Recently, steam turbines are often used on the oil tankers engaged in Persian Gnlf-Japan route. However, in this route, the standard cooling water temperature 24°C for condenser design is not so suited to the actual sea water temperature and it is very difficult to maintain ordinary the design condenser vaccum 722 mmHg.
The author investigated the relation between the inlet cooling water temperature and the condenser vaccum, using a local overall heating transfer coefficient K as follows,
K=a (1+bt) uⁿ
where a, b, n are constant which are determined with cleanliness factor, t is the local cooling water temperature °C and u is the water velocity in m/s. Then, those results are in good agreement with the some actual data from several tankers in that route.
As a result of this study, the actual condenser vaccum is given by the inlet cooling water temperature, the heating surface area and the cooling water flow rate, and the actual vaccum is lower than ordinary the design vaccum. Therefore, those steamer's condenser vaccum is desired to be designed with suitable sea water temperature of her anticipated route.

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This paper describes the theoretical investigations about the thermal boundary conditions of heated parts in diesel-engine, from the side of heat conduction problems.
In this case, it is very important, how precisely we can solve the differential equation with arbitrary boundary conditions. Therefore we propose two analytical methods for heat conduction problems, that is, conductive sheet analogous and numerical method. Lastly these methods are applied to the piston crown in diesel engine.
So, this paper includes two main sections as follows:
1-a. In conductive sheer analogous metnod, the problems in (r-z) coordinate system is favora bly transferred to the problems in (r-θ) coordinate system, making use of some, assumptions, and the problems are solved with customary technique.
1-b. In numerical method, steady and unsteady heat conduction problems of plane and axisymmetric solids are solved by following process.
Region is divided into trianqular shape elements and analyzed by well-known Heat Balanced method.
As a developing technique of this method, thermal boundary conditions are directly determined by least square method.
2. For example of these methods, measured data of temperature about the piston crown in diesel engine are analyzed, and the relation of running condition and thermal boundary condition are determined.

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