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► We investigated a space CO2 condenser’s heat transfer coefficient and pressure drop. ► A CO2 condenser with mini-channel of 0.9mm. ► HTCs agree with the prediction by Thome ...correlation within errors of ±30%. ► Flow pressure drops agree with the prediction by Friedel correlation within errors of ±30%..
We present the flow condensation heat transfer characteristics of CO2 in a mini-channel condenser. The condenser consists of seven tubes in parallel, which are thermally connected to two aluminium base-plates by using thermal glue. At saturation temperatures ranging from −5°C to 15°C, with mass velocities of 180, 360 and 540kg/(m2s), respectively, and average vapour qualities from 0.2 to 0.8, we obtained the CO2 condensation heat transfer coefficients, ranging from 1700 to 4500W/(m2K). We compared the measured heat transfer coefficients with those predicted by the established correlations, and found that Thome’s was applicable to the condenser under investigation, with deviation less than 30%. We also discussed the measured pressure drop over the condenser, which increased with the mass velocity and the vapour quality, but decreased with the saturation temperature.
A mechanically pumped CO sub(2) two-phase loop cooling system was developed for the temperature control of the silicon tracker of AMS-02, a cosmic particle detector to work in the International Space ...Station. The cooling system (called TTCS, or Tracker Thermal Control System), consists of two evaporators in parallel to collect heat from the tracker's front-end electronics, two radiators in parallel to emit the heat into space, and a centrifugal pump that circulates the CO sub(2) fluid that carries the heat to the radiators, and an accumulator that controls the pressure, and thus the temperature of the evaporators. Thermal vacuum tests were performed to check and qualify the system operation in simulated space thermal environment. In this paper, we reported the test results which show that the TTCS exhibited excellent temperature control ability, including temperature homogeneity and stability, and self-adaptive ability to the various external heat flux to the radiators.
A mechanically pumped CO
2 two-phase loop cooling system was developed for the temperature control of the silicon tracker of AMS-02, a cosmic particle detector to work in the International Space ...Station. The cooling system (called TTCS, or Tracker Thermal Control System), consists of two evaporators in parallel to collect heat from the tracker’s front-end electronics, two radiators in parallel to emit the heat into space, and a centrifugal pump that circulates the CO
2 fluid that carries the heat to the radiators, and an accumulator that controls the pressure, and thus the temperature of the evaporators. Thermal vacuum tests were performed to check and qualify the system operation in simulated space thermal environment. In this paper, we reported the test results which show that the TTCS exhibited excellent temperature control ability, including temperature homogeneity and stability, and self-adaptive ability to the various external heat flux to the radiators.
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► The active-pumped CO
2 two-phase cooling loop passed the thermal vacuum test. ► It provides high temperature homogeneity and stability thermal boundaries. ► Its working temperature is controllable in vacuum environment. ► It possesses self-adaptive ability to imbalanced external heat fluxes.
A novel approach for designing the next generation of vertex detectors foresees to employ wafer-scale sensors that can be bent to truly cylindrical geometries after thinning them to thicknesses of ...20-40\(\mu\)m. To solidify this concept, the feasibility of operating bent MAPS was demonstrated using 1.5\(\times\)3cm ALPIDE chips. Already with their thickness of 50\(\mu\)m, they can be successfully bent to radii of about 2cm without any signs of mechanical or electrical damage. During a subsequent characterisation using a 5.4GeV electron beam, it was further confirmed that they preserve their full electrical functionality as well as particle detection performance. In this article, the bending procedure and the setup used for characterisation are detailed. Furthermore, the analysis of the beam test, including the measurement of the detection efficiency as a function of beam position and local inclination angle, is discussed. The results show that the sensors maintain their excellent performance after bending to radii of 2cm, with detection efficiencies above 99.9% at typical operating conditions, paving the way towards a new class of detectors with unprecedented low material budget and ideal geometrical properties.
To provide a stable thermal environment for the AMS-Tracker, a thermal control system based on mechanically pumped CO2 two-phase loops was developed. It has been operating reliably in space since May ...19, 2011. In this article, we summarize the design, construction, tests, and performance of the AMS-Tracker thermal control system (AMS-TTCS).
Children have reduced severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection rates and a substantially lower risk for developing severe coronavirus disease 2019 compared with adults. ...However, the molecular mechanisms underlying protection in younger age groups remain unknown. Here we characterize the single-cell transcriptional landscape in the upper airways of SARS-CoV-2-negative (n = 18) and age-matched SARS-CoV-2-positive (n = 24) children and corresponding samples from adults (n = 44), covering an age range of 4 weeks to 77 years. Children displayed higher basal expression of relevant pattern recognition receptors such as MDA5 (IFIH1) and RIG-I (DDX58) in upper airway epithelial cells, macrophages and dendritic cells, resulting in stronger innate antiviral responses upon SARS-CoV-2 infection than in adults. We further detected distinct immune cell subpopulations including KLRC1 (NKG2A)
cytotoxic T cells and a CD8
T cell population with a memory phenotype occurring predominantly in children. Our study provides evidence that the airway immune cells of children are primed for virus sensing, resulting in a stronger early innate antiviral response to SARS-CoV-2 infection than in adults.
The Alpha Magnetic Spectrometer AMS-02 1-4 is an astro particle physics experiment running on the International Space Station (ISS; see Figure 1) since May 19, 2011. Its missions include the search ...for antimatter and the identification of the nature of dark matter. The AMS silicon tracker is the only subdetector inside the AMS permanent magnet that can detect the charge of a moving particle to distinguish an anti-particle from particle (see Table 1 for nomenclature).
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