Обґрунтування вибору параметрів струминної системи підведення сушильного агента до рухомого полотна

Authors

  • О. В. ШЕЛІМАНОВА

Abstract

THE REASONING OF THE CHOICE OF THE JET  SYSTEM’S PARAMETERS FOR THE DRY AGENT’S SUPPLYING TO THE MOVING CLOTH OF MATERIAL

O. Shelimanova

 

 

The need to save heat energy in the process of drying agricultural raw materials while preserving the quality of the final product encourages specialists to look for ways to intensify the external heat and mass transfer, among which one of the most effective is the jet blown. This method was proposed to be used in the installation for drying the moving fabric of the material with air.  In this dryer the stream system is realized with the bilateral symmetric taking of air for to the flat channels equivalent diameter of which – dе| = 2h and 160  for a channel above linen and 240  is evened - for a channel under linen. The amount of rows of streams for the step of motion of air is evened 3.

Injecting the drying agent contributes to a significant increase in the intensity of the drying process, but at the same time the power required for pumping of the coolant  is increasing too. The purpose of this study is to determine the geometric parameters of the jet system, which would provide the highest intensity of heat transfer with minimum hydraulic losses.

The calculations were carried out using a channel model of transport processes with the flow around a surface by a system of jets], which was adapted to the case of jet flow around a moving surface.

The distances from the nozzle grate to the material h were chosen from the conditions for optimal heat exchange intensification by recommendations. Therefore, in the further analysis h remains unchanged.

Thus, the real parameters of the control for the heat transfer processes are the length of the nozzle grate B1 and the perforation surface fo, that depends on the number and diameter of the perforation holes. In this case, the decrease of B1 leads to a decreasing in the length of the air path in the channel, and the decrease of fo - to increasing the speed of the jets, and, as a consequence, to the intensification of heat transfer.

The resulting effect will be determined by the combined effect of all parameters characterizing the heat transfer process.

As a result of the study, the optimal parameters of the jet system were established: 520 holes with a diameter do = 0,015 m, located in 5 rows with a uniform step S1 = 0.035 m. This configuration of the jet system will provide an increase in the heat transfer coefficients by 40% with a hydraulic resistance increase of no more than 20 %.

 

 

 

 

 

 

References

Dyban, E. P., Mazur, A. Y. (1982). Konvektyvnyi teploobmen pry struinom obtekanyy tel [Convective heat transfer in jet flow around bodies]. Kyiv: Naukova Dumka, 303.

Dyban, E. P., Mazur A. Y., Shelimanova E. V. (1993). Struinoe okhlazhdenye orebrennykh poverkhnostei polumatryts hofratorov [Jet cooling of finned surfaces of corrugator semimatrixes]. Promyshlennaia teploenerhetyka, 3, 3–10.

Shelimanova, O. V. (2008). Vdoskonalennia protsesu soplovoi sushky rukhomoho polotna materialu [Perfection of process of nozzle drying moving cloth of material] Elektronne vydannia „Naukovi dopovidi Natsionalnoho ahrarnoho universytetu. Tekhnichni nauky”, 2 (10), 1–8. Available at: http://nd.nubip. edu.ua/2008-2/08sovcnd.pdf

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Published

2018-09-10

Issue

No. 283 (2018)

Section

Статті

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