Thermal Condition in the Channels of Plate Heat Exchangers

Abstract

Equipping heat points with plate-type heat exchangers is an integral structural element of the 3rd generation heat and power network and a component of the reliability of the heat supply system as a whole. It has been established that the optimization calculations of heat exchangers of this type are difficult due to the absence of dependences on heat transfer and hydraulic resistance between the channels in the structural space of the heat exchanger.Purpose of research. To clarify the method of calculating plate heat exchangers, excluding the equality of thermal and hydraulic conditions from the generally accepted assumptions.Methods. The research methodology is based on the use of the law of conservation of mass in order to determine the temperature parameters of working fluids in each channel. The solution of this problem is proposed in the form of a system of equations, each of the equations of which characterizes the thermal balance of the channel under consideration. A computer model of the heat exchanger is constructed in order to conduct a numerical study of the thermal regime of the heat exchanger.Results. It is indicated that as an assumption in the well-known mathematical model for calculating the thermal regime of a plate-type heat exchanger, the condition of equal distribution of fluid flows between channels is accepted. This restriction leads to equalization of liquid temperatures in each channel. Taking into account the geometric arrangement of the channels, the excess of the final temperature of the heating and heated coolant in the first and last channels with respect to known data is up to 10%. The results of the study confirm the hypothesis of uneven heating of the coolant along the length of the plate package due to the uneven flow distribution between the channels.Conclusion. The results of analytical calculation and modeling in the SolidWorks environment of the temperature regime in the channels of a plate-type heat exchanger indicate a significant influence of the geometric arrangement on the thermal regime in the channels. The formulated provisions of the mathematical description of the unevenness of the thermal regime of heat exchange channels, taking into account the location of the plates, are recommended to be used when improving the design parameters of plate-type heat exchangers.