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Abstract

Helical coil heat exchangers are widely used in a variety of industry applications such as refrigeration systems, process plants and heat recovery. In this study, the effect of Reynolds number and the operating temperature on heat transfer coefficients and pressure drop for laminar flow conditions was investigated. Experiments were carried out in a shell and tube heat exchanger with a copper coiled pipe (4 mm ID, length of 1.7 m and coil pitch of 7.5 mm) in the temperature range from 243 to 273 K. Air – propan-2-ol vapor mixture and coolant (methylsilicone oil) flowed inside and around the coil, respectively. The fluid flow in the shell-side was kept constant, while in the coil it was varied from 6.6 to 26.6 m/s (the Reynolds number below the critical value of 7600). Results showed that the helical pipe provided higher heat transfer performance than a straight pipe with the same dimensions. The convective coefficients were determined using theWilson method. The values for the coiled pipe were in the range of 3–40 W/m2 ·K. They increased with increasing the gas flow rate and decreasing the coolant temperature.

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Authors and Affiliations

Krzysztof Kowalski
Dorota Downarowicz
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Abstract

The cyclic Electrothermal Temperature Swing Adsorption (ETSA) process in a fixed-bed column with Supersorbon K40 activated carbon (AC) was applied to remove propan-2-ol (IPA) from air. The bed was electrothermally regenerated using direct resistive heating method. The tests were performed in the range of operating parameters: IPA loading 0.18-0.26 kg/kg, voltage 19.5 V, set-point temperature 393–403 K, nitrogen flow rate 0.12 m3/h.

The analysis revealed, that raising the bed temperature resulted in an increase of desorption degree of adsorbate, reduction of regeneration time and an increase in the energy consumption. The application of insulation enabled reduction of energy consumption and regeneration time by 27% and 10%, respectively.

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Authors and Affiliations

Krzysztof Kowalski
Elżbieta Gabruś
Dorota Downarowicz

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