Is the boiling point of freon and its condensation point the same?
So freon basic boils at a temperature that is optimal for the operating conditions of a typical air conditioner? The lower the boiling point of a gas the better it is at cooling when it expands?
jodocus boiling point and condensation point is the same point. BUT this point is a function of pressure. at higher pressure this point is at a higher temeprature. so if in AC condensation occurs at higher pressure than evaporation, then it should also occur at a higher temperature.
as for your last question, the amount of energy transferred is simply a pressure change multiplied by a volume change, does not matter what substance you’re compressing the formula is just that.
Also, fwiw, the high electronegativity of the halogens reduces the attractive forces (dispersion forces) between the molecules of the freon.
So in summary, extremly strong intramolecular forces within and low intermolecular forces between the halocarbon molecules.
The reduced attraction of the halocarbons to other molecules leads to the properties such as low viscosity and low surface tension.
A refrigerant (Freon is a brand name, another example is Genetron) is a substance that can be changed to a vapor by boiling it and back to a liquid by condensing it. R-22, a common refrigerant in the state, has a boiling point of -39F. When it boils it changes state from a liquid to a gas. When this happens it absorbs heat from objects near by, a process called superheat. This gas is compressed which causes the gas to reject its heat and condense back to a liquid, sub-cooling. By the way, propane is very similar to R-22. I have heard that they are interchangable but one of them is flammable.
I refrigerator that uses ammonia does not need electrcity. Evaporation is achieved by applying heat to the liquid and it condenses readily at a lower temperature so there is no need to compress it. It goes through the system by convection. A friend of mine has a small refrigartor that uses ammonia. It is powered entirely by propane. I took it to school, my teacher could not find one to show us.
Source:Refrigeration & Air Conditioning Technology ; William C. Whitman and William M. Johnson
Woohoo! I knew electronegativity was in there somewhere.
You are confusing different issues: Ammonia and absortion refrigeration. Different things. Ammonia is also used as a refrigerant in compressor heat pumps and an absorbtion heat pump does not necesarily need to use ammonia.
No Sailor , I am not. I can go right now and put my hands on a small refrigerator, about 2 or 3 cubic feet, that was removed from an RV. It uses ammonia as a refrigerant. A reservior holds the liquid ammonia and a small propane gas flame is used to promote evaporation. There is a prominent warning on the side of the unit that says it contains ammonia. Small absorbtion units use ammonia as an attractant.
Typically larger scale absorbtion chiilers are used where there is a supply of wasted heat. They use a solution of lithium-bromide and water as an attractant. Circulating pumps are used on large units and not compressors.
Um, yes, I am quite familiar with both kinds of refrigeration as I have worked with them professionally. I can assure you that (as has been mentioned by several people in this thread) ammonia is often used with compressor driven heat pumps. Please read and understand what I posted and tell me exactly what you believe is wrong. I assert that both types of heat pumps (absorbtion and compressor) can exist which use or not use ammonia. There is nothing special about ammonia. Just because you found an absorbtion type refrigerator which uses ammonia does not mean only absorbtion heat pumps use ammonia or that all absorbtion heat pumps use ammonia.
So, unless I misunderstood your earlier post, I assert it is mistaken. Or please explain to me how I am misunderstanding it.
After considering your argument, I now understand your point. My intent for using ammonia as an example was to demonstrate that electricity and the use of a compressor were not necessarily needed for the refrigeration cycle to be created. The understood limiting conditions only and all change the tone of my examples, however I did not use them.
Sailor, I condcede, I will be more careful in future posts. Isn’t a free exchange of ideas nice? You have worked on systems that use ammonia as a refrigerant/attractant? I would be too afraid.
Ammonia is routinely used as a refrigerant in large industrial installations. You have large compressors in a single location, cooling towers (condensers) and then the liquid, compressed is distributed with pipes all over the plant where it is evaporated as needed and recirculated back.
I worked in the installation of machinery used in the manufacture of carbonated beverages (soft drinks & beer). Our machines required the water to be (among other things) chilled to a given temperature so a chiller was installed right before the machine. These big industrial chillers (10k - 35k l/hr) used the ammonia piped in from the central plant installation.
During the installation, adjustments and maintenance it was not uncommon to have ammonia leaks which would permeate the entire plant and make the air barely breathable for long periods of time. We were expected to grin, bear it and continue with what we were doing.
AFAIK ammonia is the refrigerant of choice for large installations.