Abstract 1

An Assessment of Pre-Prototype Engineering Risks

October 22, 2010

The objective was to collect and document the current engineering knowledge with respect to design risks. The risk areas identified the uncertainties inherent in the development of a relatively complex integrated mechanical system. Realizing risks and overcoming problems by design modification is considered a natural part of the development phase. This process has been taken into consideration in formulating predictions of performance, development time, and cost. The risks were reduced to a single table, which included the risk type, the risk level, and the associated cost. Recommendations were given to focus the first verification tests.

Abstract 2

Subsystem Performance Matching – Constrained Predictions

January 11, 2011

The performances of the major subsystems interact to determine the performance of the distiller as a whole. Whether during the design phase or during the verification phase, quantifying the design trade-offs provides the information required to optimize design decisions. To accomplish this, a mathematical model was developed of the overall energy budget. The method used was to constrain the distillate and the evaporator pressure to spec while independently setting the compressor efficiency, CFHX effectiveness, dewar R value, high pressure vent flow, influent temperature, and concentrate flowrate. The results were summarized in a series of performance matching plots.

Abstract 3

An Updated Analysis of the CFHX Using Variable Fluid Properties

January 22, 2011

The counterflow heat exchanger (CFHX) was analyzed in a previous study using constant fluid properties. The objective of this current study was to eliminate the error associated with fluid properties in the CFHX predictions by extending the model to variable fluid properties. The numerical results were compared to an ideal CFHX.

Abstract 4

An Unconstrained Global Distiller Simulation – With Application to CFHX and HP Venting

February 16, 2011

A global distiller simulation was developed. Artificial constraints associated with past models were removed. Subsystem performance characteristics were incorporated using performance curves. Assumptions and sources of error were discussed. The model was applied to the CFHX and HP venting scheme. It was shown that as venting increased, the distillate flowrate increased, the evaporator pressure decreased, and specific energy consumption (W*hr/gal) increased. Performance plots were developed quantifying the results.

Abstract 5

An Analysis of the Dewar – Thermal and Structural

June 9, 2011

The objective of the current study was to generate performance design curves for the dewar. The thermal and structural models of past studies were used as a starting point. The thermal model was extended to account for a non-ideal vacuum. A series of performance based design plots were generated.

Abstract 6

A Transient ECHX Model – With Application to the Sump Plumbing Configuration

August 30, 2011

The objective was to develop a periodically unsteady ECHX model coupled with a sump flow network model. The model was used to evaluate four sump plumbing configurations. The compressor pressure rise was varied to constrain a common evaporation flowrate, and the configurations were evaluated in terms of energy consumption (W*hr/gal) and local concentration levels. The energy consumption correlated to the concentration of the irrigation water via an increase in boiling point. The results show that one of the four variations was determined to be the best with respect to concentration levels and energy consumption.

Abstract 7

A Flow Model of the Irrigation Supply Network – With Application to Pump and Orifice Specifications

September 8, 2011

The objective was to determine the orifice sizes and pump specifications required to control the evaporator film thickness on each evaporator surface. A flow network model of the irrigation supply system was developed. The required pump specs and orifice diameters were determined.