Refrigerant Compression and Temperature
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- Опубликовано: 20 июл 2024
- This video covers refrigerant compression and temperature. It will help you understand what occurs to the refrigerant inside the compressor and why the temperature changes so radically from the suction line to the liquid line.
A compressor is not necessarily a pump; it does move the vapor, but it also changes the volume, temperature, and pressure as it does so.
The refrigerant absorbs heat in the relatively cold evaporator coil, and it proceeds to the suction line. The suction line carries all of the heat in the home to the compressor, although you will feel just a cool vapor when you grab the suction line. That vapor will be very hot when it leaves the compressor.
In some cases, the cool vapor refrigerant goes into the head of the compressor from the larger suction line, where some of it cools the compressor. From there, the vapor undergoes compression and is pumped out of the compressor via the smaller discharge line.
You can think of a compressor as a room with a bunch of ping pong balls that keep bouncing. (The ping pong balls are molecules, and the speed at which they move is the temperature.) Those walls will start moving in, which moves against the force of the balls and causes them to bounce a lot faster. The molecular velocity increases, so the temperature increases. Although the compressor does generate some heat, most of the temperature increase inside the compressor can be attributed to the molecules being squeezed into a smaller space.
The gas laws also explain that; the temperature increases as the pressure increases, and they both decrease proportionally.
Read all the tech tips, take the quizzes, and find our handy calculators at www.hvacrschool.com/
Great Video. The visuals were very helpful.
I was trying to look up exactly what heat is a few weeks ago for so long and didn’t get the answer I was looking for. He just answered it. Great video! Totally helping me understand the refrigeration cycle better. Thank you
PERFECT TIMING with the video I just finished reading a chapter about compressors and pressures!
Thank you for the great metaphors, you give a clear picture to whats going on.
The heat is travelling down the cold suction line and we raise its temp to get rid of heat to air. I really like that description. Thank you.
Another analogy is a Diesel engine works off heat of compression, the compression is what ignites the fuel.
I can only imagine my bosses face when I begin explaining to him that temperature is actually a measure of the average molecular velocity...
True, it’s revelation 😎
Another great video Bryan everyday I learn new things about your video thank sr
I really love how the compressor differential temperature explanation ties in nicely to the sponge humidity relative video. It's crazy how HVAC makes you think. It's always difficult to explain these concepts that sometimes seem contrary to guessed belief
Physics dude. HVAC is applied physics.
Thx for the podcast :) As a technician at an icerink however i consider this basic knowledge for any refridgeration technician. It is the core of how refridgeration works...
fenna pel what refrigerant are you using? R-22 is what the city using here until they can upgrade.
@@kidalwys , we have a 2 stage system with R-717 in the first stage (containened in the engine room) and R- 744 in the second stage (in the icerink floor piping)
thanks for all your videos, I just got in the military and its kind of a teach your self type deal where im at. I was wondering if you had any information on what the different relays do.i cant remeber the fuction of the k1,k2,k3,k4
That was great Bryan!
Very nice and clear explanation ... thanks
This is the best video I've ever seen!
Amp her awesome video Bryan. Good stuff
Great video.Good job😜
Good job. If most hvac techs really understand the difference between heat and temp, they'd have a much happier career.
Huh?
@@maness2112 I've long since lost count of techs that don't know how AC works.
great summary
Actually decreasing the volume rises the pressure - from the ideal gas law you cant see the way the temperature rises. The multiplication cant be predicted since one goes up and one goes down. If you are familiar with joule thomson law, when gas spreads its usually cooled down because it leaves interactions which makes him increase potential energy on the expense of kinetic energy. I assume the opposite is the same principle. The particles get closer, more interactions, loses potential energy and get kinetic energy - temperature rises.
nice video , very good information . Thank you for shared ^_^
cool video bryan im really a fan of yours. but im still learning. im maintaining a water chiller tank and im having trouble with my compressor. due to the fact that my compressor is freezing around its suction line. huhuhu i dont know what are the reason behind it.
Question: if you didn’t have a metering device in the evap would you still have compression? My thinking is the compressor is a pump unlike a car engine. The engine actually compresses the gas on the compression stroke with both valves closed. So in a compressor you have an intake valve and exhaust valve but no compression stroke. So does the dammed up liquid bearing against the metering device one of the “walls” which allows compression?
Thanks from Bangladesh.
Great videos 😜
Dope video!!
Glad you liked it!!
Well presented. I’ve had this backwards my whole life. Always thought the suction line was cooled refrigerant on its way into the evaporator coil and the liquid line was carrying hot refrigerant to the condenser to be cooled. Still don’t quite understand how the hot (liquid line) ends up cooling the evaporator coil so much, on a day where outdoor ambient temps are high the liquid line on my home system will be extra warm.
The temperature is higher than the suction line but the energy content is lower. Energy was just rejected as heat into the condenser. Immediately after the metering device the liquid refrigerant now has a boiling point which is colder than its surrounding. The liquid refrigerant begins to absorb heat. The low energy state begins to increase as it absorbs heat. The refrigerant absorbs a large amount of heat as it changes state from liquid to vapor. It is now much colder but also has a higher total amount of energy content within it.
@@Practicing_HVACR thank you I have a much better understanding now. It’s fascinating stuff!
in my studytime I have always wondered where this energy to accelerate the molecules comes from. I'm really thankful for your video, but I think I did not quiet understand this yet.
Right now, I think the model of explaining temperature with average molecule velocity does not sum it up correctly when it comes to compression:
when s is the way an average molecule moves and t is the time it needs for this way you can state:
steady-state:
s1 -----------------------------------------> with t1
compression:
s2 ---------------------> with t2
i'm not sure: v1 = v2 or v1 < v2
i'm sure: t1 > t2
So, what is really making it hotter, is an decreased interval of contact between the gas and e.g. the skin. You get contact with more molecules in the same time.
This can have 2 reasons that do not contradict each other:
1st assumption: Velocity v increased, so they travel faster through sapce and hit you more often in the same time
2st assumption: Way s is shorter, so they don't have to travel through the same size of space resulting in more contacts in the same time.
I do not understand where the acceleration comes from and since the room and the gas are compressed the way s is definitly shorter. Thus an increased velocity sounds less convincible than a shorter distance.
So maybe in the end temperature is not velocity of molecules alone? Is it a bit more complicated?
Please let me know if I am wrong! Cheers.
Yeh im thinking the same way as you, I would've imagined that the speed of the molecules remains the same, but the amount of collisions would increase at the same speed. After all im pretty sure temperature is related to collisions more so than just the speed of the molecules alone. That is that if pressure were the same but there were 2 different temperatures, then you would be feeling different moleculre speeds. But if pressure and temperature were proportionally higher, then you would be feeling the same molecule speed but just more collisions for the hotter one. Excuse my rough explanation. I could be wrong though, after all that's why I'm looking up these videos right now lol.
What if the compressor is ice cold to touch and suction line from compressor has small amount of ice build up? All fans work correctly and could not blocked
There is a temperature difference between condenser and ambient temperature. how does the compressor adjust its discharge pressure with ambient temperature to keep this temperature difference? Is there any sensor on compressor discharge or a Hi pressure on discharge line is considered by designer?
Wow.. what a voice..
If we install a really big condenser, can we give up on compressor? in a refrigerant cycle ? (theoretic)
So if we say suction is around 50 degrees and discharge is around 160 degrees, why do we compress it although exchanging heat with environment will return it to around 50 C? ( assuming environment temperature is around 50 degrees)
great info, but adjust that sound, way too much BASS, very annoying , keep them coming, I'm learning lots of stuff
Is diesel effect possible inside the compressor ? R32 + air inside the compressor can blow up the compressor ?
How fast does refrigerant assume cold and warm compared to water?
3:30 why are all your room surfaces and AC unit dirty and broken?
If the temperature increase of the compressed gas is related to the molecules being closer together then why is it that you can remove the heat and have a lower temperature even though the molecular density of the gas remains the same or even better why is it that liquid refrigerant can be cool while the discharge temp of the compressor is hot even though it is a gas? Toward the end of the video you mention that the increase in temperature is due to a given amount of heat energy for a larger volume being compressed into a smaller volume thus an increase in temp. Also gas law does apply. It seams that there is some gaps or contradictory explanations here. I understand your latter explanations to be correct and to be the way I was taught personally. Did I misunderstand your explanation?? Thanks
Why with a lower suction pressure the gas heats up higher?
Can someone explain me compressors hp???
Hot god to cold at both points , evaporator takes heat from the room puts it in the refrigerant , condenser takes the heat and dumps it in the cooler air outside. It’s all about refrigerant behavior. It’s boiles on the cold side and condenses on the hot .
What temperature should the discharge superheat be?
onemischiefmaker On the discharge side it’s called Sub-cooling. You usually want around 10 degrees sub-cooling but it depends on getting other measurements to get the correct sub-cooling.
With a TXV the nominal superheat is 8-12F. With piston type metering device, refer to manufacturers specs or calculate target superheat. For a faster and better way, just make sure that your suction line temp is right above freezing: typically in comfort cooling settings and many more applications this will mean you are just right or well within reason of having a good charge. Check the split to further validate.
Refrigerant is not Sub-Cooled until it makes its way through the Condenser.
How to make that gas at home
Why would I say Auto or paws due on already
why refrigirant needed to compress?
I will try to answer you in my Q/A video
What always makes me confused about is:
When you see the pressure/temperature chart of freon for e.g r410..
It shows that with reduced pressure, temperature falls..
But i wonder then why when an AC is low on gas, it reduces cooling, although the pressure on low side reduces when gas level is low in the system, which means now it should cool more..
Ahhhh...so much confusion..
I believe the its because there is less refrigerant (gas) to do the work of cooling the air. Yes there is low pressure. But also there are less molecules to absorb heat energy. Less volume of actual fluid to pull heat out of the air. Does that make sense? I hope it makes sense becuase Im trying to figure this out too.
@@jerm5772 yes i think you are right... it is making sense..thanks :-)
So why do HVAC systems "freeze-up" if they get low on refrigerant? What exactly "Freezes up?"
Froman Abe low charge=low pressure=low temperature
Anything below 32 degrees is going to freeze up. If the refrigerant is below 32 degrees the evaporator coil and Suction line will freeze up as well as the compressor.
@@ChineseChicken1 Those parts of an HVAC system don't actually freeze themselves, do they? They just get moisture freezing onto them, right? Of course that's a problem for the evaporator coil since it will block airflow.
Froman Abe Yes, it’s on the outside of the copper coil or line-set. I’ve seen coils frozen up into a solid block of ice.
Refrigeration Systems freeze up when they are low on refrigerant and certain criteria is met. As the system loses refrigerant, pressures decrease and subsequently, refrigerant velocity throughout the system decreases. On the Evaporator, discharge Superheat is rising at this point, but the metering device is still receiving and is allowing some liquid refrigerant into the inlet. Low velocity means that liquid boils completely at the beginning of the evaporator, where it used to require a majority to do the same. Now temperature at one finite point on the coil dips below 32dF and formed condensate now freezes. This ice insulated that section of the evaporator, which means this “low velocity, reduced surface area boiling point” moves down; until it is in the air stream where it collects condensate and then freezes it. This process continues until the evaporator is completely frozen, then it can do the same thing to the suction line.
Hi
Use chapters please
#Video_chapters
ypu just took all the fun out of feeling,,,anything.
I want sexy scroll patent artwork....😟
I love your videos, however, at times you talk so fast it's hard to grab ahold of what you're saying. I generally have to listen to it over and over just to process it.
Speak slowly then more understanding
😂 to much blah blah