Evaluation of using thermoelectric coolers in a dehumidification system to generate freshwater from ambient air

Dropwise condensation of atmospheric water vapor is important in multiple practical engineering applications. The roles of environmental factors and surface morphology/chemistry on the condensation dynamics need to be better understood to enable efficient water-harvesting, dehumidication, and other psychrometric processes. Systems and surfaces that may promote faster condensation rates and selfshedding of condensate droplets could lead to improved mass transfer rates and higher water yields in harvesting applications. In the present study, experiments are performed in a facility that allows visualization of the condensation process on a vertically oriented, hydrophobic surface at a controlled relative humidity and surface subcooling temperature. The distribution and growth of water droplets are monitored across the surface at different relative humidities (45%, 50%, 55%, and 70%) at a constant surface subcooling temperature of 15 °C below the ambient temperature. The droplet growth dynamics exhibits a strong dependency on relative humidity in the early stages during which there is a large population of small droplets on the surface and single droplet growth dominates over coalescence effects.At later stages, the dynamics of droplet growth is insensitive to relative humidity due to the dominance of coalescence effects. The overall volumetric rate of condensation on the surface is also assessed as a function of time and ambient relative humidity. Low relative humidity conditions not only slow the absolute rate of condensation, but also prolong an initial transient regime over which the condensation rate remains significantly below the steady-state value.Keywords: dropwise condensation, relative humidity, growth dynamics, droplet distribution,

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“…Condensation of atmospheric water vapor is exploited in water harvesting [1]- [2], dehumidification Error! Reference source not found.…”

Section: Introductionmentioning

confidence: 99%

The effect of relative humidity on dropwise condensation dynamics

Castillo

Weibel

Garimella

2015

International Journal of Heat and Mass Transfer

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“…Active thermal window (ATW) and transparent active thermoelectric wall (PTA) were also introduced for room cooling application in applications where conventional air-conditioning Bringing Thermoelectricity into Reality system is not easy to install [28,29]. Thermoelectric cooling has also been applied in other occasions, such as generating fresh water [30][31][32][33] and active building envelope system [7,34]. TE systems can be directly connected to a PV panel.…”

Section: Applications Using Thermoelectric Coolersmentioning

confidence: 99%

Thermoelectric Cooling

Atta¹

2018

Bringing Thermoelectricity Into Reality

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In this chapter, design and analysis study of thermoelectric cooling systems are described. Thermoelectric (TE) cooling technology has many advantages over the conventional vapor-compression cooling systems. These include: they are more compacted devices with less maintenance necessities, have lower levels of vibration and noise, and have a more precise control over the temperature. These advantages have encouraged the development of new applications in the market. It is likely to use TE modules for cooling the indoor air and hence compete with conventional airconditioning systems. These systems can include both cooling and heating of the conditioned space. In order to improve the performance of the TE cooling systems, the hot side of the TE should be directly connected to efficient heat exchangers for dissipation of the excessive heat. Finally, TE cooling systems can be supplied directly by photovoltaic to produce the required power to run these cooling systems.

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“…Several literatures have reported on the performance of the water generated from the atmospheric water vapor via TECs. Milani et al [19] used psychrometric analysis to investigate the influence of relative humidity variation on saturation temperature, power consumption, water production rate and the economy of generated water in maximal thermal conditions. Vian et al [20] used theoretical and experimental methods to investigate the performance of thermoelectric dehumidifiers with different input power, inlet temperature and humidity, and concluded that the water productivity could reach 0.969 L/day.…”

Section: Introductionmentioning

confidence: 99%

“…The effect of using the discharged air from the cold side of the TEC to cool the hot side has been rarely discussed in open literature. Additionally, it has been demonstrated that the heat transfer rate between the cold side and near air in the condition of drop-wise condensation is 10 times larger than that in the condition of film condensation [19], therefore, the wetting property of cold side surface was an important factor influencing the amount of water generated and it is worthy to be studied further. Either the utilization of discharged air or the hydrophobic material theoretically can reduce the energy requirement of a TEC device.…”

Section: Introductionmentioning

confidence: 99%

Experimental Study and Performance Analysis of a Portable Atmospheric Water Generator

Zhen

et al. 2019

Energies

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Found in some specific scenarios, drinking water is hard for people to get, such as during expeditions and scientific investigations. First, a novel water generator with only two thermoelectric coolers (Model A) is designed for extracting water from atmospheric vapor and then experimentally studied under a small inlet air flow rate. The impact of operating conditions on surface temperatures of cold/hot sides and water yield are investigated, including the air flow rate and humidity. Alternately, to determine the super performance of Model A, a comparative experiment between Model A and a reference model (Model B) is carried out. The results suggest that both the cold/hot temperature and water yield in Model A increases with the humidity and air flow rate rising. Seen in comparisons of Model A and Model B, it is found that, at an air humidity of 90% and air flow rate of 30 m3/h, the total water yield was increased by 43.4% and the corresponding value reached the maximum increment of 66.7% at an air humidity of 60% and air flow rate of 30 m3/h. These features demonstrate the advantage of Model A especially in low air humidity compared to Model B.

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Evaluation of using thermoelectric coolers in a dehumidification system to generate freshwater from ambient air

Cited by 90 publications

References 21 publications

The effect of relative humidity on dropwise condensation dynamics

The effect of relative humidity on dropwise condensation dynamics

Thermoelectric Cooling

Experimental Study and Performance Analysis of a Portable Atmospheric Water Generator

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