Evaluation of Phase Change Materials for Pre-Cooling of Supply Air into Air Conditioning Systems in Extremely Hot Climates

IF 3.1 3区工程技术 Q2 CONSTRUCTION & BUILDING TECHNOLOGY

Buildings Pub Date : 2023-12-29 DOI:10.3390/buildings14010095

Usman Masood, M. Haggag, Ahmed Hassan, Mohammad Laghari

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Abstract

This research investigates the use of phase change materials (PCMs) in thermal energy storage (TES) unit-based cooling systems to increase the efficiency of air conditioners (ACs) by reducing the air inlet temperature. This study aims to evaluate different configurations of PCM enclosures, and different PCMs (paraffin and salt hydrate), by changing the speed of inlet air to achieve heat reduction of inlet air. The study includes experimental and simulation investigations. Every configuration simulates the hot-season atmospheric conditions of the UAE. A duct containing enclosures of paraffin RT-31 and salt hydrate (calcium chloride hexahydrate) was used for the simulation study using ANSYS/Fluent. A conjugate heat transfer model employing an enthalpy-based formulation is developed to predict the optimized PCM number of series and optimum airflow rate. Four designs of the AC duct were modelled and evaluated that contained one to four series of PCM containers subjected to different levels of supplied air velocities ranging from 1 m/s–4 m/s. The simulation study revealed that employing four series (Design 4) of PCM enclosures at a low air velocity of 1 m/s enhanced the pre-cooling performance and reduced the outlet air temperature to 33 °C, yielding a temperature drop up to 13 °C. The performance of salt hydrate (calcium chloride hexahydrate) was observed to be better than paraffin (RT-31) in terms of the cooling effect. Characterization of paraffin wax (RT-31) and salt hydrate was performed to establish the thermophysical properties. The experimental setup based on a duct with integrated PCM enclosures was studied. The experiment was repeated for three days as the repeatability test incorporating RT-31 as the PCM and a 3 °C maximum temperature drop was observed. The drop in the outlet air temperature of the duct system quantifies the cooling effect. Net heat reduction was around 16%.

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评估相变材料在极热气候条件下用于空调系统送风预冷的效果

本研究探讨了在基于热能储存（TES）装置的冷却系统中使用相变材料（PCM），通过降低进气温度来提高空调（AC）的效率。本研究旨在评估不同配置的 PCM 外壳和不同的 PCM（石蜡和水合盐），通过改变进气速度来实现进气热量的降低。研究包括实验和模拟调查。每种配置都模拟了阿联酋炎热季节的大气条件。使用 ANSYS/Fluent 对包含石蜡 RT-31 和水合盐（六水合氯化钙）外壳的管道进行了模拟研究。开发的共轭传热模型采用基于焓的公式，用于预测优化的 PCM 串联数和最佳气流速率。在 1 m/s-4 m/s 的不同送风速度水平下，对包含一到四个系列 PCM 容器的四种交流管道设计进行了建模和评估。模拟研究表明，在 1 米/秒的低风速下使用四个系列（设计 4）的 PCM 容器可提高预冷性能，并将出口空气温度降至 33 °C，使温度下降达 13 °C。从冷却效果来看，水合盐（六水合氯化钙）的性能优于石蜡（RT-31）。对石蜡（RT-31）和盐水合物进行了表征，以确定其热物理性质。研究了基于带有集成 PCM 外壳的管道的实验装置。将 RT-31 作为 PCM 进行了三天的重复性测试，观察到最大温度下降了 3 °C。管道系统出口空气温度的下降可以量化冷却效果。净热量减少了约 16%。

本文章由计算机程序翻译，如有差异，请以英文原文为准。

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来源期刊

Buildings Multiple-

CiteScore

3.40

自引率

26.30%

发文量

1883

审稿时长

11 weeks

期刊介绍： BUILDINGS content is primarily staff-written and submitted information is evaluated by the editors for its value to the audience. Such information may be used in articles with appropriate attribution to the source. The editorial staff considers information on the following topics: -Issues directed at building owners and facility managers in North America -Issues relevant to existing buildings, including retrofits, maintenance and modernization -Solution-based content, such as tips and tricks -New construction but only with an eye to issues involving maintenance and operation We generally do not review the following topics because these are not relevant to our readers: -Information on the residential market with the exception of multifamily buildings -International news unrelated to the North American market -Real estate market updates or construction updates