series flat plate pulsating heat pipe: fabrication and experimentation

Pulsating heat pipes have recently become popular due to their capability in removing heat at higher rates, over short or long distances. their passive operation and relative ease of manufacturing have been added to their popularity.  in this study, a combination of two flat plate pulsating heat pipes in series configuration is proposed and their thermo-hydraulic behavior is investigated experimentally in vertical bottom heated mode. the series configuration provides the possibility of heat removal from the heat source within longer distances at acceptable efficiencies. fluid type, filling ratios, and input powers were the factors chosen to study their influence on the operation of the setup. the results showed that the 60% filling ratio for the water filled channel together with the 40% filling ratio for the methanol filled channel present the lowest thermal resistance in the range of considered input powers. it was observed that for all of the filling ratio combinations used, the methanol channel started oscillation before the water channel and it presented lower thermal resistance as compared with the water channel. the experimental results demonstrated that the dominant hydrodynamic fluid pattern is slug flow with the pulsation of fluid columns together with sporadic circulation at higher input power rates.