramatically in laminar flow regime due to the highest thermal conductivity of Cu among ordinary materials. However, the heat transfer coefficient of Cu/water nanofluid decreases comparing that of distilled water in the transition flow regime, furthermore, it has the trend that the heat transfer coefficient displays worse as increasing the concentration. Thus the application of Cu/water nanofluid should carefully avoid transition regime.