Consider the following cyclic process: Each cycle 800J of Energy is transfered from a reservoir at 800K and 600J of energy from a reservoir at 600K. 400J of heat is rejected to a reservoir at 400K and 1000J of work is done. I think that the process doesn't violate the first or second laws of thermodynamics: 1st law: dU= dQ+dW The internal energy of the system is constant: dU= 600+800-1000-400 = 0 so first law is not violated. 2nd law: Taking the Kelvin Planck statement: The engine not only extracts heat from a source and turns it into work but also has to pass some heat on to a colder reservoir, therfore I think that the second law is also not violated. If I'm mistaken please correct me. If I'm not please reassure me that my logic is correct.