A/W Intercooler - Coolant flow direction?
10-03-2015, 10:20 AM
#1
A/W Intercooler - Coolant flow direction?
Doing a little investigation on the intercooler below my Kenne Bell 2.8L, I have discovered that the dual pass design is an over/under rather than side to side as have seen on heat exchangers. This has me wondering in the respect of both coolant flow and thermodynamic heat transfer, which direction of coolant flow would be most beneficial.
Thermodynamically:
Heat transfer is made due to temperature differential, hot to cold. The greater the differential, the more heat is absorbed over a given amount of time. With the over/under design with both passes of coolant being in the same air flow stream, the first pass will see the greatest possible temp differential between air charge and coolant if the coolant enters the top chamber first. If it were to enter the bottom pass first, the air charge would already be cooled somewhat from the top pass and the coolant in the top pass would already warmed some reducing the over all temp delta on both passes. However from a total delta stand point, it may be not make a difference which direction it goes. :dunno:
Cliffnotes: coolant top to bottom, greater temp delta on first pass less on second or coolant bottom to top, somewhat equal deltas on each pass.
Hydrodynamically:
Simple fluid flow, it will take the path of least resistance. The least resistance the circuit has, the higher the flow rate for a given pressure. I don't think connecting the in/out in either direction is going to effect total resistance of the ic's portion of the circuit. I am concerned about flow path internally in the ic. The end tank seems to be separated top to bottom in the manner sketched on the end tank in the pic below. I do not believe the bars (coolant passages) are separated though. Therefore once the coolant leaves the separator/end tank, the going and returning coolant have a chance to blend and could result in a 'short circuit' so to speak. If the resistance were high enough on the end of the ic, there may not be much coolant flow thru the ic at all, just jumping from one tank to the other. If the passages are indeed not separated (which I thoroughly believe) i believe bringing the coolant into the bottom chamber first would provide an opportunity for more coolant to actually flow down the ic before circulating back up to the outlet.
With all that said, I am perplexed as to which direction to flow the coolant thru the ic as my theories support one direction thermodynamically and the opposite direction hydrodynamically.
Thermodynamically:
Heat transfer is made due to temperature differential, hot to cold. The greater the differential, the more heat is absorbed over a given amount of time. With the over/under design with both passes of coolant being in the same air flow stream, the first pass will see the greatest possible temp differential between air charge and coolant if the coolant enters the top chamber first. If it were to enter the bottom pass first, the air charge would already be cooled somewhat from the top pass and the coolant in the top pass would already warmed some reducing the over all temp delta on both passes. However from a total delta stand point, it may be not make a difference which direction it goes. :dunno:
Cliffnotes: coolant top to bottom, greater temp delta on first pass less on second or coolant bottom to top, somewhat equal deltas on each pass.
Hydrodynamically:
Simple fluid flow, it will take the path of least resistance. The least resistance the circuit has, the higher the flow rate for a given pressure. I don't think connecting the in/out in either direction is going to effect total resistance of the ic's portion of the circuit. I am concerned about flow path internally in the ic. The end tank seems to be separated top to bottom in the manner sketched on the end tank in the pic below. I do not believe the bars (coolant passages) are separated though. Therefore once the coolant leaves the separator/end tank, the going and returning coolant have a chance to blend and could result in a 'short circuit' so to speak. If the resistance were high enough on the end of the ic, there may not be much coolant flow thru the ic at all, just jumping from one tank to the other. If the passages are indeed not separated (which I thoroughly believe) i believe bringing the coolant into the bottom chamber first would provide an opportunity for more coolant to actually flow down the ic before circulating back up to the outlet.
With all that said, I am perplexed as to which direction to flow the coolant thru the ic as my theories support one direction thermodynamically and the opposite direction hydrodynamically.
