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In recent years there has been a growing need for reduction of energy consumption in an effort to solve problems of global warming and the shortage of petroleum resources. For example, in the power generation field, thermal power generation now occupies 60% of the power generation demand, and the need for improved thermal efficiency is thus considerable. In this paper, the pressure drop characteristics of the finned tube banks used for the heat exchanger in thermal power generation were clarified by testing the serrated finned tube banks for improvement of higher heat transfer and the conventional spiral finned tube banks under the same test conditions, and equations for predicting the pressure drop coefficient which is necessary to design the heat exchanger were proposed.

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A fan consisting of a piezoelectric bimorph tipped with an additional flexible blade is introduced. Since the flexible blade resonates in a large amplitude but the bimorph vibrates in a very small amplitude, the fan can supply sufficient and constant air flow without any structural destruction for a long time. The fan case has two air outlets which are directed oppositely each other. The fan with such outlets can supply an air flow of 4 m3/hr at an applied voltage of 140 Vp–p. Another type of a piezoelectric fan using multi-layered PZT ceramic elements produced by a thick film printing technique is introduced. This fan is suitable for low voltage operation and it can supply an air flow of 1 m3/hr at an applied voltage of 17Vp–p.

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