Design of a Shuttle Air and Water Prefilter for Reduced Gravity Operation

Ungar, Eugene K.; Ouellette, Fred A.

doi:10.4271/921161

Cited by 6 publications

(6 citation statements)

References 1 publication

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“…were found to be the root cause of the issues. The space shuttle humidity separator (a condensing heat exchanger) experienced issues of liquid droplet carryover resulting from debris clogging pitot tubes [18]. A prefilter for the humidity separator was developed to alleviate the problem.…”

Section: Improper Design Of Hydraulic Diameters Between Condenser Andmentioning

confidence: 99%

Non-Contact Distillation

Rasheed¹

2000

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Leidenfrost phenomenon has been studied extensively for its role in applications ranging from nuclear reactor cooling, to metals manufacturing, combustion, and other fields. Herein, Leidenfrost phenomenon is pursued towards non-contact distillation processes with hopes of reducing or even eliminating contaminant fouling. In particular, the microgravity environment of a drop tower is exploited to demonstrate the facility with which droplets achieve and sustain the Leidenfrost state. Dynamic Leidenfrost impacts in microgravity are presented for impacts on hydrophilic and superhydrophobic planar substrates, macro-pillar arrays, confined passageways, and others. Nearly ideal elastic non-contact impacts and droplet oscillation modes are observed. Dynamic Leidenfrost impacts in microgravity for uniquely low velocity impacts are investigated analytically and experimentally. We find Leidenfrost vapor layer thicknesses on the order of millimeters for a 1 mL droplet of water with impact velocity 1 mm/s -a 100-fold increase relative to terrestrial vapor layers. Such results are supported by preliminary experimental observations. Further droplet distillation experiments are conducted in a terrestrial gravity environment using a heated tilted rotating hemi-circular track. Droplet evaporation rates and lifetimes are tabulated for the sliding/rolling drops at varying angular velocities and tilt angles. An analytical model for the evaporation rate of a rolling Leidenfrost droplet is developed and compared to the experimental results with good agreement. The empirical and analytical results serve as key design tools for sizing a prototypical non-contact distillation system for terrestrial desalinization or spacecraft water recycling.ii

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Section: Improper Design Of Hydraulic Diameters Between Condenser Andmentioning

confidence: 99%

Non-Contact Distillation

Rasheed¹

2000

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“…The two‐phase mixture is separated by the use of a rotary separation device. A description of the above system may be found in Eckart 1 and Ungar and Ouellette 2 …”

Section: Introductionmentioning

confidence: 99%

“…A description of the above system may be found in Eckart 1 and Ungar and Ouellette. 2 Hasan et al 3 have proposed an alternative design for the condensing heat exchanger using a porous medium. The advantage of this system is that the heat exchanger would remove water from the air stream while simultaneously separating the gas and liquid phases.…”

mentioning

confidence: 99%

Analysis of Heat and Mass Transfer during Condensation over a Porous Substrate

Balasubramaniam

Nayagam

Hasan

et al. 2006

Annals of the New York Academy of Sciences

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Condensing heat exchangers are important in many space applications for thermal and humidity control systems. The International Space Station uses a cooled fin surface to condense moisture from humid air that is blown over it. The condensate and the air are "slurped" into a system that separates air and water by centrifugal forces. The use of a cooled porous substrate is an attractive alternative to the fin where condensation and liquid/gas separation can be achieved in a single step. We analyze the heat and mass transfer during condensation of moisture from flowing air over such a cooled, flat, porous substrate. A fully developed regime is investigated for coupled mass, momentum and energy transport in the gas phase, and momentum and energy transport in the condensate layer on the porous substrate and through the porous medium.

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“…The capillary pores of a porous media, when hydrophilic, develops capillary suction pressure P c given by θ σ cos 2 r P c = (3) where, σ is the surface tension of the liquid to air and θ is the contact angle of water with the porous solid. The contact angle depends on the hydrophilic characteristics of the pore.…”

Section: Condensate Retention In the Porous Substrate -mentioning

confidence: 99%

“…A brief description of this system can also be found in Ref. [3]. A more efficient design of a CHX would condense and remove the water directly from the air stream without the need for an additional water separator downstream.…”

Section: Introductionmentioning

confidence: 99%