Sankey Trees: Visualization of energy flows

thoughtgreenpepperMechanics

Oct 27, 2013 (3 years and 8 months ago)

63 views

ABSTRACT : World Mining Congress in Montréal, Aug 2013.

Sankey Trees: Visualization of energy flows

Adam Turcotte
a

and Dean Millar
a,b

a

Mining

Innovation Rehabilitation and Applied Research Corporation, Sudbury, Ontario, Canada

b

Bharti School

of Engineering , Laurentian University, Sudbury, Ontario, Canada

Mining operations consume a considerable amount of energy, and while reduced energy consumption is
desirable, it is not always clear how to achieve this goal. Understanding the opportunities

to optimize
energy consumption is crucial, and the key to understanding is visualization. One option is the Sankey
diagram, which has been used for over 100 years to visualize the flow of energy, materials, or cost
through various processes. However, ther
e are drawbacks to this approach that must be addressed.

In a Sankey diagram, each flow is represented by an arrow possessing a width proportional to the
magnitude of the flow it represents.

T
he diagrams show input flows
,

how energy is converted and into
w
hat form, and also output flows. As per the first law of thermodynamics, the total energy output is
equivalent to the total energy input, so any energy that is not transferred to another process is
considered to be wasted. These waste flows are depicted in

Sankey diagrams

and make it
straightforward to associate energy

sources
, sinks and waste flows.

Unfortunately
, Sankey diagrams do not
convey all

information
required to support
practical
decision
making for
redirecting
individual energy flows
.
Based
only
on a Sankey diagram
,

it may become evident
that a significant flow of waste heat is of the appropriate grade (temperature) and volume to meet an
on
-
site heat demand currently being met with paid
-
for, possibly carbon intensive fuel. However without
augmenti
ng the Sankey diagram with 3D spatial, true geometric analysis, the practicalities of the
concept or idea may not be fully appreciated.

Another issue with a Sankey diagram is that the magnitude of the energy flowing between processes
may have temporal fluc
tuation or variability on different timescales (diurnal, seasonal, inter
-
annual).
Currently
,

Sankey diagrams only provide a static picture of energy conversion and consumption, so that,
for example, 4 separate diagrams could have to be prepared for each se
ason.

A new energy flow visualization technique which we have called Sankey Trees has been developed.
Process locations are defined within a 3D model of the site being studied, and the magnitude of the flow
between each pair of processes considered is repl
aced with a time series. Branches of sustained and
diminishing flows are represented through variation of the geometric properties of the branches of th
e

trees. These branches are animated to indicate the direction of flow, and branch joints are used to
in
dicate that a process is transporting one form of energy to multiple processes.