12 VDC compressor location?

[Steve from Socal]

I want to use a stand alone 12 volt a/c compressor to cool a heat exchanger in a vehicle. The mounting location of the compressor is flexible to a degree. The compressor would likely be located in an area with little natural airflow. The idea of using a fan to cool the compressor is possible but, if the compressor can run without forced cooling it would open site options.

How much heat could the compressor be expected to produce cooling at 1~1.5 KW?

 

[johnre]

A/C systems have both an evaporator and a condenser mounted somewhere. The former is placed where it can draw thermal energy from something, in your case it would be your heat exchanger (presuming an oil cooler?). The latter is placed somewhere to efficiently get rid of the thermal energy in the system, including that which is generated from the compressor itself. It is usually fan cooled.



My wife's Prius uses a 12 V compressor, and it isn't mounted in that strategic location to get air flow - in fact, it's very cluttered and hard to get at. The condenser, however, is in front of the radiator, like in most conventional automotive AC systems, so it gets the coldest outside air prior to the radiator core.

 

[Steve from Socal]

The condenser will be mounted in front of the radiator, the compressors ideal location is in dead air? The evap/is the HE

 

[PoorUB]

I want to use a stand alone 12 volt a/c compressor to cool a heat exchanger in a vehicle. The mounting location of the compressor is flexible to a degree. The compressor would likely be located in an area with little natural airflow. The idea of using a fan to cool the compressor is possible but, if the compressor can run without forced cooling it would open site options.

How much heat could the compressor be expected to produce cooling at 1~1.5 KW?

The compressor gets cooling from the refrigerant returning from the evaporator. It shouldn't need any additional cooling.

 

[johnre]

.... the compressors ideal location is in dead air?

The compressor's ideal location is wherever it fits and you can easily route the lines.

 

[fitter30]

Be sure the refrigerant and oil is compatible.

 

[American Locomotive]

The compressor doesn't need active cooling. Any cooling it needs is provided by the refrigerant.

Also keep in mind the 12v compressors available these days aren't really that powerful. What are you trying to cool?

A/C systems have both an evaporator and a condenser mounted somewhere. The former is placed where it can draw thermal energy from something, in your case it would be your heat exchanger (presuming an oil cooler?). The latter is placed somewhere to efficiently get rid of the thermal energy in the system, including that which is generated from the compressor itself. It is usually fan cooled.



My wife's Prius uses a 12 V compressor, and it isn't mounted in that strategic location to get air flow - in fact, it's very cluttered and hard to get at. The condenser, however, is in front of the radiator, like in most conventional automotive AC systems, so it gets the coldest outside air prior to the radiator core.

The prius compressor actually runs off the main inverter. If I recall its around 160v?

 

[johnre]

The prius compressor actually runs off the main inverter. If I recall its around 160v?

Good to know; I just assumed it was the 12 V DC system as I didn't have the service manual.

And it's a Gen 3 Prius, so it's a 201 V battery system, and as you noted, the three phase inverter system that runs off of that.

 

[Steve from Socal]

The compressor will be liquid to liquid for charge air cooling on a supercharged engine. The heat exchanger for the liquid is a plate type and the heat rejection will be minimal unless under boost. A reservoir for the CAC will hold a couple gallons and the volume in the HE and CAC is less than half a gallon.

 

[pbon]

I like the concept. Have been thinking about an intercooler chiller for one of my turbo cars that taps into the AC system. At least a couple of companies make them, but I assume you either do not have AC or want to save money by making your own.

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[PoorUB]

The compressor will be liquid to liquid for charge air cooling on a supercharged engine. The heat exchanger for the liquid is a plate type and the heat rejection will be minimal unless under boost. A reservoir for the CAC will hold a couple gallons and the volume in the HE and CAC is less than half a gallon.

Really? This is a real thing? I would have guessed that the horse power needed to cool intake air sufficiently was more then it would be worth.

 

[Steve from Socal]

I don't want to use the engine driven compressor, I have heard that some aftermarket systems that use the factory A/C system often have problems?

The need to run the A/C to cool the charge is also not a great idea IMHO.

 

[PoorUB]

I don't want to use the engine driven compressor, I have heard that some aftermarket systems that use the factory A/C system often have problems?

The need to run the A/C to cool the charge is also not a great idea IMHO.

Whether you run a belt from the crankshaft to run the compressor, or run wires from the battery to a 12 volt compressor I don't see it making much difference. The alternator will be loaded heavily to run the "AC" for the air intake. I wonder how much horse power is required? An automotive belt drive unit takes 2 HP and up, depending on the vehicle. That would be a pretty large 12 volt compressor to do the same.

 

[Steve from Socal]

I am going to be using a 220 amp alternator, the engine was originally equiped with a 185 and this was in a car with a much higher accessory load than the car it is going into. My rough guess is the compressor is load is 40~45 amps and the duty cycle would be somewhere between 40~60% most of the time.

This car has little space to mount an air/water heat exchanger for the innercooler and, the best you get is ambient with air. The goal is to have the water in the cooling loop at 50F The boost events are what passing or a speed run 20~30 seconds? The blower is clutched and there is a bypass valve for NA driving.

 

[The Metric System]

Do you know approximately how much water you will have in that loop, and if so have you done the math for how much it will warm during a boost event?

 

[fitter30]

Need a engineer. 400 ci in V8 at 6500 rpm 800 cfm natural aspirated. Like to see the design for temperature drop ,hp needed and how they get all that air thru 4.5" pipe.

 

[Steve from Socal]

Do you know approximately how much water you will have in that loop, and if so have you done the math for how much it will warm during a boost event?

The total volume of water is expeced to be around 12 liters, with a water flow through the system of 8~12 liters per minute. I don't have any numbers on the system this is a new install. These engines using a simmilar system have seen innercooler temps as low as 25~30F That is for drag racing where a burnout and pass are the only goal.

These systems used on street cars see charge air temps in the 60~70F using a portion of the cars A/C capacity with less total volume of coolant in the loop.

 

[American Locomotive]

Do you know which specific compressor you will be using?

If the supercharger is clutched, you shouldn't be rejecting too much heat into the coolant loop. Just make sure everything is insulated well to reduce engine bay heat getting into the system.

A couple of gallons of water can absorb quite a bit of heat.