Heat Engines, Refrigerators, and Cycles: Crash Course Engineering #11

Heat Engines, Refrigerators, and Cycles: Crash Course Engineering #11


Cycles are a big deal in engineering. Today we’ll explain what they are and how they’re used in heat engines, refrigerators, and heat pumps. We’ll also discuss phase diagrams and the power of using renewable energy resources

Crash Course Engineering is produced in association with PBS Digital Studios:

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RESOURCES:
Çengel, Yunus A., and Michael A. Boles. Thermodynamics: An Engineering Approach. 8th ed., McGraw-Hill Education.

https://www.livescience.com/57797-refrigerator-history.html

https://en.oxforddictionaries.com/definition/cycle

https://www.asme.org/engineering-topics/articles/manufacturing-processing/jacob-perkins

https://practicalaction.org/zeer-pot-fridge

https://www.nwwindandsolar.com/solar-power-in-seattle-and-the-northwest/how-do-solar-systems-produce-energy/

http://www.qrg.northwestern.edu/thermo/design-library/refrig/refrig.html

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80 Comments on "Heat Engines, Refrigerators, and Cycles: Crash Course Engineering #11"


  1. As far as social impact goes, electric refrigeration is probably one of the top 5 engineering solutions of all time, right there with the wheel, iron smelting, movable type, radio, and computerized automation. No way the world population is where it is today if the food to feed all these people spoils at its natural rate.

    Reply

  2. Thanks I've always wanted to know how a fridge works. I found it pretty wierd that you can all energy to something to make it colder.

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  3. It's great that you point out that solar panels and wind turbines are a great alternative but why don't you point out the amount of energy and resources required to build these items and the hazardous-waste left over after producing them

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  4. Aren't freons banned ? To my knowledge they are banned in the EU but is it just the EU or is this video simplified?

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  5. Great host although it seems like your voice is straining to talk for such long periods. Consider vocal excercises to improve your range. You'll find it improveds speeech

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  6. Glad to know when I get stuck doing the same thing I'm just playing my part in a powerful cycle.

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  7. LJ 😏 you are a hot little scientist aren't you😍 sorry I'm speaking my mind again lol 😊

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  8. i cant wait for the next episode … fluid momentum! like shockwaves thru substances. Vacuums and compression!

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  9. Please become more knowledgeable about the topic before lecturing on it. 1) heat is NOT a substance and it is NOT energy, as is implied in the video and this is THE topic where it is important to get it right, 2) when heating a place or thing, the work is 0% and waste is 100%, because the waste is what is actually wanted in that case, (4:56 – 5:09 sounds a little confused).

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  10. Perkins, Perkins, Perkins, why does that name sound familiar? Oh yeah they made engines in the 30s. Sorry different Perkins

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  11. That would have also great to learn all that from our favorite power hank but she is also doing good and her accent is really very impressive like the way benedict cumberbatch speaks.

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  12. I lose proper understanding about 3 minutes in most times πŸ˜‚ but it's still pretty interesting to watch.

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  13. I am very sorry but that was the worst explanation for refrigeration I have ever heard. I now understand
    why I have to teach refrigeration basics to the cadets who come out of school. Sorry again I know you
    mean well and I love your site. For those who were confused
    Pretend you put a pot of water on the stove turned the flame on high and went out for a beer.
    Water boils at 100 C the water will heat up to 100 C and stay there. Not getting any hotter, the
    pot will stay near that temp and be fine , until the water boils away. After the water is gone the pot
    melts and your wife is pissed. The water was keeping the pot cool I know 100 C seems hot but
    its way colder then fire. It takes energy to make something boil or even evaporate. Thats why
    your hand feels cool when you poor rubbing alcohol on it and blow. We make freon it boils
    at what ever temp we want say at a nice 5 C to keep that beer cold.
    Second water does not always boil at 100 C think of a pressure cooker higher pressure
    means that it boils at over 100 C or a persons blood boiling in outer space It boils there
    because the pressure was 0 so low that it boils at your body temp.
    ( I know not exactly correct but easy to picture)
    Third steam turns back into water at 100 C same temp. same temp I know sounds wrong
    but its true.
    So you have 2 radiators 1 inside 1 out. A compressor that is sucking on the radiator inside
    and pushing into the radiator outside. Just before the radiator inside your home there is a
    blank with a tiny hole in it so only a small bit of freon can get through. There is a fan on
    both radiators. You turn of the compressor the press in the inside radiator goes down
    while the outside radiator press goes up. Remember there is that blank only letting a small
    amount of freon to flow. the pressure outside goes up while the fan on the radiator keeps
    it at outside temp. ( compressing any gas makes it hot. More you compress it the more
    the temp goes up) Remember boiling temp goes up when pressure goes up and the boiling
    temp is also the temp it condences at. the pressure goes up enough with the temp staying
    the same that it turns back into a liquid. It puts out a lot of heat when this happens.
    That liquid freon now flows to your inside radiator ( through the small hole in the blank
    that maintains the pressure difference) where it now boils at a nice 10 C . The fan
    inside blows air over the radiator keeping it warm enough to boil the freon and cooling
    your home. The compressor now starts it all over again. A cycle.
    sounds complicated but really easy when you go over it a few times.
    Sorry for the super long post. Again I love your site just hate this vid.
    Tom

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  14. I know that this is a little bit off from engineering but who here would like a crash course criminology

    Reply

  15. ? if another Big Bang occurred. Would our universe get scattered and a new space would occupy our place in that 2nd Big Bang universe?

    Reply

  16. Can someone answer me a quick little fluid dynamics question?
    I have an exam question here that's simply:
    How can you increase the maximum flow of a Laval nozzle with fixed geometry?
    And I'm really confused. Is the answer simply that you can't? I'm unsure and my script doesn't exactly help me.

    Reply

  17. πŸš€πŸš€πŸš€πŸš€πŸš€πŸš€πŸš€πŸš€πŸš€πŸš€πŸš€πŸš€

    Reply

  18. Solar power is more damaging to the environment. Look at materials, cost to get materials, pollution from getting and transporting materials. If panels lasted forever, maybe. Chemicals are toxic and the lifespan is too short. Speeding up the process of climate change instead of slowing it down.

    Reply

  19. She did miss out a bit i think on the properties of the refrigerant and other gases . As being a mechanical engineer we are aware of these things . Its basically about pressure and temperature . Everybody knows water boils at 100 Degrees but not everyone is aware that boiling point of liquid changes with the change in pressure . If pressure increases boiling point increases and if the pressure decreases the boiling point decreases . For example at an altitude of 20000 feet water boils at near 40 or 44 degrees celsius because the pressure is less at that altitude . The same happens in a refrigerator . When the compressor compresses the gaseous refrigerant its pressure increases so does its boiling and condensation temperature . And the heat because of compression of the gas is rejected to the atmosphere in the condenser and the refrigerant condenses . The expansion valve then reduces the pressure of that liquid refrigerant thus reducing its boiling point and temperature . this low temperature refrigerant is the passed on to the evaporator to absorb the heat and cool the surroundings .

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  20. I lost track of the lessons because I kept looking at that cool shelf in the background. I'm gonna build one of those

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  21. This is such a great playlist. I was writing a letter to my father and asked him why an air conditioner works because he has been an HVAC guy for most of his life. From his prison cell of almost 10 years, he was able to draw me a very similar diagram. Given that I am somewhere in between my 2nd and 3rd year of aerospace engineering, I was astonished at his ability to explain such a concept with just a pen and paper where most of my instructors had not fully succeeded. I thought I'd share that story because it hits home pretty well. Thanks for this. I have much to share with him upon his liberation.

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  22. WE DON'T NEED FRIDGES, NOR ENGINEERING NOR DREAMS OF 100% OR EVEN FUNNIER OVER-UNITY EFFICIENCY. OUR MISSION IN LIFE AS INTENDED BY NATURE / UNIVERSE IS TO TAKE PART OF THE PLANT EATING CYCLE = MOSTLY FRUITS AND SOME OTHER EDIBLE PLANT LIFE EXCEPTIONALLY WERE THEY THRIVE UNTOUCHED = NOT WERE WE FORCE THEM TO FUNCTION AND WONDER WHY THINGS DO NOT WORK. YOU WILL NOT ONLY / JUST BE EATING THE RIGHT STUFF IN THE RIGHT CONDITIONS WITH ALMOST ZERO EFFORT BUT YOU WILL HAVE PLAYED A MUCH MORE CRITICAL ROLE THAN INDIVIDUAL SURVIVAL = BUILDING A COHERENT AND LIFE PROMOTING SYSTEM FOR ALL TO THRIVE. THUS WE WOULD BE AT OUR BEST INSIDE THE MOST EFFICIENT AND LIFE (HUMAN) FRIENDLY "MACHINE" POSSIBLE = MOTHER NATURE / PLANET EARTH. OR, IN OTHER WORDS WE WILL ENJOY THE HEALTHIEST AND SANEST EVER VERSION OF OUR SELVES INSIDE THE ONLY OVER-UNITY SYSTEM = LIFE. STOP WITH THIS NONE-SENSE OF NEEDING COOLING, WARMING, EXTRACTING AND PUSHING ENERGY WHILE THINKING > 100 EFFICIENCY NEEDS ONLY MORE WORK TO BE CRACKED. THIS ATTITUDE WILL ONLY BURY US DEEPER WITH THE NEWEST GENERATIONS IN THE FRONT-LINE. UNDERSTAND YOUR PLACE IN THIS UNIVERSE. PLAY THE CARDS THAT YOU WERE DEALT. STOP CHEATING ON YOUR SELF. START REINTEGRATING HUMANS INTO THE NATURE CIRCUIT AND MAYBE EVEN IN ONE GENERATIONS LIFETIME WE COULD WITNESS THE SALVATION SO MANY SEEK THROUGHOUT ALL HUMAN HISTORY AND CREATIONS (just look into how many movies, songs, books, poetry, literature, philosophy, science, religion have sought exactly just that). YOUR ARE KILLING EVERYTHING INCLUDING ME AND I WILL NOT HAVE IT πŸ˜‰ IN SHORT: START LOVING YOUR SELF AS A VITAL PIECE IN NATURE'S DESIGN , THEN YOUR CHILDREN WILL LEARN DO DO IT ALSO AND THEN ALL WILL RE-ENTER IN THE STATE WERE ALL OF THIS FUSS WILL NOT EVEN BE RECORDED / REMEMBERED BECAUSE OUR "WY" OF LIFE WILL APPEAR INCOMPREHENSIBLE / ANTI-LOGICAL TO THE NEW HUMANS THAT WILL ACTUALLY DESERVE AND TRULLY VALUE THEIR LIVES, THE EARTH AND MANY MORE PLANETS.

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  23. You can work and research heat engines, refrigerators and cycles following the career of Mechanical Engineering.

    Reply

  24. I'm having hard time understanding the concept of heat engines and how refrigerators work in a detailed-manner. Damn, I guess I'll read and explore more on other resources.

    I'm taking engineering in the next two months, hopefully I can finish this series before my college starts. I wanna be prepared.

    Reply

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