Evaporation and Condensation of HFC-134a in Micro-fin Copper Tubes

การระเหยตัวและการควบแน่นของสารทำความเย็น HFC-134a ภายในท่อทองแดงที่มีครีบเล็กมากอยู่ภายใน

Name: Thipjak Nualboonrueng

Name: ทิพย์จักร นวลบุญเรือง

Organization : King Mongkut's University of Technology Thonburi. Faculty of Engineering. Mechanical Engineering

keyword: Heat Transfer Coefficient

; สัมประสิทธิ์การถ่ายเทความร้อน

Abstract: The average heat transfer coefficient and pressure drop of HFC-134aduring evaporation and condensation in smooth and micro-fin tubes are reported. Ahorizontal smooth copper tube with an outside diameter of 9.52 mm, and two microfintubes with outside diameters of 9.52 mm are employed. The data are taken attemperatures of 10,15 and 20?C for evaporation test and 30, 40 ?C for condensationtest. The mass flux is in a range of 400 to 800 kg/m2s and the heat flux is between 5to 20 kW/m2.For evaporation test the experimental results for both smooth and microfintubes show that the average evaporation heat transfer coefficient tends to increasewith an increase in average quality, mass flux, heat flux, and evaporatingtemperature. For smooth and micro-fin tubes, the pressure drop during evaporationincreases with an increase in average quality and mass flux, but tends to slightlydecrease with a rise of evaporating temperature. The average evaporation heattransfer coefficient of type A micro-fin tube is 40 to 80 percent higher than thesmooth tube while the pressure drop is 5 to 30 percent higher. For type B microfintube the average evaporation heat transfer coefficient is 50 to 100 percent higher thansmooth tube while the pressure drop is 10 to 60 percent higher. In addition, theresults show that the heat transfer coefficient of type 3 micro-fin tube isapproximately, 5 to 15 percent higher than type A micro-fin tube. The pressure dropin type B micro-fin tube is approximately 5 to 25 percent higher than type A microfintube.For condensation test the experimental results for both smooth and microfintubes show that the average condensation heat transfer coefficient tends toincrease with an increase of average quality, mass flux, heat flux, but it tends todecrease with an increasing condensing temperature. For smooth and micro-fintubes, the pressure drop during condensation increases with an increase of averagequality and mass flux, but tends to slightly decrease with a rise of condensingtemperature. The average condensation heat transfer coefficient of the type A microfintube is 5 to 60 percent higher than the smooth tube while the pressure drop is 10to 30 percent higher. For type B micro-fin tube the average condensation heattransfer coefficient is 10 to 85 percent higher than smooth tube while the pressuredrop is 30 to 50 percent higher. Another observation, the results show that thecondensation heat transfer coefficient of type B micro-fin tube is approximately 5 to20 percent higher than type A micro-fin tube and the pressure drop in the type Bmicro-fin tube is approximately 5 to 40 percent higher at mass flux of 600 and 800kg/m2s but the average condensation heat transfer coefficient for the type A microfintube is higher than type B micro-fin tube approximately 10 percent at mass flux of 400 kg/m2s.

King Mongkut's University Technology Thonburi. Library

Address: Bangkok

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

Name: Somchai Wongwises

Role: Advisor

Created: 2001

Issued: 2008-01-18

Modified: 2016-01-07

วิทยานิพนธ์/Thesis

CallNumber: MEE1374

eng

DegreeName: Master of Engineering

Level: Master's Degree

Descipline: Mechanical Engineering

Grantor: King Mongkut's University of Technology Thonburi

©copyrights King Mongkut's University of Technology Thonburi

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