Linear Stirling Engine with a Buffer Tube

带缓冲管的线性斯特林发动机

• 批准号: EP/S03174X/1
• 负责人: C Stone
• 金额: $ 70.27万
• 依托单位: University of Oxford
• 依托单位国家: 英国
• 项目类别: Research Grant
• 财政年份: 2019
• 资助国家: 英国
• 起止时间: 2019 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=EP%2FS03174X%2F1
• 关键词: Linear; Stirling; Engine; Buffer; Tube

Domestic CHP systems are an obvious way of both generating electricity with a high efficiency and reducing strain on the grid and local distribution systems. The move to electric and plug-in hybrid vehicles will place additional demand on the grid and overload the local electrical distribution system that can currently only cope with about 10% of households recharging vehicles. With domestic CHP systems a different mind-set is needed as it is necessary to consider the electricity generation to be a by-product of the heating demand, as the electricity can be exported. Although a small domestic boiler might have a rating of 12 kW the heating demand in the summer is of course much smaller and this leads to a lower power (but high efficiency) requirement for the Stirling engine. Consider the following example which assumes a baseline efficiency for a conventional boiler of 90%:For an electrical output of 1 kW the 'indicated power' of the Stirling engine would need to be 1.3 kW (to allow for losses that are mostly electrical losses in the generator and power electronics). With a pessimistic 28% efficiency assumption (Net W[e] out/Heat in), this will require a heat input of 3.6 kW, with 4 kW of fuel energy. The waste heat from the engine will provide 2.3 kW for domestic heating, and in a conventional boiler this would have required 2.6 kW of fuel energy. So, 1kW of electricity has been generated from an increased fuel energy consumption of 1.4 kW (= 4.0 - 2.6); an overall electrical efficiency of 71% assuming the heat is needed. This is about double the efficiency of a conventional power plant, once allowance is made for the grid transmission efficiency.The ultimate aim is for a Stirling engine with an electrical output of at least 1 kW, but as a demonstration unit the current work will produce a Stirling engine with an electrical output of 100 W. This smaller size has been chosen because we have a moving magnet motor of this rating that can be used as a generator. This will avoid the need to scale-up the motor design and will give a significant reduction in the project cost. This 100 W system will be large enough to install pressure transducers, thermocouples and displacement transducers, and the experimental data can be used to validate the modelling, so that there will be confidence in the model predictions of the larger engines. The smaller size will also reduce the manufacturing costs. Electrical heating will facilitate accurate measurements of the heat input, and avoid the need to develop a combustion system. Longer term, a catalytic combustion system would operate at a sufficiently low temperature so as to make NOx emissions negligible, and be suitable for a range of gaseous fuels.The attraction of CHP systems has already led to small linear Stirling generators being developed (e.g Sunpower/Microgen and Infinia/QEnergy systems). Although the idea has been well demonstrated these technologies have not been successful due to high ownership costs and reliability issues. The low cost manufacture of conventional displacer configurations is extremely challenging. A very significant benefit of the research proposed here will be the demonstration of a new engine configuration that radically simplifies the design and manufacture of the displacer - a key component. The cost reductions possible will greatly enhance the prospects of Stirling CHP systems.The US Department of Energy has recently funded several Stirling engine projects for domestic CHP (https://arpa-e.energy.gov/?q=news-item/department-energy-announces-18-new-projects-accelerate-technologies-efficient-residential). Although the mass market is envisaged to be domestic CHP there are other niche markets for silent power generation that can be exploited, and these would support greater costs associated with small scale manufacture. Examples of this include auxiliary power generation on yachts and military applications.

国内CHP系统是一种显而易见的方法，即以高效率发电并减少网格和局部分销系统的压力。移至电动和插电式混合动力汽车将对网格增加需求，并超载当地的电气配电系统，目前只能应对约10％的家庭充电车辆。使用国内CHP系统，需要不同的心态，因为有必要将发电是供暖需求的副产品，因为可以出口电力。尽管小型家用锅炉的额定值可能为12 kW，但夏天的供暖需求当然要小得多，这会导致对斯特林发动机的功率（但效率高）。考虑以下示例，该示例假设传统锅炉的基线效率为90％：对于1 kW的电输出，斯特林发动机的“指示功率”需要为1.3 kW（以允许在主要是电气损失的损失发电机和电力电子）。在悲观的28％效率假设（净[e]输出/热量）的情况下，这将需要3.6 kW的热量输入，燃油能量为4 kW。发动机的废热将提供2.3 kW的家庭供暖，在常规的锅炉中，这将需要2.6 kW的燃油能量。因此，通过增加1.4 kW的燃料能源消耗（= 4.0-2.6），已经产生了1kW的电能。假设需要加热，则总体电效率为71％。这是传统发电厂的效率的两倍，一旦为电网传输效率付出了津贴。最终的目标是用于电气输出至少1 kW的Stirl Engine，但作为示范单位，当前的工作将产生选择该较小尺寸的电气输出的Stirl引擎之所以选择该评级的移动磁铁电动机，可以用作发电机。这将避免扩展运动设计的需要，并大大降低项目成本。该100 W系统将足够大，可以安装压力传感器，热电偶和位移传感器，并且可以使用实验数据来验证建模，以便对较大发动机的模型预测有信心。较小的尺寸还将降低制造成本。电加热将有助于准确测量热输入，并避免开发燃烧系统的需求。从长远来看，催化燃烧系统将在足够低的温度下运行，以使NOX排放量可以忽略不计，并且适合一系列气态燃料。CHP系统的吸引力已经导致了开发的小线性stirl发电机（例如SunPower /Microgen和Infinia/Qenergy系统）。尽管这个想法已经很好地证明了这些技术由于所有权成本和可靠性问题而没有成功。常规置换配置的低成本生产极具挑战性。这里提出的研究的一个非常重要的好处将是一种新的发动机配置的演示，该配置从根本上简化了置换剂的设计和制造 - 一个关键组件。可能的降低成本将大大提高斯特林卫生卫生卫生系统的前景。 - 能源nounces-18-新预测 - 进度技术效率 - 住宅）。尽管设想大众市场是国内卫生卫生卫生，但可以利用沉默的发电的其他利基市场，这些市场将支持与小规模生产相关的更大成本。其中的例子包括在游艇和军事应用上发电的辅助发电。