Speaker
Dr
Haishan Cao
(University of Twente)
Description
A major issue in long-term operation of micromachined Joule-Thomson coolers is the clogging of the microchannels and/or the restriction due to the deposition of water molecules present in the working fluid. To verify which microcooler design is the least sensitive to clogging, the operating times of various microcoolers with a cold-end temperature of 120 K are compared. In these experiments, relatively low-purity nitrogen gas (5.0) is supplied from a gas bottle and led through a filter to control the concentration of water vapor. The filter consists of a tube-in-tube counter flow heat exchanger and a heat exchanger that is stabilized at a certain temperature by using a Stirling (other) cooler. The set-point temperature determines the equilibrium water partial pressure at the exit of the heat exchanger, as given by the water sublimation curve. Meanwhile, we have developed a model for predicting the deposition rate of water molecules in a previous study. An updated model is developed to investigate how the deposition rate affects the mass-flow rate of a microcooler and thus to predict the operating time of the microcooler.
Author
Dr
Haishan Cao
(University of Twente)
Co-authors
Cris Vermeer
(SuperACT)
Harry Holland
(University of Twente)
Marcel ter Brake
(University of Twente, The Netherlands)
Srinivas Vanapalli
(University of Twente)
