| As an efficient and compact heat exchanging element, plate heat exchangers are widely used in engineering fields such as petroleum, chemical, metallurgical, and power. It plays an important role in national economy and industrial production. Therefore, the development of new type of plate heat exchanger, the optimization design, and the improvement of heat exchanger performance have very important practical significance and application value, combined with experiment and numerical simulation, this paper studies the flow and heat transfer characteristics of chevron plate heat exchanger.Three parameters of plate heat exchanger are investigated numerically, which are the corrugated inclination angle β, the ripple spacing λ, and the corrugated height H. The influence of them on inner flow field and heat transfer characteristics of plate heat exchanger is obtained. The flow field shows "cross flow" pattern, when β is little. It presents" zigzag flow" pattern, when β is bigger. Nu, which reaches its climax at70°, first increases then decreases with the increase of/β. It also gradually declines with the increase of λ and the decrease of H. The pressure drop increases with the increase of β and decreases with the decline of λ and H. The heat exchange efficiency near contact point is highest. With the shrinking of flow passageway, a series of vortices are evoked, which increases the turbulence near the contact points, hence improve the effect of heat transfer.The parameters, which influence the distribution of the contact points, are studied numerically. The distance between the lower wave crest line and the symmetry axis in the length direction of plate heat exchangers is an important parameter, which affects the distribution of contact points, named L for short. When the three parameters,β, λ, and H, are determined, L mainly affects the y coordinate of the first layer. The x coordinate doesn’t change with the change of L. Pressure drop, Nu and the area of quality factor j/f change periodically with the increase of L. The period is λ/2sin β. They all reach their climax when L=λ/4sinβ. When designing plate heat exchanger, the parameter L=λ/4sinβ can be adopted to get the optimal comprehensive performance of plate heat exchanger.The "thermal mixing" plate heat exchanger was studied numerically. Under fixed bottom wall angle βb, Nu and pressure drop increase along with increasing of top wall angle βt. The viscous dissipation, which gets its climax when the sum of βt and βb is100°, first increases then decreases with the increase of βt. Pressure drop and Nu increase with the increasing of Re at entrance of flow passageway. The entransy transfer efficiency choppily decrease with the increase of Re. The entransy transfer efficiency of hard plate assemble is much higher than soft plate assemble.A water-water experiment of plate heat exchangers is carried out. A series of heat performance of plate heat exchanger are obtained and compared with the numerical data. The trends correspond well with each other. The experiment data are processed using the method of Wilson graphic and equal velocity. Both of the results show that, the outlet temperature in hot existence, obtained from simulation, is higher than the one obtained from experiment. With the method of Wilson graphic, the pressure drops at both cold and hot existence are lower than that obtained from experiment. The maximal errors are both lower than10%, indicating the numerical simulation method can get the performance of plate heat exchangers accurately. It also can provide a guidance in the design of new plate pattern and save a lot of experimental expense. |
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