MODELLING with IpsePro: Basics

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1 Aškerčeva 6 SI-1000 Ljubljana, Slovenia tel.: fax: dekanat@fs.uni-lj.si Department for energy engineering Laboratory for Heat and Power LABORATORY PRACTICUM MODELLING with IpsePro: Basics Authors: Boštjan Drobnič Mitja Mori Content - CASE 1: Steam boiler and turbine - CASE 2: Condensing steam turbine with steam extraction - CASE 3: The steam cycle Ljubljana, October 2015

2 2 Simulation of energetic systems with IPSEpro The program IPSEpro enables simple calculations of energetic systems. With the graphical interface in the program the scheme is modeled with standard elements (heat exchanger, turbine, boiler, pump, condenser...) that should be coupled together. In points that are known, the properties of working media is inserted (temperature, pressure, mass flow...). The program forms the linear equations system on the basis of elements and calculates this system numerically. The system of equations has to meet the demand that the number of unknown parameters is equal to number of equations. If that is not the case, the program returns the warning. The same case is also in cases when the system is not soluble because of the unsuited data (for example: the temperature of the cold media in the heat exchanger is higher than the temperature of the hot media; the pressure behind the turbine is higher than the pressure before turbine). If the system is soluble, the program for every connection (the flow of the media) calculates the basic parameters (mass flow, pressure, temperature, enthalpy), for elements and additional values (heat flow in heat exchanger, turbine power...). The working environment of the IPSEpro is shown on the picture below and is divided on: - Main window in that field we graphically model the system, put elements of the system on the sheet and connect them into the system. After successful calculation the parameters of the working media is shown near at the connections, we can check also others calculated values at specific elements. In the case of the error the separate window is opened, where the warnings and errors are explained. - The ikons of elements system is modeled from elements that are predefined. - Toolbar in the menus and icons the additional functions, tools and settings are available. - The lists of used objects for some elements that are in the modeled system the settings are available only through specific list.

3 3 Case 1: Steam boiler and turbine Model the system that consists of steam boiler and turbine. The water is pumped into the boiler with pressure of 150 bar and temperature of 120 C, the temperature of the steam from the boiler is 520 C, the pressure behind the turbine is 0,06 bar. In the boiler the pressure lost is 15 bar, the efficiency of the boiler is 87 %. The turbine has the internal efficiency of 83 % and the mechanical efficiency is 95 %. Steam mass flow is 18 kg/s. Calculate the heat power required from the fuel and the turbine power. Between elements look up for following: the source of working media the sink of working media steam boiler turbine (steam or gas turbine), pick up 'turbine' and not 'turbine_end' generator Every single element has specific inflow and outflow points that connect elements in the one system: working media inflow working media outflow power supply power extraction The chosen elements should be arranged through the active sheet in the way that they can be connected. For rotating specific element use the combination CTRL-R, for deleting DELETE. Elements are connected with the pipe in which the media is water or steam. Therefore the first step is to define working media. Select the command Objects New Global Object.

4 4 In the opened window define the working media with specific composition (composition) and select the name (for example: water ). In the list of objects select defined working media and prescribe the properties with the click on the button on the right side of the list. For system of equations to be soluble the number of unknowns should be minimized. For that reason the composition of the media is defined in the manner that all compositions except one (is on estimate) is set on (set). At all compositions except water pick set and enter the value of 0.

5 5 Confirm the settings with OK. Connect elements in the system. It is possible to connect just empty (outflow) and full (inflow) symbol of the same color. Connections represent the working media that can be defined every time. When the connection is made and picked (bold line), open the its properties with double click on the connection or with the button on the elements list right side in which the connection is chosen, for example: 'stream001 (stream)'. At Composition pick up previously defined working media. The name of the connection can be changed (Name), otherwise the name is automatically named 'stream###'. The sane connection should be done between turbine and generator. The connection between blue symbols is mechanical therefore the name is automatically set on 'shaft###'. For this connection there is no need to define the working media. The wrong connection can be deleted with DELETE, or it can be cut off element with the CTRL-F, or Objects Free Connection. The separate sections of connection can be deleted by BACKSPACE ( ).

6 6 When all elements are connected the values of parameters should be entered. The values are given in the instructions of the exercise. With double click on the connection between feeding water and boiler, the properties of this connection are opened. With the selection set and entering values the temperature, pressure and mass flow rate are defined. In the boiler the efficiency and pressure drop (due to flow resistance) should be defined. At turbine eta_s means the internal efficiency, eta_m mechanical efficiency. Because for the generator mechanical (eta_m) and electrical (eta_el) efficiency are unknowns, they should be set on 1. With that the power of the generator will be equal to turbine power. When all values are inserted, the calculation is run with F5, button, or command Calculation Run. When all settings are correct and system is soluble, after calculation results are shown on the connections between elements.

7 7 At more complex schemes the possibility of show/hide of the specific connection date is possible with the CTRL-H, or Objects Show Result Cross. With right click on elements of the system the additional calculated and given values are shown. The heat input of the fuel is found out to be kw, turbine power (generator) pa kw. The efficiency of the system is 33 %. With the variation of the known parameters try to find out how these parameters influence on the system efficiency. For more simple variation of the efficiency, the scheme of the efficiency variation should be added on the sheet. Pick up Object New Data Frame.

8 8 'Data frame' is the table that is defined in the next step: the number of rows (Number of Rows) and number of columns (Number of Columns) are defined. In our case the number of rows is 1 and number of columns is 2. The position of the table should be set additionally. If the table is not active, pick up the left cell of the table and write system efficiency. Then pick up the right cell and write '=', then click on generator and pick up power, write the symbol for divided by '/' and with the click on the boiler pick up the 'heat_input'. Click on the scheme somewhere out the table and in the right cell the calculated value of the efficiency will be written. It will be changed every time when calculations id rerun.

9 9 Case 2: Condensing steam turbine with steam extraction In steam turbine with steam extraction the 7,5 kg/s steam enters at the pressure 90 bar and temperature 475 C. At pressure 20 bar and temperature 285 C is extraction, where from turbine is extracted 3 kg/s of steam. The rest of the steam is expanded to pressure 0,05 bar and dryness of 0,85. The steam from low pressure turbine flows into condenser, where it condensates to boiling water. Calculate the turbine power, internal efficiency of low pressure turbine, overall internal turbine efficiency and heat flow in the condenser. Among elements that are available for this exercise are in addition to previously used (Case 1) necessary: splitter condenser The energetic system should be connected and looks like this: For working media is the procedure equal to Case 1 (water). Define parameters on specific connections and elements. The splitter doesn t need any additional parameters, for the condenser define the temperature of the condensate cooling (dt_sub) to 0 C, pressure drops on the hot and cold side (delta_p_hot in delta_p_cold) also to 0 bar. After successful calculation determine the efficiency of specific part of the turbine with the left click on the turbine. It is written: - eta_s internal turbine efficiency - delta_hs entalphy drop at isentropic expansion - eta_m mechanical turbine efficiency As at condenser, check the heat flow removed (q_trans). The data can be also written in the table (Data Frame). Additionally calculate/determine the internal efficiency of the turbine. Check out how the: - extraction pressure - extraction mass flow Influence on - turbine power - heat flow removed from condenser - the overall internal turbine efficiency

10 10 Case 3: The steam cycle The steam cycle operates between boiling pressure 85 bar and condensing pressure 0,08 bar. The highest temperature in the process is 490 C. The internal efficiency of steam turbine is 0,88, feeding pump 0,9, the steam boiler efficiency 0,85. The steam mass flow is 22 kg/s. The parameters of the atmosphere are 22 C and 1 bar. Calculate the energetic and exegetics efficiency of the process. Among elements additional for this excercise are: pump connector Set up the scheme: The connector can be placed anywhere in the system. It should be used in the closed systems without source and sink of working media. It doesn t need additional settings and it doesn t change the properties of the working media. Fro the pump the internal efficiency is (eta_p = 0,9) and the mechanical efficiency is (eta_m = 0).