[Hazel]

PROB 1:I have found this data in Concentric Tube Heat Exchanger H952:

Tube Outer Diameter = 15 x 0.7mm Wall

Ｆｒｏｍ　ｔｈｅ　ｄｉａｇｒａｍ，　Ｉ am not sure the data indicates A+B = 0.7mm or A and B is 0.7mm respectively.

Prob 2 : When I calculate a log mean temperature for a counter current flow,i found that the difference of THin and TCout is the same as the difference of THout and TCin.Therefore,the log mean temperature will become zero.In this case,is it unnecessary to count for the log mean temperature?I　ｊｕｓｔ　ｎｅｅｄ　ｔｏ　ｆｉｎｄ　ｉｔｓ　ｍｅａｎ　ｔｅｍｐｅｒａｔｕｒｅ，ｒｉｇｈｔ？．．ｉｅ，ｗｈａｔ　ｉｓ　ｔｈｅ　ｓｉｇｎｉｆｉｃａｎｔ　ｔｏ　ｕｓｅ　ｌｏｇ　ｍｅａｎ　ｔｅｍｐｅｒａｔｕｒｅ？．．

[amitjthakkar]

Dear Hazel

PROB 1: A=0.7 mm and B=0.7 mm

Prob 2: In an Heat Exchanger there is not an exact temp diff. every where the heat transfer area, so LMTD is used as a more accurate measure.

Thanks
Amitjthakkar

PROB 1:I have found this data in Concentric Tube Heat Exchanger H952:

Tube Outer Diameter = 15 x 0.7mm Wall

Ｆｒｏｍ　ｔｈｅ　ｄｉａｇｒａｍ，　Ｉ am not sure the data indicates A+B = 0.7mm or A and B is 0.7mm respectively.

Prob 2 : When I calculate a log mean temperature for a counter current flow,i found that the difference of THin and TCout is the same as the difference of THout and TCin.Therefore,the log mean temperature will become zero.In this case,is it unnecessary to count for the log mean temperature?I　ｊｕｓｔ　ｎｅｅｄ　ｔｏ　ｆｉｎｄ　ｉｔｓ　ｍｅａｎ　ｔｅｍｐｅｒａｔｕｒｅ，ｒｉｇｈｔ？．．ｉｅ，ｗｈａｔ　ｉｓ　ｔｈｅ　ｓｉｇｎｉｆｉｃａｎｔ　ｔｏ　ｕｓｅ　ｌｏｇ　ｍｅａｎ　ｔｅｍｐｅｒａｔｕｒｅ？．．