Evaporation heat transfer characteristics inside the U-bend of the smooth and the microfin tube using alternative refrigerant

Title & Authors
Evaporation heat transfer characteristics inside the U-bend of the smooth and the microfin tube using alternative refrigerant
Jo, Geum-Nam; Kim, Byeong-Gi;

Abstract
The present work experimentally investigated the effects of mass flux, heat flux, inlet quality on the heat transfer performance inside the U-bend of smooth and microfin tube using R-22 and R-407C refrigerants. The parameters were 200 and 400 kg/m$\small{^{2}}$ s for mass flux, 6 and 12 kw/m$\small{^{2}}$ for heat flux, 0.1 and 0.2 for inlet quality under the pressure of 0.65 MPa. The apparatus consisted of the test section of four straight sections and three U-bends, preheater, condenser, refrigerant pump, mass flow meter etc. The average heat transfer coefficient at the downstream straight section after U-bend was affected by U-bend due to the centrifugal force and mixing of two-phase flow in the U-bend. The average heat transfer coefficient at the U-bend was 4 ~ 33 % higher than that at the straight section. The average heat transfer coefficients were affected in the order of mass flux, heat flux and inlet quality. The average heat transfer coefficients in the microfin tube were lager by 19 ~ 49% and 33 ~ 69% than that in the smooth tube at the straight section and at the U-bend separately. The average heat transfer coefficients for R-407C were larger by 33 ~ 41% and 17 ~ 29% than that for R-22 in the smooth tube and the microfin tube separately.
Keywords
Microfin Tube;R-407C;U-Bend;Heat Transfer Coefficient;
Language
Korean
Cited by
1.
마이크로핀관 곡관부내 대체 냉매의 응축 열전달에 미치는 냉동기유의 영향,태상진;조금남;

설비공학논문집, 2000. vol.12. 6, pp.541-549
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