We focus on the saturated pool boiling with aluminum heat transfer surfaces. Considering the matching of aluminum surface with working fluid, fluorine refrigerant HFE7000 is used. We have used seven types of heat transfer surface (smooth and six curl-skive surfaces: fins A, B, C, D as group 1, fins E, F as group 2). Curl-skive fin surfaces have many fine tunnel structure machined by squashing of fins after biting. Curl-skive fin A is considered as a standard which has similar specification with previous high performance surfaces. Curl-skive fins B, C and D are shifted in fin width, gap width, fin pitch and fin height from curl-skive fin A. Curl-skive fin C has the closest structure and largest number of tunnels in group 1. Curl-skive fins E, F in grope 2 have closer structure than curl-skive fin C. Absolute pressures cited are 0.10MPa, 0.14MPa and 0.18MPa. Comparing the heat transfer surface type, curl-skive fin C shows the highest heat transfer performance among all heat transfer surfaces examined in this study. And, heat transfer performance of curl-skive fin C is 4.8 times higher than that of smooth surface and 2.8 times higher than that of curl-skive fin A under 0.14MPa. On the other hand, curl-skive fins E, F show pour performance which is almost equivalent to that of smooth surface.

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For the measurement of the thermal conductivity of an electrical conductor laminated by insulating material, measurement accuracy by conventional steady state longitudinal heat flow method is decreased by the effect of heat loss from the specimen surface to ambient. We have developed “Modified Temperature Profile method (MTP method)” by modifying the conventional method to measure thermal conductivity of a thick specimen with low thermal conductance ranged from 10 to 100 W/(㎡･K). The temperature profile in the thick specimen with low thermal conductance is not linear, which is the main reason of the large measurement error in the conventional method. So, we applied the analytical solution of the straight fin for the temperature profile of the specimen. We successfully demonstrated that the measured thermal conductivities by MTP method were within ±10% error band by experiments using single component specimens made of acrylic plates and composite specimens consisted of copper and acrylic plates alternately piled up, which thermal conductance was ranged from 10 to 250W/(㎡･K).

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Composite slabs and cylinders have a various thermal function and character, depending on a combination of two materials. For example, these work a heat reservoir, a storage tank for hydrogen and make a rapid temperature change of other material slow using a thin insulation layer of Teflon and oxide as heat shock absorber. In analyzing unsteady heat conduction in these materials, one has to choose a suitable analyzing method, depending on their thermal properties and geometric dimensions and a time range dealing with these temperature change. The correctly adopted boundary conditions may make analysis and calculation for these temperature change ease. The present paper shows some examples encountered in the third type boundary condition and explains their analytical procedure and exact solution.

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