Energy
Z. Rahimi-Ahar; M. Sadegh Hatamipour
Abstract
Humidification-dehumidification (HD) desalination has been identified as a sustainable, reliable, and energy-efficient technology for producing freshwater on a small scale. VP-HD systems operated at one-stage, multi-stage, and multi-feeding vacuum humidification-over atmospheric pressure dehumidification ...
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Humidification-dehumidification (HD) desalination has been identified as a sustainable, reliable, and energy-efficient technology for producing freshwater on a small scale. VP-HD systems operated at one-stage, multi-stage, and multi-feeding vacuum humidification-over atmospheric pressure dehumidification arrangements can be the recent modifications of an HD system. The present study offers a theoretical investigation and experimental verification of two VP-HD systems, encompassing both sub-atmospheric pressure humidification and over-atmospheric dehumidification. Two designs are evaluated, one comprising a three-stage humidification setup and the other featuring a three-feeding one-stage humidification apparatus. The results show which design has better performance than previous conventional and variable pressure HD systems. The parametric analysis reveals that an upsurge in freshwater generation is observed with an increase in air temperature, feed salinity, and a decrease in humidifier pressure. Additionally, an optimal water-to-air ratio is identified. The study further highlights that multi-stage humidification yields better results concerning freshwater productivity and specific power consumption. Three-stage humidification is found to be the most efficient in terms of freshwater production and specific power consumption, achieving the highest values of 1.93 L h-1 m-2 and 0.21 kWh L-1, respectively. The agreement between theoretical and experimental outcomes is deemed satisfactory.
Transport Phenomena,
Leila Omidvar Langroudi; hassan pahlavanzadeh; sara nanvakenari
Volume 13, Issue 4 , November 2016, , Pages 96-112
Abstract
This study introduces an experimental and theoretical investigation of the performance of a proposed air dehumidification system using a nanofluid of γ-alumina nano-particles in LiBr/H2O as a desiccant. Comparative experiments organized using a central composite design were carried out to evaluate ...
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This study introduces an experimental and theoretical investigation of the performance of a proposed air dehumidification system using a nanofluid of γ-alumina nano-particles in LiBr/H2O as a desiccant. Comparative experiments organized using a central composite design were carried out to evaluate the effects of six numerical factors (air velocity, desiccant flow rate, air humidity ratio, desiccant solution concentration, air temperature, desiccant temperature) and one categorical factor (adding nano-particles) on outlet air humidity ratio and outlet air temperature as responses. Reduced quadratic models were derived for each response. The results revealed that the concentration of LiBr/H2O solution and air temperature had the largest effect on outlet air humidity ratio and outlet air temperature, respectively. It was found that the average increase in mass transfer rate was 12.23% and heat transfer rate was 13.22% when γ-alumina nano-particles (0.02% wt) were added to the LiBr/H2O solution. The average increase in mass transfer coefficient was 22.73% and heat transfer coefficient was 26.51%.