Revision with unchanged content. The book summarizes the comprehensive research of convective heat transfer enhancement by the use of pin fins. The applicability of the analytical method to assess the heat transfer enhancement has been checked by experimental investigations of a double-pipe pin fin heat exchanger. The results for the pin fin heat exchanger have been compared with the results for a smooth-pipe heat exchanger. Based on the literature survey, it has been concluded that all proposed methods for the performance comparison, offer only an approximate comparison of heat transfer surfaces. Hence in this book, a more consistent comparison method is proposed and its applicability is demonstrated. The method is further applied to perform a detailed numerical study of the influence of pin cross-section on the performance of pin fin arrays used in the electronics industry, air conditioning, and automobile industry. The performance comparison of a louvered fin heat exchanger with a model of a pin fin heat exchanger, carried out in the last part of the research work, has shown that the pin fin heat exchanger is able to perform the same function as a louvered fin heat exchanger, but with 22% reduced volume.