Transient inverse heat transfer problem in control of plate fin and tube heat exchangers

A transient inverse heat transfer problem encountered in control of fluid temperature or heat transfer rate in a plate fin and tube heat exchanger was solved. The objective of the process control is to adjust the speed of fan rotation, measured in number of fan revolutions per minute, so that the water temperature at the heat exchanger outlet is equal to a time-dependent target value (setpoint). The least squares method in conjunction with the first order regularization method was used for sequential determining the number of revolutions per minute. Future time steps are used to stabilize the inverse problem for small time steps. The transient temperature of the water at the outlet of the heat exchanger was calculated at every iteration step using a numerical mathematical model of the heat exchanger. The technique developed in the paper was verified by comparing the calculated and measured number of the fan revolutions. The discrepancies between the calculated and measured revolution numbers are small.