The thermal storage tank can improve the peaking flexibility of the cogeneration unit to a certain extent

but the heat storage performance of the thermal storage tank is affected by the thermocline inside the tank. In this study

the thermocline characteristics of the thermal storage tank during operation are analyzed. And then the onedimensional non-steady-state model of the thermal storage tank is established based on the energy balance equation. The concept of EDDY is introduced in the model

and the implicit difference equation of one-dimensional nonsteady-state heat conduction is used to solve the model numerically. In addition

the effects of different mixing modes and different mixing intensities on the thermocline inside the tank are studied. Taking the heat-filling process as an example

under different mixing modes

the temperature distribution of the thermocline in the observing zone and the change of thermocline thickness with the heat-filling time are analyzed and compared. The results show that the thermocline thickness increases with the operating time

and the growth rate gradually slows down. The mixing intensity of the inlet section of the thermal storage tank has the greatest influence on the development of the thermocline thickness. Besides

under the same conditions and at the same moment

the larger the value of EDDY is

the greater the thermocline thickness is. This model runs steadily and computes quickly

and it can clearly reflect the change of the thermocline thickness

which provides guidance for the efficient

safe and flexible operation of the unit.