The devices employ a rotor with disks which features surface irregularities. The rotor rides a shaft which is driven by external power means. Fluid injected into the device is subjected to relative motion between the rotor and the device housing, and exits the device at increased pressure and/or temperature. The device is thermodynamically highly efficient, despite the structural and mechanical simplicity of the rotor and other compounds. Such devices accordingly provide efficient, simply, inexpensive and reliable sources of heated water and other fluids for residential and industrial use.
Water moves from the centre to the activator periphery under centrifugal force. There is exhaustion in the centre and excessive pressure near the case. Besides disks have apertures and a special surface profile which generate turbulence in water flow. Conditions for origination of hydraulic cavitation are created.
Cavitation (from latin cavitas — hollow) is a formation of cavities in liquid filled with gas, steam or their mix (so-called cavitation bubbles or caverns). Cavitation bubbles are formed in those places where pressure in liquid becomes below some critical value pcr (in a real liquid pcr approximately equal to the pressure of saturated steam of this liquid at current temperature). Moving with the flow and getting to pressure area š < šcr they lose stability and get ability to unlimited growth. After transition in a pressure zone and exhaustion of kinetic energy of extending liquid bubble growth stops and begins to decrease. If a bubble contains a lot of gas after achievement the minimum radius, it recovers and makes several cycles of damped vibrations, and if gas is not enough a bubble fully collapses at the first period of life.
If liquid were ideally homogeneous, and a solid surface, with which it bounds, were ideally moistened, break would occur at pressure much lower than the pressure of saturated steam of liquid. Water tensile strength calculated with the account of thermal fluctuations is equal to 150MN/m2 (1500kg/cm2). Real liquids are less strong. The maximum extension of carefully cleared water achieved in water extension at 10°Ń makes 28MN/m2 (280kg/cm2). Usually breakage occurs at pressures just a little smaller than the pressure of saturated steam. Low strength of real liquids is connected with presence of so-called cavitation germs: badly moistened sections of a solid, solid particles with cracks filled with gas, microscopic gas bubbles protected against dissolution by unimolecular organic shells, ionic formations.
Bubbles originate in the exhaustion zone of heat-generator and are thrown back to the periphery by centrifugal force, where they collapse. Hydrodynamic cavitation is characterized by that fact that all liquid weight is involved in formation processes (development and collapse) of cavitation bubbles. Conditions for generating of the cavitation bubbles with similar diameter are created.
Gases and steams in a bubble constrict intensively generating heat which raises the liquid temperature in immediate proximity from the bubble and creates a hot microarea. In spite of the fact that the temperature of this area is extremely high, this area is so small that the heat disperses fast. According to estimations of the Illinois university in Erbana-Shampen speeds of liquid heating and cooling exceed 109°C/sec. It conforms to speed of molten metal cooling at its slopping on a surface chilled to temperature about absolute zero. Thus, the bulk liquid has ambient temperature at any time. Exact values of temperatures and pressures achieved at bubble collapse are difficult to define both theoretically and experimentally. Various theoretical models characterized by different accuracy have been offered for an approximate description of bubble collapse dynamics. Disadvantage of all these models is impossibility of the exact description of bubble collapse dynamics at final stages. Temperature of collapsed bubble cannot be measured by thermometer as heat dispersion occurs too fast. D.Hammerton identified presence of two various temperature areas connected with bubble collapse. Gas in a bubble achieves temperature about 5500°C, and liquid in immediate proximity from a bubble - 2100°C. For comparison the temperature of acetylene burner flame is approximately 2400°C. Though the pressure achieved at bubble collapse is more difficult to define experimentally than temperature, there is a correlation between these two values. Thus estimation 500atm can be used for the maximum pressure.
Actually depending on the heat carrier temperature on the inlet fitting and the pumping volume for one pass through the activator heat carrier heats up on 14 - 24°Ń.
As a liquid passes through the thermal hydrodynamic pump it is subjected to “controlled cavitation”. The heart of the device is a specially designed rotor that spins. The spinning action generates hydrodynamic cavitation in the rotor cavities away from the metal surfaces. The cavitation is controlled and therefore there is no damage. As microscopic cavitation bubbles are produced and collapse, shockwaves are given off into the liquid which can heat and/or mix.