Evaluation of performance an air conditioning systems using t-junction flash gas refrigerant
The purpose of this study was to determine the performance of air-cooled chiller system using T-junction flash gas bypass refrigerant. The experiment was conducted by installing T-junction after expansion device to separate the phase of refrigerant liquid and gas which flows to the evaporator. The working fluid is used as a cooling medium is R-290. To get performance data, measurements performed at the time of steady state when the water chilling temperature T = 15 C up to T = 10 C and flow rates kept constant at 1 GPM (6.3 x 10-5 m3/s). Finally, the use of T-junction mode in AC system generates an increase in the refrigerating effect and coefficient of performance systems (CoP) by 6% and 17.8 %, respectively. Also, it can decrease the heat of compression by 8.5%. This has implications for the lighter compressor work and saving the power consumption of the AC system.
Oil-Water Two-Phase Flow Inside T-Junction
Abstract The oil / water two-phase flow inside T-junctions was numerically simulated with a 3-D two-fluid model, and the turbulence was described using the mixture κ - ɛ model. Some experiments of oil / water flow inside a single T-junction were conducted in the laboratory. The results show that the separating performance of T-junction largely depends on the inlet volumetric fraction and flow patterns. A reasonable agreement is reached between the numerical simulation and the experiments for both the oil fraction distribution and the separation efficiency.
Noctilucent cloud observations over Greenland by a Rayleigh lidar
We report on the detection of noctilucent clouds (NLCs) by a Rayleigh lidar system located on the west coast of Greenland during operations in July and August 1994. The lidar detected NLCs in the zenith on three nights (July 28–29, July 31–August 1, and August 4). The lidar measurements are presented at temporal (1 minute) and spatial (192 meter) resolutions exceeding previously reported lidar measurements of NLCs and reveal significantly more structure in the clouds. Unique cloud features are observed for each night NLCs were detected. Because of the large backscatter ratio associated with NLCs, the volume backscatter coefficient for the cloud particles can be determined more accurately from the lidar signal than the backscatter ratio as the upper mesospheric molecular number density is negligible in the volume backscatter coefficient calculation. The volume backscatter coefficient values determined from the three nights of NLC observations would be classified by current models as moderate to extreme. The extreme backscatter from NLC measurements on August 4 tests the assumptions used in existing models.