• Journal of the Korean Applied Science and Technology
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• v.4 no.2
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• pp.43-48
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• 1987

Isoelectric point and surface tension of twelve of the alkylcarboxy betaines such as 2-(trimethylammonio) dodecanoate, 2-(trimethyammonio) tetradecanoate, 2-(trimethylammonio) hexadecanoate, (dimethyldodecylammonio)ethanoate, (dimethyltetradecylammonio)ethanoate, (dimethylhexadecylammonio) ehtanoate, 2-(dimethylododecylammonio) propanoate, 2-(dimethyltetradecylammonio)proopanoate, 2-(dimethylhexadecylammonio)propanoate, 2-(dimethyltetradecylammonio)-3-phenyl propanoate, 2-(dimethyltetradecylammonio)-3-phenyl propanoate are tested. From the measurement of the isoelectric point, it was found that the isoelectric point were leaned toward the alkaline zone for c-alkylarbrxybetaines, and toward the acidic zone for N-alkylcarboxybetaines. At the range of the carboxybetaine concentration $2\;{\times}\;10^{-2}{\sim}2\;{\times}\;10^{-5}$mole/l, the surface tension of the aqueous solution were decreased to 30-38 dyne/cm, showing the tendency that the ability of lowering the surafce tension was depending on the increase of carbon atom number in the lipophilic alkyl chain. The critical micelle concetration measured by the surface tension and concentration curves have been found at the range of $10^{-2}{\sim}10^{-5}$mole/l.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.8 no.3
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• pp.330-337
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• 1996

The effects of pump and temperature on drag reducing characteristics were investigated with a polymer(PAAM : Polyacrylamide) and three kinds of surfactants(CTAC, STAC, Habon-G) in fully developed turbulent pipe flows with various experimental parameters such as additive concentration(30~500ppm), pipe diameter(4.65mm, 10.85mm), Reynolds number($4{\times}10^4{\sim}10^5$) and working fluid temperature($20{\sim}80^{\circ}C$). The pump effect on PAAM was severe such that the drag reduction rates obtained with pump were decreased upto 30% as compared with those obtained with compressed air in 4.65mm test section. The temperature effect on PAAM was noticeably considerable, that is, the higher temperaute, the less drag reduction rate. On the other hand, no significant pump effect on the surfactants was observed. The drag reducing effectiveness of CTAC was totally lost in the temperature ragne of 60 to $80^{\circ}C$, whereas STAC and Habon-G kept their distinct drag reducing capability at a temperature of $80^{\circ}C$. This study clearly elucidated that for DHC application of drag reducing additives, the pump and temperature effects as well as additive concentration and pipe diameter should be carefully taken into consideration.