Hisaharu Sakai

Novel Cleaning System Using Shell Powder Produced from Scallop for Plate-Type Heat-Exchangers

Plate-type heat-exchangers are increasingly being used in the cooling systems of vessels. While these systems have numerous associated benefits, one disadvantage is decreased performance associated with the formation slime on the cooling surface of the heat-exchanger. A new cleaning system for plate-type heat exchangers involving the addition of powder made from insertion scallop shells and air to the cooling water has been developed. Evaluations of slime removal efficiency were shown to be affected by the flow of cooling water, concentration of shell powder, quantity of air injected, washing time, and decreased air-bubble size.

Trial Production of Inverter Driven Electric Winding Device for Tuna Long Line

Inverter driven electric winding devices were devised to wind tuna long line using mono-filament nylon continuously. The system devices were a dancer roller device, electric motor driven winder, inverters, synchro generator, and signal adder. Test were conducted to evaluate the mechanical characteristics of this system.The results show that the operating rango of the dancer roller device is kept to within an allowable range when operating at a line speed of 1.5m/s, whem increasins from 0 to 0.5m/s rapidly. The objective of synchronized operation with the line hauler was fully satisfied.

Lighting by Fluorescent Lamp in Fishing Boat

The space for acommodation and engine room of a fishing boat are much narrower than those of a merchant ship. Thus it is impossible to install all lighting apparatus on the required position. Judging from ”the recommended levels of illumination” of the Japanese lndustrial Standard, some parts where illuminance are lower than the standard level are found.The heigh frequency operation of the fluorescent lamp. as the countermeasures of increase in the illumination and decrease in the electric power were noted. Likewise, experiments on the fundamental characteristic amd the continuous action performance were conducted to compare the electronic invertor ballast and the conventional coil ballast.The following could be concluded;1) Performance of the fluorescent lamp using invertor ballast was independent of f luctuatuons in the voltage and frequency of power source.2) Luminous flux amd luminous efficiency of the fluorescent lamp using the invertor ballast increased to 18% and 23% respectively, compared with those using coil ballast.3) Each secular change of luminous flux showed approximately a similar decreasing tendency. The extended lifetime of the fluorescent lamp was assumed to be 107 days approximately in consideration of the increased luminous flux within the invertor ballast.4) Saving of running cost using high frequency operation was estimated to be 142, 000 yen per year on a research and training fishing boat.

Electric Power Saving of Cooling Sea Water Pump of Fishing Vessel Using Inverter

Experiments on twe variable discharge systems of cooling sea water pump for main engine and for generator engines were conducted to evaluate the effects of electric power saving. One was a combination of a general purpose inverter, an automatic controller and a pair of temperature sensors, and maintained the required temperature difference of cooling sea water between inlet and outlet of main engine. The other was a combination of the inverter, the controller and a pressure sensor, and maintained the required delivery pressure within cooling sea water pump for generator engines.The results showed that it was possible to control the discharge of these pumps, so that the temperature difference amd delivery pressure were kept constant all the time. These systems could save the electric power consumption. In the case of the cooling sea water pump for main engine, the cost of equipment could be offset from the saving of the running cost in approximately 2 years, also the cooling sea water pump for generator engine, 0.6 years. These were suitable for small-powered pump unit (5.5-7.5 kW ) on fishing vessels, these methods also could be widely introduced to fishery machines.

Study on Electric Power Consumption Table for Fishing and Training Vessel

Determination of generator capacity on fishing and training vessel is based on the estimations of necessary power under the various operating conditions, using the electric power consmption table, the same table as a merchant ship uses, which is adopted also on fishing boat. In spite of such a determination on Shinyo-maru (Tokyo University of Fisheries), generator was forced the operation under low load.We researched, here the operationg condition of automatic start-stop machines on Shinyo-maru, as well as the power consumptions on large fishing and training vessels of other national universities.Then we found out the real situation concerning the necessary power on fishing and training vessel, and the difference between the standpoints of a merchant ship and ours concerning the table. The diversity factor and demand factor were also estimated.We came to the following conclusions;1) The operations of the generator under low load frequently occurred.2) Comparing to a merchant ship, we are apt to overestimate the necessary power.3) As the special generator during the anchorage generate little electricity, which can hardly supply the airconditioning units with enough power, generator capacity of that suitable for all-seasuns, is, therefoer, desirable.4) As a value of diversity factor, we recommend the use of 35%, 5) Normal necessary power (Y) under summer service condition is related to gross tonnage (X), complement (Z) and length between perpendiculars (W), by the following equations.Y=0.0988X+59.0, Y=2.11Z-25.5, Y=6.72W-232