Известия Томского политехнического университета: Инжиниринг георесурсов (Mar 2020)
EXPERIMENTAL STUDIES OF PERSPECTIVE METHODS OF HEAT TRANSFER INTENSIFICATION IN A TUBULAR HEAT EXCHANGER
Abstract
The relevance of the research is caused by the need to increase the intensity of heat transfer in tube heat exchangers of the chemical and petrochemical industries. Devices of this type are bulky, as a rule, characterized by high metal consumption, occupy large production areas. Intensification of heat transfer will reduce the dimensions of heat exchange equipment, reduce heat loss to the environment and increase technical and economic performance indicators. The experimentally obtained criterion equations can be used in development of intensified heat exchangers. The main aim of the study is to experimentally determine the dependence of the Nu criterion on the Re criterion in laboratory intensified tube-in-tube heat exchangers that implement the following methods of heat transfer intensification: 1) the use of mesh and spiral turbulators; 2) the use of a fluidized bed of spherical metal particles; 3) rotation of the heat exchanger pipe due to the kinetic energy of the coolant flow. Methods: experimental determination of dependence of the Nu criterion on the Re criterion in laboratory intensified tube in tube heat exchangers, instrumental determination of temperature and fluid flow, fluidized bed height; video shooting. Results. The dependence of the Nu criterion on the Re criterion in laboratory intensified tube-in-tube type heat exchanger is experimentally determined. For the turbulators investigated at 10000<Re<25000, empirical criterial dependencies were obtained within the error margin of ±5%. The study of the method of intensifying heat transfer through the use of a fluidized bed in a vertical heat transfer tube showed that the best hydrodynamic conditions for intensifying heat transfer are achieved in a fluidized bed of lead spherical particles with a diameter of d=0,002 m. For a fluidized bed of spherical lead particles d=0,002 m at 5000<Re<15000, an empirical criterial dependence was obtained within an error of ±6%. It was found that in a rotating cooled horizontal heat exchange tube with a constant frequency of 2,0 r / s, the Nu criterion rises on average 1,24 times in the range of 10000<Re<40000. The analysis showed that an increase in the heat transfer intensity in the investigated heat exchanger is ensured by improving mixing of the fluid flow, as well as by turbulization of the parietal layer. The results of experimental studies allow us to conclude that the considered methods of intensifying heat transfer are promising for further research and use in chemical and petrochemical production.
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