- 21 Μάιος 2016, 13:01
#258268
Με τόσο μεγάλη συμπίεση, γιατί τα καυσαέρια του ντίζελ είναι πιο κρύα;
We 're on a mission from God.
funkyreverend έγραψε:Με τόσο μεγάλη συμπίεση, γιατί τα καυσαέρια του ντίζελ είναι πιο κρύα;
Δεν παίζει ρόλο η συμπίεση αλλά η συνεχής παρουσία αέρα από την εισαγωγή έως την εξαγωγή που κρυώνει τα καυσαέρια στους diesel και όχι μόνο αυτό, δες εδώ είναι πολύ απλοποιημένα και απόλυτα κατανοητά για να μην τα γράφω ξανά.
Gasoline engine air intakes are throttled, meaning the airflow is restricted by a valve to deliver only enough air to burn the fuel charge and no more. This ensures the exhaust gasses are minimally diluted and therefore hotter. Diesel engines have no air throttle and tend to run leaner, diluting the exhaust gasses with uncombusted air, reducing the exhaust temperature.
Most Diesel engine powered vehicles get 20-40% better gas mileage than gasoline engine vehicles. This is because the Diesel engine is more efficient; that is, per pound of fuel burned the Diesel engine extracts more work (energy). Even though the Diesel engine has a higher peak temperature during the ignition and power stroke, the expansion ratio of the hot gas is significantly higher than that of the gasoline engine, followed by a turbo expander and the resultant exhaust is cooler.
This is intuitive for anyone who has studied thermodynamics. The more efficient and engine gets, the cooler the exhaust must be. "More efficient" simply means more of the combustion heat was converted into useable work, which leaves less heat in the exhaust gas, which is manifested as lower temperature exhaust gas. Rankine cycle power plants might be 30-40% efficient and produce a 500-700F flue gas. Combined cycle power plants might be 50-60% efficient and produce a 300-350F flue gas. One can't compare two processes and find that one of them is simultaneously more efficient and wasting more energy heating exhaust gasses that are discarded.
Eδώ η τηλεοπτική διαφήμιση του Χόντα Λέτζεντ Γουίνγκ τούρμπο 