Optimization and Invasive Monitoring for the Local Flow Velocity Maldistribution in Plate-Fin Heat Exchangers

The flow maldistribution inside plate-fin heat exchangers is a decisive factor leading to the deterioration of heat transfer performance. This article proposes the configurations of flat and curved baffles with different holes to optimize flow distribution. The invasive method using fiber Bragg grating (FBG) sensors for monitoring the local flow velocity in heat exchangers is first proposed. Multiple FBG sensors are embedded in the plate-fin core to measure the flow velocity of each channel. The effectiveness in balancing the flow velocity of flat and curved baffle configurations is compared against a header configuration without a baffle. The results indicate that adding a baffle, whether it is flat or curved, is profitable to facilitate the flow field inside the plate-fin core. Compared with no baffle configuration, the flat and curved baffle configurations achieve a decrease rate of 61% and 66% in the sum flow nonuniformity of heat exchangers. The standard deviation has been reduced by 60% and 80%, respectively. The energy loss caused by the curved plate configuration is relatively low. The embedded FBG sensors address real-time monitoring of local flow velocity in the plate-fin heat exchanger. The ameliorative baffle structure in the header and FBG sensing technology provide ideas for optimizing and monitoring the internal flow field inside plate-fin heat exchangers.