Modeling of Variable Operating Modes of Water-to-Water Heat Exchangers

Abstract Heat exchangers used in heat supply systems operate in conditions of variable flow rates and temperatures of heat carriers. Existing theories for calculating variable modes of heat exchangers are based on the use of dimensionless constant parameters, regardless of their mode of operation. The use of such theories with a large change in temperature or flow rates of heat carriers in the heat exchanger leads to a significant error. Modeling of various variable operating modes of a counter-flow water-to-water heat exchanger with a change in its heat capacity allowed us to establish patterns of change in the parameters of heat exchangers and to construct a technique available for engineering calculations. This task becomes especially relevant when upon transition to new methods of central and local regulation of heat supply systems. Verification of the developed method was carried out on a heat exchanger model in the ANSYS Fluent package. This method is quite accurate; however, it requires the construction of a calculation model and takes a very long time, which does not allow it to be used for operational control of the operation modes of heat supply systems. Comparison of the calculation results showed a rather high accuracy of the developed methodology for different operating modes of heat ex-changers.