Feasibility Study of Optimisation of Scroll Air Motors and Energy Recovery from Exhaust Compressed Air

尽管可再生资源巨大，但要用所有的可再生能源来满足我们的电力需求似乎是遥不可及的。可再生能源，如太阳能和风能，具有分散性和间歇性。因此储能对于获得稳定的电力供应是非常重要的。压缩空气储能是当今公认的一种可控、经济的储能方式。储存在压缩空气中的能量将在需要时用于发电。然而，常用的空气马达(空气变压器)是一种性价比高的传统叶片式空气马达，但叶片式空气马达的能效较低，不到30%。这是在可再生资源供电中采用压缩空气储能系统的一大缺点。气动执行器通过运动技术在一系列应用中提供解决方案。在英国，大量的能源，超过国家电网发电量的10%，被用来产生压缩空气。此外，向制造商/工厂供应的电力中，约有20%用于产生压缩空气。然而，气动执行机构系统的能效仍然很低。在欧洲国家，工作系统的能效在23%-30%之间。认为这种低能效主要是由于气动执行机构系统的开路结构造成的。虽然已经作出了许多努力，但人们认为没有适当的机制来回收通过排气损失的能量。因此，在废气再利用这一课题上有相当大的研究空间。涡旋气动马达对气动执行机构来说是一个相对较新的概念。其独特的结构特点是比传统的气动执行机构具有更高的能量转换能力。涡旋技术目前主要应用于空调和制冷压缩机。最近，这个概念被重新发明，以制造涡旋空气马达，这种马达立即被用来驱动发电机发电。它们已被Energetix Group Plc、本田和Climate Energy等多家公司成功用于微型热电联产系统。涡旋式空气马达为回收排气口的能量损失和高效地为可再生能源发电提供了一种可能合适的执行器。预计涡旋气动马达作为一种新型的高能效气动执行机构，在不久的将来将在工业和家庭中得到广泛的应用。然而，在这一领域取得实质性进展之前，需要解决一些根本性问题。这项建议旨在寻求EPSRC的支持，在数学家和工程师之间建立联系，以开展解决与卷轴结构及其应用有关的一些基本问题的可行性研究。该项目的任务是：-根据目前的涡旋结构和在MatLab/Simulink中的软件程序开发一个完整的涡旋数学模型；-在伯明翰的实验室建立一个新的系统来回收气动执行器的废气，以提高能源效率；-研究涡旋空气马达在可变空气流量的压缩空气供应的低压下工作时的动态行为；-调查下游的回收设备如何影响气动执行器的行为；-研究一种可行的控制策略，以在流量不确定的压缩空气供应的可变压力下产生稳定的电力；-使用微分几何方法研究不同形状的涡旋将导致高能效；-通过建模和模拟研究-优化来研究设计参数如何影响涡旋气动马达的能效；-验证数学模型和模拟结果。

Although renewable resources are immense, it seems far-fetched to use all the renewable supply to satisfy our power requirement. The renewable sources, such as solar and wind power, are diffuse and intermittent. So energy storage is very important for obtaining a stable power supply. Compressed air energy storage is a well known controllable and affordable approach nowadays. The energy stored in compressed air will be used to generate electricity when required. However, the commonly used air motor (air transformer) is a cost effective traditional vane type air motor but the energy efficiency of vane type air motors is rather low, less than 30%. This is a big drawback in adopting compressed air energy storage system in the renewable resources power supply. Pneumatic actuators provide solutions through motion technology in a range of applications. In the UK, a massive amount of energy, over 10% of the National Grid output, is used to generate compressed air. Also, around 20% of electricity supplied to manufacturers/factories has been employed to generate compressed air. However, the energy efficiency of pneumatic actuator systems remains low. In European countries, an energy efficiency of between 23%-30% is achieved in working systems. It is considered that such low energy efficiencies are mainly due to the open-circuit structure of pneumatic actuator systems. Although much effort has been made, it is considered that there are no suitable mechanisms to recover energy lost through the exhaust. Therefore, there is considerable scope for research in the subject of reusing the exhaust air. A scroll air motor is a relatively new concept to pneumatic actuators. Its unique structure features its higher ability of energy conversion than conventional pneumatic actuators. The scroll technique is now mainly implemented in air conditioner and refrigeration compressors. Recently, the concept was re-invented to build scroll air motors, which are immediately adopted to drive generators for electric power generation. They have been successfully used in Micro Combined Heat and Power systems by a number of companies, such as Energetix Group Plc, Honda and Climate Energy. Scroll type air motors provide a possibly suitable actuator for recovering the energy loss at the exhaust and generating electricity efficiently for renewable power sources. It is anticipated that scroll air motors as a new type of energy efficient pneumatic actuator will be found in wide industrial and domestic applications in the near future. However, a number of fundamental problems need to be addressed before substantial progresses can be made in this area. This proposal is to seek the EPSRC support to set up a link between mathematicians and engineers to conduct the feasibility study of solving a number of fundamental issues associated with the structure of scrolls and their applications. The tasks of the project are:- to develop a complete mathematical model of scrolls based on the current scroll structure and a software program in Matlab/Simulink;- to set up a novel system to recycle pneumatic actuator exhaust air to improve energy efficiency in the laboratory at Birmingham;- to investigate the dynamic behaviour of scroll air motors while they are working at a low pressure of compressed air supply with variable air flow rates;- to investigate how the recycling equipment at down stream affects the behaviour of the pneumatic actuators;- to investigate a feasible control strategy for generating a stable electrical power at a variable pressure of compressed air supply with uncertain flow rates;- to investigate different shapes of scrolls which will lead to high energy efficiency using a differential geometry method;- to investigate how the design parameters affect the energy efficiency of scroll air motors through madelling and simulation study - optimisation;- to verify mathematical model and simulation results.