Present status of research activities in cryopreservation of fish gamete in aquaculture field was introduced. More than 59 fish species have been reported in the research histories and nearly half of them were studied during recent 10 years. This means that the research activities are increasing, though commercial profit have not obtained yet. Fish species of which sperm can successfully cryopreserved is still limited comparing to numerous species in telost. One of the major obstacle for improvement of the technique is existence of wide specie specific variance in the freezing tolerance of fish sperm. The varianc can possibly be explaind thorugh the informations obtained by the studies in comparative spermatology, which is recently activated field in fish biology.

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Frozen dough method have been adopted in the baking industry to reduce labor and to produce fresh breads in stores. New freeze-tolerant yeasts for frozen dough preparations were isolated from banana peel and identified. To obtain strains that have fermentative ability even after several months of frozen storage in fermented dough, we attempted to breed new freeze-tolerantstrain. The hybrid between S.cerevisiae, which is a isolated freeze-tolerant strain, and a strain isolated from bakers' yeast with sexual conjugation gave a good quality bread made from frozen dough method. Freeze-tolerant strains showed higher surviving and trehalose accumulating abilities than freeze-sensitive strains. The freeze tolerance of the yeasts was associated with the basal amount of intracellular trehalose after rapid degradation at the onset of the prefermentation period. The complicated metabolic pathway and the regulation system of trehalose in yeast cells are introduced. The trehalose synthesis may act as a metabolic buffer system which contribute to maintain the intracellular inorganic phosphate and as a feedback regulation system in the glycolysis. However, it is not known enough how the trehalose protects yeast cells from stress.

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A dynamic model of a vapor compression refrigeration cycle composed of a compressor with a high-pressure chamber, cross finned heat exchangers, an expansion valve and pipes is developed. In order to prove the effectiveness of the model, start-up simulation results are compared with experimental result obtained for a prototype refrigeration cycle. In these experiments, the refrigerant mass distribution in the refrigeration cycle is set and two start-up operations are performed. One operation is called "hot-start", which means starting-up from a high temperature in the compressor chamber. The other is called "cold-start", which means starting-up from a low temperature. The simulation results well support the experimental results for both operations and prove the effectiveness of the developed model.

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Relating to the problem of supercooling phenomenon for ice storage system, the effect of ice nucleating substances (Xanthan gum, Silver iodide, Copper sulfide, Cholesterole and Ice nucleating bacteria) in still bulk supercooled water was investigated. In the experiment, the test water sample containing the ice nucleating substance was cooled below the equilibrium freezing point temperature in low-temperature room maintained at -40 °C, and its freezing temperature was measured for various mass ratios of ice nucleating substance to water. The supercooling degree for the test water sample decreased with an increase in the mass ratio. It was found that the supercooling degree for the test sample with the insoluble ice nucleating substance was smaller than that for the soluble one. Among test ice nucleating substances, Cholesterole had a pronounced effect on the ice nucleation of supercooled water. However, it was clarified that the supercooling degree for each test sample increased by repeating the process of freezing and melting.

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The numerical estimation was performed on the heat transfer and flow characteristics of a laminar annular impinging jet with confined insulated wall. Numerical values were obtained for the diameter ratio d/D=0~0.9, the dimensionless distance between nozzle and impingement surface h/ro=0.25~1.0, the Reynolds number Re=100~2000 at Prandtl number Pr=0.72and Grashof number Gr=3×10³. The flow was divided into major flow and minor flow. Two kinds of recirculating flows on the upper insulated wall and impingement surface affected the local heat transfer on the impingement surface. Positions of maximum and minimum Nusselt number depend on diameter ratio and Reynolds number, respectively. In addition, the diameter ratio, which mean Nusselt number becomes minimum, exists.

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As pressure increases and approaches the critical pressure, density difference between liquid and vapor becomes small, latent heat of condensation approaches zero and other physical properties show remarkably different behaviors from those at lower pressure. Therefore it is expected that condensation heat transfer near the critical pressure differs from that at lower pressure.
An experimental study of natural convection condensation on a vertical cylinder surface was carried out using Carbon Dioxide as a working fluid in the pressure range of 5.0 to 7.1 MPa. Filmwise condensation was observed, and heat transfer coefficients were obtained from measuring condensate volume and compared with Nusselt's theory and with experimental results under usual pressure conditions.

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An experimental study for convective heat transfer from an open cavity has been made in the range of Reynolds numbers from 10⁴ to 10⁵. The cavity model of which both depth and width are 25 mm is made of brass for the study of effect of temperature non-uniformity on the wall surface of the open cavity. The fluid temperature distribution in the open cavity is almost uniform except a thin portion immediately adjacent to the wall surface of the open cavity. The representative mean temperature of the fluid in the open cavity is used for the fllowing treatment. The wall surface temperarture distribution of the open cavity is as follows : the vertical wall surface temperature is decreased steeply from the bottom to the opening regin of the open cavity. In the present paper, the average temparature of cavity wall surface is used for the follwing treatment. Convective heat transfer from the open cavity is treated by the following two phenomena ; one the heat transfer related to the temperature difference between the wall surface and the fluid in the open cavity, and the other the heat transfer related to the temperature difference between the fluid in the open cavity and the external main stream. Experimental data obtained for the open cavity which is made of brass coincide with the existing data obtained under the conditions that the wall surface temperature distribution is almost uniform.

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Convective heat transfer from an open cavity has been studied in the range of Reynolds numbers from 10⁴ to 10⁵ in the case of depth-to-width ratio H/L=1.0. Convective heat transfer from an open cavity is treated by the following two phenomena one the heat transfer related to the temperarure difference between the wall and the fluid in the open cavity, the other the heat transfer related to the temperarure difference between the fluid in the open cavity and the external main stream. In part 1, effect of temperature non-uniformity on the wall surface for convective heat transfer is experimentally studied by the cavity model which is made of brass . In the presnt report, effect of temperature non-uniformity on the wall surface for convective heat transfer is studied by numerical calculation of heat transfer model. Heat transfer rate obtained by numerical calculation almost coincide with the existing experimental data obtained under the conditions that there is temperature non-uniformity on the wall surface of the open cavity.

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Condensing heat transfer coefficients of HFC-134a and CFC-12 were measured inside a horizontal and a vertical smooth tub with an inner diameter of 4.35mm. The mass velocity of refrigerant ranged from 60 to 170 kg/(m²s) and the saturation temperature was about 450°C.
The results obtained are as follows ; (1) According to the difference in flow directions, condensing heat transfer coefficients in low mass velocity range (below 100 kg / (m²s)) were ranked as follows ;
horizontal›vertical upward›vertical downward.
(2) Condensing heat transfer coefficient of HFC-134a was 15-20% higher than that of CFC-12 with both horizontal and vertical tubes.

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The scroll wrap profile is very important for improving performance and reliability of scroll fluid machines. An involute curve of a circle is gerally used in current scroll compressors. In this paper,we have adopted an algebraic spiral (r=aΦ^k)as the basic volute curve of the scroll wrap profiles,and described its geometric shape and volume characteristics. The advantages of using the algebraic spiral as the basic volute curve are as follows. (1)The scroll wrap thickness can gradually be changed with the wrap angle,and can be changed according to the strength requirement. (2)Scroll wrap dimensions can be reduced to some extent than those with an involute curve under the same design conditions. (3) The top clearance volume can be reduced or brought to zero.

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An experimental study on enhancement of nucleate pool boiling heat tranfer by placing a sponge metal close to a plain heated surface was conducted in order to improve the heat transfer performance of the high temperature generator of absorption chiller/heater. The sponge metal has three dimensional porous mesh framework like sponge.
Boiling curves of water under the atmospheric pressure were compared with those of lithium bromide aqueous solution of mass concentration 55 to 58%. Heat transfer characteristics were improved by 2 to3 times both for water and lithium bromide aqueous solution when the sponge metal was placed on the heated surface with and without cleareance.
Three kinds of sponge metals were used for lithium bromide aqueous solution under the reduced pressure (24 kPa). At lower heat fluxes,#6 sponge metal which has the finest mesh and the lowest porosity shows excellent results. At high heat fluxes, however,it causes deterioration of heat transfer. Over the wide range of heat fluxes,# 4 sponge metal was found to be most suitable and the optimal clearence was determined as 0.5 mm.
The sponge metal is of good practical use as a device to enhance the boiling, since no special manufacturing is required for placing it on the heated surface.

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This work aims at clarifying the possible operating temperature ranges for silica gel-water adsorption refrigeration cycles driven by near-environmental temperature heat sources (between 50°C and 85°C), with relatively small regenerating temperature lifts (10 K to 65 K). A newly developed three stage advanced silica gel-water cycle, which is operational with 50°C driving heat source and 30°C cooling source is introduced and compared with a conventional single stage cycle. The cycles are evaluated in terms of cooling capacity, COP and the viability of operation with near-environmental temperature driving heat sources. The analysis is based on experimental and cycle simulation work. The results showed the advanced three stage cycle to be particularly suited for operation with low grade waste heat driving sources, since it worked with small regenerating temperature lifts (ΔT_regen)of 10K to 30K. Another significant advantage of operation with small ΔT_regen is the possibility to reduce irreversible heat losses from batched cycle operation. Experiments carried out on full-size machine suggested that, even with smallΔT_regen, adsorber /desorber heat exchanger improvements such as higher thermal conductance and smaller heat capacitance can contribute to reduce heat losses while improving cycle performance in terms of cooling capacity and COP.

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The present study introduces a humidity control apparatus which can hygienically and automatically maintain the appropriate humidity level of indoor air without either a water supply or drainage system. In humidification, the desiccant takes up water vapor from the outdoor air in the adsorption process, and release it indoors by desorption. Therefore, no water supply is required to humidify. An apparatus having no water supply is more hygienic, because it does not propagate bacteria and does not scatter the calcium and magnesium salts found in the water. In dehumidification, water vapor is removed from the indoor air by the desiccant and is released outdoors by desorption, eliminating the need for a drainage system. The absence of a drainage system also eliminates problems such as water leakage and installation. The performance of a system based on this new method was compared with that of conventional products, whereby the modes of dehumidification, humidification and humidification with ventilation were evaluated. In addition, the new system was tested to reveal the time-dependent charaeteristics of the concentration of indoor odor and the dust collection efficiency.

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The existence of several regimes of condensation heat transfer is well known. Regimes are given academic names as dropwise, transition, film and glacial condensation along the condensation curve showing the relationship between heat flux and surface subcooling. In case of comparatively large vertical surface, the lower part on the gravitational direction is affected by condensate from the upper part, and will be covered by water stream like a rivulet. It has no longer an existence as dropwise condition, and it is absolutely impossible that heat transfer problems under constant temperature or constant heat flux take place. The reason is why as follows, heat transfer of film condensation is some orders of magnitude less than dropwise condensation, and various regimes exist together simultaneously. In the present paper we shall try to observe the coexisting appearance of regimes in steam condensation at atmospheric pressure and make researches in the local condensation curve from top to bottom on the same surface, that is divided into eight parts in the rear side. The main results are shown as follows
(1) Enhancement of heat transfer by wiping of drops appears toward somewhat lower position from top.
(2) Frazil ice is observed in the supercooled liquid film flowing down on glacial condensation.
(3) The regime of glacial condensation describes a thermal hysteresis loop.

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