Half a croissant, on a plate, with a sign in front of it saying '50c'
h a l f b a k e r y
Flaky rehab

idea: add, search, annotate, link, view, overview, recent, by name, random

meta: news, help, about, links, report a problem

account: browse anonymously, or get an account and write.

user:
pass:
register,


             

LCO2 Hydraulic Hybrid

Modern Transportation Conceptual Origami #4
 
(0)
  [vote for,
against]

Hydraulic hybrids <link> are known for their simplicity, (relatively) low cost and very high regeneration efficiency. A pump loads up an (high pressure) accumulator, which is tapped to run an hydraulic motor, the spent fluid then flows into a (low pressure) reservoir, rinse and repeat.

The BMW TurboSteamer <link> brings to reality a long-held desire to harness otherwise-wasted heat from internal-combustion engines.

Research is underway for using supercritical carbon-dioxide in closed loop turbines <link>. At 30ºC, LCO2 enters the supercritical phase, its density decreasing dramatically as the temperature rises further. Supercritical fluids are very slippery.

-------

The idea then is to use liquid/supercritical CO2 as regular engine coolant and exhaust coolant (extracting thermal energy from same) to create a thermal-engine within the workings of an hydraulic hybrid system using sc-CO2 as working fluid.

We combine a regular engine cooling system...
engine -> coolant-pump -> radiator -> engine,

with a regenerating hydraulic system...
reservoir -> pump -> accumulator <-> motor -> reservoir,

creating...
reservoir -> pump -> engine/exhaust-cooling -> accumulator <-> motor -> radiator -> reservoir.

(note how the heating and cooling steps bracket the motor)

Pros (compared with regular hydraulic hybrid system and Turbosteamer)
- decreased complexity: the heat conversion is part of a full-featured hybrid
- increased effectiveness: sc-CO2 starts expanding at 30ºC, not 100ºC
- safe compared to steam
- the hydraulic-fluid/engine-coolant(/aircon charge) is environmentally inconspicuous and costs basically nothing.

Cons
- liquid CO2 means a base pressure of 74 atmospheres, meaning heavier construction of both the engine cooling system componentry (jackets, pipes, radiator) and the hydraulic system
- shared single point of failure for both components of the hybrid system.

Etc.
The system of course includes an electrically-operated CO2 sequesterer to top off, or fill from scratch. All components of the system are cross-valved so you can, for instance, run the engine without having to run the hydraulics, and perhaps have a chance of isolating a leak.

Regarding hydraulic hybrids in general, the system could/should be used for cheaper/simpler power-braking/steering, windows/doorlocks, winches, etc.

FlyingToaster, May 03 2014

http://en.wikipedia...ki/Hydraulic_hybrid [FlyingToaster, May 03 2014]

http://en.wikipedia.org/wiki/Turbosteamer [FlyingToaster, May 03 2014]

http://en.wikipedia...oxide#Working_fluid [FlyingToaster, May 03 2014]

Please log in.
If you're not logged in, you can see what this page looks like, but you will not be able to add anything.
Short name, e.g., Bob's Coffee
Destination URL. E.g., https://www.coffee.com/
Description (displayed with the short name and URL.)






       Erm, how about just using water, in a "thermal engine" at say 1/5 of atmospheric pressure on the radiator water, and just a boring old closed cycle steam engine on the exhaust pipes?   

       <realises I am repeating myself here...it must be that kimchi>
not_morrison_rm, May 03 2014
  

       ^ You mean apart from the "Pros" section of the post ?   

       From the sole viewpoint as an hydraulic-fluid, CO2 might not have much going for it: even though it's probably much easier to pump through the lines due to superlow viscosity, it has to be kept at ~1,000psi or it's not a liquid/scf, meaning some components have to be more robust: there's not as much headroom as in a system which can theoretically use ambient (or less) as a base pressure.   

       On the other hand, from the viewpoint of integrating a heat-engine and hydraulic subsystem together, which is the meat of the idea, it completely blows away the Turbosteamer idea.   

       The fact that they're putting together a 550ºC sc-CO2 closed-loop turbine for electricity production would lead one to assume that its properties as a working fluid are comparable or superior to water in such an application, which is similar to this one.   

       Basically, if you have an hydraulic hybrid concept, you can add heat-recovery to it by running it through the engine and around the exhaust, replacing the existing engine-cooling system.
FlyingToaster, May 03 2014
  

       There's quite a difference between water in its liquid and gaseous states, including a large energy cliff at the boiling point. The post uses a supercritical fluid with no chaotic transitional properties throughout the entire temperature range.   

       Apart from the base pressure considerations, it's rather less complicated than a steam engine.
FlyingToaster, May 03 2014
  


 

back: main index

business  computer  culture  fashion  food  halfbakery  home  other  product  public  science  sport  vehicle