Pro/Forums - View Single Post - Single vs. two-pass heater core

fvr · 09-30-2003, 06:33 PM

As I understand the number of passes refers to the number of times fluid reverses its direction of flow. For example, two-pass heater core will have a U turn internally. Correct? If so, then what is the point of this design and why not just make all heater cores single-pass? The answer I’m not looking for, because it’s obvious, is that it is easier to have the inlet and an outlet close together.

Here is my take on this:
1. The two-pass construction is like connecting two smaller HC in series, thus increasing fluid velocity. Increase in velocity may result in a higher convection coefficient if the flow rate stays the same.

2. However, dT entering the "second" radiator (or second half if you will) is lower. This makes the second half less efficient at displacing heat, which is a common argument.

I might consider modifying my existing two-pass heater core into a single-pass type, but only if there is going to an improvement.

Thanks.

09-30-2003, 06:33 PM	#1
fvr Cooling Neophyte Join Date: Sep 2003 Location: Canada Posts: 5	Single vs. two-pass heater core As I understand the number of passes refers to the number of times fluid reverses its direction of flow. For example, two-pass heater core will have a U turn internally. Correct? If so, then what is the point of this design and why not just make all heater cores single-pass? The answer I’m not looking for, because it’s obvious, is that it is easier to have the inlet and an outlet close together. Here is my take on this: 1. The two-pass construction is like connecting two smaller HC in series, thus increasing fluid velocity. Increase in velocity may result in a higher convection coefficient if the flow rate stays the same. 2. However, dT entering the "second" radiator (or second half if you will) is lower. This makes the second half less efficient at displacing heat, which is a common argument. I might consider modifying my existing two-pass heater core into a single-pass type, but only if there is going to an improvement. Thanks.