ON THE EXPERIMENTAL STUDY OF COMPOSITE DESSICANTS FOR ENERGY EFFICIENT AIR DEHUMIDIFICATION
This paper presents the development and performance characterization of new composite desiccants. The main compositions for the composite desiccants include silica gel, lithium chloride, calcium chloride and bentonite. Different percentage compositions of these four components were tested to determine the optimal material composition for improving moisture removal capacity under varying inlet air temperature and humidity, and amount of moisture released under different regenerative temperature. For the first time, four-layered composite desiccants were developed and tested experimentally to determine their moisture removal capacity and moisture regeneration capacity at temperature of about 60oC under inlet air conditions similar to Singaporeâ€™s tropical climate. The performances of these composite desiccants were benchmarked with the performance of pure silica gel - the most commonly used desiccant in the market today. It was observed experimentally, that employing a four-layered composite desiccant, comprising silica-gel (SiO2), Bentonite, Lithium Chloride (LiCl), and Calcium Chloride (CaCl2), has enabled greater moisture removal capacity for varying inlet air temperature and humidity ranging from 25 to 35oC and 55 to 95% relative humidity (RH). The percentage improvements, in contrast to pure silica gel, are 14 to 22.5%, and 10 to 26.3% for varying inlet air temperature and varying inlet RH, respectively.
KEYWORDS: experiments; composite desiccant; dehumidification; energy efficiency
 Arundel, Sterling E, Bigging J, Sterling T. (1986) Indirect health effects of relative humidity in indoor environment. Environmental Health Perspectives, 65:351-361.
 Air-Con System Efficiency Primer: A Summary. (2011). [Online]. Available: http://app.nccs.gov.sg/data/resources/docs/TechPrimers/Aircon%20Primer.pdf?AspxAutoDetectCookieSupport=1. [Accessed 23 February 2013].
 Daou K, Wang R, Xia Z. (2006) Desiccant cooling air conditioning: a review. Renewable and Sustainable Energy Reviews, 10:55-77.
 Katejanekarn T, Kumar S. (2008) Performance of a solar-regenerated liquid desiccant ventilation pre-conditioning system. Energy and Buildings, 40:1252â€“1267.
 Techajunta S, Chirarattananon S, Exell R. (1999) Experiments in solar simulator on solid desiccant regeneration and air dehumidification for air conditioning in a tropical humid climate. Renewable Energy, 17:549-568.
 Li X, Li Z, Xia Q and Xi H. (2007) Effects of pore sizes of porous silica gels on desorption activation energy of water vapour. Applied Thermal Engineering, 27:869-876.
 Demir H, Mobedi M, Ulku S. (2011) Microcalorimetric investigation of water vapor adsorption on silica gel. J Therm Anal Calorim, 105:375-382.
 Chang K, Wang H, Chung T. (2004) Effect of regeneration conditions on the adsorption dehumidification process in packed silica gel beds. Applied Thermal Engineering, 24:735-742.
 Jia C, Dai Y, Wu J, Wang R. (2007) Use of compound desiccant to develop high performance. International Journal of Refrigeration, 30:345-353.
 Ng K, Chua H, Chung C, Loke C, Kashiwagi T, Akisawa A, Saha B. (2001) Experimental investigation of silica gel-water adsorption isotherm characteristics. Applied Thermal Engineering, 21:1632-1642.
 Ã–zdinÃ§ MC, Yildirim M. (2004) Energy and exergy analyses of an experimental open-cycle desiccant cooling system. Applied Thermal Engineering, 24:919-932.
 Proverbio E, Restuccia G, Russo F, Bonaccorsi L, Freni A. (2006) Zeolite coated copper foams for heat pumping applications, Microporous and Mesoporous Materials, 91:7-14.
 Aristov Y, Restuccia G, Cacciola G, Parmon V. (2002) A family of new working materials for solid sorption air conditioning systems. Applied Thermal Engineering, 22:191-204.
 Smith, DM, Lucky, EA, Natividad, V. (2000) Desiccant composition. USA Patent 6559096.
 Zhang X, Sumathy K, Dai Y, Wang R. (2006) Dynamic hygroscopic effect of the composite material used in desiccant rotary wheel. Solar Energy, 80:1058-1061.
 Zhang X, Qiu L. (2007) Moisture transport and adsorption on silica gelâ€“calcium chloride composite adsorbents. Energy Conversion and Management, 48:320-326.
 Mandegari M, Pahlavanzadeh H. (2009) Introduction of a new definition for effectiveness of desiccant wheels. Energy, 34:797-803.
 Jia C. (2011) Study on adsorption mechanism and dehumidification property of composite desiccant. Advanced Materials Research, 150-151:912-916.
 Gordeeva L, Grekova A, Krieger T, Aristov. (2009) Adsorption properties of composite materials (LiCl + LiBr)/silica. Microporous and Mesoporous Materials, 12:262-267.
 Thoruwa T, Johnstone C, Grant A, Smith J. (2000) Novel, low cost CaCl2 based desiccants for solar crop drying applications. Renewable Energy, 19:513-520.
 Tretiak C, Ben Abdallah N. (2009) Sorption and desorption characteristics of a packed bed of clayâ€“CaCl2 desiccant particles. Solar Energy, 83:1861-1870.
How to Cite
The IIUM Engineering journal follows the open access policy.