This Gas HEATS up when it should cool down

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  • Опубликовано: 23 фев 2024
  • In this video I talk about Joule-Thomson Expansion and how it is being used as a treatment to kill cancer cells
    Simulators I used in this video:
    physics.weber.edu/schroeder/m...
    www.falstad.com/gas/gas.html
    phet.colorado.edu/sims/html/g...
    physics.bu.edu/~duffy/HTML5/P...
    demonstrations.wolfram.com/Jo...
    Read about Argon-Helium Cryoablation:
    radiologykey.com/2-cryoablati....
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Комментарии • 385

  • @TheActionLab
    @TheActionLab  2 месяца назад +95

    Who can guess what happens to the outlet temperature of an ideal gas coming out of a valve?

    • @trixy8719
      @trixy8719 2 месяца назад +9

      the outlet temperature of an ideal
      gas decreases

    • @TheDroneOperator.
      @TheDroneOperator. 2 месяца назад +2

      Couldn't this work as a power plant using some sort of refrigeration cycle on a huge scale in the arctic or something?

    • @TheReaverOfDarkness
      @TheReaverOfDarkness 2 месяца назад +3

      What real gases seem to do is come out at only slightly reduced temperature while it is the liquid in the container which cools drastically.

    • @bokchoiman
      @bokchoiman 2 месяца назад +1

      What's an "ideal gas"?

    • @cybi124
      @cybi124 2 месяца назад

      not me

  • @profdc9501
    @profdc9501 2 месяца назад +106

    This is one of the best discussions of the Joule-Thompson effect I've seen. Wonderful!

  • @HawkyStudying
    @HawkyStudying 2 месяца назад +89

    You are the best sciece RUclipsr, divulgative, you go straight to the point, you don't oversimplify, you don't take yourself too seriously and you always have things to surprise us

    • @cybi124
      @cybi124 2 месяца назад +1

      fr

    • @yaykruser
      @yaykruser 2 месяца назад +8

      I wouldnt say the best, there are others that are very good too!
      Codyslab, Veritassium, Smarter every day, Nile red, braniac etc.

    • @Auroral_Anomaly
      @Auroral_Anomaly 2 месяца назад +2

      ARE YOU HAVING A STROKE?💀💀

    • @can_aliens_pls_adopt_me
      @can_aliens_pls_adopt_me 2 месяца назад +2

      ​@@yaykruserI don't get why he's compared to them, his style of videos are very different. He shows everything as a practical demonstration, hence "Action Lab" and yes the explanations of it can sometimes fly over my head, the experimental observations always stick with you, and the explanation doesn't leave anything out so it can be used as a teaching tool without overly simplifying it as other RUclipsrs might do.

    • @timelessperspective
      @timelessperspective 2 месяца назад

      Agreed!

  • @navintrg8422
    @navintrg8422 2 месяца назад +38

    Chemical engineer here and this is one of the best explanations i have seen here. But all this can be totally changed when mixture of gases come into picture. I deal with hydrogen and even with above 50 mol% of hydrogen and rest being nitrogen and methane when you expand the gas mixture it cools. Thats different story

    • @patrickbowen9395
      @patrickbowen9395 2 месяца назад +2

      What if its only hydrogen and nitrogen? Your comment made my brain shout, " Haber-bosch" and how could this be temp and pressure difference be manipulated in some way to not need "9 gazillion" bars of pressure to produce ammonia.

    • @navintrg8422
      @navintrg8422 2 месяца назад +2

      @@patrickbowen9395 still the mixture cools. Newer process of ammonia production has only nitrogen and hydrogen as reactants and they still go to that higher pressure but comparrably lower than conventional ones

    • @ILI.D.
      @ILI.D. 2 месяца назад +1

      You can tell he's an Engineer by the fact he used lowercase I when addressing himself

  • @xanderclemons6306
    @xanderclemons6306 2 месяца назад +20

    Even with arguably complicated topics you always manage to make the explanation clear and simple enough for anyone to understand. I can’t imagine how much work it takes to read the research papers full of technical jargon and “translate” them in a way that makes sense

  • @4RILDIGITAL
    @4RILDIGITAL 2 месяца назад +1

    Never realized that gas expansion could be so complex and useful in medical procedures. Thanks for the deep dive into the topic, learned a lot.

  • @1495978707
    @1495978707 2 месяца назад +12

    The Joule Thompson expansion shows specifically how real gases are different from ideal. An ideal gas would not change temperature when undergoing free expansion, but real gases are sticky from van der waals. Except these rare exceptions. To be very explicit: refrigeration without phase change is only possible because of real gas being imperfect.
    Excellent video on thermal physics!

    • @HeyChickens
      @HeyChickens 2 месяца назад +1

      It would also be possible if expansion were to be done without massive turbulence, by reusing that energy to re-compress the expanded gases from the low pressure side of the system. Then your main losses would just be the extra work needed to compress the same volume of air at a warmer temperature vs at a cooler temperature.

    • @skipper472
      @skipper472 Месяц назад +1

      Refrigeration without phase change is possible even with an ideal gas. Just run the Carnot cycle in reverse...

  • @davezhu7651
    @davezhu7651 2 месяца назад +7

    You described Joule-Tomson coefficient better than my Physical Chemistry professor! Absolutely best science youtuber!

  • @michaeljordan215
    @michaeljordan215 2 месяца назад +16

    The visuals you added in this video is great.

    • @rasimbot
      @rasimbot 2 месяца назад +2

      Audibles are even better

  • @bengio_10
    @bengio_10 2 месяца назад +257

    The gas isn't gasing

    • @giosuezze
      @giosuezze 2 месяца назад +3

      YOU THINK YOU CAN SMOKE ALL MY GAS AND GET AWAY WITH IT?!? -a hood sage

    • @bengio_10
      @bengio_10 2 месяца назад +1

      @@giosuezze maybe

    • @memories1778
      @memories1778 2 месяца назад

      ​@@giosuezzeWanna smoke my fart, i haven't pooped for 4 days, u can use it to cook food or use as perfume

    • @mikayahfox1328
      @mikayahfox1328 2 месяца назад +1

      Yes

    • @Vikanuck
      @Vikanuck 2 месяца назад +1

      That’s how we ask for Pepto Bismal at the drug store in Canada 😀

  • @chalklandingplace
    @chalklandingplace 2 месяца назад +68

    Wow, it’s so nice seeing your video production continue to improve year after year with your popularity and success! I love seeing this channel grow 😁

    • @Kwint.
      @Kwint. 2 месяца назад

      Ty babe!

    • @Amkjmi99
      @Amkjmi99 2 месяца назад +2

      You love this channel? Name every video on this channel!

    • @NobbsAndVagene
      @NobbsAndVagene 2 месяца назад +3

      ​@@Amkjmi99 foreach video in videos
      regurgitate video title

    • @bluestraveler2980
      @bluestraveler2980 2 месяца назад

      I could not stand the music/sounds, could not watch!

    • @cybi124
      @cybi124 2 месяца назад +1

      this channel better than teachers so its good

  • @AdrianHereToHelp
    @AdrianHereToHelp 2 месяца назад +3

    This whole time I was thinking about duster cans as a way of applying this information. I'm glad you mentioned them at the end so I didn't come away with a false conclusion!

  • @CKILBY-zu7fq
    @CKILBY-zu7fq 2 месяца назад +2

    I've watched many of your videos, I just want to say BRILLIANT, I don't always like each one of them but. You do a dam good job in your delivery on most everything I've seen. So.. thanks for your diligence and subject matter, I believe I'm learning great things to know. Peace.

  • @ulrichraymond8372
    @ulrichraymond8372 2 месяца назад +4

    Your scientific explanation is superb. Never understood what the concept of enthalpy and learnt something interesting. Absolute gold!

  • @lees3935
    @lees3935 2 месяца назад +1

    Wow! Saving this video to watch again to integrate full understanding. Thank you for teaching beyond Charles and Boyles laws.

  • @zendhan2517
    @zendhan2517 2 месяца назад +2

    this is the type of video i subscribed for. amazing video and always happy to learn something new.

  • @gnuffe7778
    @gnuffe7778 2 месяца назад +1

    Yo i love the editing on this vid. Good job!

  • @bloom2272
    @bloom2272 2 месяца назад +1

    Awesome videos like always BUT i resently went on a marathon watching ur older videos and the ideas and things you tried were so cool it felt like i was kiddo again... Feel free to post any crazy videos thx!

  • @stevebriggs4448
    @stevebriggs4448 2 месяца назад

    Thank you, what an excellent video, clearly explaining the science with observations, and giving it a very real and useful practical example, these videos should be used in schools!

  • @benmcreynolds8581
    @benmcreynolds8581 2 месяца назад +2

    It really shows the important impact of even the Slightest differences in a given environment. Temperature, density, pressure, charge, etc. Etc.

  • @silvenshadow
    @silvenshadow 2 месяца назад

    This was really great. Thanks for the amazing content

  • @brushmasterspaintingfranchise
    @brushmasterspaintingfranchise 2 месяца назад +2

    this is one of your harder videos to understand. great jobs explaining

  • @Lucius_Chiaraviglio
    @Lucius_Chiaraviglio 2 месяца назад +1

    Finally a clean explanation of the Joule-Thompson coefficient/effect.

  • @tomholroyd7519
    @tomholroyd7519 2 месяца назад +3

    I love the counterintuitive things. One time at CalTech a student in a lecture about hypersonic airflow said to the prof, "But that's counterintuitive". The professor said, "When it comes to hypersonic flow, you have no intuition."

    • @JustWasted3HoursHere
      @JustWasted3HoursHere 2 месяца назад +1

      Reminds me of the famous quantum mechanics saying: "If you think you understand quantum mechanics then you don't." [Richard Feynman]

  • @MattH-wg7ou
    @MattH-wg7ou 2 месяца назад +1

    I never knew this was a thing! I like learning new things. Thank you.

  • @arzuozturk6460
    @arzuozturk6460 2 месяца назад +5

    the quality of the videos got so good

  • @slengoslengaw8510
    @slengoslengaw8510 2 месяца назад +2

    Brilliant video! One thing to improve on would have been to explain inversion temperature which you indirectly mentioned but would have been useful to go into it in a little bit of depth to fully explain the concept here. Thanks

  • @notarealperson87
    @notarealperson87 2 месяца назад +2

    this is probably (no pun intended) your coolest video yet!

  • @ishanr8697
    @ishanr8697 2 месяца назад

    An excellent story, well told! I have been teaching ideal gas laws to students for over 10 years and this is going to help me teach real gases better. Thanks!

  • @DavidFMayerPhD
    @DavidFMayerPhD 2 месяца назад

    excellent explanation of Joule-Thomson effect.

  • @notweewee
    @notweewee 2 месяца назад

    Awesome, I learnt joule Thompson effect in chemistry, but helium and some other gases were exceptions. Good to see it practically.

  • @29-vibhusingh74
    @29-vibhusingh74 2 месяца назад +1

    Idk why but I am getting info about things right after or after sometime I study them in my classes.
    It has happened to me at least 10-12 times. Example my chemistry sir taught the states of matter and explained us ideal gas, real gas you have explained it a little better but as I have studied it so my info has been set in stone thanka

  • @austingirdner92
    @austingirdner92 2 месяца назад

    I love how you edit pauses just enough for me to mentally guess and then be like ohh yeah, that makes more sense when you explain shortly after asking a question.

  • @SF-fb6lv
    @SF-fb6lv 2 месяца назад

    Dang it, I keep learning stuff when I watch your channel!

  • @kevingreig9577
    @kevingreig9577 2 месяца назад

    That was great, felt like I learned something today!

  • @darmok3171
    @darmok3171 2 месяца назад

    Wow! This is super cool! I had no idea this was a thing!

  • @simongross3122
    @simongross3122 2 месяца назад

    That's fascinating, thank you.

  • @hijmestoffels5171
    @hijmestoffels5171 2 месяца назад

    I’ve learned something! Very interesting and well explained.

  • @lake5044
    @lake5044 2 месяца назад +1

    I want more of these videos about things I actually have never heard about before, not the usual science facts that are covered by every other science channel over and over.

  • @sturgeondtd9522
    @sturgeondtd9522 2 месяца назад

    Never knew about the mechanism for Argon/Helium cryoablation, neat!

  • @satyasivasubrahmanyam272
    @satyasivasubrahmanyam272 2 месяца назад +2

    Every video lets me learn new things Thank you 💖.

  • @tommythetoe
    @tommythetoe 2 месяца назад

    Thank you. I worked on ships in engine room. The exhaust gas from main engine has temperature sensors all along
    its path. I never understood why the temperature went up at 1 point as it expanded. Got it now

  • @rossmennie4903
    @rossmennie4903 2 месяца назад

    Always love your videos! Sometimes I play them at .25 speed. It makes you look like you’re drunk! I’m easily amused!!

  • @blamokapow137
    @blamokapow137 2 месяца назад +2

    Excellent video!

  • @whifta
    @whifta 2 месяца назад +4

    I was guessing Helium in the intro, and I got it right! My physics class is paying off, now I can properly pretend to be smart on the internet!

  • @homelanduniversitypress1150
    @homelanduniversitypress1150 2 месяца назад +1

    Add longer fade-in / fade-out ramps to the mood music snippets to make it feel less jarring.
    Nice addition.

  • @ChiragIP
    @ChiragIP 2 месяца назад

    Why wasn't this taught to me in school?! Thank u so much!

  • @boredlikealways2000
    @boredlikealways2000 2 месяца назад

    New editing! New editing?! Nice! Its like a new season of the action lab, thats so cool hah

  • @robinoja
    @robinoja 2 месяца назад

    Any chance you got the video idea from my recent post in ELI5 about the same topic and cryoablation? If you did, thats awesome! Glad you shared this amazing medical procedure.

  • @Studentofhvac
    @Studentofhvac 2 месяца назад

    Thank you for this.

  • @andrepqumetal
    @andrepqumetal 15 дней назад

    i work for oil and gas industry and we use this a lot (really a lot, arround 120 tons/h). We use some light hidrocarbons (C2/C3) im the cicle compression-cooling-expansion for a few times to reach -100Cº, and the JT effect will help to isolate H2 from C1, 90% of all oil polimers (PP/PVC/ and many others) start to take shape with this.. so almost everything cool you have today make use of this phenomena.
    I knew how it worked , but never been able to fully explain it to new workers. Thanks to this video i am fully capable of

  • @teddp
    @teddp 2 месяца назад

    Very nice and well explained 👍

  • @B_r_u_c_e
    @B_r_u_c_e 2 месяца назад

    Excellent. Thank you.

  • @rochemist5975
    @rochemist5975 2 месяца назад +2

    1. The Video quality improved a lot 💯
    2. I was wondering why H,HeNe heated up instead of being cold (I was too lazy to read all these complex words in the text book for morethan a year ).
    Thank you for making a video on this topic.

  • @lasagnahog7695
    @lasagnahog7695 2 месяца назад

    This one really blew my mind

  • @jonahjerryson4913
    @jonahjerryson4913 2 месяца назад

    This was so interesting to know.

  • @klaudiopeqini3500
    @klaudiopeqini3500 2 месяца назад

    Amazing! When some people ask why learning physics!

  • @RaymondDay
    @RaymondDay 2 месяца назад

    Wow that was good I always thought that down to the atom the faster the vibrate the hotter they are and that's what makes heat so when you compress them it slows down the vibration and that makes them colder but how you show it I guess that isn't right. Thanks for your video. Good job.

  • @mrfinesse
    @mrfinesse 2 месяца назад

    Learn something everyday..Very nice.

  • @Loknath009
    @Loknath009 2 месяца назад

    Really good explained, you have definitely improved over the years.

  • @wallyhall
    @wallyhall 2 месяца назад +10

    It forgot how to gas.

  • @cheeseparis1
    @cheeseparis1 2 месяца назад +1

    4:09 Slightly attracted to eachother, or repelled, with music from Carmen. Perfectly on point!

  • @alexandru5316
    @alexandru5316 2 месяца назад +2

    Very informative!
    Also: Thank you for not using AI generated images for this video! (weird that I have say this, but most channels go the AI content farm route and it's depressing)

  • @ahmadhasan8607
    @ahmadhasan8607 2 месяца назад

    Very interesting and useful.

  • @ronanclark2129
    @ronanclark2129 2 месяца назад

    Great topic

  • @soul-candy-music
    @soul-candy-music 2 месяца назад

    jesus, you went ham on the SFX this time.

  • @mo3azmagdy
    @mo3azmagdy 2 месяца назад

    Could you try performing the communicating vessels experiment inside the vacuum chamber as what keeps them aligned is the atmospheric pressure so this experiment would prove it and you could try involving other phenomena and properties related to that experiment

  • @davidcroft95
    @davidcroft95 2 месяца назад

    Great video! My question is: why I have a physics degree and never heard about this effect???

  • @calholli
    @calholli 2 месяца назад

    Physics is so dynamically complex. lol.. I love it

  • @godorhell8405
    @godorhell8405 2 месяца назад

    I love this channel

  • @rajmaurya6552
    @rajmaurya6552 2 месяца назад

    Please make a detailed video on demonstration and explanation of the super cool phenomenon called "Sonoluminescence

  • @marcfruchtman9473
    @marcfruchtman9473 2 месяца назад

    Very Interesting...

  • @sebastiand152
    @sebastiand152 2 месяца назад

    Cool video. One remark: the availalbe helium on earth is practically finite. We should use it accordingly for medicine, science,... and not waste it on bloons at parties and similar stuff.

  • @markberardi109
    @markberardi109 2 месяца назад

    Thanks for a great video...however I have some questions: @4.44 you say the "attractive forces are huge compared to the molecules".....if either nitrogen or helium is under placed under pressure in a confined volume, would it be true to say repulsive forces will exist between the gas molecules, causing them to want to move apart once released? Or put another way: when a gas is pressurized, on average, repulsive forces outweigh whatever attractive forces there might be. My second question: is the heating of helium local (at the throttle point), or does the entire system heat up (the bottle, the throttle and the discharged volume)?

  • @robertheinrich2994
    @robertheinrich2994 2 месяца назад

    I wish professors could have explained that part of chemistry (physikalische chemie) in this manner to me back when I studied chemistry 20 years ago.

  • @mtart5595
    @mtart5595 2 месяца назад

    What a good video :)

  • @abhinavabcd
    @abhinavabcd 2 месяца назад

    Thanks!

  • @corl4147
    @corl4147 2 месяца назад

    hey @TheActionLab, is this potential energy also responsible as to why supersonic flow speeds up in a (converging-)diverging nozzle?

  • @Mike__B
    @Mike__B 2 месяца назад

    Now that was very interesting, I couldn't process why a gas would cool, my only thought was that in some way under certain pressures the gas may have more degrees of freedom, more places to store energy other than through movement (kinetic energy), and by releasing to the air you lower the degrees of freedom hence transferring that energy to kinetic energy.

  • @bowieinc
    @bowieinc 2 месяца назад +1

    I just had a cryogenic nerve ablation where they shot nitrous at nerves to create ice balls around nerve and ablate outer part of nerve, cutting off pain signal.

  • @galaxybidhan1034
    @galaxybidhan1034 2 месяца назад

    Will the system under compression, entropy increases or decreases?
    Entropy is a measurement of randomness. Randomness can be anything among atoms from being different in atom's orientation or spin. Calling out a combination. If this is so then combination depends on temperature provoke by compression and expansion.

  • @bdg77
    @bdg77 2 месяца назад

    I learned something!

  • @WerWeiss
    @WerWeiss 2 месяца назад

    Does the Joule-Thompson Coeficient correlate with the speed of sound in the compressed gas?

  • @galaxybidhan1034
    @galaxybidhan1034 2 месяца назад

    Can temperature change be defined by flow of gas from the high pressure to low presssure. Applying fluid mechanics. Where pressure is great velocity is low. With this prespective, when molecules from valve opens and starts to spread. So, pressure is low outside and high inside the valve,shouldn't the velocity of any gas increase after opening the valve?

  • @YodaWhat
    @YodaWhat 2 месяца назад +1

    Very interesting, but you don't need an exotic effect like this to cause localized heating and cooling of a spot. It could be done by alternating hot and cold flowing brine, or by electrical resistance heating combined with a cooling fluid, or by periodically reversing the current flow through one junction of a thermocouple. So this innovation in surgery is just a way to get a patent.

  • @catman8965
    @catman8965 2 месяца назад

    INTERESTING 😊

  • @TheIMGmedia
    @TheIMGmedia 2 месяца назад

    Yeaaaa… this may have been the least fascinating video I’ve seen from this channel. Which is STILL interesting.

  • @OddcessiveNooBurrito
    @OddcessiveNooBurrito 2 месяца назад

    Has the Joules Thompson coefficient ever been used in supernova calculations?
    I remember seeing something that scientists aren't sure how certain post-nova objects seem to gain heat the further away from the explosion source: could this possibly be explained away by such high temperatures that the pressure decrease increases the temperature?
    This one much more abstract: what if a similar coefficient could be applied to space-time and gravity, explaining potentially the dark matter or dark energy problem?

  • @zecuse
    @zecuse 2 месяца назад +1

    0:57 No, it just means you equalized the pressure between the 2 containers. The volume of 9g of air is the combined volume of both containers + tube. With the way you said this, you'd have to vacuum out the air from the smaller container instead of just connecting them with a tube.
    Edit: Quoting what he said: "Since I vacuum the air out of this [pointing at the *larger* ] container, if I just connect the two, then all of the air from this [touching the *smaller* ] container will now *mix between the two* ".
    The pressure in the system he made is equalized between BOTH containers connected by the tube. In order for the LARGER container to get all of the 9g of air, he'd have to use a vacuum device INSIDE the already vacuumed larger container to suck all of the air out of the smaller container to make the smaller container a vacuum now (aka no air).

    • @koharaisevo3666
      @koharaisevo3666 2 месяца назад +2

      That's what he said though?
      "since I vacuum the air out of this container if I just connect the two then all the air from this container will now mix between the two and now this will be the volume of nine grams of air"

    • @zecuse
      @zecuse 2 месяца назад

      @isevo3666 He said "Since I vacuum the air out of this [pointing at the *larger* ] container".
      Next he said "If I just connect the two, then all of the air from this [touching the *smaller* ] container will now mix *between* the two".
      The *larger* container does NOT contain 9g of air given what he said! The way he said and performed all of this describes *equalizing* the air between BOTH containers. That means BOTH containers (+ the tube) contain the 9g of air, NOT that ONLY the larger container has all 9g of air.

  • @leonardoalbuquerque9375
    @leonardoalbuquerque9375 2 месяца назад

    Blendtec? Fancy.
    Will it blend though?

  • @sikhswim
    @sikhswim 2 месяца назад

    You could basically build a high school chemistry and physics curriculum with all of these videos!

  • @JyotiTiwari-jl4bh
    @JyotiTiwari-jl4bh 2 месяца назад +1

    Now this is an actual practical explanation which should have been done in the Thermodynamics class

  • @diogenes5118
    @diogenes5118 2 месяца назад

    Please explore the Mpemba effect, please!!

  • @shribalajiv2806
    @shribalajiv2806 2 месяца назад

    If possible can you try an experiment that I came up with. The things you need are an empty room, a light source and you inside the room. What I have in mind is that , when the light source is turned on you are able to see the walls of the room because they reflect light from the light source. But what if we make the surface of the walls so imperfect that in whatever direction light may hit the wall it does not get reflected to atleast a single point in the room. Which means if you observe the room from that point, even if there is a light source in that room, you would not be able to see anything like the wall and the ceiling in the room.

  • @dahmc59
    @dahmc59 2 месяца назад

    awesome

  • @JonathanMBardsley
    @JonathanMBardsley 2 месяца назад

    Can I ask if you can show a gas next to a vacuum doesn’t need a container because the gas is not pressurised and can you show it at the bottom of the vacuum tank

  • @196cupcake
    @196cupcake 2 месяца назад

    My only note is that it might have been good to mention early on that temperature is a measure of the energy of the molecules giggling around.

  • @AKG58Z
    @AKG58Z 2 месяца назад

    This just made it more complex for me

  • @jensklausen2449
    @jensklausen2449 2 месяца назад

    Should the helium atoms not do the opposite of clumping together, if they repel each other at short distances?

  • @echo01d
    @echo01d 2 месяца назад +2

    I just had an interesting thought. If I was in a closed space with equal parts of oxygen and helium (or one of those other gases), and I want to turn up the temperature in the "room". Can I decrease the pressure to do so? Please let me know if I need to clarify my question.

    • @carultch
      @carultch 2 месяца назад

      For this process to work as James demonstrated, it is an isenthalpic process to expand the gas. An isentropic process will decrease the temperature significantly more, and will decrease the temperature in a way that is independent of the flavor of gas.
      Isentropic means the process takes place with constant entropy. Meaning no heat transfer and no irreversible processes. All expansion turns into mechanical work in some form or another.
      Isenthalpic means the process takes place with constant enthalpy. This means no heat transfer, and a process that is as irreversible as possible. In other words, all the work that the gas could do, is dissipated thermally by friction.