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Copyright of Transactions the Japan Society of Refrigerating & Air Conditioning Engineers is the property of Japan Society of Refrigerating & Air Conditioning Engineers and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Transactions the Japan Society of Refrigerating & Air Conditioning Engineers is the property of Japan Society of Refrigerating & Air Conditioning Engineers and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The purpose of this study is to clarify the effect of a component for high-pressure water separation, which is included in the air conditioning system of the general commercial aircrafts, on the air-cycle operation (reverse Brayton cycle); the high-pressure water separation consists of water separator and two heat exchangers called reheater and condenser, respectively. This paper briefly describes the typical system configuration of the air-cycle refrigeration progressed with evolutions in turbofan engine. Since nowadays, 4-Wheel air-cycle has been a trend on the aircraft air conditioning system, this paper theoretically shows its advantage on the basis of the thermodynamic cycle study. In the following chapters, an analysis was conducted on the interaction between a reheater and a condenser when each heat transfer performance changes from the baseline operating point. Also, the comparative study was made on the system performances by the 3-wheel and 4-wheel air-cycle. In addition, this paper describes how the heat transfer performance is designed for the reheater and the condenser under the system requirements for the entire air conditioning system.

Copyright of Transactions the Japan Society of Refrigerating & Air Conditioning Engineers is the property of Japan Society of Refrigerating & Air Conditioning Engineers and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The purpose of this paper is to develop an analytical model of frost/ice formation on the heat exchanger (condenser) of high-pressure water separation used in the air conditioning system of commercial jet aircraft. The high-pressure water separation is based on the heat exchange between the upstream and downstream sides of the same air flow with pressure difference. That is, relatively high-pressure and warmer air upstream of a condenser with high humidity is cooled by relatively low-pressure and cooler air discharged from a turbine downstream of the condenser; condensed water in the high-pressure side is removed by a water separator while in the low-pressure side the super-cooled water mist is produced by adiabatic expansion process in the turbine. In the both sides, when the heat-exchange fins are below the freezing temperature of the humid air, frost/ice formation occur, although their physical mechanism are utterly different. In this study, a phase-change model taking the features of a cross-flow heat exchanger into account is newly proposed. In particular, attention is focused on the increase of the pressure drop in the lower pressure side due to frost/ice formation. The validity of the analytical model is checked by the comparison with the experiment.

This paper proposes a new method for predicting the supercharging effect to easily and precisely design the dimensions of the suction line in inverter rotary compressors, including two-stage ones. First, we obtained experimental data on the rotational speed characteristics of volumetric efficiency ηv and overall adiabatic efficiency ηad with three types of single-stage one-cylinder compressors using R22 and a two-stage two-cylinder one using R410A. We introduced a function for only increasing ηv with supercharging by approximating the phenomenon by simple acoustic theory and calculated the numerical constants of the function by fitting dimensionless experimental data. Second, we proposed a basic prediction equation for only the resonant rotational speed fn, which was adjusted for the effect of the crank angle where the suction process ended, by modeling the interaction between the constant acoustic wave in the suction pipe and the roller movement as a rectangular wave. Additionally, we introduced the damping factor β to express the effect of the scale of the suction chamber in relation to the constant acoustic wavelength in the suction pipe. We confirmed that 95% of the predicted values of increasing ηv were within an accuracy of ±3% when the rotational speed ratio (f/fn) was 0.8 - 1.2 and all predicted values of fn were within an accuracy of -3 - +1%.