# Heat Transfer Performance and Flow Characteristics of Helical Baffle-Corrugated Tube Heat Exchanger
## 2 Numerical Simulation and Verification
### Experimental Verification  
In this paper, the device shown in Figure 3 was built to verify the validity of the numerical algorithm, and the parameters of the test device are consistent with the parameters in the numerical calculation model. The device consists of a hot- and cold-water circulation system, a continuous helical baffle heat exchanger, a temperature control system, and a data acquisition system. During the experiment, the inlet and outlet temperatures of the heat exchanger, the differential pressure in the tube course, the differential pressure in the shell course, and the volume flow rate of the cold- and hot-water pipelines were recorded.  
\begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Size (mm)** & **Node No.** & **Pressure Drop (Pa)** & **Error (to Exp.) (\%)** & **Heat Transfer Coefficient** & **Error (to Exp.)** \\  & & & & **(W/(K\(\cdot\)m\({}^{2}\)))** & **(\%)** \\ \hline
1 & 1,721,994 & 11,853.25 & 6.71\% & 2014.13 (2173.22) & 7.32\% \\
3 & 2,828,456 & 11,246.15 & 1.25\% & 2109.58 (2173.22) & 2.93\% \\
5 & 5,958,327 & 11,107.44 & 0.00\% & 2173.18 (2173.22) & 0.00\% \\ \hline \hline \end{tabular}
\end{table}
Table 1: Mesh independence verification (experimental values in parentheses).  
The experiments were repeated three times for each condition to reduce the effect of errors generated during the experimental process, and the temperature data and pressure data were recorded every 2 s for each set of conditions. Convective heat transfer experiments were carried out with different shell flow rates. The main influence of the continuous helical baffle on the heat exchanger studied in the experiment lies in the shell course, and the flow rate of the tube course remains unchanged during the experiment and simulation. Only the influence of the change of the flow rate of the shell course is investigated, so the heat transfer coefficient of the shell course and the pressure drop are used as the comparative parameters. The variation in the shell heat transfer coefficient with the shell flow rate for the continuous helical baffle heat exchanger in experimental and numerical simulations is shown in Figure 4a, and the variation in the pressure drop with the shell flow rate is shown in Figure 4b.  
Figure 3: Test device (**a**) Schematic diagram; (**b**) Heat exchanger for test.  
Figure 2: Numerical simulation flowchart.  
As demonstrated in Figure 4, the shell heat transfer coefficient and pressure loss exhibit a linear increase with rising shell flow. The experiments conducted using a continuous helical baffle heat exchanger were compared to the experimental and simulation results for the shell heat transfer coefficient and pressure loss under similar conditions. The experimental and simulation results have a maximum deviation of 6.15% for the shell heat transfer coefficient, and the maximum difference in the shell-stage pressure drop between the experiment and simulation is 13.19%, which is within a reasonable range. The mutual verification attests to the reliability of the numerical and experimental outcomes of the simulation model. It is also observed that when the shell flow rate is 3.5 m\({}^{3}\)/h, the experimentally obtained heat transfer coefficient has a high uncertainty. After verification of the data, we initially judge that this is due to the instability of heat transfer in the experimental equipment at lower flow rates. However, combining the performance at all flow rates, the experiments and simulations are still in good agreement.