A thermodynamic systemThermodynamic_systems_and_properties a collection of components which either takes in heat from the environment and produces energy, or takes in work and produces some transfer of heat from one region of the environment to another, perhaps as a refrigerator or as a heat pump.  Examples of thermodynamic systemsDiagrams_of_Library_Examples_of_Cycles include power plants, refrigerators, propulsion plants, and engines.  CyclePad helps you:

•        Specify the structure of your designBuild_Mode , in terms of the physical parts and processes of the cycle and how they are connected to one another.

•        Analyze your designAnalyze_Mode, by making assumptions about it and figuring out the consequences of those assumptions.  Such assumptions include numerical values, e.g. operating temperatures and pressures, and modeling assumptionsModeling_Assumptions, e.g., whether or not to consider a turbine as isentropic.

•        Plot the T-s and P-v diagrams of a cycle to understand where the working fluid is in its property space (e.g. how hot is it, how high is its pressure, et cetera).

•        Perform sensitivity analysesInvestigating_a_Cycle_via_the_Sensitivity_Analysis_Tool 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 parametersParameters, such as a turbine inlet temperature.

CyclePad performs steady-state analyses of both open and closed cycles.  In an open cycle, the working fluid passes through various "open" components, while in a closed cycle different processes act upon a closed volume or mass of working fluid (sometimes called the control volume).  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 with steady-state and equilibrium analysis; it does not deal with transient analysis.)

CyclePad works in two phases, build modeBuild_Mode and analyze modeAnalyze_Mode.  In the build mode, you use a graphical editor to place componentscomponents and connect them with stuffsstuff.  Such a structure might look like this:

{bml bm0.BMP}

(To read more about how CyclePad construes this cycle, click hereHow_CyclePad_Views_Thermodynamic_Cycles)

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 phaseAnalyze_Mode

In the analysis phase, you specify:

•        What working fluidsubstances you are using

•        What modeling assumptionsModeling_Assumptions you wish to make in analyzing your design.

•        Numerical values for the propertiesParameters 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 approximationIdeal_Gas_Law.  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 systemInvestigating_a_Cycle_via_the_Explanation_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 performancecop_R (if you are designing a refrigerator), the thermal efficiencyeta_thermal (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 analysesInvestigating_a_Cycle_via_the_Sensitivity_Analysis_Tool.  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.


Created with the Personal Edition of HelpNDoc: Easily create EBooks