Manufacturing DA - A New Chiller

[Phil@PnP Tech]

The chiller idea really sparked my interest but none of the current solutions really gave me warm feeling I would be happy with the installation and results. So the engineer in me got to work and I think I feel comfortable enough with results so far to share. First off, my background as an engineer is with a defense contractor designing conditioned systems for a wide variety of military applications. If it needed to change temperature and was painted green or tan, we probably had something to do with it. Now my role was the mechanical structure side of things but I worked along side some of the industry's best refrigeration engineers. I felt pretty comfortable taking this on myself with my experiences.

So here is a my first prototype.
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The Taps
So I want to start off with the what I have dubbed the "taps" which are the two items pictured below the HX. These are two taps that I have designed to seamlessly integrate into the car with ease of installation and function in mind. The "liquid tap" (pictured in the lower right) is a CNC'ed 6061-T6 aluminum manifold that fastens into the discharge of the AC condenser where the sub-cooled liquid refrigerant can be diverted to the new heat exchanger. This tap contains a normally open solenoid valve (aka race valve) that can block the liquid refrigerant from entering the cabin evaporator. This is a low amp draw sealed valve rated for all types of weather and temperature exposure. A single Deutsch DT04 sealed connector connects to the coil. This is a NORMALLY OPEN valve so it will only operate in "race mode" when 12vdc is applied. The whole liquid tap mounts directly to the evaporator discharge port for a simple clean installation. There are no welds or brazing. The factory line mounts just as it normally would to the condenser and the port on the side is a automotive industry standard male pilot oring port.

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The other manifold pictured in the lower left is the suction manifold. This manifold simply inserts between the factory connection of the suction line along the frame rail by the power steering pump. This is where the expanded now superheated gas refrigerant can be returned back to the compressor. It too is a one piece CNC'ed manifold with the industry standard male pilot oring fitting for the chiller HX return hose. Again, no weld or brazing here. A single piece of 6061-T6 aluminum.

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The Heat Exchanger
The heat exchanger took a lot of thought to design and layout. Requirements such as refrigeration capacity, refrigerant distribution, coolant flow/pressure drop, connections, materials, size, weight, and operating pressures were all considered. The HX is manufactured from 304 stainless steel and copper brazed to withstand operating pressures of over 400psi. This is key especially dealing with high pressures of refrigerants. Cross contaminating the cooling system with the refrigeration system could lead to costly failure of your compressor as well as other AC components. Flow rate is extremely important in a cooling system. The more flow, the higher the deltaT, the more heat transfer. The wrong HX could inhibit flow and really slow down your thermal transfer rate. Most aftermarket pumps operate in the 8-11gpm range. This HX will only induce a 4-5psi pressure drop across the chiller which is well within the system range. The refrigerant lines are mandrel bent stainless steel tubing which are TIG welded to the HX. The thermal expansion valve (TXV) is a self contained type and conveniently mounts to the side of the HX. Again, pilot oring fittings here. The water ports are -12AN stainless steel fittings (-16AN will be available). This allows use of a multitude of fittings available for a leak free connection. The HX is insulated in with a tough closed cell foam that wont collect dust, imprint, or easily tear (refrigerant lines are insulated once installed on the car. The complete HX weighs in just under 11 lbs fully insulated. It is roughly 13.5" in length, 5" wide, 6" tall (includes lines and TXV).

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The refrigerant lines are extremely simple crimp style and can be DIY with some help of your local Napa or Hydraulic hose supply house. The first prototype is on my car and operating. It is currently fitted with a bunch of RTD's as I am testing temperatures of the system as well as performance with varying amounts of charge. So far the initial results are promising and I will share some numbers soon.

Measuring delta T of the HX
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Measuring delta T of the LSA lid
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I will also try to get some pictures of the system installed on my car. I will keep this updated with my progress as well as some driving and dyno numbers (hp and heat).

-Phil

[-Ray-]

Very nice Phil. Would this work with a standard GM HX?

[hflores3]

That really looks good!

[STL_G8GT]

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[tchr49]

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Me too!

[Greg@PacePerformance]

Nice work!

[Phil@PnP Tech]

Would this work with a standard GM HX?

Yes. A diverting valve would need to be added to bypass the air to water HX while the chiller is operating.

[TooManyHobbies]

Nice work Phil. I hope to see it run down the track soon.

[Phil@PnP Tech]

I was able to do a bit more testing with the car this evening.

First off, ambient temperature here in SW Ohio this evening was 77ºF and 52% RH. Not quite the scorcher here but decent thermal load. The water temperature started off at 80.6º which is about right for sitting in the garage all day. At about the 4.5 mins of the chiller running, the water planed out around 30.2ºF. I think this is plenty of thermal capacity to meet the goals of the system. I may tweak the charge and/or superheat to bring the temperature down a bit. Also, I currently have a 50/50 mix of Ethylene Glycol (antifreeze) and water. I will probably bump the mix down to 25%Ethylene Glycol to gain a bit more thermal capacity without the risk of freezing.

At the beginning of this, I was kind of expecting a system to that I could let idle in the pits and then pop to hood to discover a supercharge lid coated in condensation with IAT's in the 30's. I do not think that is a valid scenario the more I think about it and the more I test. I am making plenty of chilled water, but my iat's would sit around 84ºF. This evening, I tapped into the MAF card where the original IAT sensor still resides (This would be the IAT1 sensor in a factory SC car). With the car at a 187ºF engine coolant temp, fan on high, and the hood open, I was getting a 114ºF IAT at the MAF. So roughly a 30ºF drop in IAT from the MAF and through the SC at idle. This issue here is that there just isnt enough airflow through the brick in the lid to reject the heat at idle. My car idles at 1.71lb/min. At first I thought that at idle, the bypass is open. On the LSA, bypass air acutally bypasses the SC and the cooling brick (LS9, Maggie, HB the bypass air still goes through the cooling bricks). So I rigged the bypass closed to make sure all inlet air was actually going through the cooling brick. Well this did not seem to change the IAT's still. There is just too much heat lingering around the engine and engine bay while sitting still idling for a measly 1.71 lb/min of air to cool down the lid. Next I increased the idle to about 1000rpm which brought up the airflow to 3.39 lb/min which is almost double. The MAF IAT dropped slightly to 108ºF but the IAT2 dropped to 64ºF. A 44ºF delta T now... which is getting somewhere.

Right now the fascia of off the car and I still need to clean up to wiring before I drive it. I feel pretty confident once I get it on the road where the load/airflow increases, less heat soak and closer to ambient IAT1's... I think I will see some IAT2's in the 30's. We will find out soon enough.

Expansion tank condensing.
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Discharge vent temperature.
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[Phil@PnP Tech]

Adding a few pictures.

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