A Numerical Investigation Of Flow Distribution In A New Type Of Shell-and-tube Heat Exchanger

This thesis mainly foucus on the numerical simulation research of a new type shell-and-tube heat exchanger which has a special structure called comb baffle. The structure of comb baffle has many holes on its edge, and because of that, the comb baffle has the function of inlet flow distribution. Compared to the traditional shell-and-tube heat exchanger that has single shell, this new type shell-and-tube heat exchanger has a double shell, and its flow distribution is better. For the tube bundles in the shell of new type shell-and-tube heat exchanger, we choose three types, including the ordinary smooth tube bundles, the symmetrical convex corrugated tube bundles and the convex helical tube bundles. In our research, we change the parameters of geometrical structure, such as the tube bundles’ array type, the space among tubes and the inlet Reynolds number. And then we need the help of mathematics and statistics knowledge. There are a few atatistical formulas that can quantitatively describe the inlet flow’s velocity distribution. And we do this numical simulation in the use of the commercial software of FLUENT. Through the simulation, we can draw some important conclusions about the issue of flow distribution in the new type of shell-and-tube heat exchanger which has the comb baffle structure.(1) Compared to the traditional shell-and-tube heat exchanger, the new type heat exchanger is better on the flow distribution.(2) For the new type of shell-and-tube heat exchanger, it can be categorized into two types based on the structure of comb baffle: type 1 and type 2. Compared to the traditional shell-and-tube heat exchanger, the new type heat exchanger is better on the flow distribution. We change the geometrical parameters of tube bundles and comb baffle, and select the best parameters for inlet flow distribution. In the shell region of heat exchanger, for the three types of tube bundles, including smooth tube bundles, the symmetrical convex corrugated tube bundles and the convex helical tube bundles, low Reynolds number, large space among tubes and the tranigle array of tubes are better for flow distribution in the heat exchanger. When comes to the parameters of comb baffle, the height of comb baffle h=50 mm, the area ratio of holes on the comb baffle Ф=12.97% and type 1 are the best choice for smooth tube bundles. On the other hand, he height of comb baffle h=40 mm, the area ratio of holes on the comb baffle Ф between 10.95% and 12.97%, and type 2 are the best parameters for corrugated tube bundles and helical tube bundles.(3) Compared to the three types of heat exchangers, on the field of the inlet flow distribution, smooth tube bundles heat exchanger is better than the special pipes. And the corrugated tube bundles heat exchanger is better than the helical tube bundles heat exchanger.