A compact platform for the investigation of material dynamics in quasi-isentropic compression to ~ 19 GPa

This paper reports on the development of a magnetically driven high-velocity implosion experiment conducted on the CQ-3 facility, a compact pulsed power generator with a load current of 2.1 MA. The current generates a high Lorentz force between inner and outer liners made from 2024 aluminum. Equally positioned photonic Doppler velocimetry probes record the liner velocities. In experiment CQ3-Shot137, the inner liner imploded with a radial converging velocity of 6.57 km/s while the outer liner expanded at a much lower velocity. One-dimensional magneto-hydrodynamics simulation with proper material models provided curves of velocity versus time that agree well with the experimental measurements. Simulation then shows that the inner liner underwent a shock-less compression to approximately 19 GPa and reached an off-Hugoniot high-pressure state. According to the scaling law that the maximum loading pressure is proportional to the square of the load current amplitude, the results demonstrate that such a compact capacitor bank as CQ-3 has the potential to generate pressure as high as 100 GPa within the inner liner in such an implosion experiment. It is emphasized that the technique described in this paper can be easily replicated at low cost.

Performance Evaluation of Modified Low-Temperature Cascade (MLTC) Type Refrigeration System

An experimental investigation was carried out to study the performance evaluation of Modified Low-Temperature Cascade (MLTC) system, based on two-stage cascade type refrigeration system using the combination of R404A/R23 refrigerants. This system was developed using chilled water (CHW) in the condenser of high-temperature circuit (HTC) and pre-cooler (PC) in the low-temperature circuit (LTC). Isentropic compression efficiency is computed in this work and used here as an important parameter. Performance of MLTC system was compared with or without the introduction of PC into LTC. System’s coefficient of performance (COP) has also been compared with using CHW, cooling tower water (CTW), normal water (NW) into the HTC condenser. It has also been shown that COPs of the system are significantly affected by slight variation in the LTC and HTC evaporating temperatures. Presented parameters and comparisons are likely to help in developing a low-temperature (LT) refrigeration system with higher efficiency for industrial and other applications.

The effect of the chilled water temperature on the performance of an experimental air-cooled chiller

This paper presents the study results on the effect of the chilled water temperature on the coefficient of performance (COP) of an experimental air-cooled chiller. The measuring sensors and instrument were calibrated, and the uncertainty of the measuring temperature and pressure were evaluated. The uncertainty of measured temperature and pressure at 95% confidence level is 0.12 °C and 1.4 kPa, respectively. The isentropic compression efficiency and the COP of the air-cooled chiller operating at a condensation temperature of 48.05 °C and evaporation temperature of 3.17 °C are 63% and 2.69, respectively. The chilled water temperature has a significant influence on evaporation pressure and the COP of the chiller. If the temperature of the air entering the condenser of the chiller is maintained at 35 °C, the COP of the chiller increases from 2.55 to 2.89 when the temperature of the chiller water increases only 4 K, from 8 °C to 12 °C.

Volumetric and Acoustic Properties of D(+) Glucosamine·HCl and L-Lysine·HCl in Aqueous Solutions at Different Temperatures

In present work, density and speed of sound of aqueous binary mixtures of biologically important amino acid derivatives namely D(+) glucosamine·HCl and L-lysine·HCl have been measured at three different temperatures i.e. (278.15, 288.15 and 298.15) K and in the concentration range of 0.0-0.2 mol kg-1. Using density and speed of sound data, different thermodynamic and acoustic parameters like apparent molar volume (Vφ) and apparent molar isentropic compression (Kφ) of solute have been computed at different temperatures. Speed of sound data have also been used to calculate hydration number (nH) of solute. The temperature dependence of the limiting apparent molar volume of solute has been used to calculate thermal expansion coefficient (α*), apparent molar expansivity (E0 φ) of solute and Hepler’s constant (∂2V0 φ/∂T2). The final outcome of the study has been discussed in terms of various interactions among solute and solvent molecules.

The effect of recuperator on the efficiency of ORC and TFC with very dry working fluid

Organic Rankine Cycles (ORC) and Trilateral Flash Cycles (TFC) are very similar power cycles; ideally, they have a reversible adiabatic (isentropic) compression, an isobaric heating, an isentropic expansion and an isobaric cooling. The main difference is that for ORC, the heating includes the full evaporation of the working fluid (prior expansion); therefore, the expansion starts in a saturated or dry vapour state, while for TFC, the heating terminates upon reaching the saturated liquid states. Therefore, for TFT, expansion liquid/vapour state (in bubbly liquid or in vapour dispersed with droplets), requiring a special two-phase expander. Being ORC a more “complete” cycle, one would expect that its thermodynamic efficiency is always higher than for a TFC, between the same temperatures and using the same working fluids. Surprisingly, it was shown that for very dry working fluids, the efficiency of TFC can exceed the efficiency of basic (i.e. recuperator- and superheater-free) ORC, choosing sufficiently high (but still subcritical) maximal cycle temperature. Therefore in these cases, TFC (having a simpler heat exchange unit for heating) can be a better choice than ORC. The presence of a recuperator can influence the situation; by recovering the proper percentage of the remaining heat (after the expansion), the efficiency of ORC can reach and even pass the efficiency of TFC.