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The material presented here is based upon work supported by the National Science Foundation under Award No. EEC-0813570, Grant Number EPSC-1101284 . Any opinions, findings, and conclusions or recommendations expressed in this material are those of the author(s) and do not necessarily reflect the views of the National Science Foundation. Sustainable Liquid Desiccant System Research Mackenzie Betz , Esdras Murillo , Shan He , Ulrike Passe Dallas Center-Grimes High School, Iowa State University There are many techniques used for cooling buildings, one method is to dehumidify the air. Liquid desiccant systems can be used to reduce the relative humidity of a given area 30%- 80% if used correctly. Desiccant systems use sorption processes to remove water vapor out of the air and then heat the solution in a rechargeable box to evaporate the excess water to be expelled outside. Lowering the relative humidity in a building makes the air more comfortable, and reduces the reliance of an air conditioning system. BACKGROUND ABSTRACT The goal of my research project was to find a desiccant to be implemented into the liquid desiccant system and reduce relative humidity by at least 30%. The current desiccant being used is calcium chloride. The desiccant system’s results were analyzed, the system was tested many times to try to achieve 30% dehumidification. Ideally once the system can reduce relative humidity 30% it will be installed into the solar powered Interlock House to reduce energy consumption by reducing the reliance of the AC on electricity use. Organic desiccants were also researched to improve the system’s results, as well as remove some of the negative effects caused by CaCl . RESEARCH QUESTIONS How much is the current liquid desiccant system lowering the relative humidity? What organic desiccants can be implemented to improve the current liquid desiccant system? METHODS The current desiccant, calcium chloride is averaging 10% dehumidification, in its most ideal circumstances, and works best in high relative humidity input. Calcium chloride has not shown it can decrease the absolute humidity by 30% consistently like needed, and is also causing corrosion on the piping, that an organic desiccant would not. Many organic desiccants have a large percent dehumidification at only 50% relative humidity input. Although organic desiccants tend to be more expensive they wont cause corrosion and don’t require as strict of conditions as calcium chloride. Suggested Desiccants DISCUSSION & CONCLUSION RESULTS & DATA ANALYSIS OTHER WORK ACKNOWLEDGEMENT I would like to thank CBiRC and Iowa State University for supporting the YES program, Adah Lesham, Stacy Renfrow, Diana Loutsch, and Yadira Cano Camacho for their work. I would also like to thank Ulrike Passe, Shan He, Esdras Murillo for their mentorship and supervision during my internship, Iowa NSF EPSCoR for funding, and Joshua Mangler for his recommendation. REFERENCES AH= Absolute Humidity RH= Relative Humidity Pws= Water Saturation Pressure Pvw= Water Vapor Pressure T=Temperature (Celsius) A= 6.116441 m= 7.591386 Tn=240.7263 While keeping the input humidity constant, this compares the absolute and relative humidity. The AH shows a change, while the RH is almost the same for input and output. This shows that the output temperature of the air is cooler than the input. This data was taken as the input AH was growing throughout the experiment. This shows that the system achieves a higher percent dehumidification when the input AH is higher. While the liquid desiccant system is running, sensors are retrieving data which is used in the following equations to find the absolute humidity and relative humidity. These values are used with temperature to determine how the air feels. Teaching: Taught two classes of third and fourth graders about thermo-radiation, heat transfer, and what causes them to feel hot and cold. Cauc, C.K., and W.M. Worek. “Cosorption Processes of Triethylene Glycol in a Packed-Bed Dehumidifier.” HVAC & R Research. Online: Taylor & Francis, 2011. 189-210. Print. Kazemi, Pezhman, and Roya Hamidi. "Sensitivity Analysis of a Natural Gas Triethylene Glycol Plant in Persian Gulf Region." Petroleum & Coal. N.p., 9 Nov. 2010. Web. 17 July 2014. <http://www.vurup.sk/sites/vurup.sk/archivedsite/www.vurup.sk/pc/vol53_2011/issue1/pdf/pc_1_2011_kazemi_101.pdf>. Sun, Jin, and Robert W. Besant. International journal of heat and mass transfer. Oxford: Pergamon Press., 2005. Print. Prices found at chemistrystore.com Although silicon dioxide is cheaper, it comes already in a water solution. The triethylene glycol can have water added to it and work efficiently, it also has a stronger capability to remove contaminants from the air. Both desiccants are non-corrosive, and preform best at room temperature. ² Interlock House 1 1 2 2 2 2 Liquid Desiccant System Diagram Organic Desiccant Silicon Dioxide Triethylene Glycol Regeneration Temperature Up to 150˚C 60˚C - 240˚C Sorption Process Adsorbs water Absorbs water Removal Efficiency Can drop RH to 40% Adsorbs 40% it's own weight Has been proven to have 96% absorption efficiency Price 1 Gallon = $16.48 1 Gallon = $27.80
