Therefore, E net1 ≠-E net2 note that ≠ means “not equal to” Radiation Exchange under The Real Second LawĮ 1 = εσT 1 4 E 2= εσT 2 4 (Stefan-Boltzmann law) And E net2 as the change in energy experienced by body 2 (per unit area). We define E net1 as the change in energy experienced by body 1 (per unit area). In our example, we can ignore that by considering two very long plates close together.Į 1 is the energy radiated from body 1 (per unit area) and we consider the case when all of it reaches body 2, E 2 is the energy radiated from body 2 (per unit area) and we consider that all of it reaches body 1. In typical examples, we have to consider the view factor – this is a result of geometry – the ratio of energy radiated from body 1 that reaches body 2, and the reverse. We will keep it very simple for those not so familiar with maths. Even if you find maths a little difficult to follow, the concept will be as simple as “ two oranges minus one orange” vs “ two oranges” so stay with me. Now, let’s take a look at the radiative exchange that would take place under the two cases and compare them with a textbook. What the Equations Look Like for Both Cases Everyone agrees that net heat flows from hotter to colder. Hopefully everyone can clearly see the difference between the two “points of view”. In a radiative exchange, the hotter body does not absorb the energy from the colder body as this would be a violation of the second law of thermodynamics The Imaginary Second Law of ThermodynamicsĢe. Due to the higher energy radiated from a hotter body, the consequence is that net heat flows from the hotter to the colder (see note 1) This energy from the colder body increases the temperature compared with the case where the energy was not absorbedġg. In a radiative exchange, the hotter body absorbs the energy from the colder bodyġf. In a radiative exchange, the colder body absorbs the energy from the hotter bodyġe. In a radiative exchange, both hotter and colder bodies emit radiationġd. Entropy of a closed system can never reduceġc. Net heat flows from the hotter to the colderġb. Feel free to correct me if you understand this law in detail.ġa. I’m relying on the various proponents of the imaginary law because I can’t find it in any textbooks. So I should explain again the difference between the real and imaginary second law of thermodynamics once again. Perhaps the blog owner never grasped the key element of the difference between the real law and the imaginary one. However, despite my pressing (you can read the long painful exchange that follows) I didn’t find out what the blog owner actually thought that the writers of this book were saying. It’s not a climate science book as the title indicates. I had cited the diagram from Fundamentals of Heat and Mass Transfer by Incropera and DeWitt (2007). Provide your reference that he said heat can spontaneously flow from cold to hot. For those committed to their cause, well, even if Clausius were to rise from the dead and explain it. So for those prepared to think and question – it should be reasonably easy, even if discomforting, to realize that an idea they have accepted is just not true. Well, most people haven’t studied thermodynamics and so an erroneous idea can easily be accepted as true.Īll I want to present here is the simple proof that thermodynamics textbooks don’t teach the false ideas circulating the internet about the second law of thermodynamics. ![]() Understanding the laws that govern thermodynamic processes and the relationship between the system and its surroundings is therefore paramount in gaining scientific knowledge of energy and energy consumption.Probably many, most or all of my readers wonder why I continue with this theme when it’s so completely obvious. We will see that the first law of thermodynamics explains that a change in the internal energy of a system comes from changes in heat or work. ![]() The roles of heat transfer and internal energy change vary from process to process and affect how work is done by the system in that process. ![]() (credit: modification of work by NASA)Įnergy is conserved in all processes, including those associated with thermodynamic systems. To understand changes in weather and climate, such as the event shown here, you need a thorough knowledge of thermodynamics. \): A weak cold front of air pushes all the smog in northeastern China into a giant smog blanket over the Yellow Sea, as captured by NASA’s Terra satellite in 2012.
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