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.

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There reported many troubles caused by the transverse vibration of an engine column. It not only damages the attachments but may bring about horizontal or torsional vibration of hull and local vibration around the engine room. Especially in recent years, as the size of the hull and engine are becoming larger and larger, the natural frequencies of the column, lower and lower.
So, it may happen to resonate at the usual running condition. In this paper the recent study on this problem are introduced.
First, by measuring the vibration of the prototype of an engine column at the shop test and sea trial, vibration chavacteristics are investigated and showen that the natural frequencies are affected with the rigidity of a foundation or a double bottom. Next the column is simulated to the lumped mass beam system or equivalent plane framework structure and calculated by Myklestad method or matrix method, and compared with the plastic model test and measured results. As mentioned above, to the vibration of an engine column, the double bottom must be considered, so the authors carried out the plastic model test of the double bottom only and the coupled system of the column and double bottom, and examined the coupled vibration taking into the consideration of the calculated results as a plane framework stucture by the matrix method.

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