Alphacool NexXxoS XT45 360 Radiator

Thermal Testing

I’m using my new V2 radiator test bench for testing which nets significantly lower watts dissipated numbers than my old open air testing.  This new bench is both insulated and shielded from getting any external cooling help and likely more accurately simulates a closed case condition.  The tested parts are as follows:

Test Specifications:

• Thermal Sensor logging: Crystalfontz CFA-633, logs up to 32 temperature probes and up to 4 fan channels: http://www.crystalfontz.com/products/633/index.html

• Temperature Probes: Dallas Digital One Wire DS18B20 probes.  These are good to about .2C absolute accuracy in normal water cooling temp ranges and have a nice fine .0625C resolution.  Also since they communicate digitally, you can string the power, ground and Vdd wire in series between all the sensors limiting the amount of wires significantly.

• Pump: Swiftech MCP-35X2 at 40% PWM.  Simulates medium pumping power and results in roughly 1.5GPM +- depending on radiator restriction.
• Block: Danger Den MC-TDX block
• Heater: Standard Aquarium 300W Heater with safety switch soldered in the closed position so heat remains on regardless of temperature.  This requires removing the heater element from the glass tube, soldering the two tabs together and putting it all back together.
• Heater/Reservoir Bath:  I fabricated this from 1″ schedule 40 PVC with a T and elbow to 1/2″NPT threaded fittings and then used NPT nylon barbs to connect tubing.  The cap I had to use a 1-1/4″ threaded cap and turned it in my lathe to fit the exterior of the 1″ T fitting.
• Insulation was a combination of 1″ and 1/2″ pipe insulation cut to fit.
• Tubing is 3/8″ ID x 1/2″ OD tubing. Koolance 3/8″ barbs are also used as the test standard for thermal testing.
• Case Material – 1/2″ x 8″ Pine it’s a little over 24″ wide to barely fit 4x140mm rads.  The bench overall height is about 18″.
• Inlet port was fabricated from a 4″ flange material making an ID opening of 4.540″ Diameter.  I shaved the threads out of it and tapered the inlet on the lathe for a smoother inlet.
• Acrylic panels are all .100″ thickness and I dado cut slots into the shelves for them to fit into.
• Current Fan Controller is a Scythe Kaze Master, fed by a Koolance SPD-24 to slightly overvolt fans to 2200RPM.
• Heater Control is via a 3A  generic Variac, although 5A would be better for higher heat loads.  I am using the variac to dial in the Watts into the variac to 100W, 200W, and 300W for each RPM.  5Watts is then added for the pump heat minus variac heat, so each test is targeting approximately 105W, 205W, and 305W.
• For Watt Metering – P3 Kill-A-Watt and just manually observing and correcting wattage is used.  Wattage normally does not vary by more than 2-3 Watts.
• Fans- Titan Kukri H PWM fans – I picked these fans because they had a good RPM range and I thought would better represent 25mm fan performance over using 38mm fans.  They do have a more dense 9 blade fan design similar to the Gentle Typhoons. I’m not using them because I think they are superior in noise over other fans, I am simply using them because I can run them from about 650RPM clear up to 2200RPM to get a good broad range of RPM levels tested with a single fan type.  They seem like a pretty good fan, but I wouldn’t suggest they are superior over other 25mm fans.

The radiator is installed into the radiator cabinet with only the bottom three fans push condition.  The fans are all permanently fixed to the acrylic template below with a foam gasket so the fans are installed, run, and logged exactly the same on each radiator. The system is filled with distilled water and allowed to bleed and fans allowed to warm up.  Then the variac is turned on to apply heat load and dialed in to 100W and the fans are adjusted to 640RPM.  The Crystalfontz is then used to monitor fan RPMs and adjusted to a good stable level and all 17 of the thermal sensors are also turned on to start recording air in, air out, water in, water out over those 17 sensors and the fan RPM.  All of these are then recorded each second and allowed to run and log temperatures for approximately 1 hour while carefully controlling ambient temperatures.  After about 30minutes the data log is brought into excel and reviewed for stability and ambient results.  After the system reaches stability while ambients are nice and level, the data is saved and trimmed and an average of the stable data is averaged.  This averaging includes the average of the fan rpms at the time of the test as well as all the temperatures.  That data is then copied to the below chart to calculate the results.  At that point the radiator fan speeds are increased to 1400RPM and heat load to 200W and the test is repeated.  Next the fans are increased to 2200RPM and heat increased to 300W and data logged and extracted again.  The most critical and difficult part of this is maintaining a constant ambient temperature.  It doesn’t have to be any one number, but it needs to hold constant with no more than about .5C rise or fall in any 30minute period.  This is why logging is used to evaluate and continue logging data if needed to collect a good data point.  Simple things like someone opening the front door for a minute will cause a sudden drop in ambient and the test has to be redone. In a nutshell, I am spending a great deal of effort to review logged data and extending the data logging period as needed to ensure a good stable ambient temperature which results in more time per data point but a much more accurate data point.

Summary of 3 tests:

Comparison

CLICK TO ENLARGE

The Alphacool XT45 performed extremely well and matched that of the SR-1 in the 600RPM category for first.  It is a bit more slow speed fan tuned than the UT60, but the copper channels seem to make a difference here as well since the XT45 outperforms several of the brass tube thicker rads.

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