การวัดค่าการถ่ายเทความร้อนในระบบการไหลแบบสองวัฏภาคโดยวิธี Liquid Crystal

Name: มธุรดา จิโนรส

Organization : มหาวิทยาลัยเทคโนโลยีพระจอมเกล้าธนบุรี

keyword: Aseptic Processing

; Convective Heat Transfer Coefficient

; Color-Temperature Relationship

Abstract: The present study aimed at developing a technique to determine the values of the liquid-to-particleheat transfer coefficient (hfp) in an aseptic food processing system. The technique involved the useof liquid crystal, which charges color with temperature, along with an image processing technique,to measure the temperature of a moving particle in a holding tube. In the first part, a colortemperature relationship was developed by video-taping the changes of color of liquid crystal,which was coated on a still particle, analyzing the images obtained to determine the values of theaverage color of the particle by fixing the required pixels on the particle surface and comparing thedata with those obtained from a thermocouple welded to the surface of the particle. The mean colorvalues were then used to develop a correlation for prediction the temperature of the particle movingthrough the holding tube. For the measurement of the temperature of a particle moving through atube, the changes of color of liquid crystal, which was coated on the particle, were again videotapingand these images were then analyzed to determine the average color changes of particle.Since, in this step, both the position and size of the particle was not constant, it was necessary tochange the method, which was used to fix the position of the particle, i.e., changing the colorimages to gray-scale images using saturation values from the HSV color system, in order to separatethe particle from the dark background. This was done by fixing the position of the particle based onits threshold band; the mean color of the particle was then determined. The temperature values werethen predicted from the developed correlation; the values of hfp were then obtained. The values ofthe calculated hfp were compared with those obtained from the relative velocity method, whichreported the values of hfp in the range of 220 to 1129 W/m2K, slightly different from those obtainedusing the liquid crystal method of 186 to 1115 W/m2K, over the range of the particle Reynoldsnumber of 829 to 1460. This method can therefore be applied to determine hfp in an aseptic processbut with some limitation depending on the system.

มหาวิทยาลัยเทคโนโลยีพระจอมเกล้าธนบุรี

Address: กรุงเทพมหานคร (Bangkok)

Email: info.lib@mail.kmutt.ac.th

Name: ผศ. สุวิช ศิริวัฒนโยธิน

Role: อาจารย์ที่ปรึกษา

Created: 2546

Issued: 2005-11-10

Modified: 2006-05-10

วิทยานิพนธ์/Thesis

ISBN: 9741835299

CallNumber: FDE227

tha

DegreeName: วิศวกรรมศาสตรมหาบัณฑิต

Level: ปริญญาโท

Descipline: วิศวกรรมอาหาร

Grantor: มหาวิทยาลัยเทคโนโลยีพระจอมเกล้าธนบุรี

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3	FDE227ab.txt	2.55 KB	23	2022-01-28 22:25:04

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