Impingement Heat Transfer Innovations and Enhancements: a Discussion on Selected Geometrical Features

Abstract

Abstract Impingement heat transfer is considered as one of the most effective cooling technologies that yields in high localized convective heat transfer coefficient. This paper studies different configurational parameters involved in jet impingement cooling such as, exit orifice shape, crossflow regulation, target surface modification, spent air reuse, impingement channel modification, jet pulsation, and other techniques to understand what are critical and how these heat transfer enhancement concepts work. These enhancement factors have been explored in detail by many researchers, including standard parameters such as normalized distance between adjacent jets and jet-to-target spacing, and those known benefits are not repeated here. The aim of this paper is to stimulate the current scientific knowledge of this efficient cooling technique and instill some thoughts for future innovations. New orifice shapes are becoming feasible due to 3D printing technologies. However, the orifice studies show that it is hard to beat a sharp-edged round orifice. Any attempt to streamline the hole shape indicated a drop in the Nusselt number. Reduction in crossflow has been attempted with channel modifications. Use of high porosity conductive foam in the impingement space has shown marked improvement in heat transfer performance. A list of possible research topics based on this discussion are provided in conclusion.