This paper describes a solution for the heat-transfer in a circular pipe of constant temperatur, in which the velocity distribution of fluid is the Poiseuille's flow. The basic equations are the same as that of Graetz or Nusselt, and as a mathematical method we applied the Karman-Pohlhousen's method which is used on the boundary layer problems. We derived an equation from the bsic equations, which correspond to the momentum equation of the bouodary layer problems, and used the conception of thermal boundary layer, in which we assume dthat the temperature distribution varies as the 4th degree equation with respect to the distance from the pipe wall. As a result we obtained the following equations, for the relation of dimensionless mean temperature of fluid θ_m and Graetz number Wc/kL, [numerical formula][numerical formula] Where t_i is an initial temperature of fluid, and t_w is a temperture of pipe wall, t_m is a mean temperature of fluid after passed the pipe length L, Wc/kL is a Graetz number. And δ is a dimensionless thickness of the thermal boundary layer at the pipe end. We can δ between equations (1) and (2), but practically it is more advantageous to draw θ_m-Wc/kL curve by calculate the values of equations (1) and (2) corresponding δ=0.1, 0.2 etc.. This solution will be used over a range between the ranges in which Nusselt-Groeber-Yamagata's solution and Leveque's solution were used respectively. And moreover for the range of Leveque's solution, perhaps this solution will be more exact than the Leveque's solution.

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As one of the test results of the single stage free piston air compressor of the Junkers type, the fact has been found that the compressor cylinder acts for the most part as a heat pump when the travel distance of the suction stroke is about 5∼10% of the whole stroke. Even in case of the long suction stroke, existence of some heat pump action may be easily ascertained. In the present paper, the compressor cylinder is thermodynamically analysed, using a new fundamental cycle for the reciprocating air compressor, which containes adiabatic processes and the heat pump action.

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A free piston gas generator, the remodeld free piston air compressor of the Junkers type, was tested under the operational conditions in which gas delivery pressure is 0 to 2.57 atm and the outer dead centers are limited to 220±5 mm, in order to obtain the fundamental data available to design. Besides, by analysing the indicator diagrams, the distribution of internal losses were ascertained, which revealed that the frictional loss in the power cylinder is largest.

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By motoring a kerosene engine mixture being sucked, the rate of vaporization of gas oil in the horizontal suction pipe has been studied varying the air-fuel ratio and the wall temperature of heater. Results of motoring test have been compared with results of blower-test, which was performed under equivalent air velocity and the same conditions as motoring test. Thermal efficiency of vaporization has been proposed as standard of effective vaporization in the suction pipe. For vaporization of fuel oil in the suction pipe under continuous air flow, the lower air velocity, the less fuel flow, and the more heat supply, the higher thermal efficiency of vaporization has been obtained.

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Using gas oil in a kerosene engine, the degree of crankcase oil dilution is studied experimentally varying the air-fuel ratio, degree of mixture heating, and load. The ratio of leakage-quantity to the supplied quantity of fuel oil is less in case of the larger air-fuel ratio, degree of mixture heating, and load. The rate of leakage of fuel oil is unexpectedly small, namely the maximum rate at 3 B 〓 is only 3.5%. Further this rate is decreased to 0.3% by means of increasing air-fuel ratio and degree of mixture heating.

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A small out-put industrial diesel engine was used and the conditions of its piston-rings were changed, for the study of phenomena on the piston-ring leakage. And the following conclusions were obtained mainly : (1) Leakage occurs at three passages which are the clearance spaces at the lower, outer side and gap of the ring. And the rates of leakage through each passage are nearly equal when these passages are of the similiar shape and size. (2) Angle and step joint cannot reduce the increase of the leakage as same as straight joint when the gap is enlarged. (3) When rings of the good and bad tightness are used together, the good ring only makes the gas-tight. (4) the greater part of the gas that leakes out is air, and it is believed that the harmfully incomplete combustion products are caused by combustion of the oils on the gas passages. (5) For reducing the specific fuel consumption, a smaller number of rings of good-tightness must be used.

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This report refers to the critical concentrations of aldehyde for ignition of kerosene-air mixture compressed rapidly. There are experiments in which the effects of compression ratio and cylinder temperature to the critical aldehyde dentity have been researched. The critical fuel concentration for igntion of kerosene-air mixture appears to be controled by the thermal explosion theory as well as the static phenomena. The thermal explosion theory makes the ignition critical condition such that the rate of chemical enthalpy transformation is equal to that of thermal dissipation. Similarly the behavior of the critical aldehyde concentration can be understood applying the thermal explosion theory to the imaginal aldehyde oxgen mixture instead of the real system, provided that the aldehyde concentration represents well the degree of inactive combustion in kerosene air mixture.

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We reach the well known conclusion that the coefficient of performance of vapor-compression evaporators becomes higher as the temperature difference in the heat-exchanger becomes smaller, if we consider the system to be an application of the inverse-Carnot cycle. However, when we take into account the condition that the steady state should be maintained under thermal equilibrium, we find that the coefficient of performance is not merely a function of the temperature difference alone. The authors have studied the effectes of "relative heat transfer number", "supplied energy coefficient" or "coefficient of heat supply", "extraction ratio", effectiveness of the preheater, rise of the boiling point of the solution and so forth upon the thermal equilibrium and the coefficient of performance of evaporators, and clarified the steady state characteristics of vapor-compression evaporators under the condition of thermal equilibrium. The diagrams showing the effects of the above stated factors are given in this paper. The "relative heat transfer number" is a dimensionless one newly introduced by one of the authors and it represents the characteristic feature of vapor-compression evaporators regardless of their geometrical dimensions. The authors believe that the diagrams shown in the paper are of use for the design as well as for the choice of operating conditions of this kind of evaporators.

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The feed water treatment before it is fed to boilers is mostly practised. rencently, but for small or middle type boilers the treatment to soften the boiler water is more used. In both cases, it is necessary to saoften the boiler water by blowing-off. The concentration of boiler water is a problem of boiler in its handling. Here, the boiler handling may be exressed in terms of a sequence of 3 steps considered chiefly on blowing-off of boiler water, and the concentration ratio of boiler water and feed water is solved. Next, by the representation of the continuous process of water feeding, steam generation and blowing-off of boiler water, the concentration ratio of boiler and feed water are obtained. The continuous process assumed shows nearly the actual boiler operation on the concentration ratio from the relations above. So the nomographs and charts of this expression will be made to be used by the boiler engineers. In the present paper the differences of the above expressions are discussed and numerical expamples are given.

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The blowling-off of the steam boiler is a necessary measure in the boiler operation. Although the present author has published a paper on the concentration and blowing-off the boiler water, he discusses the pressure change due to the blowing-off in the present paper. First, the relation of the boiler water quantity and the pressure change is introduced basing on the material and heat energy balance in the boiler. From these, the pressure change due to the blowing-off in general case is expressed by an equation. The change of the pressure and water quantity due to the water feeding and blowing-off on the constant firing of boiler are described, using the steam qualities : specific volume, enthalpy and so on, assumed the logaritymic changes under 20 kg/cm² abs. pressure.Second, assuming that the feed water, blowing-off, steam generation and heat sbsorbed under the constant boiler water quantity are continuously, the pressure change by blowing-off may be determined. By the comparison between the first and second cases, its difference obsereved is about 20∼30%. It will be found in this paper that the self-evaporation or condensation is largely effected by the pressure change in the boiler.

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