The Case for cavitation induced heating - PowerPoint Presentation

Slide1

The Case for cavitation induced heating

A suggested mechanism for the heating observed in

CONTROLLED CAVITATION ENERGY STEAM generation (CCES)Slide2

THE CASE FOR MIST AND CAVITATION

Energy balance alone cannot account for the observed levels of heating.

Heat output cannot exceed hydraulic kinetic energy input.

Release of hydrogen bonding energy (23KJ/mole) cannot explain the observed heating.

Electrolysis likely not responsible for observed Oxy Hydrogen disassociation. Temperatures above 3000°K required for 50% covalent disassociation.Cavitation is the only (non-nuclear) physical process capable of generating such heat levels.

Where Does the Heat Come From?Slide3

What causes cavitation ?

Cavitation occurs if the local pressure drops below the vapor pressure of the liquid at local

temperatures.

The

high pressure drop across the injection nozzle tends to accelerate the liquid within the small nozzle holes. This acceleration of liquid inside the nozzle thereby generates a high level of turbulence, which has an instability effect on the jet leaving the nozzle exit. At the sharp edges inside the nozzle holes, such as the inlet of the nozzle hole, the streamlines are contracted such that the effective cross section of the flow is reduced leading to accelerated velocity of the liquid. According to Bernoulli principle, this causes a reduction in the local static pressure and it can reach values as low as the vapor pressure of the liquid. Slide4

FUEL INJECTORS & CAVITATION

Flow inside injection system and the nozzle is highly unsteady and

cavitating

Ejection fraction is saturated with cavitation bubbles

Video complement of Fluid Research - Computational Fluid Dynamic software (CFD).Slide5

Theoretical background for fuel injector cavitation

CAVITATION

IN INJECTOR NOZZLE HOLES - A PARAMETRIC STUDY

Balaji

Mohan, Wenming Yang * and Siawkiang Chou Department of Mechanical Engineering, National University of Singapore, 9 Engineering Drive 1, 117576, Singapore *E-Mail: mpeywm@nus.edu.sg (Corresponding Author)

ABSTRACT:

The fuel injection system in diesel engines has a consequential effect on the fuel consumption, combustion process and formation of emissions. Cavitation and turbulence inside a diesel injector play a critical role in primary spray breakup and development processes. Thus understanding the phenomenon of cavitation is significant in capturing the injection process with accuracy. In this study, the

cavitating

flow inside an injector nozzle hole was numerically investigated. The two-phase mixture model by

Schnerr

and Sauer (2001) was adopted along with

k

-ε turbulence model and Fluent CFD package was used to solve the governing equations numerically. Slide6

THE ENERGY OF CAVITATION

Collapsing cavitation bubbles release enormous heat energy.

Cavitation routinely damages machinery and is an unwanted side effect.

Observation of light pulses emitted by collapsing cavitation bubbles revealed unexpectedly

extreme conditions within the collapsing bubble cores. Temperatures in excess of 30,000K (5 times hotter than the surface of the sun) have been measured directly and even higher Temperatures (in millions degrees K) have been inferred (Flannigan & Suslick, 2010).Cavitation damage is most commonly observed in rotating machinery. Impellers, propellers and turbines.Significant engineering resources have been applied towards eliminating this type of damage; however there has never been a practical way of harnessing this energy, although vast funds of have been invested to aaccomplish this result with no practical outcome. (UNTIL THE ADVENT OF MIST)Slide7

What happens when the ejection fraction

collides with the impact chamber surface

The gas bubble in the expanding cloud of injector vapor collides with the

Surface geometry of the impact chamber

The impact chamber is very close to the output of the injector The cloud of bubbles within the water droplet impacts the surface of the impact chamber normal to its surface.At the moment of impact the droplet experiences a shockwave with a rapidly moving shock front.Within the droplet computed and observed water hammer pressures on the order of (45,000 psi) crushes these bubbles. As they collapse energy is released.Super computing record with bubble collapse simulationSlide8

Impact chamber geometries Essential

and energies released considerable

Hong-Hui et al. (Wear 186-187 (1995)) Found that impact pressures for hypersonic water jets were

Dependent on distance and angle of impact.

The kinetic energy of the implosion grows as a cube of the maximum bubble radius Rmax:E = 4/3 π Rmax3 Pmax (1)where Rmax – is the maximum bubble radius and Pmax is theliquid pressure during the collapse phase (constant pressure is assumed).What makes this energy concentrating process useful is that this energy can be focused onto a minuscule amount of gas trapped in the initially small (micron-size) gas bubble .From the equation of state for an ideal gas:P0 V0 = N kB T0 (2)where P0 – initial bubble gas pressure,

V0 = 4/3 π R03

is

the initial

bubble volume

,

N

– number of atoms of gas in

the bubble

,

kB

–

Bolzmann

constant,

T0

– initial bubble gas temperature

, we can estimate maximum energy concentration per atom of gas (Ea) as

Ea

= (kB T0)-1 (

Rmax

/R0)3

Pmax

/P0Slide9

The initial evidence

During our first tests heat increased from

375 degrees

F to 575 degrees

f in 2 seconds.Instantaneous change of state from liquid to gas in millisecondsSlide10

Our experimental evidence confirms this

Oxy-hydrogen explosions at 900 psi and

620 degrees FSlide11

Controlling cavitation is the key to our energy future

No commercial inventions exist that functionally harness cavitation

MIST is the only system capable of instantaneously producing steam on demand with significantly less energy than

conventional Rankine Cycle heating

Cavitation is the only way to generates these temperatures short of Low Energy Nuclear Reactions (LENR)CCES is the only steam based system which creates a usable source of energy through a mechanical process rather than internal or external combustion.CCES uses modern technologies only now available that are financially viable (ie. Common rail piezo injectors, computer Controllers, ultra high pressure pumps, carbon fiber and ceramics)CCES impacts almost every aspect of modern living. Power generation, transportation, desalination, heating, refrigeration, shipping