TY - JOUR
T1 - Performance of a miniature ejector for application in a nitrogen Joule-Thomson cycle
T2 - Experimental and numerical analysis
AU - Cao, H. S.
AU - Geng, L. H.
AU - Hammink, G.
AU - Tirolien, T.
AU - ter Brake, H. J.M.
PY - 2021/3/5
Y1 - 2021/3/5
N2 - The performance of Joule-Thomson (JT) cryocoolers can be improved by introducing ejectors. Ejectors with various geometric features have been proposed and investigated for cryogenic cooling in earlier studies, but only limited research is done on ejectors with a nozzle throat diameter less than 1 mm. In this paper, we present a miniature ejector with a nozzle throat diameter of 162 μm that was measured using X-ray computed tomography. When the ejector was operated with nitrogen gas at 295 K with a primary inlet pressure of 80 bar, a secondary inlet pressure of 0.5 bar and an outlet pressure of 1.2 bar, the primary and the secondary mass-flow rates were 394 mg/s and 83 mg/s, respectively. The measured primary mass-flow rate was quite close to the value predicted by a dynamic model, whereas the measured secondary mass-flow rate was lower than the predicted value, which was mainly caused by a non-axisymmetric machining defect of the nozzle that was assumed to be axisymmetric in the dynamic model. Besides, the effects of operating pressures and nozzle position on the ejector performance were analyzed. The study demonstrates the applicability of a miniature ejector in a JT cooling cycle.
AB - The performance of Joule-Thomson (JT) cryocoolers can be improved by introducing ejectors. Ejectors with various geometric features have been proposed and investigated for cryogenic cooling in earlier studies, but only limited research is done on ejectors with a nozzle throat diameter less than 1 mm. In this paper, we present a miniature ejector with a nozzle throat diameter of 162 μm that was measured using X-ray computed tomography. When the ejector was operated with nitrogen gas at 295 K with a primary inlet pressure of 80 bar, a secondary inlet pressure of 0.5 bar and an outlet pressure of 1.2 bar, the primary and the secondary mass-flow rates were 394 mg/s and 83 mg/s, respectively. The measured primary mass-flow rate was quite close to the value predicted by a dynamic model, whereas the measured secondary mass-flow rate was lower than the predicted value, which was mainly caused by a non-axisymmetric machining defect of the nozzle that was assumed to be axisymmetric in the dynamic model. Besides, the effects of operating pressures and nozzle position on the ejector performance were analyzed. The study demonstrates the applicability of a miniature ejector in a JT cooling cycle.
KW - 3D printing
KW - Cryocooler
KW - Ejector
KW - Joule-Thomson effect
KW - Turbulence modeling
KW - UT-Hybrid-D
UR - http://www.scopus.com/inward/record.url?scp=85098961202&partnerID=8YFLogxK
U2 - 10.1016/j.applthermaleng.2020.116357
DO - 10.1016/j.applthermaleng.2020.116357
M3 - Article
AN - SCOPUS:85098961202
VL - 186
JO - Applied thermal engineering
JF - Applied thermal engineering
SN - 1359-4311
M1 - 116357
ER -