A fusion reactor must be fueled by solid pellet injection at the high field side to ensure uniform fuelling and meet the fuel cycle requirements. A reliable extrusion system must be developed to solidify and extrude the fuel in the form of a fine filament. Over the past few decades, various extrusion systems such as in-situ, piston-cylinder, single screw, twin screw extrusion were developed to progress into achieving the extrusion rate specified by ITER (International Thermonuclear Experimental Reactor). Among these techniques, twin screw extruder promises to be reliable due to its continuous operation and stable throughput. This review article has twin objectives. First, it seeks to provide an overview of developments carried out so far for the cryogenic extruders like conceptualization, prototype development and performance. The numerical modelling of cryogenic extruders is at infant stage. Therefore, the second objective of this paper is to review various numerical models from polymer extrusion research and explain the need to adopt those models to arrive at the more optimal design of an extruder. In addition, the thermo-physical properties of hydrogenic fuels are reviewed, which is very important for developing numerical models. Also, this paper brings out the critical gaps that exist in the CFD modelling of a twin screw extruder. The present review work would be of great importance to the scientific community working toward plasma fueling.

聚变反应堆必须通过在高场侧注入固体颗粒来提供燃料，以确保均匀地提供燃料并满足燃料循环要求。必须开发一种可靠的挤出系统，以固化和挤出细丝形式的燃料。在过去的几十年中，开发了各种挤出系统，例如原位，活塞缸，单螺杆，双螺杆挤出，以逐步达到ITER（国际热核实验反应堆）规定的挤出速率。在这些技术中，双螺杆挤出机由于其连续运行和稳定的生产量而具有可靠性。这篇评论文章有两个目标。首先，它寻求概述迄今为止低温挤压机的发展情况，例如概念化，原型开发和性能。低温挤出机的数值模型尚处于婴儿阶段。因此，本文的第二个目的是回顾聚合物挤出研究中的各种数值模型，并说明采用这些模型以实现挤出机更优化设计的必要性。另外，对氢燃料的热物理性质进行了综述，这对于开发数值模型非常重要。此外，本文还指出了双螺杆挤出机CFD模型中存在的关键缺陷。当前的审查工作对于致力于等离子燃料的科学界非常重要。本文的第二个目的是回顾聚合物挤出研究中的各种数值模型，并说明采用这些模型以实现挤出机更优化设计的必要性。另外，对氢燃料的热物理性质进行了综述，这对于开发数值模型非常重要。此外，本文还指出了双螺杆挤出机CFD模型中存在的关键缺陷。当前的审查工作对于致力于等离子燃料的科学界非常重要。本文的第二个目的是回顾聚合物挤出研究中的各种数值模型，并说明采用这些模型以实现挤出机更优化设计的必要性。另外，对氢燃料的热物理性质进行了综述，这对于开发数值模型非常重要。此外，本文还指出了双螺杆挤出机CFD模型中存在的关键缺陷。当前的审查工作对于致力于等离子燃料的科学界非常重要。