Heat transfer to impinging isothermal gas and flame jets

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.

/pdf/jet-impingement-heat-transfer-physics-correlations-and-3h1zkpep1u.pdf

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

Publisher Summary Impinging liquid jets have been demonstrated to be an effective means of providing high heat or mass transfer rates in industrial transport processes. This chapter summarizes the available analytical and experimental work in the area with the objective of correlating the research findings. Significant progress has been made in understanding the fundamentals of heat, mass, and momentum transport in these systems. This chapter suggests that, there is considerable need for further research in liquid jet array applications, both in submerged and free-surface jet configurations. Cross-flow effects in these systems, which have been quite well characterized for submerged jets, have received only superficial treatment for free-surface jets. The physical phenomena are highly complex, requiring careful experimental investigation.

Single-Phase Liquid Jet Impingement Heat Transfer

Publisher Summary Thermal control of electronic components has one principal objective, to maintain relatively constant component temperature equal to or below the manufacturer's maximum specified service temperature, typically between 85 and 100°C. It is noted that even a single component operating 10°C beyond this temperature can reduce the reliability of certain systems by as much as 50%. Therefore, it is important for the new thermal control schemes to be capable of eliminating hot spots within the electronic devices, removing heat from these devices and dissipating this heat to the surrounding environment. Several strategies have developed over the years for controlling and removing the heat generated in multichip modules, which include advanced air-cooling schemes, direct cooling, and miniature thermosyphons or free-falling liquid films. The chapter summarizes analytical, numerical, and experimental work in literature, in order to facilitate the improvement of existing schemes and provide a basis for the development of new ones. The chapter focuses on investigations performed over the past decade and includes information on the thermal control of semiconductor devices, modules, and total systems.

Thermal Control of Electronic Equipment and Devices

Experimental study and theoretical analysis of local heat transfer distribution between smooth flat surface and impinging air jet from a circular straight pipe nozzle

Heat transfer from round impinging jets to a flat plate

Heat transfer from a row of impinging jets to concave cylindrical surfaces

Heat transfer from impinging jets to a flat plate with conical and ring protuberances

With the use of the heat balance integral method, a formula for the depth of solidification in a stratified medium is derived that applies to Newton's cooling at the surface, where the temperature of the cooling medium is variable. The presence of a surface layer with zero latent heat is given a special consideration. Comparison of the proposed formula with the direct field measurements and the calculations carried out by others shows a satisfactory coincidence. For the simplified boundary conditions, the formular reduces to a known analytical solution.

Peter Hrycak

Papers

Heat transfer from round impinging jets to a flat plate

Heat transfer from a row of impinging jets to concave cylindrical surfaces

Heat transfer from impinging jets to a flat plate with conical and ring protuberances

Heat conduction with solidification in a stratified medium

Analysis of instabilities in round pipes and infinite channels by stochastic methods