Topic
Countercurrent exchange
About: Countercurrent exchange is a research topic. Over the lifetime, 2255 publications have been published within this topic receiving 28687 citations. The topic is also known as: Countercurrent exchange.
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TL;DR: In this article, the authors applied the Reynolds analogy and its modifications to forced convection laminar in-tube condensation to predict the heat transfer coefficient of R134a by means of well-known two-phase friction factors and agreed void fraction models and correlations explained in the authors' previous works.
Abstract: The Reynolds analogy and its modifications are applied to forced convection laminar in-tube condensation to predict the heat transfer coefficient of R134a by means of well-known two-phase friction factors and agreed void fraction models and correlations explained in the authors’ previous works. The vertical test section is a 0.5 m long countercurrent flow double tube heat exchanger with refrigerant flowing in the inner smooth copper tube (8.1 mm i.d.) and cooling water flowing in the annulus (26 mm i.d.). The test runs are performed at average saturated condensing temperatures of 40 °C (Pr = 0.92) and 50 °C (Pr = 0.97). The heat fluxes are between 10.16 and 66.61 kW m−2 while the mass fluxes are between 260 and 515 kg m−2 s−1 for the vertical test sections. The Reynolds’ model is modified by various two-phase flow models and correlations to account for the partial condensation inside the tube. The refrigerant side heat transfer coefficients are determined within ±30% using the two-phase friction factors of Wallis, Moeck, Fore et al., while all the proposed friction factor correlations for the Reynolds analogy, Prandtl and Taylor analogy, and Colburn analogy predict the experimental friction factor within a ±20% deviation band. The importance of altering the Prandtl number to the Reynolds analogy (Pr = 1) is also shown in the paper.
5 citations
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27 Apr 1996TL;DR: In this article, a waste gas containing e.g. methyl chloride is passed through a heat exchanger to condense or freezing-out the vaporised and/or gaseous impurities.
Abstract: This procedure cleans a waste gas containing e.g. methyl chloride. It is passed through a heat exchanger (1), hence condensing or freezing-out the vaporised and/or gaseous impurities e.g. VOCs, pref. in indirect counter current heat exchange with a cooling medium. In this novel process, the now precleaned gas is supplied for further freezing out and/or condensation, to a second heat exchanger (3) such that it passes the heat exchange surfaces in upward flow. Also claimed are single- and combined heat exchangers with appropriate inlet and outlet connections for use in the process described.
5 citations
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TL;DR: In this article, the authors determined flooding limits and pressure drop of gas−liquid countercurrent flow in internally finned tubes, representing a single channel of a monolith with a single finned monolith and showed that with the appropriate liquid outlet geometry it is possible to achieve countercurrent annular flow at velocities that are relevant for hydrotreating of petroleum fractions.
Abstract: Flooding limits and pressure drop of gas−liquid countercurrent flow have been determined in internally finned tubes, representing a single channel of an internally finned monolith It was found that with the appropriate liquid outlet geometry it is possible to achieve countercurrent annular flow at velocities that are relevant for hydrotreating of petroleum fractions Comparison with an unfinned tube showed that the longitudinal fins inside the tube stabilize the liquid layer against slug formation, especially at high liquid velocities The pressure drop was calculated using a countercurrent film flow model By taking the extra pressure drop caused by the end-effects into account, it was possible to predict the pressure drop of both the finned and the unfinned tubes in the wavy annular flow regime
5 citations
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01 Jun 1993TL;DR: In this paper, the Laplace Transform Method is applied to solve the transient response of the counter flow heat exchanger with finite wall capacitance problem, which is based on three local energy balance equations which are solved assuming that only the fluid 1 inlet condition is perturbed (step change).
Abstract: The Laplace Transform Method is applied to solve the transient response of the counter flow heat exchanger with finite wall capacitance problem The mathematical model is based on three local energy balance equations which are solved assuming that only the fluid 1 inlet condition is perturbed (step change) As any counter flow problem could be reduced to an adequate integral equation, collocation method is used for solving such equation in the presented case Results are given for the outlet temperatures of both fluids and temperature distributions for both fluids and the wall as an explicit analytical formula
5 citations
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TL;DR: In this article, the authors characterized the dynamic motion of a countercurrent flow reactor with complex dynamics by constructing the space-time dependence of the temperature or concentration, and showed that the time average of heat removal by cooling through the wall is either equal or exceeds that of the convective heat removal.
5 citations