While I have done radiator shroud testing before using more conventional 7 bladed fans, I wanted to do an update to both serve in shroud results and also give me some hands on time with my new radiator testing bench to see if there are any tweaks remaining before settling on a test method. I had noticed in my previous shroud testing that push vs pull optimization was different depending on the fan used, but I didn’t really have enough data to conclude it was fan speed alone or if it was simply the type of fan.
After testing many more fans, the Gentle Typhoons were again one of the stronger in CFM/dbA ratio on a radiator, so I figure it only makes sense to follow up with that fan to see what if any change is apparent there. In addition I used TFC 30mm shrouds in the old test and I wanted to compare that shroud to using an old gutted 25mm fan which is cheaper and many people do use.
So with that, I’m updating to a new radiator test bench with more controlled air flow measurements and the ability to also measure air flow volume.
Before getting started, I’d like to thank the sponsors that provided parts I used in this test:
Swiftech sponsored the MCR120QP radiator
Koolance sponsored the PMP-450 pump
Danger Den sponsored the MC-TDX waterblock
TFC sponsored the TFC 30mm shroud
TEST METHOD
Using my new radiator test bench V2, I’ll be running the system with the pump at setting 3 which is producing approximately 1.7GPM or so. Heat is provide via a modified aquarium heater and tuned to 125W for approximately a 10C delta system with the fan running at full speed. Seventeen thermal probes are measuring water in, water out, air in, and air out. In addition a hot wire anemometer is measuring air velocity, a “Kill-a-Watt” is measuring heater wattage, and another multimeter is measuring voltage at the fan plug.
Here is the setup with the access window temporarily opened. During testing the top acrylic panel will be closed so all air out goes through the air out port for air measurement.
I’m looking to log temps for about an hour after stability is reached to average out the ambient fluctuations.
As with any good testing, I think it’s important to show not only the testing rig, but also the data collected to develop the conclusion. While many go straight to the results, I’m sticking to my usual “testing story” approach and going to share the details of how I came to any conclusions.
TEST 1 No Shroud 125W Full Speed GT15
I figured for starters, I will test with the fan in pull at full speed as my baseline measurement with the expectation that shrouding will be better.
I got roughly 10.5C with a 53% efficiency or a 119C watt result at a 10C delta. That is a bit lower result than my previous test bench, but that is to be expected since I am now insulating the lines and reservoir so very little heat is lost external to the radiator.
TEST 2 TFC 30mm Shroud 125W Full Speed GT15
Continuing with the fan in pull condition, I quickly placed the shroud under the fan and carried on with the same test:
While previous tests with the conventional 7 blade fan and slightly smaller RS120 radiator provided really good shroud gains, I’m measuring practically nothing with the GT15. My only explanation is the lack of turbulence by the GT fan blades, since there is virtually no fan chop noise, it’s just not getting much of any benefit from the shroud (Less than .1C). I’m a bit surprised by this, but it appears to be correct. I’ll try again with the 25mm gutted fan as the shroud next.
TEST 3 Gutted 25mm Fan Shroud 125W Full Speed GT15
And while the TFC shroud is much nicer looking, most long term computer users end up with some sort of old fan collection in time and what better way to recycle than to snip off the motor and use the old fan housing as a shroud. I did exactly that and sanded down the stubs flush for a nice cheap recycled 25mm shroud.
That did a hair bit better than 30mm, but still not really enough that I would be bothering with it.
PULL @ FULL SPEED CONCLUSION
The GT-15s are different than most fans, different in sound and apparently different in shroud benefits as well.
I really could not measure much of any gain in a pull scenario with the fans at full speed. I measured less than .5C gains with both shroud tests while in pull using an MCR120 and the GT15s at full speed with an average 10C water delta. In the end, I’m a bit surprised there is so little gains with GTs, but that’s what I’m getting so far. Of coarse the higher the water delta the more gain you would get, but in a pull scenario I’m just not seeing much.
Regarding air flow CFM numbers, I really didn’t see any notable change. The anemometer pretty much bounced around a bit but hovered mostly in the 400 feet per minute range which equals about 43CFM using the port area as an assumed perfect conversion. The actual amount of air moving through the radiator remained much the same regardless of shrouding…no air flow change.
PUSH CONDITIONS COMING SOON….
Now to move the fan to the other side and see what happens.
0 comments:
Post a Comment