Graduation Year

2010

Document Type

Thesis

Degree

M.S.M.E.

Degree Granting Department

Mechanical Engineering

Major Professor

Delcie Durham, Ph.D.

Committee Member

Nathan Gallant, Ph.D.

Committee Member

Nathan Crane, Ph.D.

Keywords

lca, sustainability, dishwasher, cell, biology, analogy

Abstract

An ambitious and novel approach to engineering design and sustainability has been taken to explore the potential of drawing parallels between mechanical and biological systems for the possible development of sustainable engineering design metrics using a thermodynamic model. This approach looks to biology. Natural selection has given biological beings and processes high exergetic efficiencies, even while being only 30-40% energy efficient on the cell level. This energy inefficiency, resulting in a release of heat, can then be used to aid in driving other biochemical processes. The Gibbs free energy becomes more negative proportionally with an increase in temperature, resulting in a more favorable reaction. This effective use of waste heat from cell processes actually results in an increase in overall efficiency of an organism, around 50-60%.

As in all systems the boundary defines the analysis. An exergy analysis was conducted on a residential dishwashing machine in several boundary configurations in order to develop an appropriate model. Exergy serves as a tool for identifying and quantifying losses in the system so that future works can be aimed at reducing irreversibilities. This model was then compared to data previously available regarding exergy within various processes of a biological cell. In future work, it is this comparison, which can be used to develop metrics for use early in the design stage to more efficiently use available and sustainable resources. There is a large difference between the two systems, with the dishwasher only having an effectiveness of 1.3%.

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