| (The Open Cycle daemons build upon Open Steady daemons.) |
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(Gas Power, Vapor Power and Refrigeration
cycles )
Daemons>Open Cycle> Manual |
| a. Open-Device Cycles: There are a number of important cycles, Brayton Cycle for gas turbines,
Rankine Cycle for steam power plants, and Reverse Rankine and Reverse Brayton cycle
for refrigeration, that are all handled in this branch. The characteristics
of an Open-Device cycle is the back to back arrangement of several open-steady
devices that form a closed loop. However, if only the overall cycle quantities
are of interest a much simpler daemon, Closed
Steady daemon, can be used instead.
Open Cycle daemons are divided into two categories: (i) Power Cycles daemons for the gas and steam power residing on the open.steady. specific. powerCycle page and (ii) Refrigeration Cycle daemons on the open.steady. specific. refriCycle page. As with most other system daemons, the last step before launching a daemon is selecting an appropriate model for the working fluid. The building block of the Open Cycle daemon is the Open Steady daemon (discussed in the Tutorial>Daemons> OpenSteady>Manual chapter) because a cycle is nothing more than a number of open steady devices connected in a closed network. |
| b. The Device Analysis Panel:
The Device Analysis panel
in an Open Cycle daemon is slightly different from those found in a Open Steady daemon. As
shown in Figs.1 and 2 below, the Analysis panel combines MultiflowMixed and MultiflowUnmixed (found
under Open.Steady.Generic branch) devices on a single panel. By using the radio
button an individual device can be turned Mixing , such as an open
feed water heater or a separation chamber, or Non-mixing (Fig. 1), such
as a closed feed water heater or a heat exchanger, making it possible to
analyze complicated cycles.
Although the device allows for two inlets and two exits, any combination can be used by leaving one or more ports at State-Null, which is equivalent to having a port plugged. For more details on these analysis panel, read the discussion on the OpenSteady>Manual page. |
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| Fig. 1: Image of the Cycle panel for the power cycle. |
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c. The Cycle Analysis Panel:
The Cycle Analysis panel for
the power cycle (Fig. 2a) and refrigeration cycle (Fig. 2b) are slightly
different. The Calculate operation determines if the cycle is
complete (by checking all the saved devices) and then calculates all the
cycle variables. After the devices have been calculated, the user does not
have to input any variables in the Cycle panel. d. Parametric Studies: Once an Open Cycle has been set up, it is relatively simple to evaluate the effect of changing one or more variables on the problem. Simply change the independent variable, say the turbine efficiency, to a new value, Calculate and Super-Calculate. The States, Devices and the Cycle are all re-calculated and a solution report and the TEST-codes are generated on the I/O panel. You will find a number of open cycle examples on the Applications page, Slide Show and the Problems . |
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