E. Embacher

Bio: E. Embacher is an academic researcher from Dornier Flugzeugwerke. The author has contributed to research in topics: Heat flux & Heat transfer coefficient. The author has an hindex of 1, co-authored 1 publications receiving 30 citations.

Capillary pumped loops for space applications - Experimental and theoretical studies on the performance of capillary evaporator designs

Abstract: Since several years, Dornier has been engaged with the development of capillary pumped loops for space applications. The key component of these heat transport systems is the capillary evaporator. It combines a double function: That of the heat absorbing element of the loop and that of a circulating pump. Different designs of evaporators which are able to transport heat in the range of several kilowatts were manufactured and tested with the working fluids freon, amnonia and water. The physical process of capillary pumping as a result of the coupled heat and mass transfer which takes place in the porous wick structure of the evaporator, was studied experimental ly and theoretical 1 y in detai 1. This paper presents the performance characteristics of the individual evaporator design which were tested with different working fluids. In particular, the heat transfer coefficient and the avai lable capillary pumping head both as functions of the heat flux density are shown. The understanding of the thermal and fluid dynamical properties of the evaporator designs is supported by theoretical studies on the partial steps of the coupled heat and fluid flow. Model calculations were performed which gave results regarding distribution of the dependent physical quantities of temperature, pressure and velocity of the fluid in the evaporating zone of the porous wick structure.

Approved for Public Release; Distribution is Unlimited

Abstract: PROTRACED COUNTERINSURGENCY: CHINESE COIN STRATEGY IN XINJIANG by MAJ J. Scott LaRonde, USA, 95 pages. In 1949, following the conclusion of its revolutionary war against the Chinese Nationalist forces, the People’s Liberation Army (PLA) peacefully occupied China’s western most province of Xinjiang. For nearly sixty years, the PLA has conducted a counterinsurgency against several, mostly Uyghur-led, separatist movements. Despite periods of significant violence, particularly in the early 1950s and again in the 1990s, the separatist forces have not gained momentum and remained at a level one insurgency. Mao ZeDeng is revered as a master insurgent and the father of Fourth Generation Warfare. Strategists in armies worldwide study his writings on revolutionary and guerilla warfare. This monograph concludes that Mao, as well as the communist leaders who followed him, was also successful at waging protracted counterinsurgency. For nearly sixty years, separatist movements in Xinjiang, Tibet, and Taiwan have all failed. This monograph analyzes the conflict in Xinjiang and concludes that the Chinese continue to defeat the separatist movement in Xinjiang through a strategy that counters Mao’s seven fundamentals of revolutionary warfare.

High heat flux heat pipe mechanism for cooling of electronics

Abstract: This paper discusses an advanced heat pipe mechanism that has the potential of achieving heat flux capabilities over 250 W/cm/sup 2/. The mechanism utilizes thermally driven pulsating two-phase flow to achieve high heat flux capability and heat transfer coefficient. A simplified hydrodynamic model in was developed to guide the proof-of-concept heat pipe design. A more detailed numerical model was also developed and will be solved to predict the heat pipe's thermal performance. Test results of proof-of-concept heat pipes verified the heat flux capability of the advanced mechanism and the accuracy of the simplified model. Pulsating heat pipes are feasible approaches to removing increasing heat dissipation densities in electronic equipment.

Heat transfer in the inverted meniscus type evaporator at high heat fluxes

Abstract: A one-dimensional mathematical model of the heat transfer during evaporation of the liquid from the liquid-vapor interface located in a porous structure into the dry region between the interface and the solid heated surface is developed for the case when the vapor flows through the narrow dry porous zone along the heated surface towards the vapor channel The model predicts the location and shape of the liquid-vapor interface, the overall heat transfer coefficient, and the heat fluxes which can be recognized as critical for the evaporator The numerical results are presented for the case of the miniature evaporator for electronic components cooling

Conjugate analysis of a flat-plate type evaporator for capillary pumped loops with three-dimensional vapor flow in the groove

Abstract: The physical operational mechanisms for the evaporator of capillary pumped loops are described, and possible working limits are identified. A generalized mathematical formulation for the flatplate type evaporator is given, which includes liquid flow and heat transfer in the porous wick structure, three-dimensional vapor flow in the groove, and heat transfer in the cover plate. The liquid and vapor flows are coupled via the interfacial mass flux, and the entire evaporator is solved as a conjugate problem. Numerical results under different working conditions and with different fluids are presented, which provide guidance for the evaporator design of capillary pumped loops.

Capillary heat loop technology: Space applications and recent Canadian activities

Abstract: Capillary heat loops (CHL) are heat transfer designs with high-effectiveness, high-performance, high-reliability, high-flexibility, and anti-gravitation features of interest to the space community. At the Canadian space agency a project has been initiated since 2002 to develop an understanding of CHL technology. The technology is targeted towards the thermal control systems of miniaturized satellites. This paper presents reviews of CHL modeling and space applications and introduces the recent development of loop heat pipe (LHP) technology in Canada in the hardware development, application, performance testing, analytical prediction and numerical modeling.