I didn't originate this. I reprint it with minor changes from ecatnews.com.
quote starts here *------- A curious note about the “famous” guaranteed COP of 6. Energy required to heat 1 kg of water from 20 to 100 °C (80 degrees difference)= 4.181 kJ * 80 = 335 kJ Latent heat of vaporisation of 1 kg of water: 2260 kJ I am Rossi and I declare that my water is vaporised even if it’s not: FAKE COP = (2260+335)/335 = 7.7 Let’s say my water is just 2% vaporised (very wet steam) FAKE COP=(2260+335)/(335+(2260*0.02))=6.8 Let’s say my water is just 5% vaporised (still wet steam) FAKE COP=(2260+335)/(335+(2260*0.05))=5.8 So that’s why the COP is about 6 References: http://en.wikipedia.org/wiki/Heat_capacity http://en.wikipedia.org/wiki/Latent_heat quote ends here *------- From: http://ecatnews.com/?p=1392&cpage=1#comment-9761
