Refrigerant mal-distribution in a distributor located at the inlet of the heat exchanger used for air conditioning systems plays an important role in the heat exchanger performance. The distribution performance at the distributor is greatly affected by flow conditions as well as geometrical parameters of the distributor. To clarify the distribution characteristics, it is essential to know flow rates of both liquid and vapor state at every branch tube after distribution. In other word, the information of the quality and the flow rate at the every branch tube are required. Acquiring this information, however, requires quite complicate experimental setup so far. This paper proposes a quite simple test method, however, allowing to obtain the value of quality and the flow rate of the refrigerant at the every branch tube of the distributor by measuring pressure drop and heat transfer rate of the branch tubes after distribution. By using the proposed evaluation method, the optimization for the geometrical parameters of the distributor was conducted to reduce the refrigerant mal-distribution and an optimized distributor is suggested. It is confirmed that the optimized distributor greatly reduces the mal-distribution of the refrigerant over the every branch tube regardless of the flow conditions. Meanwhile, by the flow visualization in the distributor, it is observed that certain amount of liquid refrigerant is stayed and swaying unstably at the bottom of the distributor. It is supposed that the liquid refrigerant behavior in the distributor great affects the distribution performance.
In this paper, we propose a model to control an agent's gaze behavior called Interactive Kinetics-Based Gaze Direction Model(iK-Gaze). iK-Gaze is a model used in one-to-one interaction between an agent and a human, where the agent's gaze direction is calculated using an energy function which uses the human's gaze direction as its input. iK-Gaze aims to generate the agent's gaze through interactions with a human rather than using predefined motions and predefined timings. Contrary to rule-based or statistics-based models, the agent's gaze motion changes dynamically according to the human's gaze motion. Moreover, by utilizing three parameters of the desire to look, the mutual gaze hesitation, and the mutual gaze stress in the iK-Gaze, the tendency of the agent's gaze behavior can be changed easily. From the case study, the fact that agent's gaze behavior changes according to the human gaze behavior is confirmed.
Face gears can be substituted for bevel gears or hypoid gears. However they can be used only in restricted applications today. Recently, a new application of face gears for helicopter transmissions has been proposed and face gears have attracted special interest. In the face gears, generally, the pinion is a conventional spur or helical gear with involute form. In this paper, a face gear adopting arcuate tooth profile on the pinion was proposed. And the effects of the radius of the arcuate tooth profile on the constitution of the surface of contact and on the tooth contact patterns was clarified. As a result of the numerical analysis, it was clarified that the face gear with large tooth contact pattern could be designed by choosing appropriate type and radius of the arcuate tooth form.
Using a (3 + 1)-dimensional ((3 + 1)-D) superspace group approach, a composite crystal structure model for β- and γ-phases of Zn4Sb3 is constructed. Intercalation of Zn atoms into the Zni site is found, which affects thermoelectric properties.
The cycle performance of CO2 refrigerant is worse than that of HFCs since the working pressure is higher which suffers larger compression and expansion losses. To enhance the cycle performance similar extent to HFCs, refrigerant to refrigerant heat exchangers need to be applied as one of the many components equipped into the CO2 cycle. However, when such a heat exchanger is used as an economizer, which works between high temperature refrigerant after the gas cooler and low temperature refrigerant by reducing to the intermediate pressure, it is confirmed from the visualization that the refrigerant in low temperature side is observed as a vapor-liquid dispersed flow. In such a condition, the evaporating performance is low since most liquid flows in the vapor core as droplets. In this study, aiming at weight saving and compactness for a refrigerant to refrigerant heat exchanger as an economizer, a newly designed aluminum double-tube heat exchanger in which outer channel is formed by multiports instead of annulus is introduced. Spiral fins are applied in the surface of inner channel to aim for attaching liquid flowing in vapor core to the inner tube wall. The local heat transfer coefficient was experimentally measured in a single tube and the performance of a heat exchanger assembly was estimated. These results show that this newly designed heat exchanger is effective to enhance heat transfer performance.
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