Abstract
The heat transfer coefficient to a fluid flowing inside tubes can be increased by using heat transfer promoters (H. T. P), while the pressure drop increases with the increase in heat transfer coefficient. Therefore, it is necessary to evaluate the effectiveness of H. T. P from an economical point of view.
In this paper, the optimum design of a heat exchanger with H. T. P, which is based on an economic efficiency defined by the cost of exchanged heat and of pumping power, is discussed, and an evaluation factor which evaluates the effectiveness of H. T. P is derived. By using the evaluation factor, the heat transfer performance and the effectiveness for several types of H. T. P (twisted tape, coiled wire, core tube, disk, stream line shape and embossed spiral) are investigated and the comparisons among them are made.
Few examples of the optimum design of heat exchangers with twisted tapes and with coiled wire are shown.
It is, furthermore, presented the evaluation method of effectiveness and the prediction method of the optimum geometry of H. T. P which is inserted in an existing heat exchanger.
