• Kempers R.
  • Robinson A.
  • Siedel S.
  • Smith K.

Heat pipes are generally recognized as a reliable heat transfer device for many different applications however clarity is needed to describe the thermal mechanisms driving the transfer of heat. This experiment involved the construction and testing of a transparent, sapphire heat pipe, with water as the working fluid. Through high speed imagery and corresponding temperature and pressure measurements, the dominant mechanisms of boiling and condensation were visualized in the evaporator and condenser. The tests were carried out at various internal pressures, which ranged from p = 4 - 25 kPa, at a constant heat input of q = 50 W. Of particular interest was the pulsating nature of the heat pipe at lower pressure levels. The high speed images show, at lower pressures, a liquid plug and vapor slug were seen to oscillate between the evaporator and condenser. At the higher pressures tested, film condensation becomes more dominant in the condenser and the frequency and amplitude of liquid oscillations is reduced. The overall thermal resistance of the system was also calculated, and ranged from Rtot = 0.44 K/W at low pressure, to Rtot = 0.10 K/W at higher pressure.

Recent Publications

August 09, 2017

A Cloud Native Approach to 5G Network Slicing

  • Francini A.
  • Miller R.
  • Sharma S.

5G networks will have to support a set of very diverse and often extreme requirements. Network slicing offers an effective way to unlock the full potential of 5G networks and meet those requirements on a shared network infrastructure. This paper presents a cloud native approach to network slicing. The cloud ...

August 01, 2017

Modeling and simulation of RSOA with a dual-electrode configuration

  • De Valicourt G.
  • Liu Z.
  • Violas M.
  • Wang H.
  • Wu Q.

Based on the physical model of a bulk reflective semiconductor optical amplifier (RSOA) used as a modulator in radio over fiber (RoF) links, the distributions of carrier density, signal photon density, and amplified spontaneous emission photon density are demonstrated. One of limits in the use of RSOA is the lower ...

July 12, 2017

PrivApprox: Privacy-Preserving Stream Analytics

  • Chen R.
  • Christof Fetzer
  • Le D.
  • Martin Beck
  • Pramod Bhatotia
  • Thorsten Strufe

How to preserve users' privacy while supporting high-utility analytics for low-latency stream processing? To answer this question: we describe the design, implementation and evaluation of PRIVAPPROX, a data analytics system for privacy-preserving stream processing. PRIVAPPROX provides three properties: (i) Privacy: zero-knowledge privacy (ezk) guarantees for users, a privacy bound tighter ...