Rapidly Deployable Algae Cleaning System for Applications in Freshwater Reservoirs and Water Bodies

Occurrence of large-scale harmful algal blooms (HABs) in our reservoirs and water bodies threaten both quality of our drinking water and economy of aquaculture immensely. Hence, rapid removal of HAB biomass during and after a bloom is crucial in protecting the quality of our drinking water and preserve our water resources. We reported here a rapidly deployable algae cleaning system based on a high-capacity high-throughput (HCHT) spiral blade continuous centrifuge connected with inlet and effluent water tanks and a series of feed-in and feed-out pumps as well as piping, all fitted into a standard 20 feet metal shipping container. The system separates algal biomass from algae-laden water with a maximum flow rate of 4000 L/h and a centrifugal force of 4500× g. Cells collected by the system are still intact due to the low centrifugal force used. We showed that after HCHT centrifugation, cellular contents of HAB biomass were not found in the effluent water, and hence, could be discharged directly back to the water body. Furthermore, the addition of flocculants and chemicals prior to the separation process is not required. The system could operate continuously with proper programmed procedures. Taken overall, this system offered a much better alternative than the traditional flocculation- and sonication-based methods of HAB removal in a freshwater environment. This deployable system is the first of its kind being built and had been field-tested successfully.

Dispersion Dynamics of Clustered Particles by Centrifugal Force

In this paper an approach is proposed to solve the problem of aggregation in nanomaterials through the mean of rotational separation aiming to quickly disperse clustered nanoparticles while not affecting their purity. If it is possible, this approach may replace the current mean of mechanical mixing, which may cause impurities issues. The hypothesis is that the centrifugal force due to rotational velocity acting on the nanoparticles can overcome the cohesive force between the nanoparticles, therefore dispersing the clustered nanoparticles. The experimental mean is to put different spheres connected by different types of glues imitating different nanoparticle clusters into centrifuges imitating the swivel plate. The results from both the theoretical model and the experiment show that for a cluster with a cohesive force of 1.75N, a rotational velocity of about 800rad./s is required to disperse the cluster. While for a cluster with a cohesive force of 0.25N and the same mass and position, a rotational velocity of about 150 rad./s is required to disperse the cluster. Except for the cohesive force, the mass and position of the nanoparticle on the swivel plate also have a large effect on the required rotational velocity. The observation of the physical mechanism of the dispersion has also shown that while using this way, the cluster is dispersed slowly with small parts separated from it. Therefore, this way can also eliminate re-clustering problems of nanoparticles.

Effect of Centrifugal Force On Gas Flow in a Supersonic Turbine

The flow condition between the rotor blades of a liquid rocket engine supersonic turbine was studied experimentally and numerically. The entrance Mach number was 1.94, and the turning angle of the blades was 120°. A shock wave was created at the leading edge of the blade, and the Mach number in the passage between the blades decreased to around unity. A similar deceleration has been reported in several past studies. It was found that centrifugal force created the shock wave at the leading edge, reducing both the Mach number and total pressure. This phenomenon is characteristic of high-speed blades with large turning angles. The Mach number in the passage was restricted when the mass flow rate was specified under the specified passage configuration. A convergent-divergent configuration of the passage between the blades suppresses the performance degradation of supersonic turbines.

Cleaning Air Streams from Fine Particles in Paint Booths

To solve the problem of increasing the efficiency of cleaning the exhaust air of painting chambers from fine particles, a separation device with elements of a square and rectangular shape has been developed and described by the principles of its operation. A method for calculating the design dimensions of the developed separation device is presented. Different versions of the height of the separation zone are considered, depending on the size of dispersed particles. It is shown that the device is able to capture particles smaller than 10 microns with an efficiency close to 100 %, provided they adhere to the walls. The peculiarity of the design of the separation device is that a set of small-diameter vortices is created, in which the flow regime is close to laminar, and to achieve large values of centrifugal force, it is not necessary to create high speeds in the crevices.

Magnetic-centrifugal drying of compressed air of pneumatic systems of machine-building enterprises

The article analyzes such basic methods of drying compressed air of pneumatic systems of machine-building enterprises as condensation, sorption, diffusion and force action and determines the advantages and disadvantages of each of these methods. It is noted that the method of force action on water particles due to the use of the centrifugal force allows you to remove only droplet moisture, and vaporous moisture remains in the compressed air. With further cooling of the compressed air, condensate reappears in it. Other methods are more efficient, but require consumables or complex devices for drying compressed air, which ultimately leads to an increase in the cost of such devices and an increase in operating costs. Based on the conducted analysis and on the fundamentals of theoretical mechanics, magnetic field theory and molecular physics, a method of magnetic-centrifugal drying of compressed air has been developed. The essence of the method is to use the Lorentz force, which acts on a water particle (a molecule, a dimer, a trimer, etc.) and coincides in the direction with the centrifugal force. When using the safe supply voltage of a 24 V solenoid that creates a magnetic field in which an electrically charged water particle moves, it is possible to increase the radial force (compared to the centrifugal force) acting on this particle by about 70 times. The authors also consider the methods of ionization of water particles that allow knocking out electrons from their outer shells. Experimental studies conducted on a mock-up sample showed a fairly high efficiency of this method, since it was possible to achieve the 3rd class of purity according to ISO 8573-1: 2001.

Weighty issue

A response to Nick England’s letter “Going in circles” in which he discusses the change from teaching centrifugal force to teaching centripetal force, and the definition of weight being changed from the reaction force felt from the floor to the pull of gravity on an object.