Study on convective melting heat transfer of a solid-liquid phase change slurry in U-shaped curved tubes

Abstract

As a phase change material, ice slurry has been successfully applied in HVAC&R systems due to its high energy storage density. The heat exchangers are the key equipment realizing energy conversion of ice slurry. In HVAC&R systems, U-tubes are frequently used in shell and tube heat exchanger. However, there are few studies on thermo-fluidic characteristics of ice slurry in U-tubes. Therefore, the thermo-fluidic characteristics of ice slurry in U-tubes are numerically studied in this paper using Euler-Euler approach. The results indicated that as enlarging the inlet ice content and velocity, the ice concentration distribution becomes more uniform along in vertical profile. Due to the secondary flow in bend section, the ice concentration decreases in the inner wall and increases in the outer wall as the inlet velocity increases; At the high Reynolds number, the inlet ice content and ice particle diameter have a more significant fluence on pressure drop (Δp). The local heat transfer coefficient (hlo) in bend section exhibits a tendency of first increasing and then decreasing, with the maximum value of hlo occurs at θ = 90° of the bend section. Finally, a correlation is suggested between the average resistance coefficient (fave) and local Nusselt number (Nulo).