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Progresses in Ultra-Precise Temperature Control and Thermometry Techniques
정욱철(Wukchul Joung) Korean Society for Precision Engineering 2021 한국정밀공학회지 Vol.38 No.12
In this work, recent advances in temperature control techniques and the resulting contemporary progress in precision thermometry are addressed together with a broad review of traditional temperature control methods. Particular emphases are placed on clarification of the nature of temperature control and its classification, and the relevant technical issues are addressed based on this clarification and classification. Being a thermodynamic quantity having the same dimension as energy, temperature of an object is traditionally controlled by means of the changing rate of energy (Heat) transfer; however, this approach has led to a slow, less stable, and uneven temperature field due to inherent limits caused by finite properties of materials. To overcome this problem, thermodynamic characteristics of two-phase heat transfer devices, such as heat pipes and loop heat pipes, have been extensively employed where high-speed nature of fluid flow was exploited to realize a uniform temperature field, and unique thermodynamic linkage between saturation temperature and pressure was successfully applied to attain a fast, stable, and predictable temperature control of a finite-sized isothermal space. Representative examples and applications are provided in the context of unique features of the introduced contemporary temperature control techniques, which caused significant scientific strides in the related fields.
루프 히트 파이프의 작동유체 선정을 위한 성능계수 도출
정욱철(Wukchul Joung),이진호(Jinho Lee),류태우(Taeu Yu) 대한기계학회 2009 대한기계학회 춘추학술대회 Vol.2009 No.5
Despite outstanding performance of loop heat pipes (LHPs) over other two-phase heat transfer devices, widespread applications of these devices are limited due to ambiguities on their operation. Among these, of particular interest is a figure of merit for working fluid selection. As for the selection of working fluids of LHPs, the figure of merit for heat pipes has usually been used, and qualitative approaches, such as choosing a working fluid of steep saturation curve slope, etc, has additionally been employed. However, as the figure of merit for heat pipes only concerns a maximum heat transfer capacity, it is not appropriate for assessing thermal performance of a working fluid with respect to steady state thermal performance of the LHPs. In this work, a figure of merit for LHPs, which quantitatively evaluates thermal performance of a working fluid regarding the steady state operation of the LHPs, is theoretically derived and experimentally verified.