Modes & Component Types

Modes & Component Types
THERMOFLEX THERMOFLEX Basics II Modes & Component Types © Thermoflow, Inc., 2011

© Copyright Thermoflow, Inc., 2011
THERMOFLEX Topics 1. Design & Off-design Modes 2. THERMOFLEX & PEACE components 3. Thermodynamic Design (TD) mode for both types 4. Engineering Design (ED) mode for PEACE components 5. Off-design (OD) mode for both types 6. Switching modes, global or local 7. Defined-performance mode for THERMOFLEX components September 18 © Copyright Thermoflow, Inc., 2011

1-1. Distinction between Design and Off-design Modes
THERMOFLEX 1-1. Distinction between Design and Off-design Modes Design mode computations determine the size of a component, based on its assumed thermodynamic duty Off-design (OD) mode computations determine the thermodynamic performance of a component based on its size Example 1: If a pipe is assumed to have a smaller pressure drop in design mode, the design computation will size it to be larger. In off-design mode, its pressure drop will be computed, dependent on flow rate and conditions. A larger pipe will have a smaller pressure drop at any flow rate. Example 2: If a heat exchanger is assumed to be more effective in design mode, the design computation will size it with a larger heat transfer surface area. In off-design mode, its effectiveness will be computed, dependent on flow rate and conditions. The larger its surface area, the greater its effectiveness. Size is “virtual” for THERMOFLEX components and “physical” for PEACE components. September 18 © Copyright Thermoflow, Inc., 2011

Modes & Component Types Tutorial - Topic 2
THERMOFLEX Modes & Component Types Tutorial - Topic 2 1. Design & Off-design Modes 2. THERMOFLEX & PEACE components 3. Thermodynamic Design (TD) mode for both types 4. Engineering Design (ED) mode for PEACE components 5. Off-design (OD) mode for both types 6. Switching modes, global or local 7. Defined-performance mode for THERMOFLEX components September 18 © Copyright Thermoflow, Inc., 2011

2-1. Distinction between PEACE & THERMOFLEX component types
PEACE components are only usable by licensees of PEACE Each PEACE component has an equivalent, but simpler, THERMOFLEX component PEACE components are distinguished on the Icon Selector by their green borders PEACE components are based upon the detailed, physical engineering models of GT PRO/GT MASTER, which are more accurate at off-design PEACE components provide cost estimates based on engineering specs PEACE Components THERMOFLEX Components September 18 © Copyright Thermoflow, Inc., 2011

2-2. Difference between THERMOFLEX and PEACE components, e.g. pipe
Size is “virtual” for THERMOFLEX components and “physical” for PEACE components. For a THERMOFLEX pipe: P = R m2 v R = Resistance coefficient m = mass flow rate v = specific volume R is the virtual sizing descriptor of the pipe. It is found from the flow conditions and the assumed P in the design-mode calculation, and is used at off-design to compute P as a function of flow conditions. For a PEACE pipe: P = f (Le/D) 1/2  V2 f = friction factor, depends on Reynolds Number and wall roughness Le = pipe equivalent length, after adjusting for fittings D = pipe internal diameter  = fluid mean density V = fluid mean velocity Physical sizing descriptors are pipe nominal diameter, schedule (or wall thickness), material, roughness, length, number of fittings of each type. In design mode, diameter is found based on pressure drop and other physical assumptions. At off-design, pressure drop is computed from the dimensions. September 18 © Copyright Thermoflow, Inc., 2011

THERMOFLEX 2-3. Difference between THERMOFLEX & PEACE components, e.g. Heat Exchanger Size is “virtual” for THERMOFLEX components and “physical” for PEACE components. Q= (UA) TLM = TLM/ Rt For a THERMOFLEX HX: Rt = Total Thermal Resistance = (UA)-1 = (hAAA) -1 + Rw + (hBAB) -1 The virtual sizing parameter is heat transfer ability at the design-point, (UA)D. This is found from the design-point heat balance solution. The method of Thermal Resistance Scaling allows one to scale heat transfer coefficients on the A-side and B-side of the heat exchanger in proportion to the changing A-side and B-side mass flow rates: hA,OD =hA,D (mA,OD / mA,D)x hB,OD =hB,D (mB,OD / mB,D)y Rw,OD = Rw,D Thus, heat transfer ability at off-design, (UA)OD.is computed from that at the design-point, (UA)D. For a PEACE HX: A complete physical design of the heat exchanger is performed, including number of tubes, their diameter and wall thickness, material, length, and fin geometry, dimensions and materials, if applicable. This leads to a detailed, accurate calculation of heat transfer coefficients at off-design, without resorting to the approximations inherent in the method of Thermal Resistance Scaling. September 18 © Copyright Thermoflow, Inc., 2011

2-4. PEACE components have a two-step design process
THERMOFLEX 2-4. PEACE components have a two-step design process To help the user, the program has logic that automatically selects physical design criteria for PEACE components. Examples of these design criteria are: (a) A high temperature steam pipe requires a material such as Cr-Mo steel, whereas a steam pipe at modest temperature is generally made from carbon steel. (b) A high-flow, low-head pump is typically of the “vertical turbine” type, whereas a high-head, low-flow pump is typically of the “multi-stage centrifugal” type. Such criteria cannot be applied to initialise the inputs, unless the approximate thermodynamic duty has already been established. Thus, the design process for PEACE components is in two phases: Thermodynamic Design (TD) Mode has no hardware-specific inputs, and just finds the heat and mass balance solution. Engineering Design (ED) Mode has hardware-specific inputs, to find component physical design. The inputs are automatically initialised by the program, based on the thermodynamic duty. September 18 © Copyright Thermoflow, Inc., 2011

2-5. Modes for PEACE & THERMOFLEX components
September 18 © Copyright Thermoflow, Inc., 2011

FILE: PPTutorial.tfx 3-1. Load the file “PPTutorial.tfx” after it has been computed in TD mode THERMOFLEX Review Economiser [1] inputs, by right-clicking on the component and selecting View Inputs…, then return to Edit Drawing mode to introduce a PEACE economiser in its place. September 18 © Copyright Thermoflow, Inc., 2011

3-2. Modify the model, replacing TFX Economiser [1] by an equivalent PEACE Economiser THERMOFLEX In TD mode, after you Uncheck Drawing, delete THERMOFLEX Economiser [1] and insert in its place a PEACE Economiser. September 18 © Copyright Thermoflow, Inc., 2011

3-3. Edit TD inputs for new PEACE economiser
THERMOFLEX 3-3. Edit TD inputs for new PEACE economiser Edit the TD inputs of the new PEACE economiser, to make them the same as those of the original THERMOFLEX economiser. Check Inputs and Compute. Use 2% (same as TFX economiser) Use 0.8” (about the same as in TFX economiser) Use 1% (same as TFX economiser) Use 8 °F subcooling (same as TFX economiser) September 18 © Copyright Thermoflow, Inc., 2011

3-4. View TD mode result with PEACE Economiser [1]
FILE: PPTutorial_1.tfx THERMOFLEX 3-4. View TD mode result with PEACE Economiser [1] The results in TD mode are identical (to within convergence tolerance), whether a PEACE or a THERMOFLEX economiser is used, as long as their input assumptions are identical. September 18 © Copyright Thermoflow, Inc., 2011

4-1. Switching to ED mode via the global switch
THERMOFLEX 4-1. Switching to ED mode via the global switch Examine the available modes. Because the file now contains PEACE components, the program does not allow going to Off-design (OD) mode directly after TD computation. We have to first continue with the design in ED mode, then compute to engineer the PEACE components, before we can access OD mode. Select Engineering Design (ED) mode. Hint: Selecting ED mode from the main graphic screen, whether in output or input mode, will (a) switch all PEACE components that had been in TD mode to their ED mode, with all defaults; (b) revert to the input screen; and (c) set THERMOFLEX components to their TD mode (their only design mode). September 18 © Copyright Thermoflow, Inc., 2011

4-2. Main Input Screen in ED mode
FILE: PPTutorial_1ED.tfx THERMOFLEX 4-2. Main Input Screen in ED mode ED mode is non-existent (or concurrent with TD mode) for THERMOFLEX components, but PEACE components have ED inputs to define their physical design criteria. Let’s double-click on our PEACE Economiser [1] to open its ED menus and review or edit its hardware design inputs. September 18 © Copyright Thermoflow, Inc., 2011

4-3. ED mode for PEACE Economiser: ED Main Inputs
FILE: PPTutorial_1ED.tfx THERMOFLEX 4-3. ED mode for PEACE Economiser: ED Main Inputs Gas-side mass flux will set gas duct cross-section. If you are building a HRSG model with a uniform cross-section, make sure all sections in series have the same mass flux. Water-side mass flux will decide how many passes the tube bundle should have. User-defined Hardware Design allows you to access the Hardware tab and dictate its content. With Automatic Hardware Design, the Hardware tab is inaccessible, since its content will be determined by the program during computation. The design pressure and temperature are used for the automatic selection of tube material and wall thickness. This tab defines the main design assumptions September 18 © Copyright Thermoflow, Inc., 2011

4-4. ED mode for PEACE Economiser: ED Hardware
FILE: PPTutorial_1.tfx THERMOFLEX 4-4. ED mode for PEACE Economiser: ED Hardware This tab, accessible only with User-defined hardware design, lets you set materials, geometry, tube diameter and thickness, etc. September 18 © Copyright Thermoflow, Inc., 2011

4-5. ED mode for PEACE Economiser: ED Other Inputs
FILE: PPTutorial_1.tfx THERMOFLEX 4-5. ED mode for PEACE Economiser: ED Other Inputs This tab lets you change fouling factors and other miscellaneous inputs that will affect the geometry and thermodynamic performance of the component. September 18 © Copyright Thermoflow, Inc., 2011

4-6. ED mode for PEACE Economiser: TD Main Inputs
FILE: PPTutorial_1.tfx THERMOFLEX 4-6. ED mode for PEACE Economiser: TD Main Inputs This tab lets you change your TD assumptions, except for the pressure drops, which are assumed in TD mode but set by the physical hardware design in ED mode. September 18 © Copyright Thermoflow, Inc., 2011

4-7. Compute the example in ED mode
FILE: PPTutorial_1ED.tfx THERMOFLEX 4-7. Compute the example in ED mode After ED mode computation, you are likely to notice a change in performance, in this case output changes from 28,148 kW to 28,165 kW. The difference arises from the fact that the economiser pressure drops, which were assumed in TD mode, are now computed from the physical hardware design in ED mode. Gas-side P, assumed as 0.8” H2O, turned out to be 0.315”, which slightly increases GT output. Water-side P, assumed as 2% of 25 psia (0.5 psi), turned out to be 1.34 psi. September 18 © Copyright Thermoflow, Inc., 2011

4-8. PEACE Economiser ED Mode output: Heat Balance
FILE: PPTutorial_1ED.tfx THERMOFLEX 4-8. PEACE Economiser ED Mode output: Heat Balance This output provides a succinct tabulation of the current thermodynamic solution. September 18 © Copyright Thermoflow, Inc., 2011

4-9. PEACE Economiser ED Mode output: Specification
FILE: PPTutorial_1ED.tfx 4-9. PEACE Economiser ED Mode output: Specification THERMOFLEX This output provides a description of the overall dimensions and weights of the component. September 18 © Copyright Thermoflow, Inc., 2011

4-10. PEACE Economiser ED Mode output: Heat Exchanger Hardware
THERMOFLEX This output provides a description of the tube bundle, showing its materials and all key dimensions. September 18 © Copyright Thermoflow, Inc., 2011

4-11. PEACE Economiser ED Mode output: HX Heat Transfer
THERMOFLEX This output lists the detailed results of the heat transfer calculations for the current operating conditions. September 18 © Copyright Thermoflow, Inc., 2011

4-12. PEACE Economiser ED Mode output: Hardware Graphics
THERMOFLEX This output provides a graphic sketch of the tube bundle layout, transverse and longitudinal cross sections of the economiser’s tubes, and a summary of key outputs. September 18 © Copyright Thermoflow, Inc., 2011

4-13. PEACE Economiser ED Mode output: Tube Bundle Overview
THERMOFLEX The Tube Bundle Overview provides a graphic sketch of the tube bundle layout. In our example, each full tube row has a single pass. The automatic design scheme, with all defaults, created this arrangement to maintain an adequate water-side velocity. September 18 © Copyright Thermoflow, Inc., 2011

4-14. PEACE Economiser ED Mode output: TQ Diagram
THERMOFLEX This output displays the economiser’s TQ Diagram under the current operating conditions. September 18 © Copyright Thermoflow, Inc., 2011

5-1. Switching “PPTutorial” to off-design mode via the global switch
FILE: PPTutorial.tfx 5-1. Switching “PPTutorial” to off-design mode via the global switch THERMOFLEX Select Off-design (OD) mode Hints: 1) Because this model has no PEACE components, we can switch from TD mode directly to OD mode. 2) Global mode selection is made from the main graphic screen (input or output). Selecting global off-design will (a) switch all components that had been in design mode to their default off-design mode; and (b) revert to the input screen. September 18 © Copyright Thermoflow, Inc., 2011

5-2. Main Input screen in OD mode
FILE: PPTutorial_OD.tfx THERMOFLEX 5-2. Main Input screen in OD mode Components such as Process, Sources, and Sinks, have no distinction between design and off-design. Components such as pumps or heat exchangers do. Let’s double-click on our Economiser [1] to open its menu September 18 © Copyright Thermoflow, Inc., 2011

5-3. Main OD inputs for THERMOFLEX Economiser [1]
FILE: PPTutorial_OD.tfx 5-3. Main OD inputs for THERMOFLEX Economiser [1] THERMOFLEX The Economiser Control Type pulldown allows you to specify how the economiser will react to changing flue gas and feedwater conditions. Heat loss can still be specified in OD mode, but all other TD inputs are unavailable. September 18 © Copyright Thermoflow, Inc., 2011

5-4. Other OD inputs for THERMOFLEX Economiser [1]
FILE: PPTutorial_OD.tfx 5-4. Other OD inputs for THERMOFLEX Economiser [1] THERMOFLEX TD inputs are unavailable The OD modelling parameters, introduced by default, are available for editing. The virtual sizing descriptors, established by the design calculations, are available for editing. You may make the economiser “larger in surface area”, by increasing its design-point UA (Item 4), or you may “increase its water-side flow cross-section”, by reducing its resistance coefficient (Item 19). The virtual sizing descriptors for heat transfer and pressure drop are uncoupled. They are condensed descriptors, which may be derived from a known physical hardware design, but are insufficient to define the physical hardware in and of themselves. September 18 © Copyright Thermoflow, Inc., 2011

FILE: PPTutorial_1ED.tfx
5-4. Switching “PPTutorial_1ED” to off-design mode via the global switch THERMOFLEX Select Off-design (OD) mode September 18 © Copyright Thermoflow, Inc., 2011

5-5. OD mode Main Inputs for PEACE Economiser [1]
THERMOFLEX 5-5. OD mode Main Inputs for PEACE Economiser [1] The Main Inputs tab has the control inputs intrinsic to the Economiser component. These include water pressurization, water recirculation, water bypass, and/or gas bypass to control various parameters. Please explore these inputs by selecting various control options and reviewing their corresponding inputs, which will become enabled as appropriate. September 18 © Copyright Thermoflow, Inc., 2011

5-6. OD mode Hardware inputs for PEACE Economiser [1]
THERMOFLEX 5-6. OD mode Hardware inputs for PEACE Economiser [1] The Hardware tab allows you to alter the design created by ED mode. You may explicitly edit the dimensions, geometry, or materials of the Economiser component. Please explore this screen by editing the geometric configuration variables and dimensions, and observe how the diagram adjusts to reflect your data. The physical sizing descriptors provide a comprehensive model of the hardware, enabling accurate off-design calculations, as well as size, weight, cost and labour estimates. These should be contrasted with the virtual sizing descriptors for the equivalent THERMOFLEX economiser. September 18 © Copyright Thermoflow, Inc., 2011

5-7. OD mode Other Inputs for PEACE Economiser [1]
THERMOFLEX 5-7. OD mode Other Inputs for PEACE Economiser [1] As in ED mode, the Other Inputs tab allows you to edit miscellaneous parameters that affect the geometry and thermodynamic performance of the component. September 18 © Copyright Thermoflow, Inc., 2011

FILE: PPTutorial_1OD.tfx
THERMOFLEX 5-9. OD mode outputs OD Mode outputs for PEACE components are essentially identical to those for ED mode. If any design parameter is changed in the OD mode inputs, the effect of that change will be reflected in both the performance and the cost estimate outputs when the OD mode computation is run. September 18 © Copyright Thermoflow, Inc., 2011

THERMOFLEX 5-10. Off-design performance differences between THERMOFLEX and PEACE components In TD mode, PEACE components should yield identical results to equivalent THERMOFLEX components (to within convergence tolerance, and assuming identical inputs). In ED mode, some differences from TD mode, usually minor, may arise with PEACE components. This is because many PEACE components, such as heat exchangers and pipes, have their pressure drops computed based upon their physical design, whereas equivalent THERMOFLEX components have their pressure drops assumed by the user. If the user enters the pressure drops computed by PEACE in ED mode into the equivalent THERMOFLEX components in their design mode, results would be identical (to within convergence tolerance). In OD mode, the physical details of the PEACE components allow more accurate off-design calculations. Thus, even if the design-point heat balances match, some differences, usually minor, may arise between PEACE and THERMOFLEX components. To explore these differences, we construct a HRSG model out of PEACE components, and compare its part-load behaviour with that of an equivalent HRSG constructed out of THERMOFLEX components. September 18 © Copyright Thermoflow, Inc., 2011

FILE: PPTutorial_PCE.tfx
THERMOFLEX 5-11. Construct a PEACE HRSG equivalent to the THERMOFLEX HRSG in “PPTutorial” Replace all HRSG components and feedpumps in “PPTutorial.tfx” with equivalent PEACE components (with the same TD inputs), compute in TD mode then in ED mode with all defaults. The heat balance results are almost identical in TD mode (28,146 kW vs. 28,148 kW), as expected, and are very close after the ED mode computation (28,180 kW vs. 28,148 kW). September 18 © Copyright Thermoflow, Inc., 2011

5-12. Switch to OD mode and run
FILE: PPTutorial_PCE_OD.tfx THERMOFLEX 5-12. Switch to OD mode and run Switch to OD mode then run the PEACE HRSG. Results should be similar to those obtained with ED mode. September 18 © Copyright Thermoflow, Inc., 2011

5-13. Run the PEACE HRSG across a range of GT loads
THERMOFLEX 5-13. Run the PEACE HRSG across a range of GT loads Return to Edit Inputs mode and define a 5-run classic macro (Define > Classic Macro Inputs), varying GT load from 60% to 100%. Check inputs and compute. Messages advising of a steaming economiser (acceptable within limits), as well as suggesting the need for a larger pump (a secondary detail in this example) have been ignored for brevity. September 18 © Copyright Thermoflow, Inc., 2011

5-14. Create the macro output table and export it to Excel
FILE: PPTutorial_PCE_OD_m1.tfx 5-14. Create the macro output table and export it to Excel THERMOFLEX Define a classic macro output table (Define > Classic Macro Outputs), showing process mass flow rate, process temperature, stack temperature, and overall plant performance parameters. Copy this table from the Text output view and paste it in Excel. September 18 © Copyright Thermoflow, Inc., 2011

FILE: PPTutorial_OD_m1.tfx
FILE: PPTutorial.xls THERMOFLEX 5-15. Construct a similar macro for the THERMOFLEX HRSG and compare in Excel Starting from “PPTutorial_OD”, which is built solely from THERMOFLEX components, create a similar macro. Copy its output table to the same Excel workbook. Now you can compare the results with both types of components. They are very close in this example, but greater differences may arise in other cases, particularly with supplementary firing. September 18 © Copyright Thermoflow, Inc., 2011

5-16. Compare process flow rates with both component types
FILE: PPTutorial.xls THERMOFLEX 5-16. Compare process flow rates with both component types September 18 © Copyright Thermoflow, Inc., 2011

5-17. Compare stack temperatures with both component types
FILE: PPTutorial.xls THERMOFLEX 5-17. Compare stack temperatures with both component types September 18 © Copyright Thermoflow, Inc., 2011

FILE: PPTutorial_PCE_OD.tfx
6-1. Suppose you wish to redesign the PEACE Integral D/A component only THERMOFLEX Global Mode, set at the main input or output graphic screen, applies to all components. Local Mode, set from within a component’s menu, applies only to that particular component. Double click on the PEACE Integral D/A to open its menu. Set it to ED Mode to redesign it, whilst all other components are left in their OD mode, to retain their current designs. September 18 © Copyright Thermoflow, Inc., 2011

6-2. Redesign changes the current hardware
THERMOFLEX 6-2. Redesign changes the current hardware As the message indicates, reverting to ED mode for the Integral D/A will result in its re-design. Thus, if you had explicitly edited any of its hardware parameters in OD mode, your edits may be lost and replaced by the new design if these same parameters are redefined or recomputed in ED mode. September 18 © Copyright Thermoflow, Inc., 2011

6-3. Dictate bare tubes for the Integral D/A
THERMOFLEX 6-3. Dictate bare tubes for the Integral D/A Set Hardware Design to User-defined (standard fin geometry) then open the Hardware tab Select Bare Tubes and set their Transverse Pitch to 3” September 18 © Copyright Thermoflow, Inc., 2011

6-4. Compute to redesign the PEACE Integral D/A with the new inputs
THERMOFLEX When you close the Integral D/A menu, you will notice that the Global Switch reports that we are in Mixed ED+OD mode. This is because the D/A is now in ED mode while the other components have remained in OD mode. Check Inputs and Compute to redesign the DA with the bare tubes and geometry we just dictated. The other components will not be redesigned. September 18 © Copyright Thermoflow, Inc., 2011

6-5. View outputs with redesigned PEACE Integral D/A
THERMOFLEX 6-5. View outputs with redesigned PEACE Integral D/A When you compute, the Global Switch will show Mixed ED+OD on the main output screen, and when you open the Integral D/A’s component output, you will see that it is still in ED Mode. You may review its PEACE outputs and ascertain whether the new design is satisfactory. September 18 © Copyright Thermoflow, Inc., 2011

THERMOFLEX 6-6. You may see a component’s current mode by placing the mouse pointer on it When the pointer is moved to any component, a tool-tip will show its current mode September 18 © Copyright Thermoflow, Inc., 2011

6-7. You may see/change the current mode for each component by selecting Component Modes… under the Edit menu THERMOFLEX If you highlight a component, you can change its mode using the pull-down list at the top of this window September 18 © Copyright Thermoflow, Inc., 2011

6-8. Set the PEACE Integral D/A to OD Mode
THERMOFLEX 6-8. Set the PEACE Integral D/A to OD Mode If you are satisfied with the new design of the Integral D/A, you must set it back to OD Mode via its own Local switch, to freeze it, before you compute your off-design runs. Caution: If you leave it in ED Mode and change system parameters and compute, it will be redesigned all over again! September 18 © Copyright Thermoflow, Inc., 2011

7-1. “Defined Performance” mode allows TD inputs to be imposed….
THERMOFLEX 7-1. “Defined Performance” mode allows TD inputs to be imposed…. This mode is available only for THERMOFLEX components which have an off-design mode. Defined-performance inputs and calculations are identical to those in TD Mode, but the calculation results do not overwrite any of the virtual sizing parameters or off-design inputs extant prior to the calculation. September 18 © Copyright Thermoflow, Inc., 2011

7-2. …. whilst retaining the component’s off-design inputs, which will not be overwritten as with a TD mode calculation. THERMOFLEX The virtual sizing descriptors will retain their current values Any OD modelling parameters will also retain their current values Hint: Defined Performance Mode is useful for imposing known results upon a component, or for simplified treatment of components of secondary importance to the overall system model. September 18 © Copyright Thermoflow, Inc., 2011

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