Thesis
Condensation of CO₂ in brazed plate heat exchangers
Washington State University
Master of Science (MS), Washington State University
2009
Handle:
https://hdl.handle.net/2376/102207
Abstract
The experimental study of carbon dioxide condensation in brazed plate heat exchangers is the main objective of this research project. The current level of concern for our environment is at an all-time high, and as such, it is important that we look to methods and resources that will lead to a cleaner and healthier future for the planet. This thesis details one such effort to reach this goal, focusing on how a natural refrigerant undergoes the condensation step of the refrigeration cycle in compact heat exchangers. Condensation flow consists of two phases, vapor and liquid, existing simultaneously, however, in order to analyze and formulate the two-phase flow characteristics, it is essential to characterize the single-phase flow through the tested minichannel heat exchangers. Three brazed plate heat exchangers with different interior configurations, each consisting of three channels, are considered and tested in this study. For the single-phase analysis, data were taken using hot and cold-water counter flowing through the middle and side channels, respectively. Data were also taken flowing hot water in the middle and chilled dynalene in the surrounding channels. The modified Wilson plot technique was applied to obtain single-phase heat transfer coefficients, and the Fanning friction factor was estimated for the pressure drop. The resulting correlations were within reasonable ranges of standard deviation and uncertainty, and compared well with other relevant studies. For the two-phase analysis, carbon dioxide was the working fluid, flowing through the middle channel, while dynalene, the cooling fluid, flowed through the side channels of the three different exchangers. Condensation of carbon dioxide occurred at saturation temperatures ranging from 0°F (-17.8°C) to -30°F (-34.4°C) and heat fluxes spanning 800 Btu/hr.ft2 (2.5 kW/m2) to 5,000 Btu/hr.ft2 (15.7 kW/m2). Comparisons of the two-phase heat transfer and pressure drop characteristics are given for the heat exchangers, and conclusions are made from the two-phase data. The purpose of this study is to mathematically understand the condensation behavior of CO2 in brazed plate heat exchangers; not to compare different refrigerants' capacities with that of CO2 or compare heat exchanger performances one with another.
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Details
- Title
- Condensation of CO₂ in brazed plate heat exchangers
- Creators
- Niel Martin Hayes
- Contributors
- Amir Jokar (Degree Supervisor)Stephen Solovitz (Committee Member) - Washington State University, Engineering and Computer Science (VANC), School ofWei Xue (Committee Member)
- Awarding Institution
- Washington State University
- Academic Unit
- Mechanical and Materials Engineering, School of
- Theses and Dissertations
- Master of Science (MS), Washington State University
- Publisher
- Washington State University; Pullman, Wash. :
- Identifiers
- 99900525175301842
- Language
- English
- Resource Type
- Thesis