# Is there a better coolant than water? **URL:** \ **Category:** Factual Questions\ **Created:** [June 26, 2015, 12:03am UTC](https://boards.straightdope.com/t/is-there-a-better-coolant-than-water/723491 "2015-06-26T00:03:46Z")\ **Posts on this page:** 17\ **Page:** 2
**Author:** ![Bert\_Nobbins](https://avatars.discourse-cdn.com/v4/letter/b/aeb1de/32.png) [@Bert\_Nobbins](https://boards.straightdope.com/u/Bert_Nobbins)\ **Post date:** [June 27, 2015, 6:07pm UTC](https://boards.straightdope.com/t/is-there-a-better-coolant-than-water/723491/21 "2015-06-27T18:07:11Z")
> [@Habeed](#): > > Yes. Sodium is a better coolant than water in nuclear reactors, because it boils at a higher temperature. Well. “Better” in terms of performance - it has the major drawback of exploding when it comes in contact with water, which is superbad because actual reactor designs use water in the outer coolant loop and sodium to cool the core, and a heat exchanger where there is water on one side and sodium on the other. If the heat exchanger leaks, the obvious will happen. Also it’s super corrosive. > > So from the perspective of making a reliable nuclear reactor, it’s not as good a coolant. One desperate snag is that sodium is solid at room temperature, so if you have to shut down the reactor and have no auxiiary heating system, you’re pretty well screwed with every pipe and pump jammed up solid. This happened to a Russian submarine. ---
**Author:** ![watchwolf49](https://avatars.discourse-cdn.com/v4/letter/w/e9c0ed/32.png) [@watchwolf49](https://boards.straightdope.com/u/watchwolf49)\ **Post date:** [June 27, 2015, 6:47pm UTC](https://boards.straightdope.com/t/is-there-a-better-coolant-than-water/723491/22 "2015-06-27T18:47:21Z")
> [@MichaelEmouse](#): > > How did they actively try to trash the reactor? I thought the problem was that that type of reactor had a positive feedback loop. The Chernobyl accident occurred while they were simulating a shut down of the electrical grid … [Wikipedia’s](https://en.wikipedia.org/wiki/Chernobyl_disaster) article seems fairly correct, but take it with a grain of salt. ---
**Author:** ![excavating\_for\_a\_mind](https://avatars.discourse-cdn.com/v4/letter/e/e8c25b/32.png) [@excavating\_for\_a\_mind](https://boards.straightdope.com/u/excavating_for_a_mind)\ **Post date:** [June 27, 2015, 9:11pm UTC](https://boards.straightdope.com/t/is-there-a-better-coolant-than-water/723491/23 "2015-06-27T21:11:09Z")
> [@Amateur\_Barbarian](#): > > “Dihydrogen Monoxide the Magnificent.” 🙂 > Respective of nothing much, even with a chemistry background I have trouble thinking of ammonia as a substance by itself. It’s mixture of [del]water[/del] DHM and a little other stuff… right? Right? :rolleyes: You are thinking of aqueous solutions of ammonia and water, or ammonium hydroxide. Often written as NH4OH, or NH4+(OH-), or simply NH3(aq). It can be a strong caustic with high enough ammonia concentration. NH3 is a gas at room temperature and pressure. If you keep it dry, it will work as a good refrigerant (like Freon). It has an unfortunate characteristic of a bad smell, which is one reason Freon was developed; to compete with ammonia (early refrigerators and freezers were ammonia based). ---
**Author:** ![Chronos](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/chronos/32/134_2.png) [@Chronos](https://boards.straightdope.com/u/Chronos)\ **Post date:** [June 27, 2015, 11:04pm UTC](https://boards.straightdope.com/t/is-there-a-better-coolant-than-water/723491/24 "2015-06-27T23:04:07Z")
Say rather that it has a very fortunate characteristic of a bad smell, since it smells bad enough to get people out of the area before they’re poisoned by it. ---
**Author:** ![bob\_2](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/bob_2/32/3341_2.png) [@bob\_2](https://boards.straightdope.com/u/bob_2)\ **Post date:** [June 27, 2015, 11:13pm UTC](https://boards.straightdope.com/t/is-there-a-better-coolant-than-water/723491/25 "2015-06-27T23:13:02Z")
Cold warehouses use ammonia as a coolant. I was once at a supermarket chilled distribution centre when an alarm went off. We were escorted outside in double quick time and had to stand around for hours while guys in full haz kit did their stuff. ---
**Author:** ![ralph124c](https://avatars.discourse-cdn.com/v4/letter/r/8797f3/32.png) [@ralph124c](https://boards.straightdope.com/u/ralph124c)\ **Post date:** [June 28, 2015, 2:11pm UTC](https://boards.straightdope.com/t/is-there-a-better-coolant-than-water/723491/26 "2015-06-28T14:11:39Z")
> [@Bert\_Nobbins](#): > > One desperate snag is that sodium is solid at room temperature, so if you have to shut down the reactor and have no auxiiary heating system, you’re pretty well screwed with every pipe and pump jammed up solid. This happened to a Russian submarine. Has mercury ever been tried? Seems like it could work. ---
**Author:** ![jakob](https://avatars.discourse-cdn.com/v4/letter/j/71c47a/32.png) [@jakob](https://boards.straightdope.com/u/jakob)\ **Post date:** [June 28, 2015, 2:38pm UTC](https://boards.straightdope.com/t/is-there-a-better-coolant-than-water/723491/27 "2015-06-28T14:38:45Z")
Water is still mainly used as best coolant ---
**Author:** ![scr4](https://avatars.discourse-cdn.com/v4/letter/s/59ef9b/32.png) [@scr4](https://boards.straightdope.com/u/scr4)\ **Post date:** [June 28, 2015, 3:09pm UTC](https://boards.straightdope.com/t/is-there-a-better-coolant-than-water/723491/28 "2015-06-28T15:09:29Z")
> [@bob\_2](#): > > Cold warehouses use ammonia as a coolant. I was once at a supermarket chilled distribution centre when an alarm went off. We were escorted outside in double quick time and had to stand around for hours while guys in full haz kit did their stuff. I think ammonia is used as _refrigerant_, which is slightly different. A coolant just carries heat from a hotter place to a cooler place. A refrigerant is something you compress, then allow it to expand or vaporize in order to cool something down. ---
**Author:** ![Ruken](https://avatars.discourse-cdn.com/v4/letter/r/f475e1/32.png) [@Ruken](https://boards.straightdope.com/u/Ruken)\ **Post date:** [June 28, 2015, 7:00pm UTC](https://boards.straightdope.com/t/is-there-a-better-coolant-than-water/723491/29 "2015-06-28T19:00:54Z")
> [@ralph124c](#): > > Has mercury ever been tried? Seems like it could work. I’m not sure what temperatures are used, but mercury has a much lower boiling point, and high vapor pressures below that point. I’ve accidentally boiled mercury. But never sodium. There may be materials incompatibilities with both metals. Sodium likes to dump electrons into everything, and mercury will form liquid amalgams with some other metals. ---
**Author:** ![Quintas](https://avatars.discourse-cdn.com/v4/letter/q/48db29/32.png) [@Quintas](https://boards.straightdope.com/u/Quintas)\ **Post date:** [June 29, 2015, 6:32am UTC](https://boards.straightdope.com/t/is-there-a-better-coolant-than-water/723491/30 "2015-06-29T06:32:57Z")
> [@engineer\_comp\_geek](#): > > As for heat capacity alone, ammonia has a higher heat capacity than water. I think it should be fairly obvious why we don’t use ammonia as a general coolant in the same way that we use water. What _are_ the drawbacks to ammonia as a general coolant? Smells bad? I really don’t know. ---
**Author:** ![Habeed](https://avatars.discourse-cdn.com/v4/letter/h/a587f6/32.png) [@Habeed](https://boards.straightdope.com/u/Habeed)\ **Post date:** [June 29, 2015, 7:05am UTC](https://boards.straightdope.com/t/is-there-a-better-coolant-than-water/723491/31 "2015-06-29T07:05:44Z")
> [@Quintas](#): > > What _are_ the drawbacks to ammonia as a general coolant? Smells bad? I really don’t know. It’s poisonous and it can explode. ---
**Author:** ![Ruken](https://avatars.discourse-cdn.com/v4/letter/r/f475e1/32.png) [@Ruken](https://boards.straightdope.com/u/Ruken)\ **Post date:** [June 29, 2015, 10:53am UTC](https://boards.straightdope.com/t/is-there-a-better-coolant-than-water/723491/32 "2015-06-29T10:53:48Z")
Ammonia also boils at -33 C. ---
**Author:** ![RobDog](https://avatars.discourse-cdn.com/v4/letter/r/f07891/32.png) [@RobDog](https://boards.straightdope.com/u/RobDog)\ **Post date:** [June 29, 2015, 11:33am UTC](https://boards.straightdope.com/t/is-there-a-better-coolant-than-water/723491/33 "2015-06-29T11:33:02Z")
> [@Habeed](#): > > It’s poisonous and it can explode. > [@Ruken](#): > > Ammonia also boils at -33 C. Apart from that though? ---
**Author:** ![Enola\_Straight](https://avatars.discourse-cdn.com/v4/letter/e/dec6dc/32.png) [@Enola\_Straight](https://boards.straightdope.com/u/Enola_Straight)\ **Post date:** [June 29, 2015, 3:46pm UTC](https://boards.straightdope.com/t/is-there-a-better-coolant-than-water/723491/34 "2015-06-29T15:46:59Z")
A number of automotive waterless coolants: > **[automotive waterless coolant - Bing](http://www.bing.com/search?pc=COSP&ptag=D041515-ABA01A7CCEB2146F8A7F&form=CONBDF&conlogo=CT3330961&q=automotive%2Bwaterless%2Bcoolant)** > > Intelligent search from Bing makes it easier to quickly find what you’re looking for and rewards you. ---
**Author:** ![Melbourne](https://avatars.discourse-cdn.com/v4/letter/m/b5e925/32.png) [@Melbourne](https://boards.straightdope.com/u/Melbourne)\ **Post date:** [June 30, 2015, 9:03am UTC](https://boards.straightdope.com/t/is-there-a-better-coolant-than-water/723491/35 "2015-06-30T09:03:21Z")
> [@bob\_2](#): > > Cold warehouses use ammonia as a coolant. I was once at a supermarket chilled distribution centre when an alarm went off. We were escorted outside in double quick time and had to stand around for hours while guys in full haz kit did their stuff. The engineers at work used to laugh about the effort going into the “terrorist” threat. A bad industrial accident in our refrigeration plant would have wiped out our entire suburb, and on the historical record seemed much more likely. ---
**Author:** ![Melbourne](https://avatars.discourse-cdn.com/v4/letter/m/b5e925/32.png) [@Melbourne](https://boards.straightdope.com/u/Melbourne)\ **Post date:** [June 30, 2015, 9:14am UTC](https://boards.straightdope.com/t/is-there-a-better-coolant-than-water/723491/36 "2015-06-30T09:14:15Z")
> [@Quintas](#): > > Forgive me if I mess up my chemistry/physics here: > > I realize this is probably one of those ‘why’ questions whose ultimate answer is “you need to take a physics class” The ultimate answer is “you need to take a chemistry class”, since coolants are chosen on simple physics and complex chemistry. The physical properties (melting point, boiling point, latent heat, specific heat, viscosity) you can get from a table in your engineering handbook (or now, from the www). The chemical properties you get by using specialist cooling fluids sold by specialist cooling fluid companies. Or you use water, which isn’t best, but it’s common. ---
**Author:** ![Bert\_Nobbins](https://avatars.discourse-cdn.com/v4/letter/b/aeb1de/32.png) [@Bert\_Nobbins](https://boards.straightdope.com/u/Bert_Nobbins)\ **Post date:** [June 30, 2015, 3:16pm UTC](https://boards.straightdope.com/t/is-there-a-better-coolant-than-water/723491/37 "2015-06-30T15:16:13Z")
> [@ralph124c](#): > > Has mercury ever been tried? Seems like it could work. It most certainly has: see: [http://www.douglas-self.com/MUSEUM/POWER/mercury/mercury.htm](http://www.douglas-self.com/MUSEUM/POWER/mercury/mercury.htm) It is theoretically useful in a topping cycle to improve power station efficiency, but the cost, toxicity, and other problems make it a technological nightmare. It was however given a fair trial in at least three US power stations. [Previous page](https://boards.straightdope.com/t/is-there-a-better-coolant-than-water/723491.md?page=1)