© Copyright Mistral Assoc. 1985-2013
Please note that these Help pages apply to both Linewind and Pipewind version of Mistral's refrigerant pipe sizing programs. Some features referred to may therefore not apply to the program version you are currently using.
Linewind is the basic program version and which deals with a range of only simpler circuits with single refrigeration loads. Pipewind is the more advanced program and which includes all of the features of Linewind but with the addition of multiple circuit and multiple refrigeration load circuits.
Users wishing to upgrade program licences should click here http://www.mistralassociates.com for further details along with on-line software licencing and instant download facilities.
'LINEWIND' is a Windows™© based computer program and as such closely follows typical Windows program operating conventions. A practical working knowledge of Windows is therefore desirable when using 'LINEWIND'. Reference to Windows operating manuals and 'Help' pages will thus serve to cover many questions that might arise whilst operating the program.
'LINEWIND' is designed so that all relevant information is displayed around a single main screen presentation. The program is also designed to operate with a logical order of 'user inputs' that closely mimics the way engineers would tackle the manual process of pipe-sizing. Therefore, once a question (request for input) has been satisfied, either by typing in an appropriate value or by selecting an item from a 'menu', then the program will automatically move on to the next logical input routine. This does not prevent the program user from entering inputs in a different order although sometimes the program will display an error message if another input routine must be entered before the current one can be answered. This is because some inputs may be dependant upon having information retrieved or computed from previous routines before a logical result can be computed. For example: The program will not permit entry of Condensing Temperature until the Ambient has been established. This is part of Mistral's unique care in producing programs that will not permit illogical or contradictory results.
™© Copyright Microsoft Corp. 1985-2013. All rights acknowledged.
The program comprises a series of 'Input Routines' corresponding to all of the questions that need answering to arrive at the result of viable pipe diameters for the various parts of a refrigeration system. These input routines may be accessed either by clicking on the appropriate icon or 'button' that appears in the input routine 'box' (a frame which appears around the area covering the chosen subject) or the program will also automatically move to the next logical question to be answered once data for the current one has been entered.
Inputs are achieved either by typing in data or text at the keyboard or by selecting items from 'menus' (multiple choice lists) that appear on the screen. Depending upon the type of information that the program is prompting the user to input it is sometimes necessary to press the Return (Enter) key to close the input routine box, thus confirming the entry, or to click on the next input box (white area within a sub-frame) within the routine. Experimentation is the best tutor in this respect as the program will prompt for a different key press or operation if that is what is needed.
Ambient temperature range from 20ºC to 55ºC. Condensing temperature range from (above) Liquid temperature to 20ºC above Ambient.
Changing Ambient or Liquid temperature after Condensing Temperature has been entered will force re-entry of Condensing Temperature.
Superheated Suction temperature (effectively 'evaporating temperature' for purposes of the program). Range -40ºC to +10ºC (depending upon and further limited in some cases by refrigerant selected).
Saturated Suction temperature line rises in the range 0K to 10K may be entered.
Hot gas discharge temperatures may be adjusted, generally after entering other refrigerant data. Initially the program may only permit a 'default' estimated input of 60 Degrees Celsius.
Condensing temperatures may be entered from between 5K and 15K greater than Ambient. Changing Ambient temperature after entering condensing temperature will force re-input of condensing temperature if the revised Ambient takes the difference out of the 5K to 15K permitted range.
Condenser discharge temperatures may be entered in the range of from 1K greater than Ambient to 1K below Condensing temperature. Changing Ambient temperature or Condensing temperature after entering condenser discharge temperatures may force re-input of condenser discharge temperatures if revised inputs take either of the differences out of the permitted range.
Temperature loss through Liquid Line may be entered in the range from 'above Condenser discharge temperature' to 20ºC above Ambient.
Changing Ambient after Liquid Temperature has been entered MAY force re-entry of Liquid Temperature.
Evaporating temperature inputs are limited as a function of previously input Superheated Suction temperature. Changing Superheated Suction temperature after Evaporating temperature has been entered may therefore force re-input of Evaporating temperature input.
Range 0.1kW (100 Watts) to 500.0kW.
Total Refrigeration Load for the purposes of this program is the total amount of energy absorbed by the refrigerant at the evaporator(s) and does not include work heat added by the compressor or gains to refrigerant in the Liquid Line.
Refrigerants are selected from a menu that is accessed by clicking on the Refrigerant icon.
Clicking on any refrigerant in the menu automatically enters all relevant thermal and physical properties data to the program for that selected refrigerant.
Users may access the database that stores refrigerant thermal and physical properties and add data for additional refrigerants. To do this, click on 'OPTIONS' on the program's top menu bar and then on 'CUSTOMISE' in the drop down window that appears.
The program operates by a combined process of interpolation (between set data points at 10K intervals) and iteration. ALL relevant data at each set point condition must therefore be entered to the database for the program to function correctly.
In the event that editing the program's pre-loaded data has resulted in corruption of that data then the original values may be restored simply by clicking on the 'RESTORE' button.
The program contains data for both Copper and Steel refrigerant pipes. These may be selected by clicking on the PIPE icon and then selecting the desired pipe material.
Selecting NH3 (Ammonia) refrigerant will automatically force the selection of Steel pipe.
Users may access the database that stores physical properties and dimensional data for refrigerant pipes. To do this, click on 'OPTIONS' on the program's top menu bar and then on 'CUSTOMISE' in the drop down window that appears.
The program operates by a combined process of interpolation (between refrigerant set data points at 10K intervals) and iteration. ALL relevant data, including 'equivalent lengths' of proprietary pipe fittings such as pre-formed bends and tees for a complete range of commercially available pipe sizes are included. These must therefore be entered to the database as complete sets of data for the program to function correctly.
In the event that editing the program's pre-loaded data has resulted in corruption of that data then the original values may be restored simply by clicking on the 'RESTORE' button.
In order to take into account the effect of gravity on refrigerant flow and pressure drops it is necessary to determine the vertical relationship between the major components of the refrigeration system.
Where 'Condenser above Evaporator' has been selected then the option to include 'Dual Riser' for the Suction Line will also be offered.
Please note that computations for the displayed option for multiple refrigeration load (multiple coolers and ring main circuits for example) are only available in the more advanced Pipewind version of the program. Users wishing to purchase a program licence upgrade should click here http://www.mistralassociates.com for further details about programs and upgrades from Mistral, the world's leading RAC Application Engineering software developer.
Where 'Condenser above Evaporator' has been selected a facility is provided to select Dual Riser Suction Lines.
The right hand side of the program's main page is a form used to identify and thus compute results for each of the refrigerant pipe functions.
Each pipe function is selected by clicking on the named tabs at the bottom of the Pipe Function form. Each pipe function is colour coded to help aid identification during program operation.
Hot Gas Discharge (compressor outlet)
The option is provided to enter additional descriptive text for each pipe under consideration and this text will be included on the program's printed summary. It is not essential to add descriptive text but the facility is useful to help in keeping track of complicated pipework designs.
Pipe lengths are entered in a drop down window that is accessed by clicking on the Pipe Length icon.
Both the horizontal and vertical component lengths of the total length of the pipe under consideration must be entered.
Where 'Dual Riser' Suction line has been selected (by clicking in the Dual Riser 'Check Box') then the results will be shown separately for the horizontal and each of the vertical sections. Dual Risers may be computed with unequal loads from 10% to 90%.
To speed up the input process, where as is commonly the case, refrigerant Liquid and Suction lines closely follow the same route, a facility has been provided to instantly 'clone' or copy across all previously entered Liquid line details and duplicate these for the Suction line.
Simply click on the icon found to the right side of the Pipe Function dialogue box.
Pipe bends either pre-formed or formed on site and having a nominal radius of 2 x pipe diameter or more are entered as total number of items by clicking on the Long Radius Bends icon.
Pipe length controlled inverse logarithm error traps prevent the entry of an illogical numbers of long radius bends and the error traps operate in conjunction with the input for short radius bends.
Pipe bends either pre-formed or formed on site and having a nominal radius of less than 2 x pipe diameter are entered as total number of items by clicking on the Short Radius Bends icon.
Pipe length controlled inverse logarithm error traps prevent the entry of an illogical numbers of short radius bends and the error traps operate in conjunction with the input for long radius bends.
Nominal pressure drops for proprietary isolating valves (for all practical purposes any gate or globe valve) may be entered to the program for inclusion in the computation for the pipe function under consideration. Click on the Valves icon and enter valves as total number of items.
Tees either pre-formed or formed on site and having a nominal branch radius of less than 2 x pipe diameter are entered as total number of items by clicking on the Tees branch flow icon.
Tee branch flow means that refrigerant is turned through up to 90º as it passes through (see also Tee line flow).
Tees either pre-formed or formed on site are entered as total number of items by clicking on the Tees line flow icon.
Tee line flow means that refrigerant is passes through without changing direction of flow (see also Tee branch flow).
The 'equivalent length' of various pipe fittings are entered as lengths in metres on a drop down window form by clicking on the Equivalent lengths icon.
Clearly, until the diameter of any given pipe under consideration is known then accurate entry of a pipe fitting's equivalent length cannot be made. An estimate should first therefore be entered and the equivalent length entry then compared for accuracy against the resultant computed pipe diameter. If the first entry does not agree with manufacturer's proprietary data for equivalent length for their fitting for that pipe diameter then the entry should be corrected.
If fittings manufacturers can be persuaded and convinced of the mutual benefits of fast and accurate pipe sizing through computer calculation then it is intended to add their data to the program for automatic entry. However, someone must pay for this work and Mistral is not in business to freely promote other people's products. Help us to help you by making manufacturers aware of the opportunities for sales of their products through them sponsoring this program.
The target (or desired) System Penalty is entered in ºC by clicking on System Penalty icon. The program will compute Suction and Hot Gas Discharge lines with consideration to the entered target figures but will display the optimum pipe diameter with resultant pressure drop and actual System Penalty.
By default (i.e. if no entry is made) the program will assume that the target System Penalty for Suction Lines is 2ºC and for Hot Gas Discharge Lines is 0.186ºC
The program selects optimum pipe sizes in accordance with good practice rules for the industry. The calculation process considers refrigerant mass flow, temperature, pressure, viscosity, pipe surface roughness factors, turbulent and laminar flow characteristics, acceptable noise levels, safe oil return, efficient compressor operation, system penalty and other system efficiency losses to arrive at its results. A process made even more complicated when pipe intersections and varying loads are responsible for constant changes in both the volume and the physical characteristics of the refrigerant in both its liquid and gaseous forms. However, commercially available refrigerant pipe sizes are manufactured to convenient incremental sizes and there are many situations where acceptable differences in pressure drops or 'System Penalties' mean alternative pipe sizes are technically quite acceptable. By clicking on the icon on the top menu bar any viable alternative pipe sizes, along with the resultant consequences of changes to pressure drop and where applicable, System Penalty, are instantly displayed.
Refrigerant pipes for Two Stage Compressor circuits, including Flash Intercoolers can be sized by click on the Two Stage Compressor icon
Refrigerant temperature details for the additional pipes are input through the additional buttons
Access to inputs and results for each pipe in the circuit is provided by a series of tabs on the Pipe Function form.
Refrigerant pipes for multiple circuit including Ring Mains can be sized by click on the multiple_circuit icon
Refrigerant temperature details for the additional circuits and pipes are input through the buttons
where previously input details for each evaporator may be 'cloned' or duplicated (and individually edited if necessary) in order to save key input time.
The facility to change evaporator positions within a circuit and hence instantly recompute all effected local pipes in a circuit is provided. Potentially saving many hours of laborious and error prone work compared to completing this task with manual calculation methods.
The facility to design circuits to typical 'Liquid First, Suction First' or less conventional 'Liquid First, Suction Last' designs is provide. With instant switching and instant re-computation.
Click tile under evaporator to access for editing details
Yellow spot indicator appears on evaporator when checked in circuit and currently open for input.
Click tile (as indicated above in red circle) to access evaporator description edit form.
Tip: Don't forget when 'cloning' or duplicating evaporators that previously given evaporator descriptions will be copied too. Care should be taken to edit descriptions to make each unique. Eg. 'Meat Chiiler No. 1', Meat Chiiler No. 2' etc.
Save time by clicking on the quick selection button and the program will display a menu containing a small group of 'pre-engineered' or 'template design' simple pipe circuit solutions. These contain designs nominated by experienced users of Linewind of typical small refrigeration installations frequently found in actual installations. These may be retrieved and then further edited and re-saved as new calculation files (without fear of destroying the original 'template design') safely with the confidence of knowing they are based upon real life situations. Don't forget though to edit or change the Reference given for the 'template design' to suit your own new project.
Why not create and save your own additional 'template design' solutions for future use? The 'Linewind' file you create when doing this will be given the extension .lwc and we recommend that if wishing to save a file for future use as a 'template design' that you change the file attributes to read only so as to avoid the risk of accidentally over-writing it in future. See your Windows Operating System Help pages for advice if unsure of how to make a file read only.
'Template design' solutions can also be used for staff training purposes or for passing to colleagues as examples of company policy for certain frequently repeated designs.
The program provides a convenient quick review or summary of results by clicking on the icon on the top menu bar.
The program may be switched to operate with either Imperial or SI ('Systeme Internationale' or metric) units. Simply click on the icon on the top menu bar to toggle between Imperial and SI operation. This may be done at any time during program operation and the program will automatically convert both all currently displayed and computed data. Switching between units can also be done via Options from the top menu bar.
Click on File and then on Print in drop down menu. A printed summary will automatically be loaded to the printer driver that is currently selected in Windows™©. The currently selected printer driver may be changed (if others have already been installed) by clicking on the Setup button.
The Print Range options on the standard Windows menu which appears in 'LINEWIND' may be disabled when a multiple page set is required to contain the complete calculation result summary.
If the Collate Copies box is not checked then providing more than 1 copy has also been requested, multiples of one page will be printed before multiples of the other page. To print multiple summaries as sets then the Collate Copies box should be checked (i.e.. click in check box to show a tick. This is also the default).
Options offered when the Setup button is clicked will depend upon the printer driver installed and are outside of the control of the 'LINEWIND' program. Again, Print Quality options will depend upon the printer driver installed.
Windows™© Copyright Microsoft Corp. 1985-2013. All rights acknowledged.
A summary of the completed calculation may also be sent to word processing software installed in your computer by clicking in the Print to File check box in the Print drop down menu. When 'exported' to other word processing software (for example MS WORD or MS WORKS for WINDOWS) the summary may be edited to suit your needs. Fonts may be changed, made bold, italicised, underlined or capitalised and text added or deleted as required.
When the text file is 'exported' it is necessary to direct it to the appropriate directory by selecting or entering this in the panel provided. The text file will automatically be given the extension .TXT unless changed. This means that, depending upon the word processor software system in use, the .TXT extension may have to be entered in the 'search path' in that software in order for it to find the text file. Again, depending upon the word processing software in use, you may be prompted to 'convert' or 'translate' the text file so that the word processor can understand it. Usually, selecting 'convert to text' is the correct choice but experimentation may be necessary to obtain the correct result.
Different word processors may have different interpretations of important settings such as tabs and fonts. This is obviously beyond the control of the Mistral program and the user will quickly find what changes need to be made to settings such as Page Breaks, Page Setup, Margins and Font, to obtain satisfactory results.
Click on or open File on the top menu bar and then on Save As in the drop down menu which appears. A prompt will appear inviting a file name to be entered. The file name follows Microsoft© conventions in that the name must include a maximum of eight alpha-numeric characters. The file name will automatically be given the file extension .LWC but the user may choose an alternative extension if desired. Care should though be used if using alternative file name extensions as the program is set to only expect to find calculation files with the extension .LWC and the user must therefore remember any alternative file extensions that may have been used when later retrieving files. For technical reasons it is also important that prescribed or 'reserved' file extensions such as EXE or BAT are not used as these could cause problems elsewhere on the computer.
A previously saved calculation file may be duplicated by saving it again (by using Save As) with a new file name. The duplicated calculation may then be edited to create a totally new result.
It is considered to be good 'house keeping' practice to create a separate directory, or sub-directory under the directory where the main program files are kept (usually called MISTRAL) to store calculation files. Users unfamiliar with creating directories should refer to the manuals supplied with their computer's main operating system.
©Copyright Microsoft Corp. 1985-2013 All rights acknowledged.
To retrieve a calculation click on or open File on the top menu bar and then on Open in the drop down menu which appears. A list of previously filed calculations with the extension .LWC will appear for the current Directory. The current Directory may be changed by clicking on the Path text display. Highlight the chosen file and press Return or double click with the Mouse cursor over the selected file to open it.
If calculations have been filed with user defined file name extensions (i.e. other than .LWC) then the user defined extension must be manually entered in the search path in place of the program's default of .LWC If the user defined extension is not known then the name given to the file may be typed in followed by .* . The * is called a 'wild card' and using it will open all files with common names, regardless of their extension. Wild cards may be applied to file names as well. For example *.* will search for all file names with any file extension.
Care must be taken when searching for and opening files with *.* especially if the search is for a file that has been saved in the same directory as the program's many operating procedure files. Opening some of the program's operating (or 'executable') files with the extension .EXE should never be attempted. These can very easily be corrupted and permanently prevent further operation of the program; especially if they are copied or re-saved as this would amount to invoking of the copy protection system. For this reason it is a good idea and considered to be good 'house keeping' practice to create a separate directory, or sub-directory under the directory where the program files are kept (usually called MISTRAL) to store calculation files. Users unfamiliar with creating directories should refer to the manuals supplied with their computer's main operating system.
Mistral takes care to ensure that its programs never display misleading results or data. When for example an input that was responsible for a particular result is changed, then whilst it is being changed the results from the previous input will be cleared and deleted from the screen. This is not a computer programming procedure that happens automatically but one where particular care and skill has to be applied by the programmer and which sadly is far too uncommon! The possibly catastrophic consequences of such tardy programming are obvious and need no further explanation. For the same reason Mistral programs will not display results when not all essential inputs have been made. If no results show even when it might be expected they should be then it is because one or more inputs are incomplete. For example, if all pipe lengths in a circuit or a branch to a circuit have not been input then no results for any part of the circuit will be displayed.
Remember that missing inputs may need to be input for adjacent evaporators in a circuit or branch. Try clicking on each evaporator access tile in turn and look for a ? mark in an input dialogue box and which indicates that data input is still required.
Alternatively, read the 'Cue Card' that appears and which will advise what program operation is required next. Finally, Mistral's programs are all designed to 'self navigate' so simply hitting the Return Key will automatically take you to the next logical input routine. It isn't possible to make computer programs any easier to operate. In any industry or application!Index
There are many thousands of databases (research and compilation costs to date† 4.2 million Euros) supplied with the Mistral software suite and virtually all of them may be accessed and edited by users*. A few words of caution though. A single unit cooler for example may require up to two hundred fields of data to 'pin down' every aspect of its performance and characteristics and a single mistake can have devastating consequences in future accurate selection. If you are not sure what you are doing or don't know how to test software for integrity then with some databases it might be better to leave it to the experts. Other databases, such as those containing meteorological information or properties of building and insulation materials are somewhat easier to edit and manage. Also, through sophisticated 'error trapping' logical code, Mistral software has been designed to spot and warn of any potentially critical mistakes. We have a saying at Mistral. "It is bad enough over estimating a contract at time of tender and losing it on price but there is one situation far worse. Under estimating the costs and then winning it!"
Having spent a lot of time adding your own data to the programs what happens when you re-install the software or wish to move it, along with your personalised data, to another computer? Simple. Just re-enter the database where you know you have made changes and make another 'benign' change. By benign we mean make a change that does not fundamentally effect any of your data properties, such as changing a capitalisation or adding an extra descriptive word or even delete a redundant one. When you 'close' or exit the database it will automatically be saved, including your last edits, and importantly it will be 'date-stamped' at precisely the time it was saved. This date stamp can be used easily to identify and trace the new database for purposes of copying and moving or pasting it to new locations. For new Mistral software installations for example.
All Mistral software, by default, is stored on your computer where it should be, correctly, under the 'Program Files' primary folder. The 'path' to the Mistral software installation will therefore normally be C:\Program Files\Mistral. The only time that this will be different is if you or your IT management department if you have one, has decided to change from the default path. There may be quite legitimate and sensible reasons for doing so in some computer set-ups but if that has happened then the same responsible staff should certainly be able to advise you of the alternative location (path). Look in the folder where your main Mistral program files are stored. Images though are stored in a sub folder called graphics but for the most part, all the important files along with the databases are stored in C:\Program Files\Mistral. Next, using Microsoft's Windows Explorer program, sort the files into date order (see Microsoft's own Help pages if unsure how to do this). Remembering the time and date that you made edits to the databases you wish to preserve simply copy these databases into another folder somewhere on your PC or even onto a CD-ROM or CD-RW or USB key for example. Now you may re-install software, over-writing previous installations with later versions, but still recover and re-use your own personalised databases.
IMPORTANT Some Mistral databases are 'multi-relational' and therefore one database may 'communicate' at any time with another one, two or even three databases. In these cases a 'family' of databases will always have a common name but necessarily with different 'extensions'. For example. AIRWIND.DAT, AIRWIND.IDX and AIRWIND.BLB. In such cases it is absolutely essential that all matched sets of databases are always copied and pasted together. Meaning they should all show the same time and date stamp. Mixing such sets with date stamps from differing times will result in failure and almost certainly risk losing the entire database. The only recourse left being to re-install the original one supplied.
It is hoped the above explanation is clear but as always, computer software is a big subject and sometimes jargon that can be confusing, although unwelcome, is unavoidable. If you have any questions at all then please don't hesitate in contacting Mistral through the 'On-line Help' service which can be found at http://www.mistralassociates.com
* Some databases contain 'proprietary data' and which has been supplied by paying contributors. Under the instruction of these paying contributors access to these databases may be achieved only following entry of a password. The password may or may not be available to licensed users and Mistral is unable to provide any guarantee in respect of this matter. Please contact Mistral for further details in the event access is required to a database which is found to be locked.
† from inception to date 01 Jan 2013.Index
a) Mistral guarantees that its software products will produce calculation results accurate to an aggregate of +/- 1% against the processes as defined in accompanying manuals, and which are reproduced in the text 'Program Help Pages' included with the programs.
b) Mistral guarantees that its software will be supplied in a form that will successfully transfer permanent 'Working Copies' to any IBM PC or compatible having the following minimum features:- Pentium processor, 256 Mbytes RAM; 256 mBytes free hard disk space; VGA or SVGA video system.
c) Mistral guarantees the media upon which its programs are supplied to be free of any defect for a period of 3 months from the date of supply. Any media which is found to be defective will be replaced free of charge, including the software which is supplied on it.
d) Mistral cannot, and therefore does not accept any liability or responsibility for any losses, consequential or otherwise, which are attributed to, or proved to arise from application of its software or the results of calculations produced by its software. It is up to the customer to satisfy themselves that the results produced by the use of Mistral software are fit for the purpose for which they are used.
'LINEWIND 2.3', successor to an earlier and highly popular DOS based computer program was researched between the years 1998 to 2003 by staff at Mistral Associates. It was developed by a team led by Richard Hosking BSc(Hons) Program Development Manager and under the direction of Chris Smith MCIM MInstR Technical Director. The program is based upon the proven Darcy Weisbach calculation methods, including established factors, constants and algorithms in the public domain.
'LINEWIND 2.3' selects optimum pipe sizes in accordance with good practice rules for the industry. The calculation process considers refrigerant mass flow, temperature, pressure, viscosity, pipe surface roughness factors, refrigerant turbulent and laminar flow characteristics, acceptable noise levels, safe oil return, efficient compressor operation, system penalty and other system efficiency losses to arrive at its results. A process made even more complicated when pipe intersections and varying loads and system temperatures are responsible for constant changes in both the volume and the physical characteristics of the refrigerant in both its liquid and gaseous forms.
As with all Mistral computer programs for Professionals in the Refrigeration and Air Conditioning industry it has been subjected to rigorous testing and quality checks at key commercial and educational establishments around the world. Mistral takes care to ensure that any data contained by its programs either fall within the domain of public ownership or where this is not the case then all legitimate rights will be respected and royalties duly paid.
No part of the programs, their code, unique processes or graphical images may be copied or reproduced in any form, whether electronic, printed or by any other means, without the prior express written permission of Mistral Associates, except for reproduction of printable program calculation and capital equipment selection results and associated images as clearly intended to be a progammed function and user benefit of use of the programs.Index