In japan techniques for saving energy is an important goal since energy resources such as oil and nuclear power are limited.
Recently gas fired absorption heat pumps and gas engine driven heat pumps have been installed in facilifies such as hotels, swimming pools and offices.
In this article recent techniques, applications and future aspects for gas fired heat pumps are explained.

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The determination of organic compounds in foods is very important in food industries. A various compounds are contained in foods, selective determination methods are required for food processing and analysis. Electrochemical monitoring devices (biosensors) employing immobilized biocatalysts such as immobilized enzymes, organelles, microorganisms, and tissue have definite advantages. The enzyme Sensors consisted of immobilized enzymes and electrochemical devices. Enzyme sensors could be used for the determination of sugars, amino acids, organic acids, alcohols, lipids, nucleic acid derivatives, etc.. Furthermore, a multifunctional biosensor for the determination of several compounds has been developed for food processing. On the other hand, microbial sensors consisted of immobilized microorganisms and electrodes have been used for industrial and environmental analysis. Microbial sensors were applied for the determination of sugars, organic acids, alcohols, amino acids, mutagens, me thane, ammonia, and BOD.
Furthermore, micro-biosensors using immobilized biocatalysts and ion sensitive field effect transistor or microelectrodes prepared by silicon fabrication technologies have been developed for medical ap. plication and food processing.
This review summarizes the design and application of biosensors.

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The objectives of this paper are experimentally to study the detail of heat transfer in louver-array and to propose the preferable geometrical arrangement of louver from the point of view of improving the performance of heat exchanger. Our approach toward that goal was made via the following steps. The first step in the present study is optically to visualize the temperature field around louvers by employing the primitive heated flat louver model consisting of thin bakelite plate and thin Nichrome foil as a heater, and to measure the heat transfer coefficients of the louvers. Our experiment achieved to visualize the isotherms through the Laser holographic interferometry. The clear isotherms for various louver arrangements were successfully obtained. The thermal boundary layer and wake generated by an upstream louver were clearly observed to extend toward downstream ones ; the heat transfer coefficients obtained by the experiment were virtually affected by those boundary layers and wakes.
The second step is to examine the plausible arrangement of louver for enhancing heat transfer. The slight position shift of downstream louvers toward the direction avoiding the influence of heated air wake was proposed from both the observation of isotherms and the measurement of heat transfer coefficients in staggered louver array ; its effectiveness was varified by the experiment. The improvement of the performance of heat exchanger is expected by applying the proposed minor rearrangement of louver array for enhanced fins.

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A mathematical model for a vapor compression refrigeration cycle for automotive air conditioner is developed, which basically consists of compressor, condenser, receiver, expansion valve, evaporator, suction pressure control valve and piping.
The main purpose of this model is to provide the designer with a tool for improving cooling capacity and investigating capacity control of the refrigeration cycle at transient conditions.
A lumped parameter system is used for the mathematical model of the condenser and the evaporator, that is obtained with volume integral of the equation of continuity and energy over a bounded volume region.
The compressor model and the piping models are also lumped parameter systems, and heat capacity of their walls are taken into account.
The theoretical solutions of this model are in good agreement with the experimental results.

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The purpose of the present study is to examine experimentally the transient freezing process in the curved channel containing flows and the interface heat transfer. The 180° curved test section was constructed of rectangular channel with concave and convex walls which were cooled through thin copper plates, and the insulated upper and lower parts were made of transparent acrylic plate. Inlet Reynolds number was from 200 to 3040 corresponding to Dean number from 64 to 973 and wall temperature -5∼-15°C. It was observed how the freeze layer, which developed in the straight section, be haved along the curved channel. The position of the first expansion along the flow direction X_L is experimentally arranged as the function of Rei. Acceleration of the water by freezing and the characteristics of curved channel at the water-ice interface produce a greater heat transfer through the thin freeze layer than would exist without solidification. The average Nusselt number Num around the wall at each time is expressed by the function of dimensionless time τ* (product of Fourier number and Stefan number) and inlet Reynolds number.

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The isobaric specific heat capacity of Refrigerant 23 (CHF₃) has been measured by the flow calorimeter. Forty-five measurements were obtained in the gaseous region for temperatures 253 to 383 K and for pressures 0.5 to 3.0 MPa including the region near the saturation line. The sample purity used was 99.99 wt%. The uncertainty of the measurements was estimated to be less than l.5%.
Based on the present results in addition to the isobaric specific heat capacity at the ideal gas state, the second virial coefficients and the available PVT data, an equation of state has been formulated as a function of pressure and temperature for the region of the present study. The equation of state expressed by the form of Gibbs free energy reproduces the present results with an average deviation of l.0% and most of the available PVT data within a deviation of ±1%.

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Experimental studies on performance of two gas purge systems for the lithium bromide-water absorption refrigerating machine are presented in this paper. The first purge system is that the solution flow entrains the incondensable gas from the absorber in the first purge chamber, then the incondesable gas from the condenser in the second purge chamber. The second purge system is that the solution flow entrains the incondensable gas, separates it in the separator, and then returns to the refrigerating machine through the inverted U tube.
As a result, purged gas rate of both gas purge systems conforms to the theoretical equation ; S=V₀(P-P₀), where S is purged gas rate, V₀ is exhaust gas rate, P is pressure of purge chamber, and P₀ is saturated vapor pressure of solution.

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Pressure rise due to freezing of water enclosed in metal pipes has been simulated for the case of various ambient temperatures, -10 to -30°C and heat transfer conditions, taking drop in freezing temperature due to the pressure rise and the change in volume caused by freezing into account. For three kinds of different materials, the pressure change occurring in pipes have been analyzed under the relation of the tangential stresses on the inner surface of the pipes. The dimensionless parameters have been proposed to correlate the calculated results and it has found that the criterion for the fracture of pipes can be expressed as a function mainly of the modified Fourier and Biot numbers and the ratio of the wall thickness and the inner diameter of the pipes. It has also shown that the fracture Fourier number can be increased and the dimensionless maximum pressures in pipes can be reduced by introducing voids inside pipes.

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