Translated Abstract
As one of the important parts of the very high temperature reactor system, high temperature heat exchanger is required to withstand temperature above 900℃ and pressure above 7 MPa, and excellent tightness is also needed. Printed Circuit Heat Exchanger (PCHE) is one of the promising candidates in the very high temperature reactor system. Being different from the traditional tube heat exchanger, PCHE has high compactness and heat transfer effectiveness. Under the same quantity of heat transfer, the volume of the PCHE will be smaller than that of the tube heat exchanger. Nowdays, PCHE has not been applied in the very high temperature reactor system, and only Heatic LTD in UK has the technologies to design and manufacture it. In the present paper, the heat transfer and pressure drop characteristics of two typical PCHEs, zigzag channel and airfoil fined, are numerically studied. At last, the technology of photo-chemical etching is experimentally studied. The primary work and the conclusions are summarized as follows.
1. A simulation model for the zigzag channel is established, and the numerical simulation under laminar flow has been done. The local Nusselt number and friction factor at high temperature match well with those at low temperature when the Reynolds number ranges from 900 to 2300. So PCHE can be numerically simulated by the low temperature fluid instead of the high temperature fluid.
2. A numerical simulation for the airfoil fined PCHE is performed, and the difference between the model with a single fluid and two fluids is obtained. The Nusselt number and friction factor obtained by the model with a single fluid match well with those obtain by the model with two fluids. The effect of transverse and longitudinal pitch on the thermal hydraulic performance is also numerically investigated. The result indicates that the Nusselt number and the friction factor decrease with the increase of the transverse pitch, as well as the longitudinal pitch.
3. The effect of different factors on the results of photo-chemical etching technology is experimentally investigated. It is found that the etching rate increases with the increase of the concentration of FeCl3, but decreases when the concentration of FeCl3 is more than 300 g?L-1. It is also found that high concentration seems have a good effect on the later etch. The etching experimental result indicates that the airfoil fin is not an ideal airfoil profile, but has a fin-endwall fillet. The real model with end-wall can enhance the heat transfer but also increase the pressure drop. And the difference decreases with the increase in airfoil pitch.
Translated Keyword
[Channel form, High temperature heat exchanger, PCHE, Photo-chemical etching, Thermal-hydraulic performance]
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