A thermodynamic cycle is a collection of components
which either takes in heat and produces energy, or takes in work and produces
some transfer of heat, perhaps as a refrigerator or as a heat pump. Examples
of thermodynamic cycles include power plants, refrigerators, propulsion
plants, and engines. CyclePad helps you:
Specify the structure of your design , in terms
of the parts of the cycle and how they are connected together.
Analyze your design, by figuring out the consequences
of assumptions you make about it. Such assumptions include numerical values,
e.g. operating temperatures and pressures, and modeling assumptions, e.g.,
whether or not to consider a turbine as isentropic.
Perform sensitivity analyses to understand how
different choices of your design contribute to its performance. For example,
CyclePad can figure out how the efficiency of a system changes as a function
of other parameters, such as a turbine inlet temperature.
CyclePad performs steady-state analyses of both
open and closed cycles. In an open-cycle, it is the components that are
open to the passage of mass through them, while in a closed cycle different
processes take place within a single component. Gas turbines are therefore
open cycles, and piston engines are closed cycles. Note that a closed-loop
steam cycle containing a boiler, turbine, condenser, and pump is still
considered to be an open cycle.
Steady-state analyses provide the kind of initial
guidance needed in conceptual design, because in the conceptual design
of thermodynamic cycles the important questions concern the operating conditions
and estimates of efficiency and cooling/heating/power produced by the cycle.
(Later stages of design concern issues such as the response of the system
to transients, developing procedures for safe startup and shutdown, and
ensuring that the system is easy to monitor and maintain).
CyclePad works in two phases, build mode and analyze
mode. In the first phase (build), you use a graphical editor to place components
and connect them with stuffs. Such a structure might look like this:
(To read more about how CyclePad construes this cycle,
click here)
While you can always quit CyclePad at any time, you
can only proceed to the next phase (analysis) when CyclePad is satisfied
that your design is fully laid out, that is, when every component is connected
via some other component via stuffs, and every stuff has been used as both
an input and an output for components in the design. Once your design is
laid out, the real fun begins--the analysis phase
In the analysis phase, you specify:
What working fluid you are using
What modeling assumptions you wish to make in
analyzing your design.
Numerical values for the properties of components
and stuffs
As soon as you give CyclePad some information,
it draws as many conclusions as it can about your design, based on everything
you have told it so far. When you specify a working fluid, for instance,
it knows whether to use property tables or an ideal gas approximation.
When you specify numerical values, CyclePad sees if it can then calculate
other numerical values. It displays the results of its calculations, and
you are free to inquire about how values were derived and how one might
proceed at any time, using a hypertext query system.
As you provide more information, CyclePad deduces
more about the physical system. Eventually, you may have filled in all
of the relevant information about the cycle, so that you have numerical
values for properties such as the coefficient of performance (if
you are designing a refrigerator), the thermal efficiency (if you
are designing a heat engine), or other properties of interest such as the
total amount of work produced or consumed by the cycle. How far you go
is up to you. At any time you can save your design to a file so that you
can continue working on it later, and generate reports describing the state
of your analysis of the design.
CyclePad also supports sensitivity analyses. For
instance, suppose you wanted to understand how the thermal efficiency of
the cycle varies as a function of the efficiency of a compressor or some
other component. Such analyses are quite tedious to do by hand, but CyclePad
makes them quite easy and will generate such information for you in graphical
form.