Department of Mechanical engineering

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End date: 2009Subject: search.filters.subject.Heat Exchangers

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    The combined effects of wall longitudinal heat conduction and inlet fluid flow maldistribution in crossflow plate-fin heat exchangers
    (Springer, 2000-05) Ranganayakulu, Chennu
    An analysis of a crossflow plate-fin compact heat exchanger, accounting for the combined effect of two-dimensional longitudinal heat conduction through the exchanger wall and nonuniform inlet fluid flow distribution on both hot and cold fluid sides is carried out using a finite element method. Using the fluid flow maldistribution models, the exchanger effectiveness and its deterioration due to the combined effects of longitudinal heat conduction and flow nonuniformity are calculated for various design and operating conditions of the exchanger. It was found that the performance deteriorations are quite significant in some typical applications due to the combined effects of wall longitudinal heat conduction and inlet fluid flow nonuniformity on crossflow plate-fin heat exchanger.
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    The effects of longitudinal heat conduction in compact plate-fin and tube-fin heat exchangers using a finite element method
    (Elsevier, 1997-04) Ranganayakulu, Chennu
    An analysis of the crossflow plate-fin, crossflow tube-fin, counterflow plate-fin and parallel flow plate-fin compact heat exchangers accounting for the effect of ‘longitudinal heat conduction’ through the exchanger wall is carried out using a finite element method. The exchanger effectiveness and its deterioration due to the longitudinal heat conduction effect have been calculated for various designs and operating conditions of the exchanger. The results indicate that the thermal performance deterioration of crossflow plate-fin, crossflow tube-fin and counterflow plate-fin heat exchangers due to longitudinal heat conduction may become significant especially when the fluid capacity rate ratio is equal to one and when the longitudinal heat conduction parameter is large.
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    The combined effects of longitudinal heat conduction, flow nonuniformity and temperature nonuniformity in crossflow plate-fin heat exchangers
    (Elsevier, 1999-07) Ranganayakulu, Chennu
    An analysis of a crossflow plate-fin compact heat exchanger, accounting for the combined effects of two-dimensional longitudinal heat conduction through the exchanger wall and nonuniform inlet fluid flow and temperature distribution is carried out using a finite element method. A mathematical equation is developed to generate different types of fluid flow/temperature maldistribution models considering the possible deviations in fluid flow. Using these models, the exchanger effectiveness and its deterioration due to the combined effects of longitudinal heat conduction, flow nonuniformity and temperature nonuniformity are calculated for various design and operating conditions of the exchanger. It was found that the performance variations are quite significant in some typical applications.
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    The effects of inlet fluid flow nonuniformity on thermal performance and pressure drops in crossflow plate-fin compact heat exchangers
    (Elsevier, 1996-10) Ranganayakulu, Chennu
    An analysis of a crossflow plate-fin compact heat exchanger, accounting for the effects of two-dimensional nonuniform inlet fluid flow distribution on both hot and cold fluid sides, is carried out using a finite element model. A mathematical equation is developed to generate different types of fluid flow maldistribution models considering the possible deviations in fluid flow. Using these fluid flow maldistribution models, the exchanger effectiveness and its deterioration due to flow nonuniformity are calculated for an entire range of design and operating conditions. In addition to thermal analysis, the pressure drops and their variations are also calculated for these models. It was found that the performance deteriorations and variation in pressure drops are quite significant in some typical applications due to fluid flow nonuniformity
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    Numerical study of flow patterns of compact plate-fin heat exchangers and generation of design data for offset and wavy fins
    (Elsevier, 2009-08) Ranganayakulu, Chennu
    Thermo-hydraulic design of compact heat exchangers (CHEs) is strongly dependent upon the predicted/measured dimensionless performance (Colburn factor j and Fanning friction factor f vs. Reynolds number Re) of heat transfer surfaces. Also, air (gas) flow maldistribution in the headers, caused by the orientation of inlet and outlet nozzles in the heat exchanger, affects the exchanger performance. Three typical compact plate-fin heat exchangers have been analyzed using Fluent software for quantification of flow maldistribution effects with ideal and real cases. The headers have modified by providing suitable baffle plates for improvement in flow distribution. Three offset strip fin and 16 wavy fin geometries used in the compact plate-fin heat exchangers have also been analyzed numerically. The j and f vs. Re design data are generated using CFD analysis only for turbulent flow region. For the validation of the numerical analysis conducted in the present study, a rectangular fin geometry having same dimensions as that of the wavy fin has been analyzed. The results of the wavy fin have been compared with the analytical results of a rectangular fin and found good agreement. Similarly, the numerical results of offset strip fin are compared with the correlations available in the open literature and found good agreement with most of the earlier findings.