Testing methods for a cooling system

[Brown23]

Hey Guys,
I'm putting together my first cooling system, it's a self contained system and I'm pretty sure I have all of the parts I'll need, but I'm not sure how to test it once its installed to verify it can remove the heat and keep the system operating at a good temperature.

What I'm wondering is how I verify that the heat exchanger is working. Would the best way be to include temperature gauges on either side of the heat exchanger or do I just need to measure the temp. of the piping before and after it? It isn't insulated so access to the pipe wouldn't be a problem, I just get the feeling that that would be too easy.

This system is for a concentrating solar cell, so it is removing concentrated heat from a couple hundred suns so the cells operate at peak performance.

Thanks in advance!

 

[MintJulep]

Temperature is not heat.

To measure heat you need temperature, mass flow and heat capacity; or enthalpy.

So no, just temperature gauges won't do the trick.

 

[Brown23]

Well I'll know the system flow rate, there will be a flow meter, and the coolant will be 50/50 water glycol so I know the heat capacity of the coolant, so the only part left should be the temperature right?

I'm just wondering the best way to measure that so I can determine the heat transferred away by the heat exchanger.

If I'm still missing something, let me know. Thanks

 

[DRWeig]

Yes. If you know volumetric flow and density of your glycol mixture then you have mass flow. You have enthalpy of your mixture per unit of mass. All you need is differential temperature across your exchanger.

Caution: Temperature sensor inaccuracy becomes a significant portion of your differential temperature measurement as the differential temperature gets smaller.

Example: You have a 10°F delta-T across your coil, measured by two sensors, each sensor ±0.5°F stated accuracy in your temperature range (say, 150°F entering water, 160°F leaving water). Accuracy of the pair of sensors is ±1°F, or 10 percent of your reading... On a not-so-sunny day, or in the late evening, the delta-T might be 1°F. Coupled with ±1°F accuracy, your reading is really indeterminate.

Most folks sell temperature sensors in matched pairs for applications like yours.

If you were thinking of immersion dial thermometers (you mentioned gauges), think otherwise if you want some accuracy.

Best to you,

Goober Dave

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[Sycorax]

The best way to go about this( according to me) is to weld on a compression fitting to the piping and measure the temperature of the liquid directly by using thermocouples. If you cant do this, You can tack weld thermocouple to the wall of the piping - inlet and outlet. Cover it with insulation so that there is no heat transfer from the wall of the pipe to the surroundings. If you know the material of the pipe you can calculate the temperature of the liquid. Make sure the system reaches thermal equilibrium so that you are measuring steady state temperature and not when it is changing. I wouldn't advise the second method though. This should give you a rough estimation.

I hope this makes sense. I understand its a bit late, but whatever.