majesty78
Veteran Member
THen we all need to pull our currently "state of the art" GTDXYZVKLR" turbos again to remain being up to date *haha*
well I do not think so, the last concept is for truck engines so far, and I am quite sure those turbos will many things but not for free...THen we all need to pull our currently "state of the art" GTDXYZVKLR" turbos again to remain being up to date *haha*
borg warner have some s400sx-e that specified for tip speed up to 607m/sThe wheel in and of itself doesn't determine the PR strongly. The tip speed (V=2*pi*radius*RPM/60, limit for state-of-the-art wheels is 560-580 m/s) and compressor housing A/R do. So, if you have a late-generation 52mm wheel spinning to 206-213k RPM and a numerically small A/R (e.g. 0.45), it will do as high a PR as the fundamental physics will allow.
https://www.youtube.com/watch?v=hwm62HnztQwany way upcoming Honeywell CO2RE high efficiency serial two stage boost technologies for turbocharging where stage efficiency of 63 and 64% is mighty impressive. It means compressor and turbine efficiency is about 80%. Both Turbos using ball-bearing technologies and first turbine stage can take better use of pulses from the engine in a VNT controlled stage. As far as I know the MAN 12.4L engine use the first stage in this development, interesting to see when full utilisation of this concept is going to be shown in real
Wonder if it is to avoid needing exotic materials for the HP compressor stage.https://www.youtube.com/watch?v=hwm62HnztQw
Surprise, surprise, they think an interstage cooler is a good thing to have...
Wonder if it is to avoid needing exotic materials for the HP compressor stage.
Easy to use no interstage CC with a light duty engine seeing small transient spikes of full load, but an application that sees full rated output at a hundred percent duty will need a titanium HP compressor, and something other than alu for the HP compressor cover and piping if it isn't going to have an interstage CC.
I think it doesnt really add efficiency. It makes that you can use a smaller wheel in the HP unit, possibly increasing response. But from a thermodynamic point of view it doesnt matter where you cool the air, between or after stage. (Them joules you remove anyway have to brought up by either turbine stage.)
I can't find this paper online, google brings me to a listing of it on honeywell's site, and I tried searching further from that and get nothing.
The fact that cummins QSK motors run titanium compressors and cast iron compressor covers tells me that there isn't likely to be a large efficiency gain with interstage CCs, as it'd be cheaper to run a cooler than go to all that length with nonstandard materials.
They also use tens of millions of dollars of fuel in their lifecycle, so any fraction of a percentage increase in efficiency would pay off quickly.
I think your assumption is wrong. Its not because the air after the 2nd compressor is colder, as compared to the single or dual setup with no intercharge cooling, the overall efficiency is higher.Ruben let make some easy thermodynamic calculation
total pressure ratio 5 at one stage operation
Isentropic efficiency 80%
ideal pressure ratio with two stage is square root of 5 for smallest work
let use for simplicity that we have a perfect gas that means Cp is constant, that mean efficiency is direct depending of temperature
one stage
Temperature after compressor with 80% isentropic efficiency with inlet 20 degree C will give about 507K (234 degrees kelvin)
293*(5) in power of (0,4/1,4) divide the difference between inlet and with with 80% isentropic efficiency (464-293)/0,8=213,75 that means
507K or 234 degrees celsius
air has isentropic coefficient 1,4 (Cp/Cv) (Cv is specific heat at constant volume, Cp specific heat at constant pressure)
two stage ( for simplicity temperature after intercooler 20 degree and no pressure losses)
this will give
293*(5in power of 0,5)in power of (0,4/1,4)=368
difference 368-293=75,74
with 80% isentropic efficiency 75,74/0,8=94,67
with two stage 94,67*2=189,35 total temperature rise
so we have gain
(213,75-189,35)/213,75=0,114 that mean 11,4% in efficiency gain of divided stage operation
now this is a little bit ideal but the gain is for real and very well notice if you have experience two stage operation design to utilize this ,
since each compressor has much smaller pressure ratio, and by that lower tip speed more back swept blade can be used that mean much wider map by and that also reflect on better stage efficiency, in general the map is wider at lower pressure ratio
if the same technologies would be used in one stage as in two, one stage will have less efficiency then 80%, since same efficiency level need to use constant poly tropic efficiency and that will mean less then 80% isentropic efficiency.
though the fluid rotation i tangential direction (velocity vector C2u) will not be recovered and go to losses in two stage radial turbines, that was why they was clever to explore a axial turbine in the garret ultra high efficiency turbo before spoken of
nice, thats maybe also one of the reasons why pre comp wi works so good.the higher the inlet stage temperature to a compressor stage the work is direct proportional to the temperature increase.
If you compress air at 83k at pr 5 at isentrop condition (say cp=1000j/Kkg)
the needed specific work is about 50kJ/kg air
if we rise the temperature to the double 166K the needed work for compression is about 100kJ/kg, the double amount of work for compression, the opposite can be used in turbine, the higher the temperature the more work is available for abstraction from the stage
actually a isotherm at normal temperature is the operation that will need the smallest amount of specific work, but not so easy to do in real, interstage cooling is between, and yes you can supercool the air by a Brayton cycle to -0--30 degree celsius, the same method used in air condition in airplane. But will need more exhaust pressure and ALOT of other thing to think about.
but inter cooling has another positive thing, since you keep temperature down the viscosity of the air is lower (viscosity for gases increase with temperature)
this mean we will have a higher Reynolds number in second stage then without intercooling and the air will follow the blade better in the compressor and by that work better, and more margin for surge. The generalize parameters does not take this into account as fare as I know but I can be mistaken there.
and do not forget the higher the pressure ratio in general the lower efficiency, the pollytropic efficiency is the same. This because the isentropic efficiency is less then 100%, so the more to the end you end up the more work is needed all the time because temperature is increasing.
GTD2060 - turbine is smaller, compressor has 63mm extended tip. They work well but not night and day compared to older GTB2260. GTD1752vrk on the other hand is VERY good.
I'm going to test GTD2263vzk, hopefully it makes more power