The Structural Optimization Of Liquid-vapor Separation Header With Multi-Pass Heating Tube

In this paper, numerical simulation using VOF model with Fluent was performed to optimize the structure of liquid-vapor separation headerthrough investigating the liquid-vapor separation flow property Using R134a refrigerant as the working fluid.The liquid-vapor separation header is the key component in Manifold to achieving highheat transfer efficiency in the liquid-vapor separation condenser. The main role of liquid-vapor separation is to separate the two phase flow and discharge the liquid phase to the next pass.by using the gas-liquid density variety, the liquid was deposited on a orifice plate and then discharged through the baffle holes, in the same time, vapor was discharged through the outlets branch to the downstream heating tubes resulting in high quality two phase flow which can improve overall heat transfer performance of liquid separation condenser. As the critical components necessary to achieve effective drainage, while ensuring effective vapor barrier action, both of which require structural optimization.In this paper, typical conditions wereselected. The flow characteristics of liquid-vapor header with experimental header structure was investigated, The gas-liquidseparation efficiency, two-phase working fluid distribution,Dryness distribution characteristics in header outlets, pressure distribution and volatility characteristics, and the flow distribution in baffle holes were analyzed; then the influence of baffle hole diameter on the performanceof header were demonstrated. At last, the influence of channel depth on the performance of header with vertical channel structure was analyzed.The results show that:the baffle hole diameter mainly affects the discharge flow, the channel depth mainly affects the film deposited at the bottom of liquid-vapor separation header. The discharge flow enhanced with the increase of baffle hole diameter, the liquid film deposited at the bottom of liquid-vapor separation header significantly rises when vertical channel header used. At given conditions, the baffle hole diameter and the channel depth have no effect on the pressure distribution in the header.Atgiven conditions, gas flow distribution uniformity of outlets will not change significantly with the baffle hole diameter, while the liquid flow distribution uniformity improves. The best uniformity occurs when the baffle hole diameter is 0.4mm. When the flow converged and becomes stable, the time averaged volatility of vapor flow rate remains unchanged as the baffle hole diameter increases, while the time averaged volatility of liquid flow rate decreases or remains unchanged.To the header structure with vertical channel, vapor flow distribution uniformity remains unchanged with the increase of channel depth, while the liquid flow distribution uniformity decreases.When the channel depth is too small, the liquid film is easily peeled off from the header wallresulted by the vapor flow. when the channel depth is too large, the deposited liquid film at the bottom of liquid-vapor separation header is easilydispersed by air shock on the peak of channel. When the channel depth is 0.2mm, the continuity of liquid film is of the best. As the channel depth increases, the volatility of flow rate relatively increases when the channel depth increases.