May i ask why the room is so hot?

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@onebuck, I'm not going to argue the facts of an experiment that was done 28 years ago with you. Theory cannot change facts, but more can be learned from them. You say anodizing is better - I'd be prepared to agree. But the facts stand, and your retreat to perfection in theoretical application ignores the fact that the methodology was very good. I respectfully suggest that if what you say was true, we would have recorded a temperature rise. Perhaps it would be wiser to query the paint - which was cylinder black, sold to motorcyclists top make their aircooled bikes look sexy. Goodbye.

Hi,

I'm not arguing but stating the experiment was not performed correctly or solid acquisition of valid data.

Now we are getting somewhere, the use of that type paint would certainly insulate for application to a HS. We are talking about different application requirements with the treatment of heat range paint for a exhaust system and using for heat transfer for a heat sink on a CPU that would be in a different temperature range. Poor quality!

BTW, I was not arguing but stating your application was not correct therefore misleading. Physicist or not that person was not correct in using paint as a means to provide efficient heat transfer for a CPU heat sink. Plus the method of using heat sink compound for instrumenting the thermocouple is not practical but should have been either a pod of thermocouple epoxy compound or even a insert pocket with crushed glass that is then contained. Either way you would have calibrated the efficiency bond for the material along with the thermocouple. The calibration for the thermocouple would have been independent of the mounted heat sink. Meaning that the thermocouple would have been mounted properly to the heat sink then calibrated with the heat sink before mounting to the CPU. Several simple calibration methods, easiest would be a 'ice bath'.

My answer to smeezekitty.
Temperature here reached 47C (officially) a few weeks ago and an insulated room (where the computer is) is probably 5C cooler but I suspect the machine is not in the coolest spot in the room. A few years ago the temperature was 50C on 1 day and there is usually a few weeks between 46 and 48C in most summers. Also, the wind drops completely in that heat and the only thing that forces the heat to move is the fans, even water cooled air conditionning only help a bit because they are fed inevitably with burning water due to the fact the ground, where the water pipes are, is burning.

I also suspect that the CPUs survived but it is the RAM sticks that got to hot as POST does not pass the RAM test. But I am not knowledgeable enough to find out what died or died first and I find it useless to try and salvage parts of the machine because of its age.

However I want also to solve the dust problem at the same time because I have quality machines dying one after the other over the years as heat and dust combine and damage the equipment.

I read that a fridge will not do because water vapor will condense on electronic components and freeze but, although I am ignorant of the laws of physics, I am pretty sure that freezing will only occur in the coldest spots inside the fridge (where the heat absorbers are) and not in the middle where I wanted to put the computer, after reading the very detailed explanations provided, I am still tempted to give that a try as I have a medium size spare fridge I can dedicate to the job and solve the dust problem at the same time. Incidentally, I thought of fabricating a perforated, suitable box like those used in rack systems which are better suited to be fitted in a fridge and put the board so that its cooling fan is on the underside and pushing the air up.

If I proceed, I should quickly find what the result is by putting a thermometer next to the box, on top etc.

The statement about condensing water in a fridge is nonsense. People associate a fridge with wetness because everything you take out is wet. Right, but that is because water vapor in the atmosphere immediately condenses on the cold object you just took out of the refrigirator.

As a matter of fact, air inside a fridge is dry, very dry. Water vapor condenses on the evaporator because the air is cooled and can contain less water vapor. The condensed water is drained into a pan on top of the compressor so it evaporates there. So the air inside the fridge is constantly being dried. Put a piece of uncovered meat in the fridge. Within two days the upside is completely dried out.

Since your computer is warmer than the air, and components are actually producing heat, the air in immediate contact with the components will be even dryer. Air warms up, RH drops if you don't add water. You computer stays dry.

The problem starts if you take the case out of the fridge. But even then I suppose the RH is not that high in your country. The computer might temporary cease working because of condensed water but that water will eventually evaporate and your electronics should be all right.

I have some knowledge about environmental heat and cooling. I live in a place where temperature is between 30 C and 34 C and RH at 80% at midday, higher at night.

jlinkels

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Living in that environment does not make you an expert. Saying a fridge that exits water from it is foolish if you do not know how it works. A refrigerator is a closed system, so the water has no where to go. It gets collected in some areas that is also trying to cool. Some areas might be freezing, so the water deposits in to a solid or ice at those areas. Areas that can not be turned into ice will be collected in a pool of water that you have to wipe up. If a freezer is used, you will see the water or humidity being collected on the coldest parts inside the unit.

If a refrigerator or freezer is opened, the low pressure that is inside these units will equalize with the high pressure from the outside. The equalizing will cause the outside air to take up some space in the unit as it is opening. What ever humidity is there in the outside is now in the refrigerator or freezer. When this happens the process starts all over, but the water collection is more.

The electronics should not be used in either a refrigerator or freezer because there is a possibility that water will be collected on the electronics. Sure you can do it if you want, but it is not my money you are wasting.

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No, but living in that area AND being a technician does.

jlinkels

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Being just a technician does not mean you know everything. A technician can be anything. Being a computer technician knows nothing about heating and cooling. I lived in multiple areas where there is high humidity and high temperatures. Also in areas that are low humidity and very high temperatures.

It is a fact that fridges dry exposed food put in them.

Hi,

Instead of placing the system in the refrigerator why not just use a closed loop liquid system with a secondary exchanger inside. Sure the efficiency would not be energy star compliant.

A lot of waste energy with this type system but it can be done. Plus the beer will just be slightly warmer.

You still need to be very cautious with this type of system in environments that have a wide temperature change/range which could cause condensation problems within the computer case thus potential damage to the electronics.

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Hi,

Yes, but you also need to consider the source. If you place the same material on the outside as a comparison then the dry condition will depend on the temperature, humidity and the placement with air activity. In the refrigerator these same conditions would be controlled. Circulation of the air across the drying material by circulating fans will increase the drying not just the temperature. The constant temperature along with air movement across the material will dry it out. As you lower the temperature then the molecular structure tightens (less motion) thus forcing the moisture evaporation at the surface thus the drying action.

Now if this action was used with a exchanger system then the energy would dissipate within the refrigerator environment but you would have the inverse for the exchange system within the computer thus potential problems with condensation.

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Lowering temperature increases relative humidity but, when it gets below freezing, water is extracted from the air to form ice thus decreasing humidity.

Wikipedia's Computer Cooling page describes some extreme cooling systems.

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Hi,

Thanks for the reminder! I completely forgot about that wiki.

This is true, but doesn't hold in a refrigerator.

If you have a certain amount of water vapor contained air in a closed container, and you decrease the temperature, the RH increases, just as you say.

However, in a refrigerator, air passes along the evaporator, or the cooling element. Because the evaporator is the coldest part in the air path, water will condense onto the evaporator. Which means that air at other places in the refrigerator is warmer, and has a lower RH. Now air temperature in a refrigerator is only slightly above freezing point so often the evaporator will be covered with frozen water anyway. But it is not strictly necessary that ice has been formed to dry the air.

With an airconditioner it is even easier to see. Although the air in the room is colder that outside, it is also dryer. When the air passes the evaporator it loses a lot of water as the evaporator temperature is 8-10 C as opposed to a room air temperature of say 22 C. The water exits from the airconditioner's drain tube. I am talking about 3-5 liters per 12 hours for a 12000 BTU (3.5 kW Th) unit. RH drops from 80% to 40%.

jlinkels

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The losses as you say do not have a big influence on energy waste. In fact almost nothing if you insulated the the cold water lines. You want to avoid additional warming of the cold water by the heat in the room. If these lines are well insulated you won't waste any energy.

No matter how inefficient the heat transfer is from the case to the cooler element in the case, and inside the refrigerator from the heater element to the refrigerator inside. Every Joule you extract from inside the case is cooled off in the refrigerator. If heat transfer is very inefficient, the heat transport decreases, but you don't waste any energy.

jlinkels

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