# Why do refrigeration systems commonly use CFCs/HCFCs? **URL:** \ **Category:** Factual Questions\ **Created:** [August 28, 2018, 11:29am UTC](https://boards.straightdope.com/t/why-do-refrigeration-systems-commonly-use-cfcs-hcfcs/820399 "2018-08-28T11:29:06Z")\ **Posts on this page:** 5\ **Page:** 2
**Author:** ![Snnipe\_70E](https://avatars.discourse-cdn.com/v4/letter/s/b5a626/32.png) [@Snnipe\_70E](https://boards.straightdope.com/u/Snnipe_70E)\ **Post date:** [August 28, 2018, 11:42pm UTC](https://boards.straightdope.com/t/why-do-refrigeration-systems-commonly-use-cfcs-hcfcs/820399/21 "2018-08-28T23:42:55Z")
> [@jjakucyk](#): > > But see, what’s the risk? You can have a high rise with gas kitchen appliances and furnaces and that doesn’t seem to be a problem. So why are hermetically sealed air conditioners a problem? Gas line breaks you valve off the supply. a line on a AC unit breaks it will blow off until the pressure is gone. ---
**Author:** ![Jeff\_Lichtman](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/jeff_lichtman/32/1531_2.png) [@Jeff\_Lichtman](https://boards.straightdope.com/u/Jeff_Lichtman)\ **Post date:** [August 29, 2018, 1:49am UTC](https://boards.straightdope.com/t/why-do-refrigeration-systems-commonly-use-cfcs-hcfcs/820399/22 "2018-08-29T01:49:38Z")
> [@Machine\_Elf](#): > > Sure, I get that they work “better”, but I’m wondering by what specific measures they are “better.” From the Wikipedia article on [refrigerants](https://en.wikipedia.org/wiki/Refrigerant): > [@](#): > > The desired thermodynamic properties are a boiling point somewhat below the target temperature, a high heat of vaporization, a moderate density in liquid form, a relatively high density in gaseous form, and a high critical temperature. The critical point is the combination of temperature and pressure at which both the gas and liquid phases can exist. A refrigerant wouldn’t work well at or above its critical point because it the phase transition would stop happening. ---
**Author:** ![am77494](https://avatars.discourse-cdn.com/v4/letter/a/d2c977/32.png) [@am77494](https://boards.straightdope.com/u/am77494)\ **Post date:** [August 29, 2018, 2:28pm UTC](https://boards.straightdope.com/t/why-do-refrigeration-systems-commonly-use-cfcs-hcfcs/820399/23 "2018-08-29T14:28:38Z")
In the spirit of the straightdope, I ran calculations with the OP’s configuration using the following refrigerants : Air, CO2, Ammonia, Propane and R12 (CFC). I used a cooling duty of 1919 BTU/hr (0.16 tons) - just enough to freeze 10 lb/hr of water at 80F. The results are here : [Imgur: The magic of the Internet](https://imgur.com/apyLv3V) The designs are not optimized. The compressors need intercoolers for many of the cases (ignored) and the pressures can be tuned for better numbers. However, the results will illustrate a lot of points people have been making above. Refrigerant selection is primarily a overall cost (over the lifetime) decision. 1\> The capital costs (or the initial costs) are affected by a\> The cost of the refrigerant itself b\> The compressor (higher pressure - higher cost, hazardous or flammable fluid - higher cost, corrosive material - higher cost) etc. c\> Static equipment costs are primarily a function of size (how much refrigerant is needed) and pressure (also special metallurgy if needed) d\> Instrumentation / Controls get more expensive with hazardous / flammable fluids (sometimes exponentially) e\> Capital cost is also affected if there is a need for spares (that is the system is not reliable) f\> The cost of storing the inventory or flaring it when the system is down 2\> Operating costs are effected by : 1\> Power consumption 2\> How many days of the year the system runs 3\> How easy it is to get the refrigerant (at the right concentration) 4\> Leakage rates of refrigerants 5\> Maintenance which is linked to the corrosiveness of the refrigerant. There are other factors too like regulatory ease and turndown which effects the bottomline. ---
**Author:** ![Hari\_Seldon](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/hari_seldon/32/5173_2.png) [@Hari\_Seldon](https://boards.straightdope.com/u/Hari_Seldon)\ **Post date:** [August 29, 2018, 2:31pm UTC](https://boards.straightdope.com/t/why-do-refrigeration-systems-commonly-use-cfcs-hcfcs/820399/24 "2018-08-29T14:31:59Z")
The Einstein-Szilard refrigerator, see [Einstein refrigerator - Wikipedia](https://en.wikipedia.org/wiki/Einstein_refrigerator) has no moving parts and no working fluid. The Wiki article has no discussion of the efficiency. They developed it in response to reports of the death of a Berlin family as a result of a leak in a refrigerator that used ammonia as its working fluid. It was patented but has not been used commercially, AFAIK. ---
**Author:** ![etasyde](https://avatars.discourse-cdn.com/v4/letter/e/9f8e36/32.png) [@etasyde](https://boards.straightdope.com/u/etasyde)\ **Post date:** [August 29, 2018, 5:34pm UTC](https://boards.straightdope.com/t/why-do-refrigeration-systems-commonly-use-cfcs-hcfcs/820399/25 "2018-08-29T17:34:40Z")
> [@Frankenstein\_Monster](#): > > They are not “better”, they’re merely “very good”. The thing is they are extremely safe while being very good. I wouldn’t call them “extremely safe,” I’d use “mostly harmless,” since ozone does matter just a bit. [Previous page](https://boards.straightdope.com/t/why-do-refrigeration-systems-commonly-use-cfcs-hcfcs/820399.md?page=1)