Definition of condensation two phase flow behaviors for spacecraft design

Reinarts, Thomas R.; Best, Frederick R.; Hill, Wayne S.

doi:10.1063/1.41741

Cited by 3 publications

(3 citation statements)

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“…The onset of microgravity was found to cause a steep increase of the condensation pressure up to 3% due to the reduced liquid removal from the walls and the decreased heat transfer coefficients compared to normal gravity. Such instability issues and heat transfer penalization under microgravity were confirmed by Reinarts et al 25,26 during condensation tests with R12 inside a 8.7 mm inner diameter tube aboard the NASA KC-135 plane. In the transition from hypergravity to microgravity, the working fluid temperature and pressure at the inlet of the condensation test section were found to slightly increase and a significant decrease of the condensation heat transfer (in the order of 26%) was detected under microgravity conditions compared to normal gravity.…”

Section: Experimental Studiesmentioning

confidence: 69%

“… Nebuloni and Thome 39 Numerical Circular (1 mm diameter), square (1 mm side) and equilateral triangular (1 mm side) channels R134a T sat = 24 °C T wall = 23 °C Numerical simulations of FWC inside different channel shapes to evaluate local/mean HTCs, liquid film thickness and void fraction The HTC enhancement due to surface tension is clearly visible for square and triangular channels, while the gravity effect is non-negligible for the circular tube. Reinarts et al 25 Experimental (parabolic flight) and analytical Circular 8.7 mm ID channel R12 P sat = 5.45–5.65 bar HTC measurements Flow visualizations Decrease by 26% in the condensation heat transfer in the transition from normal gravity to microgravity. Reinarts et al 26 Review of numerical, analytical and experimental works Straight circular-cross section tubes Single to multi-components refrigerants Co-current two-phase flow Review of works dealing with testing and modeling of flow regime transitions, pressure drops and condensation heat transfer under microgravity Literature on FWC under microgravity mainly focused on annular flow regime, instead of slug/bubbly flow.…”

Section: Introductionmentioning

confidence: 99%

“…Reinarts et al 25 and Best et al 62 applied a modified Dittus-Boelter correlation, given by Eq. ( 16 ), for the prediction of the condensation heat transfer coefficient of R-12 in the low vapor quality region inside a 8.7 mm inner diameter channel during microgravity: …”

Section: Introductionmentioning

confidence: 99%

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Condensation heat transfer in microgravity conditions

et al. 2023

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In the present paper, a thorough review of the experimental and numerical studies dealing with filmwise and dropwise condensation under microgravity is reported, covering mechanisms both inside tubes and on plain or enhanced surfaces. The gravity effect on the condensation heat transfer is examined considering the results of studies conducted both in terrestrial environment and in the absence of gravity. From the literature, it can be inferred that the influence of gravity on the condensation heat transfer inside tubes can be limited by increasing the mass flux of the operating fluid and, at equal mass flux, by decreasing the channel diameter. There are flow conditions at which gravity does exert a negligible effect during in-tube condensation: predictive tools for identifying such conditions and for the evaluation of the condensation heat transfer coefficient are also discussed. With regard to dropwise condensation, if liquid removal depends on gravity, this prevents its application in low gravity space systems. Alternatively, droplets can be removed by the high vapor velocity or by passive techniques based on the use of condensing surfaces with wettability gradients or micrometric/nanometric structuration: these represent an interesting solution for exploiting the benefits of dropwise condensation in terms of heat transfer enhancement and equipment compactness in microgravitational environments. The experimental investigation of the condensation heat transfer for long durations in steady-state zero-gravity conditions, such as inside the International Space Station, may compensate the substantial lack of repeatable experimental data and allow the development of reliable design tools for space applications.

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Section: Experimental Studiesmentioning

confidence: 69%