9/23/2023 0 Comments Law of entropyNote that the change in entropy is given by the energy transferred as heat and not by energy transferred as work and remember that entropy never decreases. Remember the equation from our last blog. In 1856 Clausius first introduced the concept of entropy, defining it as the change in entropy that occurs when energy is transferred to a system as heat. The Clausius statement The introduction of entropy Clausius was aware of this and searched for a way to bring them together so he could apply this theory to all phenomena in the universe. In fact, the statements of Kelvin and Clausius are both sides of the same medal. ![]() By spontaneous, Clausius meant natural, without the help of a heat pump or refrigerator. He saw that heat never spontaneously flows from a cooler to a hotter body. ![]() Rudolph ClausiusĪround the same time the German physicist Rudolph Clausius made a discovery that is also in hindsight pretty obvious. Kelvins statement asserts that no (steam) engine will work without a cold sink into which some heat must be wasted. Take away the cold sink and the engine stops running even though plenty of fuel is available and all the gears and pistons are perfectly lubricated and greased. In other words, the surroundings in which the waste heat is discarded. What will be its most essential component? The piston or the hot reservoir maybe? Imagine standing in front of a nineteenth-century steam engine. His conclusion was as obvious as it is brilliant. We still use this method today to determine the efficiency of an ideal cooling machine or heat pump, as you can read here.ĭiagram representing a steam engine Lord KelvinĪ little over half a century later William Thomson – or Lord Kelvin as we know him better – built further on the theories of Sadi Carnot. Based on this model he came up with a theory to determine the efficiency of an idealised steam engine. Sadly, cholera would take the life of this Sadi too at 36 years of age, but not before he had made himself immortal with a remarkable contribution to science.Ĭarnot considered heat to be a fluid which flowed from the heat source (burning coals) to the cold sink (exhaust pipe). Born in 1796 in Paris, he was the third and final Sadi, the two earlier children with the same name having already passed away. Therefore, the urgent task of the French to improve the efficiency of steam engines. In France, there was a lack of accessible coal. The French looked enviously at the thick plumes of smoke rising from the other side of the Channel. England was the Silicon Valley of the time. Just as the computer and social media would do a century later. Suddenly, the steam engine entered daily life and changed the social and economic structure. This created steam and with that steam he set a pump or turbine in motion and with that movement he let other things move.Ĭonnect a steam engine to a loom, for example, you can replace the work of tens of human hands by burning a large container of coal. Someone got the idea to bring water to a boil over burning coals. Later we discovered the power of wind (sailing boats and mills), whale oil (lamp oil) and peat and coal (excellent heat sources).īut the big change came with the industrial revolution early eighteenth century. When we were hunter-gatherers our primary energy sources where animals and plants. Like every animal on earth, man uses energy. ![]() Part two: birth of the Second Law Part three: the way the universe will end Ideas from a Victorian era In this blog we dive into the history of entropy and see how the German physicist Rudolph Clausius eventually came up with the concept of entropy and the Second Law. What is entropy? Part 2: Birth of the Second LawĮver wondered why heat never flows from cold to hot? Why a machine with 100% efficiency can never be achieved and why we know our past but not our future? It all has to do with a concept called Entropy.
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