根据旨在提高可再生能源在全球能源结构中所占份额的联合国“2030”可持续发展议程，太阳能家用热水（SDWH）系统在过去十年中在住宅和工业规模上的使用急剧增加。虽然可再生能源资源丰富，随着时间的推移成本效益越来越高，但这些能源大多是间歇性的、不可控的，这造成了能源需求和供应之间的差距。 因此，将高效的热能储存方法集成到这些SDWH系统中是实现可持续发展目标的关键。最常见的蓄热技术是利用大型水箱进行显式储能，然而，这种技术在空间和重量方面暴露出一些主要缺点。另一方面，基于相变材料（PCM）的潜在储能技术在尺寸、成本、热性能和化学稳定性方面具有诸多优势。 目前的研究是一个项目的一部分，该项目致力于设计一个无水箱SDWH系统，该系统受益于PCM的优点，并克服了显水储罐的缺点。提出的无槽SDWH是通过在传统真空管太阳能集热器中加入PCM材料实现的。本文的目的是利用ANSYS FLUENT 16.5对一根填充石蜡的真空管的热性能进行数值研究。具体来说，CFD模型包括焓- 孔隙率公式和熔化/凝固模型用于模拟拟用紧凑型SDWH的相变循环。本研究的主要成果是建立一个可靠的模型，用于研究设计参数、运行条件等因素对系统性能的影响。随后，验证后的模型将被用作设计工具，在不受实验研究限制的情况下，从热和经济角度对系统进行模拟和优化。 引用:2019年年度会议，密苏里州堪萨斯城，会议论文

Aligning with the United Nations '2030' Agenda for Sustainable Development that aims to increase the share of renewable energy in the global energy mix, the usage of Solar Domestic Water Heating (SDWH) systems for residential and industrial-scale increased dramatically during the last decade. Although the renewable energy sources are abundant and become more cost effective with time, the majority of these sources are intermittent and uncontrollable which create a gap between the energy demand and supply. Accordingly, integrating an efficient thermal energy storage method to these SDWH systems is pivotal to achieve the sustainable development goals. The most common thermal storage technique is sensible energy storage by using large water tanks, however, this technique discloses some major drawbacks in terms of space and weight. On the other hand, the latent energy storage techniques based on Phase Change Materials (PCM) have several advantages in terms of size, cost, thermal performance and chemical stability. The current study is part of a project dedicated to design a tankless SDWH system that benefits from the advantages of the PCM and overcome the drawbacks of the sensible water storage tanks. The proposed tankless SDWH is achieved through incorporating PCM materials in a conventional evacuated tube solar collector. The aim of this paper is to numerically investigate the thermal performance of a single evacuated tube filled with Paraffin wax using ANSYS FLUENT 16.5. Specifically, a CFD model includes the enthalpy-porosity formulation and the melting/solidification model is used to simulate the phase change cycles into the proposed compact SDWH. The main outcome of this research is a trustworthy model that will be used to study the effect of several factors include the design parameters, operation condition on system performance. Subsequently the validated model will be used as a design tool to simulate and optimize the system in thermal and economical terms without the limits of the experimental studies.