Publisher Summary This chapter presents a discussion on jet impingement heat transfer. The chapter describes the applications and physics of the flow and heat transfer phenomena, available empirical correlations and values they predict, and numerical simulation techniques and results of impinging jet devices for heat transfer. The relative strengths and drawbacks of the Reynolds stress model, algebraic stress models, shear stress transport, and v 2 f turbulence models for impinging jet flow and heat transfer are compared in the chapter. The chapter provides select model equations as well as quantitative assessments of model errors and judgments of model suitability. The review of recent impinging jet research publications identified a series of engineering research tasks that are important for improving the design and resulting performance of impinging jets: (1) clearly resolve the physical mechanisms by which multiple peaks occur in the transfer coefficient profiles, and clarify which mechanism(s) dominate in various geometries and Reynolds number regimes, (2) develop a turbulence model, and associated wall treatment if necessary, that reliably and efficiently provides time-averaged transfer coefficients, (3) develop alternate nozzle and installation geometries that provide higher efficiency, meaning improved Nu profiles at either a set flow or set blower power, and (4) further explore the effects of jet interference in jet array geometries, both experimentally and numerically. This includes improved design of exit pathways for spent flow in array installations.

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Jet Impingement Heat Transfer: Physics, Correlations, and Numerical Modeling

http://home.eps.hw.ac.uk/~tso1/Papers/307.pdf

Jet impingement heat transfer – Part I: Mean and root-mean-square heat transfer and velocity distributions

Heat transfer characteristics of synthetic jet impingement cooling

Thermo-fluid-dynamics of submerged jets impinging at short nozzle-to-plate distance: A review

A numerical study of the unsteady flow and heat transfer in a transitional confined slot jet impinging on an isothermal surface

Heat transfer and flow visualization experiments of swirling, multi-channel, and conventional impinging jets

Heat transfer of an impinging jet on a flat surface

The Phillips Laboratory Power Systems Branch (PL/VTVP) is performing vacuum testing of high performance alkali metal thermoelectric conversion (AMTEC) cells. These AMTEC cells are being built by Advanced Modular Power Systems, Inc. (AMPS) with design input from Orbital Sciences Corporation (OSC), Nichols Research Corporation (NRC), Institute for Space and Nuclear Power Studies (ISNPS), and PL/VTVP. Tests are performed in a prototypical environment to demonstrate feasibility and identify bottlenecks to performance and endurance as well as to provide design feedback. Test results for two major design iterations of the PX series cells are discussed. The data shows that continued improvements made to the cell design have continually increased electric power output and conversion efficiency. To date, the best performance from a PX-series cell tested at PL/VTVP was an electric power output of 4.3 watts and a conversion efficiency of /spl sim/14%. These data imply that design goals of 6 watts and 22% efficiency per cell will be surpassed.

Vacuum testing of high efficiency multi-base tube AMTEC cells

A detailed AMTEC performance and evaluation analysis model (APEAM) was developed to predict the performance of next-generation Pluto Express vapor-anode multitube cells. APEAM incorporates an axial electrochemical model, which accounts for the effects of nonuniform axial temperature and vapor pressure profiles along the BASE tubes; a detailed vapor pressure loss model, which includes free-molecular, transition and continuum flow regimes; and a comprehensive radiation/conduction model, which incorporates the effects of circumferential thermal shields above the BASE tubes and conduction studs between the hot end of the cell and the tubes support plate. Model results compared well with measured electrical power and experimental I-V characteristics of the PX-2C cell, recently tested at Phillips Laboratory. The cell peak electric power of 4.4 We occurred at an external load resistance of 3.0 /spl Omega/. At higher load resistance (or lower load demand), the PX-2C cell was load-following. Results also showed that the vapor flow on the low-pressure side of PX-2C was in the transition regime. The evaporator wick provided the sodium flow rate (8 g/hour) necessary to operate the cell at an evaporator temperature of about 950 K. The model predicted that using a molybdenum thermal shield on the inside of the cell wall, near the condenser, would increase the cell electric power and conversion efficiency by /spl sim/23%.

Lianmin Huang

Papers

Heat transfer and flow visualization experiments of swirling, multi-channel, and conventional impinging jets

Heat transfer of an impinging jet on a flat surface

Vacuum testing of high efficiency multi-base tube AMTEC cells

Performance analysis of a multitube vapor-anode AMTEC cell

Thermal conductivity measurements of alumina powders and molded Min-K in vacuum