Chilled Water Storage Feasibility with District Cooling Chiller in Tropical Environment

Abstract

The difficulties of efficiently operating a chiller cooling system are manifest in the high-energy consumption under partial-cooling loads. The performance of a chiller cooling system declines when operating away from the optimal design conditions, which is typically 75% of chiller capacity. One pathway has been found to overcome this problem using multiple smaller chillers within the same chiller plant, accompanied by a smart control system that is designed and constructed based on the cooling demand profile. Thermal energy storage integration with chiller cooling system is proposed to shave the cooling peak demand. This can be achieved by storing chilled water during the lower electricity-tariff period by the thermal energy storage system, which will then be discharged during the higher tariff-rate, thus, aiming for sustainable operating cost. The present paper studies the feasibility of sensible thermal energy storage to be integrated with two chillers, of 30-ton capacity each, under hot-and-humid climates. A computational model validated with experimental results is developed for three chiller cooling system case scenarios. The smart control scenario, as well as the thermal energy storage scenario results, showed great potential for energy and electricity cost saving. In addition, the carbon dioxide emissions reduction is calculated based on the amount of energy saving.

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“…In order to achieve a lower electricity price, the DHC sector has great potential when implementing thermal-energy-storage (TES) technologies [121]. Quabeh et al [134] integrated a TES system into district cooling for shaving the cooling peak demand. It was found that more than 30% of the peak-demand load was shaved for as long as 10 h, resulting in the elimination of about 30% of the initial plant capacity.…”

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“…He also mentions that temperature-change mate-Open Journal of Energy Efficiency rials require significantly larger space than phase-change materials. Al Quabeh et al [27] have reported on chilled water storage in DC systems. The authors stated that the operation of optimal chillers is achieved at around 75% of their capacity.…”