Influence of compression-expansion effect on oscillating-flow heat transfer in a finned heat exchanger

Abstract

Abstract:Compression and expansion of a working gas due to the pressure oscillation of an oscillating flow can lead to a temperature variation of the working gas, which will affect the heat transfer in the oscillating flow. This study focuses on the impact of the compression-expansion effect, indicated by the pressure ratio, on the heat transfer in a finned heat exchanger under practical operating conditions of the ambient-temperature heat exchangers in Stirling-type pulse tube refrigerators. The experimental results summarized as the Nusselt number are presented for analysis. An increase in the pressure ratio can result in a marked rise in the Nusselt number, which indicates that the compression-expansion effect should be considered in characterizing the heat transfer of the oscillating flow, especially in the cases with a higher Valensi number and a lower maximum Reynolds number.

Experimental and numerical investigations of thermal characteristics of heat exchangers in oscillatory flow

“…Research works have been carried out to study the thermal performance of heat exchangers in oscillatory flow. Finned type heat exchangers [13,23,32,33], parallel plate type [29,38], and parallel tube types [21] have been studied to determine the influence of normalised displacement amplitude, fin or plate spacing, plate thickness, and acoustic Reynolds number (based on the peak acoustic velocity between tubes), on the heat transfer performance of heat exchangers. These studies have used either a single ambient or cold heat exchanger for heat transfer performance characterisation or a pair of adjacent 'cold' and 'hot' heat exchangers (with or without gap) in an attempt to improve the heat transfer estimation and to propose oscillatory flow correlations.…”

A Comprehensive Empirical Correlation for Finned Heat Exchangers with Parallel Plates Working in Oscillating Flow

“…Tang et al [15,16] experimentally studied the influence of working conditions, as well as the compression-expansion effect, on the Nusselt number of finned heat exchangers. An empirical correlation of the Nusselt number, with the maximum Reynolds number and Valensi number, has been summarized.…”

Influence of the Water-Cooled Heat Exchanger on the Performance of a Pulse Tube Refrigerator

“…Although this is a very appropriate high-capacity design in theory, it is technically difficult. The water-cooled heat exchanger presented in References [17][18][19] Figure 1b, can also be considered a fin-tube type. The fins are machined by wire electrical discharge machining (WEDM), and the water only flows around the circumference of the case.…”