Performance of an integrated cooling system combining a cooling tower and a pipe-embedded phase-change-material slab roof

doi:10.19799/j.cnki.2095-4239.2024.0010

Abstract

Abstract:

To enhance the performance of phase-change-material (PCM) slab roofs, this study proposes an integrated cooling system combining a cooling tower with a pipe-embedded PCM slab roof. Further, leveraging the enthalpy method, the study establishes a computational heat transfer model of the developed integrated cooling system. Subsequently, the thermal performance and energy-saving potential of a similar system in Fuzhou city, China, are numerically investigated. Furthermore, the impacts of the phase-change temperature and thermal conductivity of the PCM and the pipe interval are explored, and the developed system is compared with a traditional PCM slab roof without embedded pipes. The results reveal that higher phase-change temperatures of the PCM lead to more significant solidification of the PCM within the integrated cooling system. However, with increasing phase-change temperatures of the PCM, the utilization rate of the PCM's heat of fusion within the system initially increases and subsequently decreases. Specifically, increasing the phase-change temperature of the PCM from 35 ℃ to 41 ℃ leads to a corresponding rise in the accumulated cooling load of the roof from 383 kJ/m² to 400 kJ/m², presenting an increase of 4.4%. Furthermore, higher thermal conductivities of the PCM and narrower pipe intervals improve the utilization rate of the PCM's heat of fusion within the integrated cooling system compared to that within traditional PCM slab roofs without embedded pipes. Specifically, increasing the thermal conductivity of the PCM from 0.2 W/(m·K) to 0.8 W/(m·K) boosts the utilization rate of the PCM's heat of fusion and the accumulated cooling load of the roof by 36.3% and 5.1%, respectively. Conversely, the corresponding values of the traditional PCM slab roof increase by only 33.1% and 6.3%, respectively. Moreover, when the pipe interval is decreased from 500 mm to 100 mm, the utilization rate of the PCM's heat of fusion in the integrated cooling system surpasses that in the traditional PCM slab roof by 2.7%—16.3%. Concurrently, the reduction in the accumulated cooling load of the roof increases from 3.8% to 10.9%. Overall, these findings demonstrate the potential of integrated cooling systems in promoting building energy savings and contributing toward the realization of dual-carbon goals.

Key words: PCM slab roof, cooling tower, pipe-embedded, cooling energy storage, building energy saving

CLC Number:

TK 02

Huanjie LU, Xiaoming CHEN, Zhihao WU, Jinyou QIU. Performance of an integrated cooling system combining a cooling tower and a pipe-embedded phase-change-material slab roof[J]. Energy Storage Science and Technology, 2024, 13(7): 2435-2446.

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材料	厚度/mm	导热系数/[W/(m·K)]	密度/(kg/m³)	比热容/[J/(kg·K)]	相变温度/℃	相变潜热/(J/kg)
水泥砂浆	20	0.93	1800	1050	—	—
EPS	90	0.042	30	1380	—	—
水泥砂浆	20	0.93	1800	1050	—	—
水泥炉渣	100	0.81	1700	1050	—	—
钢筋混凝土	120	1.74	2500	920	—	—
水泥砂浆	20	0.93	1800	1050	—	—
RT35HC	35	0.2	880(s) 770(l)	2000	34~36	240000
PE水管	1	0.43	920	2300	—	—

湿球温度/℃	出水温度/℃
30	31.40
28	29.63
26	27.88
24	26.15
22	24.44
20	22.75
18	21.08
16	19.43
14	17.79

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