The Development and Full-Scale Experimental Validation of an Optimal Water Treatment Solution in Improving Chiller Performances

Abstract

An optimal solution, in combining physical and chemical water treatment methods, has been developed. This method uses a high voltage capacitance based (HVCB) electrodes, coupled with biocides to form a sustainable solution in improving chiller plant performances. In this study, the industrial full-scale tests, instead of laboratory tests, have been conducted on chiller plants at the size of 5000 RT to 10,000 RT cooling capacities under commercial operation for more than two years. The experimental results indicated that the condenser approach temperatures can be maintained at below 1˝C for over two years. It has been validated that the coefficient of performance (COP) of a chiller can be improved by over 5% by implementing this solution. Every 1˝C reduction in condenser approach temperature can yield approximately 3% increase on chiller COP, which warrants its future application potential in the HVAC industry, where T a can degrade by 1˝C every three to six months. The solution developed in this study could also reduce chemical dosages and conserve makeup water substantially and is more environment friendly.

Maximizing Thermal Energy Recovery from Drinking Water for Cooling Purpose

“…In any case, the TED system can be installed to (partly) replace less sustainable cooling methods; these can either be too energy-intensive methods (chillers) [19] or possibly methods with intense water spillage (i.e., wet cooling towers) [17,18]. For example, if a TED system replaces fully or partly the cooling provided by a wet cooling tower, electrical energy may be saved (depending on the atmospheric conditions related to the temperature of drinking water; under particularly cold atmospheric temperatures, wet cooling can reach comparably high COPs too [41,42]), and make-up water and the chemicals used to treat the circulating water will be spared.…”

“…For example, if a TED system replaces fully or partly the cooling provided by a wet cooling tower, electrical energy may be saved (depending on the atmospheric conditions related to the temperature of drinking water; under particularly cold atmospheric temperatures, wet cooling can reach comparably high COPs too [41,42]), and make-up water and the chemicals used to treat the circulating water will be spared. Moreover, the temperature approach (the difference between the exit temperature of the hot fluid and the entry temperature of the cold fluid) for a liquid-to-liquid heat exchanger is in the range of 1 to 2 • C. This means that, for equal drinking water and (wet bulb) outside temperatures, a TED system will be more efficient compared to cooling towers, which have a temperature approach of 4 to 8 • C [19]. If a TED system replaces (fully or partly) the cooling provided by a chiller, energy will for sure be saved (because the COPs of these systems are always by orders of magnitude different, typically ranging between 2.40 and 6.39 [42]).…”

“…In Amsterdam (the Netherlands), the energy required for space cooling of non-residential spaces amounts to 2162 TJ/y [15,16]. Providing this energy with traditional cooling methods (i.e., mechanical cooling or cooling towers) requires a huge amount of electricity and water and results in a high carbon footprint [17][18][19]. Hence, there is a need to explore more sustainable cooling resources.…”

Model-Based Evaluation of Air-Side Fouling in Closed-Circuit Cooling Towers

“…Information regarding the influence of air-side fouling on the performance of closed cooling towers available in literature is scarce, lacks information on the operating conditions as well as cooling tower geometries and shows large variations: while Qureshi reports a performance decrease of~5% for a scaling thickness of 0.1 mm on the air-side of the tube bundle, which is the same order of magnitude specified by CTI, Hartvig claims it to be around 30% under these conditions [8][9][10]. At 1 mm scaling thickness, the literature reports performance reductions in the range of 20% to 35% (Hartvig does not specify results for this thickness) [8,9,11]. Zaza et al model the scaling process on different types of cooling tower tubes in good agreement with their experiments on laboratory scale [12].…”