A review of desiccant evaporative cooling systems in hot and humid climates

Manaf, Ismanizam Abd; Durrani, Faisal; Eftekhari, Mohammad

doi:10.1080/17512549.2018.1508364

Cited by 16 publications

(6 citation statements)

References 72 publications

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“…EC works best in hot and dry conditions as it relies on the removal of sensible heat and for it to be extended to hot and humid regions will require that the air be indirectly cooled by incorporation of desiccation medium before EC (Misra & Ghosh, 2018). Use of indirect air-cooling combined with evaporative cooling (IAC+EC) in for provision of cool environment for storage of fresh produce is undocumented and a new research focus (Manaf, Durrani, & Eftekhari, 2018).…”

Section: Introductionmentioning

confidence: 99%

Effects of indirect air cooling combined with direct evaporative cooling on the quality of stored tomato fruit

Sibanda

Workneh

2019

CyTA - Journal of Food

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A 53 m 3 solar-powered evaporative cooler for temporary storage of tomato fruit was developed to improve the shelf life of tomatoes under hot and humid climatic conditions. This study investigated the effect of indirect air-cooling combined with evaporative cooling (IAC+EC), maturity stage at harvesting and period of storage on the quality of tomatoes. The effect of total soluble solids, firmness, color, physiological weight loss (PWL), and marketability of tomatoes (star 9037) was investigated by monitoring the storage of green and pink maturity stage harvested fruit over 28 days under both IAC+EC and ambient conditions. The three factors had a significant effect (P < .001) on the overall quality of tomatoes. The tomatoes stored in the IAC+EC system were 18.9% firmer, maintained 10.5% lower concentration of sugars, increased the hue angle by 3%, had 6.31% lower PWL and were 24.8% more marketability than tomatoes stored under ambient conditions. The tomatoes harvested at the green stage were 20.2% firmer, had 6.6% lower total soluble content, increased the hue angle by 4.9%, had a 3.1% lower PWL, and were 11.6% more marketable than the pink harvested tomatoes. This study clearly demonstrated the efficacy of IAC+EC under sub-humid and hot conditions in improving the quality and marketability and increasing the shelf life of tomatoes by reducing the rate of ripening and utilization of sugar. Efectos de la refrigeración indirecta por aire combinada con refrigeración por evaporación directa en la calidad de tomates almacenados RESUMEN Para efectos del presente estudio se fabricó un enfriador por evaporación de 53 m 3 activado mediante energía solar, el cual se destinó al almacenamiento temporal de tomates, mejorando su vida útil en condiciones climáticas cálidas y húmedas. Al respecto, el estudio investigó el efecto del enfriamiento causado por aire indirecto combinado con el enfriamiento causado por evaporación (IAC+EC), la etapa de madurez de los tomates en el momento de la cosecha y el impacto del periodo de almacenamiento sobre la calidad de los tomates. Monitoreando el almacenamiento durante 28 días-bajo IAC+EC y condiciones ambientales-de tomates verdes y rosados cosechados en la etapa de madurez se investigaron: el efecto de los sólidos solubles totales, la firmeza, el color, su pérdida de peso fisiológica y la comerciabilidad de los tomates (star 9037). Se constató que los tres factores tuvieron un efecto significativo (P <.001) en la calidad general de los tomates. Los tomates almacenados en el sistema IAC+EC fueron 18.9% más firmes, exhibieron una concentración de azúcares 10.5% más baja, mostraron un aumento de 3% en el ángulo de tono, una pérdida de peso fisiológica (PWL) 6.31% más baja y eran 24.8% más comercializables que los tomates almacenados bajo condiciones ambientales. Los tomates cosechados en la etapa verde fueron 20.2% más firmes, tuvieron un contenido soluble total 6.6% más bajo, mostraron un aumento de 4.9% en el ángulo de tono, presentaron un PWL 3.1% más bajo y eran 11.6% más comercializabl...

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Section: Introductionmentioning

confidence: 99%

Effects of indirect air cooling combined with direct evaporative cooling on the quality of stored tomato fruit

Sibanda

Workneh

2019

CyTA - Journal of Food

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“…This proposed concept could be used as a substitute or to supplement the year-round freshwater production in areas with access to coastal water bodies or transported to distant inland locations, thereby assisting in alleviating water scarcity while also maintaining ecosystems and the environment. We note that the proposed concept of utilizing atmospheric humidity for potable water production is notably different from previous articulations which include water production over land by radiative cooling [30][31][32][33][34][35][36][37][38] , active cooling by vapor compression refrigeration cycle [39][40][41][42][43][44][45][46][47][48] or thermoelectric cooling [49][50][51][52][53] and desiccant method 40,[54][55][56][57][58][59][60][61][62][63][64][65] . These alternate solutions are not scalable to address water scarcity concern in a significant way because the amount of moisture flux available in the atmosphere over land is substantially smaller than over the large oceanic sources.…”

Section: Discussionmentioning

confidence: 86%

Increasing freshwater supply to sustainably address global water security at scale

Rahman

Kumar

Domínguez

2022

Sci Rep

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While significant parts of the globe are already facing significant freshwater scarcity, the need for more freshwater is projected to increase in order to sustain the increasing global population and economic growth, and adapt to climate change. Current approaches for addressing this challenge, which has the potential to result in catastrophic outcomes for consumptive needs and economic growth, rely on increasing the efficient use of existing resources. However, the availability of freshwater resources is rapidly declining due to over-exploitation and climate change and, therefore, is unlikely to sustainably address future needs, which requires a rethink of our solutions and associated investments. Here we present a bold departure from existing approaches by establishing the viability of significantly increasing freshwater through the capture of humid air over oceans. We show that the atmosphere above the oceans proximal to the land can yield substantial freshwater, sufficient to support large population centers across the globe, using appropriately engineered structures. Due to the practically limitless supply of water vapor from the oceans, this approach is sustainable under climate change and can transform our ability to address present and future water security concerns. This approach is envisioned to be transformative in establishing a mechanism for sustainably providing freshwater security to the present and future generations that is economically viable.

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“…As the process air is continuously dehumidified, the desiccant materials become saturated, and sorption ability decreases, which requires a regeneration process [52]. Thermal energy is usually used to regenerate the desiccant unit, and this could be achieved using solar energy, electrical heater, electro-osmotic and waste heat [53][54][55]. To improve the desiccant system performance, many studies have been conducted from the aspects of improving water adsorption capacity and reducing regeneration temperature [56].…”

Section: Overview Of Solid Desiccant Dehumidificationmentioning

confidence: 99%

Evaporative Cooling Integrated with Solid Desiccant Systems: A Review

et al. 2021

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Evaporative cooling technology (ECT) has been deemed as an alternative to the conventional vapor-compression air conditioning system for dry climates in recent years due to its simple structure and low operating cost. Generally speaking, the ECT includes two types of different technologies, direct evaporative cooling (DEC) and indirect evaporative cooling (IEC). Both technologies can theoretically reduce the air temperature to the wet-bulb temperature of outdoor air. The major difference between these two technologies is that DEC will introduce extra moisture to the supply air while IEC will not. The enhanced IEC, Maisotsenko-cycle (M-cyle) IEC, can even bring down the air temperature to the dew point temperature. The ECT integrated with solid desiccant systems, i.e., solid desiccant-assisted evaporative cooling technologies (SDECT), could make the technology applicable to a wider range of weather conditions, e.g., weather with high humidity. In this paper, the recent development of various evaporative cooling technologies (ECT), solid desiccant material and the integration of these two technologies, the SDECT, were thoroughly reviewed with respect to their configuration, optimization and desiccant unit improvement. Furthermore, modeling techniques for simulating SDECT with their pros and cons were also reviewed. Potential opportunities and research recommendations were indicated, which include improving the structure and material of M-cycle IEC, developing novel desiccant material and optimizing configuration, water consumption rate and operation strategy of SDECT system. This review paper indicated that the SDECT system could be a potential replacement for the conventional vapor-compressed cooling system and could be applied in hot and humid environments with proper arrangements.

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A review of desiccant evaporative cooling systems in hot and humid climates

Cited by 16 publications

References 72 publications

Effects of indirect air cooling combined with direct evaporative cooling on the quality of stored tomato fruit

Effects of indirect air cooling combined with direct evaporative cooling on the quality of stored tomato fruit

Increasing freshwater supply to sustainably address global water security at scale

Evaporative Cooling Integrated with Solid Desiccant Systems: A Review

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