Colder water better thermal conductor?

Click For Summary

Discussion Overview

The discussion centers on the thermal conductivity of water at different temperatures and its implications for cooling systems, particularly in the context of computer water cooling setups. Participants explore how colder water affects heat transfer rates compared to warmer water, considering factors such as flow rate and temperature difference.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested
  • Experimental/applied

Main Points Raised

  • One participant questions whether colder water is a better thermal conductor than warmer water, specifically asking which would cool an object at 70°C more effectively: 10°C water or 20°C water.
  • Another participant asserts that 10°C water would cool more effectively due to a greater temperature difference, explaining that the heat transfer rate is proportional to this difference, but notes that flow rate also significantly impacts cooling potential.
  • A participant shares a personal anecdote about being part of a forum focused on computer water cooling, suggesting that the discussion is relevant to practical applications in that context.
  • Another participant elaborates on the complexities of cooling systems, indicating that while colder water is desirable for the heat source, warmer water is preferred for the heat sink, and emphasizes the importance of flow rate in optimizing heat transfer.
  • One participant humorously comments on the size of radiators used by some enthusiasts, implying that larger radiators are common in high-performance cooling setups.

Areas of Agreement / Disagreement

Participants express differing views on the relationship between water temperature, flow rate, and heat transfer efficiency. There is no consensus on the optimal conditions for cooling, as various factors are considered and debated.

Contextual Notes

The discussion highlights the non-linear relationship between flow rate and heat transfer, as well as the competing requirements of heat sources and sinks in cooling systems. Some assumptions about the effectiveness of different temperatures and flow rates remain unresolved.

Pengwuino
Gold Member
Messages
5,112
Reaction score
20
Is colder water a better thermal conductor then warmer water?

Say for example you nee dsomething to be cooled at 70C and you run water to it in a system. Which would cool this "something" quicker, 10C water or 20C water?
 
Science news on Phys.org
10C water will. But its not a question of thermal conductivity, but rather approach temperature. Since heat transfer rate is proportional to temperature difference, the greater temperature difference (approach temperature), the greater the heat transfer. So 70-20=50 and 70-10=60. 60 is 20% bigger than 50, so 10C water has the potential to cool something 20% better than 20C water. I say "potential" because flow rate makes a big difference.
 
Ok check this out. I am on a forum with a lot of people who like to water-cool theri computer systems. Its not... literal water cooling lol, but a series of tubing going to the main components into water blocks and make use of a radiator and pump. This one guy proposed that:

Well, if you have time, check it out http://www.overclock.net/showthread.php?t=20358

Guess who i am on that forum :D
 
Ehh, this is a really tough issue because the he source and heat sink have similar, but opposing constraints: for the heat source (the cpu) you want the coldest water possible and the highest flowrate possible, but for the heat sink (the radiator), you want the warmest water possible (but again, highest flowrate). Increasing the flowrate will bring the two temperatures closer together.

Your idea that if you double the flowrate, you simply cut the delta-T in half and the overall heat transfer stays the same is close but not quite right. Because of the approach temperature issue I mentioned above, it isn't a linear relationship: you will get more heat transfer by increasing the flow rate. Its easiest to see this by looking at it the other way: what if you decrease the flow rate to the point where the water ends up at 70C? It can't get any warmer, so that's a limit to your delta-T.

In HVAC, you match your equipment to each other to maximize performace and efficiency, looking at performance curves and such. The way most overclockers seem to do watercooling, though, they have an absurdly large radiator - and that's a good thing. The best cooling comes from the lowest possible temperature and the highest possible flowrate entering the CPU block.
 
Last edited:
Lol some of these guys have radiators out of Buicks and Pontiacs :P
 

Similar threads

High School Why would an atmosphere without greenhouse gasses be colder than with them?
  • · Replies 33 ·
2
Replies
33
Views
5K
High School Cooling effect of evaporation occurs even if the surroundings are colder?
  • · Replies 10 ·
Replies
10
Views
3K
High School Does movement affect H2O freezing temperature?
  • · Replies 16 ·
Replies
16
Views
8K
High School Filling a bathtub (Hot water to cold water exchange)
  • · Replies 6 ·
Replies
6
Views
7K
Undergrad Pool Solar Heating - Help orienting the roof-top solar collector please
  • · Replies 1 ·
Replies
1
Views
2K
Undergrad How does evaporation generate cooling? Swamp coolers edition
  • · Replies 32 ·
2
Replies
32
Views
5K
Undergrad Is this water pumping device using the Rankine cycle?
  • · Replies 4 ·
Replies
4
Views
2K
Undergrad Ideal working gas for a Stirling engine
  • · Replies 1 ·
Replies
1
Views
4K
Undergrad Empirical temperature scales using different thermometers
  • · Replies 7 ·
Replies
7
Views
3K
Undergrad Possible error sources in thermal conductivity experiment?
  • · Replies 16 ·
Replies
16
Views
15K