Condensation heat transfer in a microgravity environment

Chow, L. C.; Parish, R. C.

doi:10.2514/3.65

Cited by 6 publications

(2 citation statements)

References 2 publications

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“…Despite the obvious merits of two-phase systems, limited understanding of the effects of microgravity is one of the biggest obstacles to their implementation. This limited understanding has spurred a series of research efforts in pursuit of mechanistic understanding and predictive tools for all aspects of two-phase flow and heat transfer in microgravity, including adiabatic flow [17][18][19][20], flow boiling [21][22][23][24][25][26], and flow condensation [27][28][29][30][31].…”

Section: Two-phase Flow and Heat Transfer In Future Space Missionsmentioning

confidence: 99%

Effects of two-phase inlet quality, mass velocity, flow orientation, and heating perimeter on flow boiling in a rectangular channel: Part 1 – Two-phase flow and heat transfer results

Kharangate

O’Neill

Mudawar

2016

International Journal of Heat and Mass Transfer

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Lack of understanding of flow boiling behavior in reduced gravity poses a major challenge to the development of future space vehicles utilizing two-phase thermal control systems (TCSs). A cost effective method to investigating the influence of reduced gravity on flow boiling is to perform ground experiments at different orientations relative to Earth gravity. This paper is the first part of a two-part study aimed at exploring flow boiling mechanisms of FC-72 in a rectangular channel heated along one wall or two opposite walls. Experiments are performed in vertical upflow, vertical downflow and horizontal flow, subject to large variations in mass velocity, inlet quality and wall heat flux. Detailed measurements are used to investigate the influences of orientation, and therefore gravity, on boiling curve, local and average heat transfer coefficients, and pressure drop, and their relationship with interfacial behavior is captured with high-speed video. For horizontal flow, the effects of gravity are reflected in appreciable stratification across the channel at low mass velocities, with gravity aiding vapor removal from, and liquid return to the bottom heated wall, while accumulating vapor along the top heated wall. For vertical upflow and vertical downflow, with both single-sided and double-sided heating, there is far better symmetry in vapor formation along the channel. The heat transfer coefficient shows significant variations among the different orientations and heating configurations at low mass velocities, but becomes insensitive to orientation above 800 kg/m 2 s, proving inertia around this mass velocity is effective at negating any gravity effects. For low mass velocities, pressure drops are fairly equal for vertical upflow and vertical downflow, but greater than for horizontal flows. However, fairly equal pressure drops are achieved at high mass velocities for all orientations. Overall, this study proves that gravity effects on two-phase pressure drop and two-phase heat transfer are dictated mostly by mass velocity and, to a lesser extent, by inlet quality.

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Section: Two-phase Flow and Heat Transfer In Future Space Missionsmentioning

confidence: 99%

Effects of two-phase inlet quality, mass velocity, flow orientation, and heating perimeter on flow boiling in a rectangular channel: Part 1 – Two-phase flow and heat transfer results

Kharangate

O’Neill

Mudawar

2016

International Journal of Heat and Mass Transfer

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“…Surface tension and capillary forces can play a significant role in two-phase systems for space by properly tuning the shape and size of the channel. Chow and Parish 92 , Faghri and Chow 30 Numerical Circular channel Saturated steam P sat = 1 atm T wall = 70, 85 °C Δ T sat-wall = 15–30 K Re G = 1000–50,000 Numerical study to investigate the effect of suction and vapor shear during in-tube condensation of vapor in a microgravity environment Simultaneous suction and vapor shear can effectively drain the condensate to ensure the continuous operation of space condensers. Da Riva and Del Col 31 Numerical Circular 1 mm ID minichannel R134a T sat = 40 °C T wall = 30 °C G = 100, 800 kg m −2 s −1 x = 0.4–1 Steady-state simulations of FWC using VOF method The heat flow rate at G = 100 kg m −2 s −1 is 5% higher in vertical downflow as compared to zero-gravity.…”

Section: Introductionmentioning

confidence: 99%

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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Microgravity Heat Transfer

Sundén¹,

Fu²

2017

Heat Transfer in Aerospace Applications

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Condensation heat transfer in a microgravity environment

Cited by 6 publications

References 2 publications

Effects of two-phase inlet quality, mass velocity, flow orientation, and heating perimeter on flow boiling in a rectangular channel: Part 1 – Two-phase flow and heat transfer results

Effects of two-phase inlet quality, mass velocity, flow orientation, and heating perimeter on flow boiling in a rectangular channel: Part 1 – Two-phase flow and heat transfer results

Condensation heat transfer in microgravity conditions

Microgravity Heat Transfer

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