Analysis on the performance and internal flow of a tubular type hydro turbine for vessel cooling system

Abstract

The temperature of the main engine cabin of commercial vessel is very high. The material SS-316L undergoes creep damage attemperatures exceeding 450°C. It is essential to maintain the highly stressed engine cabin below the creep regime. Hence, seawater is employed inthis kind of maritime vehicles as cooling liquid. It obtains the thermal energy at the cooling pipe line after passing through main engine coolingsystem. To harness the energy in the seawater, a turbine can be installed to absorb the energy in the seawater before being released into the sea. In thisstudy, a cooling pipe line is selected to apply the tubular type hydro turbine for transferring the energy. Numerical analysis for investigating theperformance and the internal flow characteristics of the tubular turbine is conducted. The results show that the maximum efficiency of 85.8% isachieved although the efficiency drops rapidly at partial flow rate condition. The efficiency descends slowly at the condition of excess flow rate. There is a relatively wide operating range of flow rate of this turbine to keep high efficiency at the excess flow rate condition. For the internal flow ofthe turbine, there is uniform streamline on the suction and pressure sides of the blade at the design point. However, the secondary flow appears at thesuction and pressure sidesat the excess flow rate.In addition, it appears only at pressure side at the partial flow rate condition.