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International Heat Transfer Conference 16

ISSN: 2377-424X (online)
ISSN: 2377-4371 (flashdrive)

PHASE CHANGE BEHAVIOR OF AMMONIA ALUM HYDRATE SLURRIES PASSING THROUGH A HEAT EXCHANGER

Kohei Nakamura
Technical Research Institute, Toho Gas Co., Ltd., 507-2, Shinpo-machi, Tokai-shi, Aichi 476-8501, Japan; Department of Chemical Science and Engineering, Kobe University, 1-1, Rokkodai-cho, Nada-ku, Kobe-shi, Hyogo 657-8501, Japan

Takashi Ina
Technical Research Institute, Toho Gas Co., Ltd., 507-2, Shinpo-machi, Tokai-shi, Aichi 476-8501, Japan

Ruri Hidema
Department of Chemical Science and Engineering, Kobe University, 1-1, Rokkodai-cho, Nada-ku, Kobe-shi, Hyogo 657-8501, Japan; Complex Fluid and Thermal Engineering Research Center (COFTEC), Kobe University, 1-1, Rokkodai-cho, Nada-ku, Kobe-shi, Hyogo 657-8501, Japan

Hiroshi Suzuki
Department of Chemical Science and Engineering, Kobe University, 1-1, Rokkodai-cho, Nada-ku, Kobe-shi, Hyogo 657-8501, Japan; Complex Fluid and Thermal Engineering Research Center (COFTEC), Kobe University, 1-1, Rokkodai-cho, Nada-ku, Kobe-shi, Hyogo 657-8501, Japan

Yoshiyuki Komoda
Department of Chemical Science and Engineering, Kobe University, 1-1, Rokkodai-cho, Nada-ku, Kobe-shi, Hyogo 657-8501, Japan; Complex Fluid and Thermal Engineering Research Center (COFTEC), Kobe University, 1-1, Rokkodai-cho, Nada-ku, Kobe-shi, Hyogo 657-8501, Japan

DOI: 10.1615/IHTC16.ecs.022545
pages 4301-4310


KEY WORDS: Thermal storage, Heat exchanger, Hydrate Slurry, Latent Heat Transportation

Abstract

In this study, flow and heat transfer characteristics and phase change behavior of ammonia alum hydrate slurries were investigated. Their phase transition temperature was set at 51°C by tuning the concentration of ammonia alum hydrate in water to 35wt%. Behenyl trimethyl ammonium chloride (2000 ppm) and sodium salicylate (1200 ppm) were added as a drag reduction surfactant and a counterion supplier. Polyvinyl alcohol (1000 ppm) was also added as an anti-sedimentation additive. Pressure loss and heat transfer coefficient of ammonia alum hydrate slurry (50°C) and solution (60°C) were measured with double-pipe heat exchangers with different inner diameters (8 mm, 13 mm and 25 mm). The solution (60°C) was also supplied to a shell-and-tube type heat exchanger and exchanged sensible and latent heat were measured. As a result, in all cases of inner diameters, drag-reduction effect of the surfactant was observed. In contrast, heat transfer coefficients of the slurry and solution with additives were lower than those without additives due to flow laminarization by the surfactant. Ammonia alum hydrate solution showed supercooling in the shell-and-tube type heat exchanger. The degree of supercooling was smaller than 5°C when its mean linear velocity was 0.41 m/s. It was also revealed that the higher its mean linear velocity was, the smaller the degree of supercooling was. These results lead to the conclusion that supercooling state of the solution with the additives can be easily broken by tuning its linear velocity in the tubes.

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