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Freeze-drying for water recovery fro...

Litwiller, Eric John.

Freeze-drying for water recovery from solid waste.

紀錄類型:	書目-電子資源 : Monograph/item
正題名/作者:	Freeze-drying for water recovery from solid waste.
作者:	Litwiller, Eric John.
面頁冊數:	94 p.
附註:	Adviser: Martin Reinhard.
附註:	Source: Dissertation Abstracts International, Volume: 66-04, Section: B, page: 2250.
Contained By:	Dissertation Abstracts International66-04B.
標題:	Engineering, Environmental.
電子資源:	http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=3171647
ISBN:	0542083760

Freeze-drying for water recovery from solid waste.
Litwiller, Eric John.

Freeze-drying for water recovery from solid waste. - 94 p.

Adviser: Martin Reinhard.

Thesis (Ph.D.)--Stanford University, 2005.

A new type of freeze-dryer was developed that uses thermoelectric heat pumps to recycle the enthalpies of fusion and sublimation associated with freezing and drying. A heat and mass transfer model was developed and validated to predict drying rate and power consumption. To validate the model, a prototype was constructed and drying experiments were performed using skim milk as a model waste. The previous research into the behavior of the frozen water within a sample during drying has produced two commonly used models that apply under different conditions: uniformly retreating ice front, and shrinking core. These models were evaluated using thermoelectric heat pump power data. Results showed that, for this material and geometry, a uniformly retreating ice front model applies until samples reach 35% dryness, after which a shrinking core model applies.

ISBN: 0542083760Subjects--Topical Terms:

212478
Engineering, Environmental.

Freeze-drying for water recovery from solid waste.
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520 # $a A new type of freeze-dryer was developed that uses thermoelectric heat pumps to recycle the enthalpies of fusion and sublimation associated with freezing and drying. A heat and mass transfer model was developed and validated to predict drying rate and power consumption. To validate the model, a prototype was constructed and drying experiments were performed using skim milk as a model waste. The previous research into the behavior of the frozen water within a sample during drying has produced two commonly used models that apply under different conditions: uniformly retreating ice front, and shrinking core. These models were evaluated using thermoelectric heat pump power data. Results showed that, for this material and geometry, a uniformly retreating ice front model applies until samples reach 35% dryness, after which a shrinking core model applies.
520 # $a Freeze-drying produces nearly complete separation of water from solids and non-volatile solutes. The process can be used to treat concentrated wastes including brines, sludges, and wet solid waste. Recovering the water from these wastes is particularly beneficial on human space missions, where resource recycling reduces spacecraft mass. This work addresses questions related to the energy efficiency of the freeze-drying process, and evaluates process improvements aimed at adapting the process to solid waste treatment.
520 # $a The shrinking core is associated with a layer of dried sample material separating the heat source from the frozen water remaining in the sample, which increases resistance to heat transfer within the sample. In the context of a freeze-dryer that recycles the heat of sublimation, this resistance reduces drying rate and energy efficiency. Experiments in which samples were compressed against a porous plate during drying, improving the heat transfer properties of dried layer, showed that this technique decreases both drying time and energy consumed per mass of water recovered by approximately 50%.
520 # $a To demonstrate the suitability of the thermoelectric freeze-dryer concept to the task of water recovery on human space missions, a pilot unit was designed and built. Experiments with this prototype show that high energy efficiency can be achieved in a thermoelectric freeze-dryer that meets the practical requirements associated with spacecraft hardware.
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