Science Forums 2

[qumf]

Working cycle analyses and efficiency (please see figure 2):

Estimate the theoretic efficiency; compare the two types of engines: the current engine and I proposed.
Firstly I state some premises:
1. Because the efficiency of the current compressor and turbine in current turbo-generator is very high, the below calculation ignore the energy loss in them.
2． In below analyses I assume that the portion's efficiencies are same if they have the similar function component. Meanwhile I ignore some small loss during courses.
I set a sample example with data to explain, I assume the pressures are same before combustion in the two type engines.
for the current jet: efficiency=1-1/{W^[(k-1)/k]} （ ^N means the Nth power）
W: the pressure rate in compressor or blower; I set: W=10, k=1.4, the theoretical efficiency of the current jet is 48.2%.
As to the new jet: efficiency=1-k*[u^(1/k)-1]/(u-1)/{w^[(k-1)/k]}
W is increase rate of gas pressure by blower. W=10; here U is the increase rate of pressure by combustion, here U=4.5;I input the data, you can see the theoretical efficiency of this closed combustion jet engine is 60%
The efficiency of the new type engine is higher than the current one by 25%.
In the example I have compare the efficiency of the two type of engine theoretically. Actually the compressor in the current engine consumes a lot of (about proportion of 2/3) energy from the burnt gas, the proportion in new engine will be much smaller (The date can be 1/4). Meanwhile the compressor's efficiency is not so high usually(the best is about 85%). So the new type of engine's actual efficiency is much higher than the current. The actual efficiency of the new type engine is higher than the current consistent pressure combustion type, expected by over 30%.
I try to explain why the new type of engine has more efficiency from another aspect, compared with current jet engine, the new engine uses up the same amount mechanical work and chemical energy but gets higher-pressure gas. The gas can make more work if its pressure is higher. So the new type engine has more efficiency.
The new engine can get higher-pressure gas because the gas pressure can increase further by the closed combustion course besides by the compressor that also is used in current jet engine.