john_jack (john_jack) wrote,
john_jack
john_jack

КПД как у паровоза?

“In steam locomotives, one should note that all the losses, except for incomplete expansion, are approximately constant for a given rotational speed. Hence, the aim is to have a longer cut-off but, given that this steeply increases the incomplete expansion losses, a compromise results at 20% to 30% (15% to 20% for the author’s proposals). Thus, the claims for poppet valves concerning their ability to work with very short cut-offs are illusory as they do not lead to low specific steam consumption because of these constant losses.

But there are economic reasons too. The Americans, who have the perverse habit of hooking as many cars as possible to their locomotives, force them to work at long cut-offs to get as high an α coefficient as possible so as to have a good use of the (expensive) adhesion weight. This of course leads to a high specific steam consumption, hence the need for massive evaporation, hence a massive boiler, hence idle axles to support a huge firebox, hence a gigantic tender, hence plants to supply coal en-route, hence immense coal stocks, hence diesel locomotives with a higher thermal efficiency (under test conditions) even if they cost twice as much and justify the Gulf War to supply them with oil.”©Ихнее всё Ливио Данте Порта.

tl;dr паровоз должен работать с умеренной нагрузкой.
Tags: Вся надежда на комментаторов, Мудрость, Пар, Цитата
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