Efficiency of mixed-flow heat exchangers

Аннотация

It has been shown that studies are aimed at improving existing apparatuses and their elements in the agitating zone of liquids. A great deal of attention is devoted to investigating heat exchange upon stirring, the problem of the intensification of which has not been solved completely. For this reason, apparatuses with vertical heat-exchange units are considered to be promising. A model that allows for the assumption of the effect of the features of the design of agitator and heat-exchange units designed as vertical tubes on the heat-exchange efficiency in the stirring apparatus has been suggested. Results of experimental investigations of hydrodynamics and heat exchange in the apparatuses under study have been given and their high heat effectiveness has been demonstrated. The effectiveness of heat transfer has been compared in the blocks with parallel and series-connected tubes at identical flow rates of the heat carrier in the pipes of each block. No difference in the effectiveness of heat transfer is observed in the entire range of the rotation frequency of a stirrer. At higher water consumption, a block with parallel-connected pipes provides a higher amount of heat flow due to the larger driving force of heat transfer. Experimental data are generalized based on the theoretical dependence for calculating the coefficient of heat withdrawal from the agitated medium. The possibility of increasing coefficients of heat withdrawal from the agitated medium is only restricted by the supplied mechanical energy. An example of the calculation of apparatuses has been given.