1、4698 Application of Advanced Software Technologies and Engineering Standards to Improve the Process of HVAC System Design Michal Ciach, Ph.D. Aleksandra Duda Michal Januszczyk ABSTRACT The softwareplatform designed and implemented in order to improve and optimize engineering processes of selection,
2、configuration, and design of indoor air qualiq equipment, products, and systems is presented. Up-to-date software tech- nologies have been used in order to construct the platform, supporting designs of complex air distribution equipment and implemented asa Web-based andstand-alone application. The w
3、hole software tool is scalable. It is constructed fiom inde- pendent components responsible for subsequent steps ofHVAC engineering system design. Several additional functionalities have been implemented within a platform: (a) CAD interop- erability developed using OpenDWG standards, (b) IFC data st
4、orage, export, and import, (c) expert tool based on CEN (European Committee for Standardization) standards, and (d) CFD (computational fluid dynamics) options. Thanks to the structure and functionaliu, the platform can serve diflerent groups of engineers and designers from diflerent world loca- tion
5、s, having dofSerent design habits and practices. INTRODUCTION Today HVAC engineering design processes are strictly connected with development of various software engineering technologies and software tools. The large group of commonly used software applications are commercial programs used in projec
6、t designs for selection, configuration, and virtual visu- alization of different air-handling equipment. Determination of an adequate HVAC system is based on finding correlation between initial indoor environmental conditions, including thermal, acoustical, and air quality, for new or existing build
7、- ings and HVAC system technical parameters connected with particular HVAC product technical specifications in order to attain the required indoor air quality conditions. Most of the commonly used software engineering tools are stand-alone computer programs sensible for selection and configuration o
8、f a particular group of HVAC products. The aim ofthe undertaking presented by the authors was to develop a tool with the possibility of selection and configuration of entire HVAC systems constructed from various air-handling equipment. This tool assists the user during the whole engi- neering design
9、 process. The platform was constructed to fulfill the requirements of specific users, giving them possibilities of optional use of particular software. Within the process of HVAC system design, CAD/CAM operations play an important role, as well as product selection and configuration design. In stand
10、ard engineering practice today, HVAC engineers use two-dimensional and, more and more, even three-dimensional CAD drawings in order to visu- alize their work and to prepare documentation for contractors. Using OpenDWG standards, a CAD component has been constructed within the system. Due to this com
11、ponent, engi- neers have the possibility of operations on DWGDXF draw- ings as well as visualization of engineering works. In addition to standard engineering design practices, in many cases, engineers often decide to use more sophisticated HVAC design technologies. Computational fluid dynamics (CFD
12、) is increasingly being used during engineering design in order to model the indoor environment and to predict the indoor air quality. This procedure enables selection ofthe most appropriate HVAC engineering solutions in order to achieve the best indoor air qualiy according to customer demands. Prop
13、osed CFD functionality of the developed software plat- form was based on assumptions that numerical analysis would Michal Ciach and Aleksandra Duda are industrial research scientists at ABB Corporate Research, Krakow, Poland. Michal Januszczyk is a student at the University of Mining and Metallurgy,
14、 Faculty of Electrical Engineering and Automatics, Krakow, Poland. 02004 ASHRAE. 55 U Fgure 1 Engineering process flowchart. be performed within the Internet environment using commer- cial software applications, supporting services promoting the on-line CFD calculations. Interoperability within diff
15、erent engineering professions and different software tools has become extremely important. In order to make the software platform interoperable, new IFC (Industry Foundation Classes) standards have been used and implemented within the engineering tool. Commonly used stand-alone HVAC computer applica
16、- tion are distributed in the form of a portable data medium with need of installation on the users computer. Some companies support Web solutions. Most of them, however, support those two solutions as separate applications. Due to the software technologies developed within the platform, Web and sta
17、nd- alone versions are the same and their development does not require additional work. ENGINEERING DESIGN PROCESS OVERVIEW The implemented software platform is a tool supporting engineering processes connected with HVAC system designs and product configuration. The main objective of this software i
18、s to determine the most adequate HVAC system devices for particular users according to their requirements. The entire tool is constructed from components responsible for selection and configuration of different HVAC equipment. They are treated as separate calculation engines responsible for selec- t
19、ion of certain HVAC equipment. All components come together, forming the whole soft- ware system. The entire computer application is constructed to avoid forcing the user to employ ali possible software func- tionality or to select a certain group of HVAC products. The user keeps full control of the
20、 system. The flowchart in Figure 1 shows the subsequent steps of using this software system. The platform user has the option of using an expert tool (Expert Wizard). The expert tool is based on CEN (European Committee for Standardization, CEN 1998, CR 1752: 1998) standards and engineering informati
21、on concerning HVAC systems. According to user data input, certain CEN values are read from the program database and then verified with system device parameters. The user has to support the system with the input data concerning building dimensions, building catego- ries, occupancy, pollution caused b
22、y occupants, type of build- ings, operation seasons, outdoor air quality, and activity in the room. On the base of those data, the analyzer within the expert tool software components is activated. The software system calculates ventilation rates required for comfort and health. This procedure result
23、s in generation of a list of systems fulfill- ing indoor environmental conditions provided by the user. The user can rank those systems according to requirements (price, indoor climate, system construction, cooling carrier, etc.) and then select the HVAC system (e.g., mixing ventilation, displacemen
24、t ventilation, activent, chilled beams, fan coils, etc.) he or she likes. The next steps involve configuration of accurate HVAC devices and then finally determination of the right system device (e.g., selection of fan coil type). Another group of users who do not want to use the expert tool can, fro
25、m the beginning, directly select certain HVAC system device configurations. The whole procedure results in a collection of adequate indoor air quality equipment. In the first stage of the project, calculation components responsible for selection and configuration of mixing ventila- tion and fan coil
26、s have been developed and integrated within the system. All calculation data are managed within a project and stored in the project database as a single XML file. The system is supported with additional services that are not indispensable in the device selection process flow but can be used optional
27、ly. Those supplementary functionalities expand the system and can adjust their form to the needs of a particular group of users. As additional functionality within the platform, engineers1 designers can view and operate on DWG/DXF files and they can prepare data in IFC files. All additional function
28、alities suit the overall system architecture and are independent compo- nents. CAD FUNCTIONALITY Graphical visualization of design work always has been connected with different engineering processes. Nowadays 56 ASHRAE Transactions: Research many HVAC engineers use different CAD software applica- ti
29、ons in their everyday design work. This helps them in visu- alizing HVAC systems or products, locating them in the building environment, and then exchanging information in graphical form among engineers from different disciplines of the construction works. Different groups of engineers and designers
30、 very often are interested in different parts of the construction drawings. Architects take care of the overall shape of the building, construction engineers calculate and select construction elements and materials of the building, electrical engineers design elecric installations and systems within
31、 a building, HVAC engineers design and determine the indoor quality of the building environment. Information from those different engineering disciplines can be stored using a single drawing with additional layers in two or three dimen- sions. The main objective of the platform CAD component is to o
32、perate on DWG/DXF drawings. Many CAD computer programs can communicate within those two standards in order to transfer and share different geometric data. Conse- quently, to enable the platform users to work with CAD draw- ings, the OpenDWG open standard has been used (http:/ www.opendwg.org). The O
33、penDWGTM Alliance was estab- lished by CAD customers to promote the AutoCAD DWG drawing file format as an open standard format used to exchange CAD drawings. The OpenDWG Alliance provides free resources and tools designed to view and manipulate the drawings, which can be subsequently used in another
34、 software system. The CAD functionality of the platform has been devel- oped according to the software architecture assumptions in the form of an ActiveX component communicating with the entire software system. Geometrical data describing design dimen- sions for HVAC engineers (room length, width, a
35、nd height), required for selection and configuration of HVAC systems, can be selected, read from the drawing, and subsequently used within the platform environment. Afterward, a selected and configured HVAC device can be send back to the CAD compo- nent in order to locate a geometrical representatio
36、n of the device in the originally selected HVAC design environment. Through this CAD component, apart from the basic HVAC product selection and configuration, the user can write a geometrical representation of the device located in the DWG/ DXF drawing. SOFTWARE INTEROPERABILITY, APPLICATION OF IA1
37、STANDARDS In 1995 the International Alliance for Interoperability was started to enable software interoperability in the AECIFM industry sector (www.iai-internationa1.org). The IA1 is orga- nized into chapters, each of which represents an international region that is organized according to local cus
38、toms. Each chapter has organized domain committees, each of which is devoted to one specialized discipline, such as architecture, HVAC, construction, or facilities management. A domain committee is represented by experts specializing in a particu- lar area of engineering sciences. Domain experts wor
39、k together with software engineers to develop specifications or models of aparticular domain as it applies to the overall shared project model. Cross-domain meetings help in cooperation and requirement definition between domains. Within IAI, many companies work together to establish new AEC/FM indus
40、try standards. Several years of work by more than 600 companies and organizations from over 20 countries resulted in, development of the IFC (Industry Foundation Classes) Object Model. This model provides formal specification of requirements for different software applications to be IFC compliant. I
41、FC-based objects allow AEC/FM professionals to share a project model. Using this standard they can construct their own view of objects contained in the model. As a result of development of that new AEC/FM standard, engineers of different industry sectors can easily exchange information concerning di
42、fferent stages of building design and service processes. Additionally, the IFC can be used as a nomencla- ture and relationship standard for construction of different database systems for profiles of industry products. The IFC model is constantly updated. New objects are added to subse- quent versio
43、ns of the IFC models. For the software platform discussed here, the latest version of IFC 2X has been used. As mentioned above, all data input by the user or calculated by software components are stored in an XML project database. As additional functionality within the software system, all those val
44、ues are mapped into the structures and dependencies of the IFC model. Within a project, HVAC product catalog data-properties, construc- tion, geometric representation-are prepared as IFC data. Thanks to that functionality, the platform user can generate an IFC file from the existing data model, thus
45、 making the soft- ware interoperable. COMPUTATIONAL FLUID DYNAMICS (CFD) Accurate prediction of the performance of cooling, heat- ing, and ventilating systems is extremely important in analysis of building HVAC system design. Physical measurements are costly and time consuming, and analytical engine
46、ering solu- tions are not sufficient in many cases. Three-dimensional airflow analysis has become a requirement for effective venti- lation design. Computational fluid dynamics (CFD) is being used more and more at the design stage for evaluation of air distribution in complex building designs. Numer
47、ical simulations are often based on the finite volume/finite element discretization of the governing fluid mechanics equations in the form of computa- tional meshes. Thus, even exceptionally complicated geome- tries can be analyzed in detail. Well prepared and analyzed CFD simulations often can be u
48、sed instead of expensive and time-consuming experimental tests. Numerical simulations are more detailed than analytical solutions, thus giving better results. It is evident that numerical simulations will perform a ASHRAE Transactions: Research 57 (a (b) Figure 2 Fsualization of the air path lines i
49、n the room: (a) simulations with modeled air terminal jet, (6) simulation using concept of virtual “bounding box.” crucial role in the next few years in development of HVAC system design (Loomans 1998). The main objective of this part of the project was to find solutions in order to support future users with the functionality of computational fluid dynamics calculation. The platform was designed to be an Intemet-based appli- cation; thus, the new challenge has been to develop on-line CFD simulation modules. The Internet environment allows for calculations performed in different Web loc
