TED-AJ03-610 A STUDY OF ROTARY HEAT EXCHANGER WITH AIR FLOW ACROSS THE ROTOR
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概要
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The developed rotary heat exchanger has three principal functions. They are as follows; a blower, a heat exchanger and a pump. Figure A-1 shows the structure of the rotary heat exchanger with airflow across the rotor. Its structure is based on a cross flow fan. Multiple annular-flattened water tubes (4) are connected to the header tanks (2) and (3) of the rotor (1), and multiple thin blades (5) are connected at a certain pitch in between the rows of fattened water tubes. The blades also work as heat transfer surfaces. When the rotor rotates in the casings (6) and (7), the airflow across the rotor occurs as shown in Figure A-1. This means that the air flows from the outside to the inside of the rotor inlet, while the air at the outlet the flows from the inside to the outside. Thus an alternative airflow occurs on the fin surfaces. On the water side of the rotor, a stationary guide impeller (9) at the outlet side and a rotary impeller (8) at the inlet side generate the pump action. The structure and characteristics are similar to a cross flow fan, but this rotor has complicated structure, so studies of conventional cross flow fans cannot be directly applied to this type of rotor. We prepared various samples that have different parameters of rotor diameter, length, inner and outer diameter ratio and fin pitches. Specifications for the experimental rotors are shown in Table A-1. Concerning the blower performances, we found some correlations among the airflow rate and various parameters. With respect to the heat transfer characteristics, we found [figure] some correlation among the heat transfer coefficients and the parameters of the rotary heat exchanger as a heater or a radiator. And we introduced an empirical equation for the heat transfer coefficients which could be compared with that of conventional heat exchangers that have corrugated straight fins. The equation shows that the heat transfer coefficients of the rotary heat exchanger are higher than those of the conventional heat exchanger within the region of a high Reynolds number (the same as that of the high rotary number region). Specifically, the effect of the alternative air-stream-direction over the heat transfer surfaces on the heat transfer coefficients is expressed as a proportion to the number of revolutions of the rotor to the 0.14th power. An experiment was also conducted to approve the performance as a cooler. The results show that the heat transfer coefficients are higher than those of a heater. In particular, condensed water droplets on the rotor blades, which are on the heat transfer surfaces, are rapidly and continually blown off by the centrifugal force.[figure]
- 一般社団法人日本機械学会の論文
著者
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Amaki Isamu
College Education Dept. Denso E & Ts Training Center Co.
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Kumada Masaya
Mecanical & System Eng. Faculty Of Eng. Gifu University