The enhancement of water and energy conservation through condensed water reclamation for evaporative cooling towers

IF 2.6 Q2 WATER RESOURCES
Yiu-Kuen Leung, Ka Wai Eric Cheng
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Abstract

Although environmental groups have declaimed the application of greywater to alleviate water consumption, the progress of condensed water implementation for high-rise buildings was still sluggish. As greywater demands wastewater treatment before any application, the novelty of this study was to demonstrate the direct use of condensed water in an existing cooling water system without wastewater treatment. Considering there is barely any practical case study research to unveil the water-energy nexus in reclaiming condensed water for evaporative cooling tower systems, this research has signified that condensed water is a simple and low-budget application for water conservation and energy saving. Given that the condensed water possesses an intrinsic impurity-free property, the water-saving potentials have been amplified to the most tolerable total dissolved solids (TDS) of system water. Furthermore, it is beneficial that water quality control ameliorated the operating working conditions, the system performances were improved, and then less power was consumed. By getting rid of the wastewater treatment, consolidating the feasibility of practical direct-use application, and its sustainability for water and energy saving, this research may revive the attention of green building claimers to expedite its implementation and tie in the green building design. The condensed water derived from the electric ventilation system was reclaimed as an alternative water source for cooling without extra power consumption, which was ideal for concentration dilution and beneficial to descaling. An evaporative cooling system consumes tons of water, and the water losses are necessarily compensated by fresh water; this process occurs gradually over time and progressively escalates the TDS with time, which evocates water scale formations. Although the bleed-off (BO) that discharges the impurity-laden system water effectively lowers the TDS, it is not a water conservation measure, and the chemical effluent poses environmental hazards. The higher cycles of concentration (CoC) reduce the frequency of BO and sustain the full efficacy of antiscaling chemicals. Whenever water scales appear as a resistance of heat transfer deposit on the heat exchangers, the heat management capability is diminished and energy efficiency drops. The water and energy saving enhancement method was accomplished by reclaiming the condensed water and setting higher CoC.
通过蒸发冷却塔冷凝水回收提高节水节能效果
尽管环保组织一直在呼吁应用中水来减少用水量,但在高层建筑中应用冷凝水的进展仍然缓慢。由于中水在应用前需要进行废水处理,本研究的新颖之处在于展示了在现有冷却水系统中直接使用冷凝水而无需进行废水处理的方法。考虑到几乎没有任何实际案例研究揭示蒸发冷却塔系统回收利用冷凝水的水能关系,本研究表明冷凝水是一种简单、低成本的节水节能应用。由于冷凝水本身不含杂质,其节水潜力已被放大到系统水最可容忍的溶解固体总量(TDS)。此外,水质控制还改善了运行工作条件,提高了系统性能,降低了能耗。该研究摆脱了废水处理的束缚,巩固了实际直接应用的可行性,以及其节水节能的可持续性,可能会重新引起绿色建筑倡导者的关注,加快其在绿色建筑设计中的实施和应用。电动通风系统产生的冷凝水被回收利用,作为冷却的替代水源,无需额外的电力消耗,非常适合浓度稀释,有利于除垢。蒸发冷却系统需要消耗大量的水,而水的损失必然要由淡水来补偿;这一过程会随着时间的推移逐渐发生,TDS 也会随着时间的推移逐渐升高,从而唤起水垢的形成。虽然将含有杂质的系统水排出的排污(BO)可以有效降低 TDS,但这并不是一种节水措施,而且化学污水会对环境造成危害。较高的浓缩周期(CoC)可降低喷淋频率,维持防垢剂的全部功效。每当水垢作为传热阻力沉积在热交换器上时,热管理能力就会降低,能源效率也会下降。通过回收冷凝水和设置更高的 CoC,实现了节水节能的改进方法。
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来源期刊
Frontiers in Water
Frontiers in Water WATER RESOURCES-
CiteScore
4.00
自引率
6.90%
发文量
224
审稿时长
13 weeks
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