Heat exchanger design and development for automotive exhaust waste heat recovery using thermoelectric devices.

摘要

In this study several heat exchanger designs were constructed, tested, and the effect of the design on the overall efficiency and power generated by thermoelectric generators was measured. The thermoelectric elements were attached to the heat exchanger and hot gas passed through the system simulating automotive exhaust. An aluminum duct heat exchanger, a copper heat exchanger, and a heat exchanger with a twisted tape insertion were tested. The heat exchangers were all rectangular with similar dimensions and minimum thicknesses near the wall. The flow of exhaust gas was created by heated air flow ranging from 100-150 LPM. The cool side heat exchanger was setup to simulate a coolant pump using ethylene glycol water mixture (automobile coolant). For measurements, all the thermocouples and thermoelectric generators were connected through the data acquisition program LabView. For the heat exchanger designs the availability, cost effectiveness, implementation probability, and overall performance based on literature was considered. It was observed that due to the insertion of the tape, heat enhancement occurred. It was determined that the tape inside the heat exchanger reduced the diameter of the heat exchanger which increased the velocity inside of the heat exchanger thus increasing the overall heat transfer coefficient. This is confirmed by the overall increase in heat exchanger efficiency of nearly 48% and output power generation of 31% when compared.