Parametric Study of Heat Transfer Enhancement Using Impingement of Multiple Water Jets

摘要

The problem of cooling of electronic components has become a subject of special interest in recent years due to the increasing capacity and rapidly decreasing size of electronic components. Direct contact cooling using multiple jet impingement is considered as the most effective method. The heat transfer problem is complex and better understanding of jet impingement method is essential for proper application of this method for electronic cooling. Investigations were carried out using electrically heated test plate. Heat flux in the range of 25 to 200W/cm~2, which is a typical requirement for cooling high power electronic components was dissipated using 0.25mm and 0.5mm diameter water jets arranged in 7×7 array with a pitch of 3mm. Temperature difference between the test plate and water was within 30℃. Tests were performed in the flow rate range of 14 to 40 ml/min. The distance between the nozzle and the test plate was maintained at 10 and 20mm with the nozzle placed in both in horizontal and vertical position. Results show significant increase in heat transfer co-efficient or Nusselt number with increase in heat flux. The effects of (i) Flow rate or Reynolds number (ii) Distance between the nozzle and test plate and (iii) The horizontal or vertical positioning of the nozzle are found to be small. A correlation has been developed to predict the heat transfer co-efficient with multiple water jet impingement. The heat transfer data from the present experiments agree satisfactorily with the data from similar experiments in the literature.