Quote:
Originally Posted by Dessertrunner
Trevor,
I know it sounds strange but in a closed loop system it is impossiable to supply postive pressure to the suction of the pump no matter how big the pipe between the two. As strange as its sound it took me a lot of head scratching to get my mind around it but it is a fact and I have confirmed it to be true.
If the pump is with out restriction then the coolant turns up at the pump inlet and any pressure the pump inlet would have been supplied with will be lost by the pump pumping faster. The pump will just pump more which will cause any pressure gains to be lost. It makes sense because at some point the coolant flow and pump revs balance.
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Tony,
Unfortunately you are arguing over a point of difference between us which does not exist. You raise matters which are not in debate.
I understand that in effect you are stating that circulating pressure, at the inlet/suction side the pump, can not exceed the outlet pressure. I agree and have never stated otherwise. What is more, if there is a circuit having very little resistance between the pump outlet and inlet, the circulating pressure within the circuit will amount to very little. In any event the the lowest pressure point will occur, immediately after the maximum point of restriction.
Circulating pressure is dependent on resistance/restriction within the circuit and can only be measured as a difference point to point within the circuit and is no way related to gauge pressure. Gauge pressure i.e. that above atmospheric, is not directly involved in the efficiency of circulation, but does have a profound side effects as I mentioned when discussing your test rig.
It would appear that you theorise that suction applied by the pump is restricted by the inlet pipe, to the extent that the pump is being prevented from drawing in as much fluid as it is capable of pumping out. For this to be true, the pipe must constitute the highest point of restriction within the circuit. There has been no evidence presented to support such a prospect.