| Recent years, plate heat exchanger(PHE) has been used widely because of its high heat transfer coefficient, compactness, ease of cleaning, flexibility to increase the heat transfer area according to the load requirement etc. In the present study, the flow and heat transfer characteristic inner the channel of a type of commonly used W-shaped (i.e. two-herringbone) PHE is studied according to computational fluid dynamics (CFD) simulation and analyses. Investigation results have important significance for type selection, design and engineering application.Two symmetric plate arrangements30°/30°and60°/60°channels which have accurate size same to the actual PHE geometry was completely modeled, including the distribution area and two channels which flow hot and cold water respectively. Within the working pressure range, various operation cases were selected and numerically simulated. The flow pattern, velocity, pressure and temperature distributions were presented. The relation curve between flow, heat transfer characteristics and channel velocity has been gotten. The results showed that flow distribution in the30°/30°passage is more badly maldistributed after comparing the two type passages. The flow resistance and heat transfer coefficient of60°/60°passage is larger than that of30°/30°passage when they have equal velocity. The flow rate of30°/30°passage is larger than that of60°/60°passage when they have approximate flow resistance and heat transfer coefficient.Both the cold and hot flow channel of the passages mentioned above is cut by6groups of faces respectively, and each group include4interfaces. Comparing the velocity, temperature of each interface and heat transfer coefficient of every heat transfer area etc, the results showed that the flow, temperature and heat transfer maldistribution is significant at the connection area between the distribution area and corrugated area.The channels composed by part corrugated plates sized216x71mm has been modeled, to investigate the influence of the number of herringbone which range1/2to3, the tilt angel of the corrugation vetical section which range35°to55°, the pitch-to-height ratio which range of2.4to9, corrugation inclination angel which range of30°to80°on the flow and heat transfer characteristic. Results showed that the herringbone inflection point can make the criss-crossing flow turn. The influence of herringbone number on the flow and heat transfer characteristics is very small.The zig-zag flow is more observed with the decrease of the tilt angel and the increase of the pitch-to-height ratio and corrugation inclination angel. The heat transfer coefficient increase first and decrease the after with the increase of the tilt angel, pitch-to-height ratio and corrugation inclination angel. The pressure drop increase first and decrease the after with the increase of the tilt angel. The pitch-to-height ratio is effected by two aspects, that are corrugation pitch and height. The pressure drop increase with the decrease of the corrugation height. When fixed the height, a pitch value whose pressure drop is largest had been found existed. When the pitch was smaller than this value, the pressure drop decrease with the increase of the pitch; when the pitch was larger than this value, the pressure drop increase with the increase of the pitch. The pressure drop increase with the increase of the corrugation inclination angel.The part of mixed passage arrangement30°/60°channel was modeled and simulated. The flow pattern has been gottern. The flow and heat transfer characteristics were compared with two symmetric plate arrangements30°/30°and60°/60°channels. The results shows that the flow resistence and heat transfer coefficient of the mixed is in the middle of the two symmetric channels. |
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