Tq-Diagram Computing Algorithm for the Multi-Flow Heat Exchanger

The study given considers a technique for computing the qT-diagram of a multi-flow heat exchanger with an arbitrary number of flows. The specified parameters of the computation are the temperature, pressure, mass rate of all hot and cold flows at the heat exchanger inlet port, and the value of the lowest allowed temperature difference between the flows. The last parameter establishes the heat exchanger's overall thermodynamic efficiency. The algorithm for calculating the qT-diagram includes the calculation of the maximum heat content of the flows, the maximum amount of heat that can be transferred in the heat exchanger, and all possible distributions of this heat between the flows. The outlet temperatures of the flows are computed for each heat distribution, and the results are sorted and ranked according to the chosen objective function. The sorted operating modes of the heat exchanger are checked from the point of view of the qT-diagram's operability in accordance with a given criterion. Comparisons with the results of calculations of similar heat exchangers in the HYSYS AspenONE verified the algorithm's accuracy and physical consistency.