Thermal characteristics of ?n-tubes. A study was conducted to model the thermal performance of integral-?n tubes used in the refrigeration and process industries (Journal of Heat Transfer, August 1990). Twenty-four specially manufactured integral-?n tubes with rectangular ?ns made of copper were used in the experiment. Vapor was released downward into each tube and the vapor-side heat transfer coef?cient (based on the outside surface area of the tube) was measured.
The dependent variable for the study is the heat transfer enhancement ratio, y, de?ned as the ratio of the vapor-side coef?cient of the ?n tube to the vapor-side coef?cient of a smooth tube evaluated at the same temperature. Theoretically, heat transfer will be related to the area at the top of the tube that is ‘‘un?ooded'' by condensation of the vapor. The data in the table are the un?ooded area ratio (x) and heat transfer enhancement (y) values recorded for the 24 integral-?n tubes.
(a) Fit a least squares line to the data.
(b) Plot the data and graph the least squares line as a check on your calculations.
(c) Calculate SSE and s2.
(d) Calculate s and interpret its value.
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UNFLOODED AREA RATIO,x
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HEAT TRANSFER ENHANCEMENT,y
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UNFLOODED AREA RATIO,x
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HEAT TRANSFER ENHANCEMENT,y
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1.93
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4.4
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2.00
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5.2
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1.95
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5.3
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1.77
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4.7
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|
1.78
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4.5
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1.62
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4.2
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1.64
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4.5
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2.77
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6.0
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1.54
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3.7
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2.47
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5.8
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1.32
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2.8
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2.24
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5.2
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2.12
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6.1
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1.32
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3.5
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|
1.88
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4.9
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1.26
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3.2
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1.70
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4.9
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1.21
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2.9
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1.58
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4.1
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2.26
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5.3
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2.47
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7.0
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2.04
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5.1
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2.37
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6.7
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1.88
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4.6
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