The effect of electrolyzed water on total microbial count was evaluated on several fresh-cut vegetables. When fresh-cut carrots, bell peppers, spinach, Japanese radish, and potatoes were treated with electrolyzed water (pH 6.8, 20 ppm available chlorine) by dipping, rinsing, or dipping/blowing, microbes on all cuts were reduced by 0.6 to 2.6 logs CFU/g. Rinsing or dipping/blowing were more effective than dipping. Electrolyzed water containing 50 ppm available chlorine had a stronger bactericidal effect than that containing 15 or 30 ppm chlorine for fresh-cut carrots, spinach, or cucumber. Electrolyzed water did not affect tissue pH, surface color, or general appearance of fresh-cut vegetables.

https://seward.co.uk/resources/wp-content/uploads/sites/3/2013/03/food-microbiology-carrot-peppers-spinach-radish-potato-TVC-stomacher-400.pdf

Electrolyzed water as a disinfectant for fresh-cut vegetables

The confluence of market demand for greatly improved compact power sources for portable electronics with the rapidly expanding capability of micromachining technology has made feasible the development of gas turbines in the millimeter-size range. With airfoil spans measured in 100's of microns rather than meters, these microengines have about 1 millionth the airflow of large gas turbines and thus should produce about one millionth the power, 10-100 W. Based on semiconductor industry-derived processing of materials such as silicon and silicon carbide to submicron accuracy, such devices are known as micro-electro-mechanical systems (MEMS). Current millimeter-scale designs use centrifugal turbomachinery with pressure ratios in the range of 2:1 to 4:1 and turbine inlet temperatures of 1200-1600 K. The projected performance of these engines are on a par with gas turbines of the 1940s. The thermodynamics of MEMS gas turbines are the same as those for large engines but the mechanics differ due to scaling considerations and manufacturing constraints. The principal challenge is to arrive at a design which meets the thermodynamic and component functional requirements while staying within the realm of realizable micromachining technology. This paper reviews the state of the art of millimeter-size gas turbine engines, including system design and integration, manufacturing, materials, component design, accessories, applications, and economics. It discusses the underlying technical issues, reviews current design approaches, and discusses future development and applications.

Millimeter-Scale, Micro-Electro-Mechanical Systems Gas Turbine Engines

Advances and challenges in the development of power-generation systems at small scales

The confluence of market demand for greatly improved compact power sources for portable electronics with the rapidly expanding capability of micromachining technology has made feasible the development of gas turbines in the millimeter-size range. With airfoil spans measured in 100’s of microns rather than meters, these “microengines” have about 1 millionth the air flow of large gas turbines and thus should produce about 1 millionth the power, 10-100 W. Based on semiconductor industry-derived processing of materials such as silicon and silicon carbide to submicron accuracy, such devices are known as micro-electro-mechanical systems (MEMS). Current millimeter-scale designs use centrifugal turbomachinery with pressure ratios in the range of 2:1 to 4:1 and turbine inlet temperatures of 1200-1600 K. The projected performance of these engines are on a par with gas turbines of the 1940’s. The thermodynamics of MEMS gas turbines are the same as those for large engines but the mechanics differ due to scaling considerations and manufacturing constraints. The principal challenge is to arrive at a design which meets the thermodynamic and component functional requirements while staying within the realm of realizable micromachining technology. This paper reviews the state-of-the-art of millimeter-size gas turbine engines, including system design and integration, manufacturing, materials, component design, accessories, applications, and economics. It discusses the underlying technical issues, reviews current design approaches, and discusses future development and applications.

http://users.ntua.gr/rogdemma/MILLIMETER-SCALE,%20MEMS%20GAS%20TURBINE%20ENGINES.pdf

Millimeter-Scale, MEMS Gas Turbine Engines

One‐center SCF MO ground‐state wavefunctions are reported for HF, CH4, and SiH4. The molecular orbitals are expressed in terms of Slater‐like functions all centered at a common origin. The basis sets employed contain more than 25 functions including, for the spherical harmonics, values of l up to 3. The results of the calculations here reported, performed by the use of a large electronic computer, refer to the geometrical configurations which, among many others considered, gave the minimum of the total energy.The equilibrium bond length thus determined for HF is 1.728 a.u. with a corresponding value of the energy of — 100.0053 a.u. and of the electric dipole moment of 2.104 D. For CH4 and SiH4 the equilibrium configurations were found to possess tetrahedral symmetry with bond lengths of 2.08 and 2.787 a.u. and energies of — 39.86597 and — 290.1024 a.u., respectively.The general features and capabilities of the one‐center expansion approach to molecular systems are discussed.

One‐Center Basis Set SCF MO's. I. HF, CH4, and SiH4

The design of a wave rotor requires an understanding of the pressure wave dynamics in the cells (rotor passages). The present paper describes a two-dimensional numerical simulation and an experimental visualization of the wave rotor compression process. First, a unique experimental apparatus with fixed cells and rotating ports was constructed for the visualization and direct measurements; this arrangement is opposite to the conventional setup. Next, experimental and numerical results were compared to verify the simulation modeling, particularly with regard to the propagation velocity of pressure waves in the cells. Last, the effects of gradually opening the cell to the ports and leakage through the clearance, which are considered to be dominant factors in the wave rotor operation, on the pressure wave dynamics were carefully investigated. The results showed that the gradual passage opening greatly influences the primary shock wave, whereas leakage mostly influences the reflected shock wave. Moreover, it was revealed that the leakage generates an extra pressure wave during the compression process due to the interaction between adjacent cells.

Visualization of Wave Rotor Inner Flow Dynamics

Cavitation is one of the troublesome problems in rocket turbo pumps, and since most of high-efficiency rocket propellants are cryogenic fluids, so called “thermodynamic effect” becomes more evident than in water. In the present study, numerical and experimental study of liquid nitrogen cavitation in 2D Laval nozzle was carried out, so that the influence of thermodynamic effect was examined. It was revealed that temperature and cavitation have strong inter-relationship with each other in thermo-sensitive cryogenic fluids.

Cryogenic cavitating flow in 2D laval nozzle

The structure of underexpanded jets issuing from nozzles with square outlets is investigated numerically and experimentally. This type of nozzle is of interest for its use in the clustered combustors of linear aerospike engines. The numerical results indicate that the first shock cell is composed of two types of shock waves; intercepting shock waves corresponding to the oblique shock wave observed in underexpanded jets from two-dimensional planar nozzles, and recompression shock waves that appear downstream of the overexpanded regions. The overexpanded regions are formed by the interaction of expansion fans generated at neighboring nozzle edges. It is shown that the jet expands almost two-dimensionally on the symmetry planes, whereas shock waves suppress expansion on the diagonal planes, resulting in a cross shaped jet cross section.

Structure of Underexpanded Jets from Square Nozzles

Numerical and experimental investigations are conducted to identify the key aspects of the flowfield that effects the performance and heating of a linear aeropsike nozzle with clustered modules. The flowfield near the linear aerospike nozzle surface is characterized by the viscid-inviscid interaction between the jet and boundary layer over the nozzle. Whereas, the off-surface flowfield exhibits the inviscid features of the jet from the rectangular-exit module and the interaction between the jets from neighboring modules. The correlation between the flow mechanism and clustering effects on the performance and heating was analyzed, based on the knowledge of the flowfield. It is revealed that the major part of the performance loss results in the shock loss due to the inviscid jet interaction in the offsurface flowfield. On the other hand, the heat-flux distribution over the linear aerospike nozzle stems from the viscid-inviscid interaction near the nozzle surface.

Clustering Effects on Performance and Heating of a Linear Aerospike Nozzle

Cavitation is one of the major problems in the development of rocket engines. There have been few experimental studies to visualize cryogenic foil cavitation. Therefore a new cryogenic cavitation tunnel of blowdown type was built. The foil shape is “plano-convex”. This profile was chosen because of simplicity, but also of being similar to the one for a rocket inducer impeller. Working fluids were water at room temperature, hot water and liquid nitrogen. In case of Angle of Attack (AOA)=8°, periodical cavity departure was observed in the experiments of both water at 90°C and nitrogen at −190°C under the same velocity 10 m/sec and the same cavitation number 0.7. The frequencies were observed to be 110 and 90 Hz, respectively, and almost coincided with those of vortex shedding from the foil. Temperature depression due to the thermodynamic effect was confirmed in both experiment and simulation especially in the cryogenic cavitation.

Toshio Nagashima

Papers

Visualization of Wave Rotor Inner Flow Dynamics

Cryogenic cavitating flow in 2D laval nozzle

Structure of Underexpanded Jets from Square Nozzles

Clustering Effects on Performance and Heating of a Linear Aerospike Nozzle

A blowdown cryogenic cavitation tunnel and CFD treatment for flow visualization around a foil