Performance characteristics of pulsating heat pipe with various non-uniform heating conditions

This paper presents heat transfer characteristics of a pulsating heat pipe under various non-uniform heating conditions. The evaporator section of the pulsating heat pipe is subjected to two individual heat sources, which can supply separate heat inputs. Non-uniformity in heat inputs is represented by the newly defined asymmetric heating ratio, which ranged from 0 to 0.2. The pulsating heat pipe utilizes HFE-7100 as the working fluid, and the filling ratio was fixed to 60%. The influence of asymmetric heating ratio on the thermal performance are analyzed with the measured pressure, the temperature difference between two parts of the evaporator section, and the thermal resistance at various heat inputs. The fluctuating frequencies of the measured pressure were examined to identify the type of internal flow motion. The results show that unbalanced heat input increases the driving force towards flow circulation, which lowers the thermal resistance and levels out the change in evaporator temperature difference, but leads to the early appearance of dry-out.