Studying the efficiency for plate-type and tubular-type enhanced heat exchangers with consideration for flow patterns
A.G. Laptev1, A.A. Ahtmitshin2
1Kazan State Energy University, Kazan, Russia
2Engineering and Development Center Inzhehim, Kazan, Russia
Keywords: thermal effciency, mathematical model, experimental study, heat transfer enhancement, flow patterns
Abstract
Experiments were conducted on lqiuid (water) heating by hot vapor in a plate heat exchanger. The coolant agent temperature and flow rates were meausred; the hat balance and heta tarnsfer equastions were applied for calculating the heat flux and heat tarnsferr coefficient asa function of heatwd water flow rate. The mathermatical models are developed for the heat number of tyrtansfer units and for liquid dispalcement in smooth channels. We developed a cellar model for coollant flow pattern while using the surface-type tarnsfer enhancers (wire inserts) and volumetric enhancers (chaotic packing). The calcuations and experimental data are in satisfactory agreement. Experimemntal and simulatiom methods demonstrated that the using of surafec-type enhancers in the problem of high-visocisty lqiuid heating (e.g., industoal oil) increaes the heat transfer coefficient by 2.75 - 6 times amnd the gain in thermal effiecny is about 2.4 - 3.2 times. The gains from using the volumetric-type enhancers are 15 - 20 times and 2 - 3 times, correspondingly, for heating with hot water. The dveloped mathematical model with accounting the flow patterns can be applied in designing or modernization of heat tarnsfer apparatuses in differnet industries.
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