DESIGN METHODOLOGY DESCRIPTION

Basic elements in the methodology can be presented in several ways. Table 3.1 gives an idea of the whole contents. In addition, decision trees are needed, be­cause the design process requires many back couplings which cannot be illus­trated in table form. The decision tree technique is a tool for dividing a process, here Design Methodology, into subtasks, which have their accurate inputs and outputs. The order of the tasks is chosen so that the data needed to do a task are given or calculated before that task to minimize the number of back couplings. Thus, the tree guides the right execution order of the subtasks. It also serves as an internal quality guidance tool for design process, because the quality of the preceding subtasks’ results will be assessed in the next task, where they are used as input data.

In real projects the number of back couplings is much higher because of the administrative process, where the accuracy of the input data will improve during design. In early stages of the design one has to work with very prelimi­nary and inaccurate information to produce preliminary results, such as cost estimates and space reservations, which have to be given in spite of missing data. Nevertheless even in such cases the whole decision tree must be gone through; the only difference is that missing data are replaced with an estimate. When missing data become available, the process is gone through again in or­der to review the plans. Such descriptions that cover all possible back cou­plings cannot be made, because completion of the projects varies among the different countries, branches, and partners that are involved. As a matter of fact, the nature of targeted design emphasizes the core idea of the design meth­odology. To achieve the optimal solution and all the original targets, one has to redesign all the tasks following the point at which a change, such as new in­put information, was made.

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CHAPTER 3 DESIGN METHODOLOGY OF INDUSTRIAL AIR TECHNOLOGY

TABLE 3.1 Design Methodology and Associated Tools Administrative Flow—Quality Assurance: Prestudies, Design, Construction, Maintenance Design Criteria Tools Given Data dependent only on the site location and do not change during Database Data Design process. Weather model Process Purpose: Identification of possible emission sources, Expert systems Description Occupational areas, effects of environmental parameters to production, needs for enclosure and ventilation. Division of process into such parts that their inputs and outputs can be defined. Databases Building Collection of properties of building layout, constructions, Databases Layout and Windows as basic values for load calculations. Construction Target Prediction of target levels for indoor and outdoor conditions Classifications Level Based on requirements of laws and orders, human health, Regulations Assessment Production processes and equipment, and type of premises and construction. Needed as a standard to which system solutions are compared. Source Characteristics of sources and calculations methods Calculation models Description For load calculation. Calculation Calculation of loads from different subprocesses. Building model Of local loads System Performance Local Examination of subprocesses in order to provide proper Calculation models Protection Working conditions by it or to reduce emissions to environment. Prefabricated In case use of local protection system effect on exposure of the process, load calculations shall be revised. Products Calculation of Calculation of total loads from different subprocesses Total loads And environment. System Based on technical calculations, conditions achievable by System description Selection Different systems are compared to target levels to identify And Acceptable systems, which are compared to each other Characterization And the most suitable system is selected on the basis Heat, mass, Of different parameters: Power and energy consumption And energy And investment and life cycle costs. Balances Equipment Based on technical specification, acceptable equipment is Equipment selection Selection Identified. Final selection is made on the same basis as in Programs and dia­ Selection of system. Grams Detailed Includes the following subtasks: detailed design of ventilation Duct design Design Systems, design of adjustment and control system, commissioning plan, programs and Diagrams CAD solutions (Drawing tools) Common items (built into tools): -Energy consumption -Ecological issues -Costs (construction, life cycle)

(continues)

TABLE 3.1 {continued) Administrative Flow—Quality Assurance: Prestudies, Design, Construction, Maintenance Construction/Commissioning Tools Construction Mounting design Management Materials handling Commissioning plan Evaluation Inspections and startup and functional performance tests, Performance tests Ot system, Checks Phase 1 Measurements Updating System descriptions CAD progra ms Records User instructions (Drawing tools) User training Training of operating and maintenance people Lectures Practical training Participating in the Evaluation Operating Time (Use) Evaluation of Functional performance tests in different situations Performance tests System, Phase 2 Maintenance Measures to keep ventilation system operating at the specified Maintenance plan Level economically. Monitoring Health surveil­ Lance Regular Measures to secure that system and equipment performance are Energy audits Checks Unchanged. Additionally, evaluation of the system toward new Environment audits Requirements. Assessment (COSSH) Process Adoption of the process changes by evaluating influences to Assessment Changes Ventilation system and to conditions. When needed, renewing (COSSH) Of ventilation system to meet targets. System simulation End of Process Demolition Design and completion of demolition, taking into account possible Assessment of the Of system Risks, (e. g., asbestos) Risk to health Special working Methods Reuse of Evaluation of the value and usefulness of the equipment and compo­ Condition analysis of Equipment Nents. The equipment Waste- Separation of different types of waste. Records of materi­ Handling Handling of problem waste. Als used Recycling materials. Marking of Components Common items (built into tools): -Energy consumption -Ecological issues -Costs (construction, life cycle)

CHAPTER 3 DESIGN METHODOLOGY OF INDUSTRIAL AIR TECHNOLOGY FIGURE 3.2 Decision tree of design process.

Correspondingly, when an existing industrial process is to be renewed, it is sufficient to redesign only such subtasks of the design methodology that are influenced by the change made. Naturally, this kind of procedure requires that the original design and previous changes have been documented properly.

A decision tree for Design Methodology is illustrated in Fig. 3.2. Each step in the tree is explained briefly below. The steps have also their own sub­trees, which are described separately.

Explanations of Fig. 3.2 Step I: Given Data

Identify and collect data that depend only on the site location and that do not change during the design process, such as outdoor conditions.

Step 2: Process Description

• Identify the industrial process and subprocesses.

• Identify possible emission sources, occupational areas, effects of environmental parameters, needs for enclosure and ventilation equipment.

• Divide process into parts such that their inputs from and outputs to the environment can be defined.

• When the process or subprocess is not well defined during the initial period of design, obtain the data from similar processes based on recent successful practices. Obtain and use more precise data as soon as possible.

Step 3: Building Layout and Construction

• Collect properties of building layout, structures, and openings and their properties as basic values for load calculations.

• Complete zoning of building based on division of the process and building layout.

• Make space reservations and add structures needed for ventilation equipment.

Step 4: Target Level Assessment

• Define target levels for indoor (zones) and outdoor (exhaust) conditions.

• Specify design conditions in which the target levels are to be met.

• Define target levels for the ventilation system, such as reliability, energy consumption, investment, life cycle costs, etc.

Step 5; Source Description

Clarify characteristics of the sources and calculation methods for calcula­tion of local loads.

Step 6: Calculation of Local Loads

Calculate loads from individual sources to the environment.

Step 7: Local Protection

Examine subprocesses (sources) in order to provide proper working con­ditions near them (local zones) or to reduce emissions to the environment.

Step 8: Calculation of Total Building Loads

• Calculate total loads (heat, humidity, contaminants) from different subprocesses and environment (building) to ventilated enclosure (zones).

• Take into account that loads are usually time dependent.

Step 9: Selection of the System

• Select acceptable systems based on target levels.

• Compare acceptable systems in order to choose the most desirable one.

• Use systems that allow maximum flexibility in air flow rates and control strategies when selection of systems is based on inaccurate (preliminary) data on production processes, volumes, and raw materials to be used in the building. Emission rates from these processes and total loads might be changed during the detailed design step.

• Consider constraints on the system selection, if some equipment has been already selected and installed in the earlier design period.

CHAPTER 3 DESIGN METHODOLOGY OF INDUSTRIAL AIR TECHNOLOGY

Step 10: Selection of Equipment

• Work out performance characteristics to the equipment.

• Select acceptable equipment based on performance characteristics.

• Compare acceptable equipment in order to choose the most desirable one.

• Make a technical specification of selected equipment.

Step 11: Detailed Design

• Do detailed layout and dimensioning design.

• Design adjustment and control system.

• Consider special issues such as thermal insulation, condensation risks, fire protection, and sound and vibration damping.

• Make commissioning plan.

Steps 12-14: Design of Conveying,

Cleaning and Discharge of the Pollutants

See details in Chapters 13 and 14.

Explanations of Back Couplings

BC I: Source Description —> Target Level Assessment

If some new agent is identified, the target level has to be defined for that

Agent too.

BC 2: Local Protection —> Calculation of Local Loads

If the local protection has an effect on the exposure of the source, recalcu­late the load.

BC 3: Local Protection —> Target Level Assessment

If defined target levels cannot be reached, reconsider target levels.

BC 4: Local Protection —> Process Description

Consider whether there is some process method to protect source/environ­ment. In that case, return to process description. For example, if thermal insula­tion is needed to reduce loads, consider what influence that has on the process itself (Insulation may, e. g., lead to a need to change material of equipment).

BC 5: Calculation of Total Building Loads —> Target Level Assessment

• Consider whether some source has governing role to total loads. At least, if returned from Selection of System, choose one of the two actions below.

• If some source has governing role over total loads, reconsider the target level of that local zone in order to reduce loads.

• If there is no source that governs total loads, reconsider the target level of main zones in order to reduce loads.

BC 6: Calculation of Total Building Loads —> Building Layout and Structures

If building loads have governing role over total loads, reconsider whether there is something that can be done with constructions (e. g., thermal insula­tion) to reduce loads.

BC 7: Selection of System —> Calculation of Total Building Loads

If target levels cannot be achieved with any system or it is not economi­cally possible, check whether something can be done with loads.

BC 8: Selection of Equipment —> Selection of System

If no acceptable equipment exists, reconsider Selection of System with available equipment.

BC 9; Detailed Design —> Building Layout and Structures

• Identify openings needed in structures.

• Identify additional space and structure needs for ventilation installations.

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