Actually it’s 3/4 of the way up
And you wouldnt be able to tell running parrellel flow because eventually the solvent and chiller fluid will reach the same temperature
Heres a good explanation
Counter flow is better than co current flow because:-
More rate of heat transfer throughout the length.
A=========================B
let above be a double pipe heat exchanger. Double pipe means it has two concentric tubes . OK now lets say
Condition A: Parallel flow
hot fluid enters from point A at say 120 degree Celsius
cold fluids enters into shell side say at 40 degree Celsius.
Now with travelling same distance x towards point B temp of hot liquid will fall and that of cold will rise say at mid the temp. of hot liq. be 80 and cold liquid be 60. now after travelling more distance toward B let temp. of hot liq be 70 and that of cold be 68. further there will be a point where both the temp may be equal.
OK , we have understood what will happen throughout length
now what we get is in parallel flow the temp. difference of hot and cold liq decreases throughout the length. Thus rate of heat transfer decreases as distance travelled increases.
Also if at a point temperature of both liquids will be same heat transfer in that case will stop thus further no drop will be possible.
Condition B : Counter current flow
A=====================B
Hot fluid enters from point A say at 120 degree celsius
Cold fluid enters from point B say at 40 degree celsius
Now as cold fluid moves toward point A its temp. rises let at point B
fluid A be at 60 degree because its has been cooled by the cold fluid that is ahead point B. thus here temp difference is 20 and thus heat transfer will take place.
now in midway let temp of hot fluid be 90 and that of cold be 65. here temp difference is 25 thus heat transfer will take place here too. also at point A hot fluid be at temp. 120 and cold fluid will experince a rise in temp. and thus will reach around 90 say.
thus heat transfer will take place here also
what we observe is
A: Proper heat transfer is maintained through out the lenght
B: there is no dead point in between where heat transfer will stop.
C: it is possible that outlet temp. of cold liq. will be greater than that of hot liq. in counter current where as in parallel flow it will give you the same temp. in the extreme case.
And i do know more than you, you obviously dont know how to use a chiller to maximize its efficiency.
I bet you over size every chiller just because youre so retarded you dont know the most efficient way to hook them up which costs your customers money
On a rotovap youll get WAYYYY more condensing power running counter flow than running parrellel just because youre actually using the whole coil but youre too dumb to realize that
Thats why most industries prefer counter current to parrellel…
. And call other nerds.