Non - Condensable Gases an D Oscillating Heat P Ipe Operation

Abstract

The Oscillating Heat Pipe (OHP) is a novel, wickless heat pipe that relies on the phase change induced motion of a contained working fluid to transport heat between the evaporator and condenser. This paper investigates the effects of non-condensable gas (NCG) on OHP operation. A brief synopsis of the existing literature is presented before discussing the experimental setup, method, results, and conclusion. This paper clearly shows that: 1) NCG injection into an OHP produces an overall rise in the steady-state operating temperature, pressure, and thermal resistance; 2) Like LHPs OHPs are more tolerant of NCG than conventional heat pipes.

Operational Characteristics of the Oscillating Heat Pipe with Noncondensable Gas

“…Before our current paper, Taft [21] has reported on the NCG effect on OHPs. Results showed that NCG degraded the thermal performance of OHPs because evaporation/boiling is suppressed by the increase in the degree of subcooling in the working fluid [22].…”

Additive manufacturing of heat exchangers: A case study on a multi-layered Ti–6Al–4V oscillating heat pipe

“…After joining successive layers, excess material is machined away, and the process is repeated until the part is completed. Taft [35] utilized this method to fabricate aluminum alloy FP-OHPs consisting of a single layer of channels; demonstrating that UC is appealing for structural integration of panel-type FP-OHPs.…”

“…In addition to end-milling and brazing methods, ultrasonic consolidation (UC) -an additive/subtractive manufacturing process that utilizes the successive build-up and end-milling of individual foils for achieving target geometries -can be utilized [35]. During UC, mating foils are held together under pressure, and ultrasonic acoustic vibrations are applied to accomplish layer-to-layer adhesion via solid state welding.…”

“…The traditional material of interest for any heat pipe (or TGP) has been copper due to its inherently high thermal conductivity; however, various other materials have been recently investigated, including aluminum [35,[37][38][39][40], titanium [16,41], copper molybdenum (CuMo) [42], polymers [43] and silicon [44]. Material selection for any TGP, and specifically FP-OHPs, is limited by the material's machinability and ability to be metallurgically bonded to like or dissimilar materials -i.e.…”

“…A c c e p t e d M a n u s c r i p t 8 A FP-OHP substrate can have one [19,29,35] or two [21,25,30] of its sides consisting of a channel network. A single-sided, or single-layer, FP-OHP typically requires one lid, while a double-sided, or double-layer, FP-OHP can require two lids.…”