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Regional Chilling Networks at the University of Arizona: Anticipating an Eventual Ban on 1,1,1,2-Tetrafluoroethane

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Regional Chilling Networks at the University of Arizona: Anticipating an Eventual Ban on 1,1,1,2-Tetrafluoroethane REGIONAL CHILLING NETWORKS AT THE UNIVERSITY OF ARIZONA: ANTICIPATING AN EVENTUAL BAN ON 1,1,1,2-TETRAFLUOROETHANE Item Type text; Electronic Thesis Authors Yarnall, Luke Brian; Batts, Iesha; Sia, Jasper; Zinyemba, Rodney Publisher The University of Arizona. Rights Copyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author. Download date 30/09/2021 23:53:40 Item License http://rightsstatements.org/vocab/InC/1.0/ Link to Item http://hdl.handle.net/10150/613808 REGIONAL CHILLING NETWORKS AT THE UNIVERSITY OF ARIZONA: ANTICIPATING AN EVENTUAL BAN ON 1,1,1,2-TETRAFLUOROETHANE By LUKE BRIAN YARNALL ____________________ A Thesis Submitted to The Honors College In Partial Fulfillment of the Bachelors Of Science Degree With Honors in Chemical Engineering THE UNIVERSITY OF ARIZONA MAY 2016 Approved by: ____________________ Dr. Kim Ogden Department of Chemical and Environmental Engineering Abstract 1,1,1,2-tetrafluoroethane, or R134a, is a hydrofluorocarbon refrigerant currently used in the University of Arizona’s central chilling networks. Due to its high global warming potential, environmental regulators in the USA and the EU have begun its phase-out. To determine the suitability of R134a substitutes, the UA central chilling plants were simulated through a purpose-built computational thermodynamic model constructed in Microsoft Excel with extensive coding in Visual Basic for Applications. The best currently available alternative refrigerant was determined to be 2,3,3,3- tetrafluoropropene, or R1234yf. However, R1234yf was substantially less apt than R134a. The Coefficient of Performance, which is the ratio between the cooling capacity provided and the energy input to the system, was estimated to be 0.081 for R1234yf, versus 1.065 for R134a. Environmental analysis found that the CO 2 equivalent emissions from an R1234yf system would greatly exceed those of a comparable R134a system under typical conditions. Similarly, economic analysis revealed that the price of an R1234yf plant surpassed the price of a similar R134a plant by roughly an order of magnitude. Our work found no suitable replacement for R134a in this application with today’s technology. Therefore, we discuss a number of recommendations on both a plant level and a nationwide policy level in order to establish a path forward towards effective emission reduction in district cooling applications. Statement of roles and responsibilities of each group member The technical core of the project was completed by two Honors students, Luke Yarnall and Jasper Sia. Luke Yarnall prepared the final document and carried out the majority of the thermodynamic and computational modelling, while Jasper Sia developed the economic analysis and much of the plant design. Rodney Zinyemba conducted health, safety, and environmental analysis, while Iesha Batts carried out much of the day-to-day project organization. A more detailed enumeration of each member’s contributions is available below: Iesha Batts • Drafted introduction with Luke • Pricing and design of ice banks • Creation design day poster • Creation of preliminary Block and Process Flow Diagrams • Organizational duties, including o Preliminary Basis of Design o Gantt Chart o College of Engineering Design Day management • Aided other group members with specific smaller tasks Jasper Sia • Estimated the costs of all equipment except the ice banks. • Estimated the total capital investments, operating costs (total production costs), and NPV. • Designed and wrote equipment descriptions, rationale, and optimizations for all the heat exchangers. • Estimated the initial and annual costs of the refrigerants for R-134a and R-1234yf. • Estimated the electricity and gas cost for the plant using R-1234yf. • Estimated the workers’ salaries for the plant using R-1234yf. • Wrote appendices relating to the work done described above. • Developed the equipment table. Luke Yarnall • Developed the central thermodynamic model of the refrigeration cycle and its implementation in Excel and VBA, including determining the total area needed for the condensers/evaporators (credit to Jasper for help in conceptualizing/planning the solution and for auditing it for errors). • Found and fit most of the data required for the thermodynamic model (see Section Error! Reference source not found. ) • Total area calculations for heat exchangers • Horsepower and head calculations for pumps • Coordinated tour of facility • Sections of report written: o Introduction (with Iesha) o Much of section 2 o Equipment description/rationale for pumps, valves o Final BFDs and PFDs (Iesha produced the initial drafts early in the semester) o Stream tables o Appendices related to the above calculations o Conclusions & Recommendations o Edited and compiled final document Rodney Zinyemba • Wrote Safety and Environmental Section • Eliminated refrigerants that were undesireable a priori , e.g. CFCs, HCFCs, and inapplicable technologies. • Waste Management calculations: o Environmental analysis of refrigerants (double checked calculations with Luke) o Energy source comparison (double checked my work with Luke) o Leakage rate sensitivity analysis (checked my calculations with Luke) o Did the Clean Air Act Pollutant Calculations, Acidification Potential and Photochemical Ozone Formation Potential Calculations o Ran Data Query from EPA and U.S. Energy Information Administration for the Irvington Generation Station • Hazardous Waste Risk Assessment Calculation Regional chilling networks at the University of Arizona: Anticipating an eventual ban on 1,1,1,2-tetrafluoroethane April 29, 2016 Prepared for CHEE 443 Taught by Dr. Kim Ogden Iesha Batts Jasper Sia Luke Yarnall Rodney Zinyemba Batts, Sia, Yarnall & Zinyemba Pg. 2 Table of contents Section 1. Introduction and Background .......................................................................... 4 1.1 Overall goal ........................................................................................................... 4 1.2 Current market information ................................................................................... 5 1.3 Project premises and assumptions ......................................................................... 6 Section 2. Overall Process Description, Rationale and Optimization .............................. 8 2.1 Rationale for process choice ............................................................................... 11 2.2 Associated tables ................................................................................................. 13 Section 3. Equipment Description, Rationale and Optimization ................................... 19 3.1 Compressor design .............................................................................................. 19 3.2 Ice Banks ............................................................................................................. 19 3.3 Heat Exchanger: Cooling Tower ......................................................................... 19 3.4 Heat Exchanger ................................................................................................... 21 3.5 Heat Exchanger – Ethylene Glycol and Product Water ...................................... 24 3.6 Centrifugal pumps ............................................................................................... 25 3.7 Valves .................................................................................................................. 26 3.8 Flash Vessel......................................................................................................... 27 Section 4. Safety/Environmental Factors ....................................................................... 27 4.1 Safety Statement – Overall Overview with Equipment Used in the Heating and Cooling System ......................................................................................................................... 27 4.2 Microscopic View – Chemicals Present in the Heating and Cooling System .... 30 4.3 Environmental regulations associated with the chemicals used in the cooling system 34 4.4 Environmental Impacts ....................................................................................... 35 4.5 Environmental Issues to consider with changes associated with new Refrigerant 38 4.6 Hazardous Waste Risk Assessment Analysis...................................................... 41 Section 5. Economic Analysis ........................................................................................ 41 5.1 Inflation ............................................................................................................... 42 5.2 Total Capital Investment ..................................................................................... 42 5.3 Total Production Cost / Operating Cost .............................................................. 45 5.4 Feedstock and Utilities ........................................................................................ 46 5.5 Direct Manufacturing Cost .................................................................................. 47 5.6 Total Production Cost.......................................................................................... 49 Batts, Sia, Yarnall & Zinyemba Pg. 3 5.7 Net Present Value ...............................................................................................
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