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Run-around membrane energy exchanger performance and operational control strategies

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dc.contributor.advisorSimonson, Careyen_US
dc.contributor.advisorBesant, Boben_US
dc.contributor.committeeMemberTorvi, Daviden_US
dc.contributor.committeeMemberNguyen, Naen_US
dc.contributor.committeeMemberSchoenau, Gregen_US
dc.creatorErb, Blakeen_US
dc.date.accessioned2009-12-19T14:54:31Zen_US
dc.date.accessioned2013-01-04T05:12:15Z
dc.date.available2011-01-18T08:00:00Zen_US
dc.date.available2013-01-04T05:12:15Z
dc.date.created2009-12en_US
dc.date.issued2009-12en_US
dc.date.submittedDecember 2009en_US
dc.description.abstractA run-around membrane energy exchanger (RAMEE) is a novel energy exchanger that is capable of transferring both heat and moisture, which can significantly reduce the energy required to condition outdoor ventilation air. The RAMEE uses a liquid desiccant to transfer both heat and moisture between two remote air streams, making it appropriate for many applications, including building HVAC retro-fits. Both initial system start-up and changing outdoor conditions require time for the desiccant to undergo changes in both temperature and concentration, and can cause significant transient delays in system performance. Under some conditions, these transients may be beneficial by increasing the system performance. However under some conditions, the transient delays can cause a substantial decrease in performance. This thesis focuses on the development of control strategies that can be used to reduce unwanted transient delays. In order to develop these control strategies, the performance of a RAMEE is first investigated using both experimental and numerical methods. The transient numerical and experimental effectiveness results show satisfactory agreement, with a maximum root mean squared error of 10%. Both the numerical and experimental data show that a long transient time of several hours, or even several days, can occur upon initial system start-up. The numerical model is used to investigate several control strategies to reduce unwanted transient delays. The control strategies investigated are: solution and air flow control, air flow bypass, solution temperature control, and solution concentration control. The solution and air flow control are shown to reduced the start-up transient time by up to 11%, but require either a reduction in air flow or an increase in solution pumping costs. Air flow bypass proves to be a better option which provides a 16% reduction in transient time, and only requires that a bypass damper be provided for each exchanger. Solution temperature control is capable of essentially eliminating the thermal transient time (time required for the solution to reach operating temperature), but the thermal transient time is found to be a minor contributor to the overall transient time (time required for the solution to reach operating temperature and concentration) when the initial concentration of the solution is different than the steady-state concentration. When thermal and moisture transients exist, total transient times may be over 18 days. A practical temperature and concentration control strategy is developed, which can reduce transient delays by over 90% and increase performance during variable outdoor weather conditions.en_US
dc.identifier.urihttp://hdl.handle.net/10388/etd-12192009-145431en_US
dc.language.isoen_USen_US
dc.subjectair-to-airen_US
dc.subjecteffectivenessen_US
dc.subjectdehumidifyingen_US
dc.subjecthumidifyingen_US
dc.subjectcoolingen_US
dc.subjectheatingen_US
dc.subjectenergyen_US
dc.subjectmembraneen_US
dc.subjectdesiccanten_US
dc.subjectenergy recoveryen_US
dc.subjectHVACen_US
dc.titleRun-around membrane energy exchanger performance and operational control strategiesen_US
dc.type.genreThesisen_US
dc.type.materialtexten_US
thesis.degree.departmentMechanical Engineeringen_US
thesis.degree.disciplineMechanical Engineeringen_US
thesis.degree.grantorUniversity of Saskatchewanen_US
thesis.degree.levelMastersen_US
thesis.degree.nameMaster of Science (M.Sc.)en_US

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