The production of OH radicals by dissociation of water vapor in oscillating argon bubbles is studied theoretically to examine a possible mechanism for the emission of the 310-nm line observed in sonoluminescence experiments. Accurate models are used for the calculation of the temperature field in the gas and for the description of the associated chemical kinetics. Heat transfer between the bubble and the liquid is found to play a dominant role in the process. At the low excitation amplitudes considered, the bubble radius is also an important parameter.

A recent detailed formulation of the dynamics of a gas bubble requires the numerical integration of a nonlinear heat equation in the bubble. In this article, a variety of numerical methods for this purpose are studied. The most efficient technique is found to be an adaptive Galerkin–Chebyshev spectral method, which is explained in detail. Examples of oscillations at high forcing and chaotic response are also given. These results differ very considerably from those obtained by use of the simpler models used by previous investigators.

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The heat dissipated by electronic equipment continues to increase at a alarming rate. This has occurred for products covering a wide range of applications. Manufacturers of this equipment require that the equipment be maintained within an environmental envelope in order to guarantee proper operation. Achievement of these environmental conditions are becoming increasingly difficult given the increases in rack heat loads and the desire for customers of such equipment to cluster racks in a small region for increased performance. And with the increased heat load of the racks and correspondingly increased air flowrate the chilled air flow supplied either through data center raised floor perforated tiles or diffusers for non raised floors is not sufficient to match the air flow required by the datacom racks. In this case some of the hot air exhausting the rear of a rack can return to the front of the rack and be ingested into the air intake thereby reducing the reliability of the electronic equipment. This paper describes a method to reduce the effect of the hot air recirculation with a water cooled heat exchanger attached to the rear door of the rack. This heat exchanger removes a large portion of the heat from the rack as well as significantly lowering the air temperature exhausting the rear of the rack. This paper describes the hardware and presents the test results showing that a large portion of the heat is removed from the rack and the temperature exhausting the rear of the rack is significantly reduced. Finally the effectiveness of the solution is shown in modeling of this water cooled solution in a data center application.

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