Showing papers by "Terrence W. Simon published in 2016"
TL;DR: In this article, heat transfer and pressure drop characteristics of micro pin fin arrays in a narrow rectangular channel with an air through flow are studied with different flow rates ranging from laminar to turbulent flow.
71 citations
TL;DR: In this article, a design analysis of a shaped liquid piston compression chamber based on CFD is presented, where the authors explore the effects on compression efficiency of varying the profile of cross-sectional diameter along the axis of the chamber.
27 citations
TL;DR: In this paper, the effects of the ratio of jet spacing to swirl chamber radius and Reynolds numbers on swirl cooling performance were investigated with numerical simulation and a Nusselt number correlation on these parameters was suggested.
Abstract: In this paper, flow and heat transfer of a swirl chamber that models an internal cooling passage for a gas turbine airfoil leading edge is studied with numerical simulation. The geometry consists of a circular pipe, and rectangular section inlets that lead inlet flow to impinge tangentially on the circular pipe. The effects of the ratio of jet spacing to swirl chamber radius and Reynolds numbers on swirl cooling performance are investigated. The results indicate how the pressure loss and globally averaged Nusselt number on the swirl chamber wall increase with increases of Reynolds number and the ratio of jet spacing to swirl chamber radius. A Nusselt number correlation on these parameters is suggested. Also shown is how Nusselt numbers on the swirl chamber surface increase with the ratio of jet spacing to swirl chamber radius.
22 citations
TL;DR: In this paper, an advanced air cooling scheme that combines both active and passive cooling components is proposed and its thermal performance is demonstrated with single channel heat transfer experiments, where the active cooling component, a piezoelectric translational agitator, generates strong air turbulence using a blade oscillating at a high frequency near either plain or micro pin-fin surfaces in the channel.
17 citations
12 Oct 2016
TL;DR: The first experimental validation of optimization of the compression/expansion trajectory in high pressure (7bar to 200bar) compression is presented, which shows that the use of optimized trajectory can increase power density significantly over ad-hoc linear or sinusoidal trajectories without sacrificing efficiency.
Abstract: In an isothermal compressed air energy storage (CAES) system, it is critical that the high pressure air compressor/expander is both efficient and power dense. The fundamental trade-off between efficiency and power density is due to limitation in heat transfer capacity during the compression/expansion process. In our previous works, optimization of the compression/expansion trajectory has been proposed as a means to mitigate this tradeoff. Analysis and simulations have shown that the use of optimized trajectory can increase power density significantly (2-3 fold) over ad-hoc linear or sinusoidal trajectories without sacrificing efficiency especially for high pressure ratios. This paper presents the first experimental validation of this approach in high pressure (7bar to 200bar) compression. Experiments are performed on an instrumented liquid piston compressor. Correlations for the heat transfer coefficient were obtained empirically from a set of CFD simulations under different conditions. Dynamic programming approach is used to calculate the optimal compression trajectories by minimizing the compression time for a range of desired compression efficiencies. These compression profiles (as function of compression time) are then tracked in a liquid piston air compressor testbed using a combination of feedforward and feedback control strategy. Compared to ad-hoc constant flow rate trajectories, the optimal trajectories double the power density at 80% efficiency or improve the thermal efficiency by 5% over a range of power densities.
6 citations
13 Jun 2016
5 citations
01 Jan 2016
TL;DR: In this paper, the dispersion coefficient is calculated based on an experimental correlation that is given in terms of flow velocity, porous medium geometry and molecular diffusion coefficient, and the amount of dissolved gas under various conditions is calculated, such as gas concentration of the inlet flow to the compressor and discharge pressure to the storage tank at the end of compression.
Abstract: Liquid piston compression technology is being explored as a way to achieve high-pressure gas compression in Compressed Air Energy Storage (CAES) systems. When combined with a porous medium, a liquid piston compressor is able to provide near-isothermal compression, and high efficiency. However, the gas being compressed can dissolve into the liquid resulting in loss of compressed gas output. Also, the dissolved gas in the liquid lines can cause aeration that causes damage to pumps and valves. To understand this gas transport phenomenon in the liquid and to evaluate the total amount of gas dissolved, a numerical model was developed. Dispersion due to the porous medium is found to be the dominant mode of mass transfer. The dispersion coefficient is calculated based on an experimental correlation that is given in terms of flow velocity, porous medium geometry and molecular diffusion coefficient. The numerical model is used to investigate a case study in which a water liquid piston is used for air compression. The amount of dissolved gas under various conditions is calculated, such as gas concentration of the inlet flow to the compressor and discharge pressure to the storage tank at the end of compression. The effects of different types of liquids are also quantified by applying in the model the different solubility values of gases in liquids.
2 citations