Heat Pump Fully Integrated with Thermochemical Store (HP-FITS)

利用可再生电力对建筑物(包括家庭和商业建筑)中的热量进行脱碳的贡献是众所周知的，也很容易理解。然而，认为有足够的风力涡轮机、光伏电池板等来生产可再生电力，有足够的电热泵来为家庭和其他建筑供暖就能解决问题的想法过于简单化了。即使有非常高效的热泵，冬天早上的峰值电力负荷也可能是目前电网和配电系统容量的2到3倍，这还不包括同时为未来大量电动汽车充电的影响。新的或重新调整用途的天然气电网中可能出现脱碳气体(无论是氢气还是沼气)，电网的部分增强等使问题变得更加复杂。缓解这些问题的可能方法将包括电力和热能储存，以在用户层面或更集中的层面管理高峰负荷。这项建议集中在储热上，每兆焦耳的成本比电力储存低许多倍。这个概念是将热量储存在消费者的(家用或商用)热泵上，这样热泵就可以在对系统最有利的时候运行，即当有多余的可再生电力(主要是风能和光伏)时。当对可再生电力的需求较高或可用程度较低时，热量从商店中提取。这里我们考虑的是几个小时到一天的存储时间，而不是几周或跨季节的存储时间。这本身并不是一个新的想法，但试图提出好的解决方案已经遇到了一些有待解决的挑战。阿尔斯特大学的休伊特教授使用了一种与热水商店相连的传统热泵，为一所(有人居住的)试验室提供热水器。利用北爱尔兰电网(风电装机容量占很大比例)的信号，该系统一直使用算法运行，这些算法将在未来用户的电力成本反映可变生产成本时使用。这为系统的运行和控制提供了宝贵的经验，但总体性能受到存储热损失和商用热泵在温度输出和调节方面的限制。我们将使用新的存储、热泵和控制系统，这将展示如何为用户和国家能源供应基础设施实现能源和经济效益：热存储将基于一种新的热化学吸收系统，该系统可以在接近环境温度的情况下，将所需的热量存储在一个更小、更低损耗的包中。热泵将结合最佳实践和在复杂的节能蒸汽喷射(EVI)循环中使用变速压缩机，在60摄氏度时实现5的性能系数(COP=热输出/电力输入)。控制策略将包括电网状态和预测的时变电价，以及热泵、商店和房屋负载模型，以确保成本效益和低排放相结合。完整的集成系统将在阿尔斯特大学的“Terrace House”中展示。这是一座新建筑，但作为20世纪初的露台建造，以促进新技术在旧建筑中的翻新，而旧建筑则由“真正的”人居住。

The contribution to decarbonising heat in buildings (both domestic and commercial) when utilising renewable electricity are well known and easy to appreciate. However, it is simplistic to think that with enough wind turbines, PV panels, etc. to produce renewable electricity and enough electric heat pumps to heat homes and other buildings that the problem will be solved.Even with very efficient heat pumps the peak electricity load on a Winter's morning might be 2 or 3 times the present grid and distribution system capacity and this does not include the effect of simultaneously charging the large number of electric vehicles expected in the future. The problem is complicated by the possibility of decarbonised gas (whether hydrogen or biogas) in a new or repurposed gas grid, partial enhancement of the electricity grid, etc.Possible ways to mitigate these problems will include both electricity and thermal storage to manage peak loads, either at consumer level or more centralised. This proposal concentrates on heat storage, which is many times less costly per MJ that electricity storage. The concept is to store heat at the consumer's (domestic or commercial) heat pump so that the heat pump can operate when most advantageous to the system, i.e. when there is surplus renewable electricity (predominantly wind and PV). Heat is drawn from the store when there is a higher demand for or lower availability of renewable electricity. Here we consider storage times of hours to a day, but not weeks or inter-seasonally.This is not a new idea in itself but attempts to come up with good solutions have met a number of challenges still to be solved. Prof Hewitt at Ulster has used a conventional heat pump linked to a hot water store supplying an (occupied) test house. Using signals from the Northern Ireland grid (which has a high proportion of wind capacity) the system has been operated using algorithms that would be utilised in future when the cost of electricity to the user reflected the variable production costs. This provided valuable experience in system operation and control but the overall performance was hampered by store heat losses and the limitations of the commercially available heat pump in terms of temperature output and modulation. We will use novel storage, heat pump and control systems in an integrated package that will demonstrate how both energy and economic benefits to the user and the national energy supply infrastructure can be achieved: Heat storage will be based on a new thermochemical absorption system that can store the required heat in a much smaller and low-loss package at close to ambient temperature. The heat pump will combine best practice with using a variable speed compressor in a sophisticated Economised Vapour Injection (EVI) cycle to achieve a Coefficient Of Performance (COP = Heat out / Electricity in) of 5 when delivering heat at 60 C. The control strategy will encompass the state of the grid and predicted time-variable tariffs with heat pump, store and house load models to ensure cost effectiveness combined with low emissions.The complete integrated system will be demonstrated in Ulster University's 'Terrace House'; a new building but built as an early 1900s terrace to facilitate retrofitting of new technology in old buildings whilst occupied by 'real' people.