Cryogenic-temperature Cold Storage using Micro-encapsulated Phase Change Materials in Slurries

低温冷库是热能储存中的灰姑娘。根据最近的能源部全球储能数据库，到目前为止，全球有166个热存储项目正在运营或正在建设中，用于可再生能源时移/容量固定或电费管理，总容量为3365兆瓦。然而，这些项目中的大多数是用于聚光太阳能（CSP）发电厂的熔盐热储存（总计2552兆瓦）和用于需求侧电力消耗管理的冷冻水或冰浆冷储存（200兆瓦）。低温蓄冷技术由于其能有效地提高蓄冷量的火用密度和热电联产的能力，其潜在的应用价值近年来才得到广泛的认可。英国正在开发的相关领先技术包括运输用低温发动机、液态空气储能、泵送热电储能等，其中低温蓄冷是提高性能的关键。此外，通过高效且具有成本效益的低温冷藏，传统低温系统的操作可以更加灵活，作为需求侧管理的有效手段（消耗更多的非高峰电力和更少的高峰电力，而不是恒定负载操作，以节省电费）。本计画将发展微胶囊化液态相变材料（Micro-encapsulated Phase Change Materials in Slurries，MPCMS）作为低温冷藏的新方法。浆料是优秀的冷存储候选者，因为它们可以通过泵输送（良好的流动性），就像CSP工厂中的熔盐一样。另一方面，利用封装在微尺寸颗粒中的相变材料（PCM），不仅可以显著提高等效热容，而且可以通过添加不同的具有合适凝固点的核心PCM的胶囊来容易地设计与温度相关的热容，以最小化充电中的（火用）损失。这种方法的关键挑战是MPCMS从室温到低温的宽工作温度范围。因此，本项目将利用申请人在微操作实验室（伯明翰大学化学工程学院）和新成立的伯明翰低温储能中心（BCCES）开发的技能和先进的研究设施，制定，表征和演示MPCMS在低温冷藏中的应用。通过本项目，我们将获得根据应用的MPCMS制造的技能以及相关冷藏设备的优化设计能力。

Cryogenic-temperatures cold storage is the Cinderella in thermal energy storage. According to the recent DOE global energy storage database, until now there are globally 166 thermal storage projects in operation or under construction for renewable energy time-shift/capacity firming or electric bill management, with a total capacity of 3365MW. However most of these projects are molten salt heat storage for concentrated solar power (CSP) plants (2552MW in total) and chilled water or ice slurry cold storage for demand side electricity consumption management (200MW). Only recent years the potential value of cryogenic-temperature cold storage has been widely recognised for the much elevated exergy density and the capability of cogeneration of cold and power. The related UK leading technologies those under development including cryogenic engine for transportation, liquid air energy storage, pumped thermal electricity storage etc, in which cryogenic temperature cold storage is a key to improve the performance. Moreover, with efficient and cost-effective cryogenic-temperature cold storage, the operation of traditional cryogenic systems can be more flexible as an effective mean of demand side management (consumes more off-peak electricity and less peak electricity instead of constant load operation to save electric bills). In a long term it will contribute to the creation of 'cold economy'.This project will develop Micro-encapsulated Phase Change Materials in Slurries (MPCMSs) as novel approaches of cryogenic-temperature cold storage. Slurries are excellent cold storage candidates as they can be transported by pumps (good fluidity), just like the molten salts in CSP plants. On the other hand with phase change materials (PCMs) encapsulated in the micro-size particles not only the equivalent heat capacity can be significantly improved, but also the temperature-dependent heat capacity can be designed easily by adding different capsules with appreciate freezing point core PCMs to minimize the exergy loss in charging/discharging processes.The key challenge of this approach is the wide working temperature range of MPCMSs from room temperature to cryogenic temperature. Therefore this project will utilize the applicants' developed skills and sophisticated research facilities in Micromanipulation lab (within School of Chemical Engineering, University of Birmingham) and new launched Birmingham Centre for Cryogenic Energy Storage (BCCES) to formulate, characterize, and demonstrate the application of MPCMSs for cryogenic-temperature cold storage. Through this project we will gain the skills of MPCMSs fabrication depending on the applications as well as the capability of optimal design of related cold storage devices.