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Heat Transfer Enhancement And Analysis Of Novel Hollow Fiber Heat Exchanger

Posted on:2015-09-08Degree:MasterType:Thesis
Country:ChinaCandidate:X J YanFull Text:PDF
GTID:2271330452469816Subject:Chemical Engineering
Abstract/Summary:PDF Full Text Request
Plastic heat exchangers have been of increasing interest for lower temperatureapplications because of their superior resistance to chemicals and foulingcharacteristics. However, the quite low thermal conductivity of polymer materialslimits their widespread use and acceptance. The Polymeric Hollow Fiber HeatExchangers (PHFHEs) with extremely large surface area overcome the constraint andhave attracted more and more attention. Nowadays, many researchers studyhydrodynamics and heat transfer characteristics, in order to find ways to enhance heattransfer and develop new types of the hollow fiber heat exchangers.In this study, we improve the heat transfer performance of the PHFHEs byoptimizing their structure. The optimized way is to place the polypropylene netbetween the inlet and the outlet of the shell side. The hydrodynamics and heat transfercharacteristics of the PHFHEs without net and with net were studied experimentallyas well as numerically. The accuracy of the numerical model is demonstrated by thecomparison with the experimental results. In this model, the heat transfer coefficientand the pressure drop, together with the velocity and temperature fields are obtainedand presented to help analyzing the heat transfer characteristics of the PHFHEswithout net and with net. The overall heat transfer coefficient of PHFHEs with net isabout30%higher than that of PHFHEs without net. The pressure drop of PHFHEswith net is about12%higher than that of PHFHEs without net. The shell-side heatresistance ratio of PHFHEs without net and with net approximately account for56%to66%, and35%to46%, respectively. It is found that at the same flow rate, theshell-side heat transfer coefficient per unit pressure drop of the PHFHEs with net isobviously higher than that without net, indicating the PHFHEs with net have theiradvantages over the ones without net.
Keywords/Search Tags:Hollow fiber, Heat exchanger, Numerical model, Heat transfer, Pressure drop, Optimized
PDF Full Text Request
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