Novel study on inverse convection–conduction heat transfer for plate-finned tube heat exchanger

In this study, the inverse 3D computational fluid dynamics method combined with the least squares method and excessive experimental temperature measurements is employed for the prediction of the unknown heat transfer rate and free convection heat transfer features and select an approximate flow model for the plate-finned tube heat exchanger. The results indicate that the heat transfer coefficient h¯_f2 on the second fin estimated by the ZEM is closer to the existing inverse result than other flow models. In addition, its root-mean-square error is also small enough in all used flow models. The obtained values of h¯_f2 and RMSE agree with those obtained from the isothermal assumption. Thus, this inverse technique has good accuracy and reliability. This inverse technique also needs less experimental temperature data than the isothermal assumption. The temperature and heat dissipation for each pipe and fin can also be estimated. The influence of the flow model and the vertical distance between two vertical pipes on the obtained estimates is also investigated. The mean dissipative heat transfer rates of per pipe for the vertical distances between centers of two pipes (S_tv) of 0.054 m, 0.045 m, and 0.036 m are 10.72 W, 12.12 W, and 10.28 W, respectively. The heat losses in this study for S_tv = 0.054 m, 0.045 m, and 0.036 m are 2.7%, 3.0%, and 4.5%, respectively.