Experimental investigations of two variants of a high pressure ratio cryogenic turboexpander, from a new series of turboexpanders for Bhabha Atomic Research Centre (BARC), are presented in the article. Both the variants are designed based on an earlier reported enhanced midstream method. The new turboexpanders are designed with larger turbine impeller-diffuser radial clearances and smaller turbine impeller L/D ratio as compared to previous series of BARC turboexpanders. The experimental investigations are carried out in BARC developed helium refrigerator CP1000 and helium liquefier LHP50. Different aspects of turboexpander performance, as defined by isentropic efficiency, pressure ratio and power developed in response to variation in parameters such as turboexpander flow and operational specific speeds, are presented in detail. The idea of using process turboexpanders for the mass flow measurements is also briefly studied using the results of the experiments. Experiment is also devised to compute heat-in-leak from turboexpander mountings and the results are used to critically analyse and provide corrections to the thermodynamic performance of the turboexpanders achieved during other experiments. From the two new variants of the turboexpanders investigated here, the better performing one is selected and mounted on LHP50 as TEX-2 for determining the maximum helium liquefaction capacity. LHP50 plant performance is then compared to the earlier reported liquefaction capacities with previous versions of BARC turboexpanders.

本文介绍了Bhabha原子研究中心（BARC）的一系列新型涡轮膨胀机中的高压比低温涡轮膨胀机的两种变体的实验研究。两种变体都是基于较早报道的增强型中游方法设计的。与以前的BARC系列涡轮膨胀机相比，新型涡轮膨胀机的设计具有更大的涡轮叶轮-扩压器径向间隙和较小的涡轮叶轮L / D比。实验研究是在BARC开发的氦制冷机CP1000和氦液化器LHP50中进行的。详细介绍了等熵效率，压力比和功率等参数变化所产生的涡轮膨胀机性能的各个方面，这些参数是诸如涡轮膨胀机流量和特定运行速度之类的。还使用实验结果简要研究了使用过程涡轮膨胀机进行质量流量测量的想法。还设计了实验来计算涡轮膨胀机安装件的泄漏热，并且将结果用于严格分析并提供对其他实验中获得的涡轮膨胀机热力学性能的校正。从这里研究的涡轮膨胀机的两个新变型中，选择性能更好的一个，并将其安装在LHP50上作为TEX-2，以确定最大的氦气液化能力。然后将LHP50装置的性能与先前报道的BARC涡轮膨胀机的液化能力进行比较。还设计了实验来计算涡轮膨胀机安装件的泄漏热，并且将结果用于严格分析并提供对其他实验中获得的涡轮膨胀机热力学性能的校正。从这里研究的涡轮膨胀机的两个新变型中，选择性能更好的一个，并将其安装在LHP50上作为TEX-2，以确定最大的氦气液化能力。然后将LHP50工厂的性能与先前报道的BARC涡轮膨胀机的液化能力进行比较。还设计了实验来计算涡轮膨胀机安装件的泄漏热，并且将结果用于严格分析并提供对其他实验中获得的涡轮膨胀机热力学性能的校正。从这里研究的涡轮膨胀机的两个新变型中，选择性能更好的一个，并将其安装在LHP50上作为TEX-2，以确定最大的氦气液化能力。然后将LHP50装置的性能与先前报道的BARC涡轮膨胀机的液化能力进行比较。选择性能最好的一种，并将其安装在LHP50上作为TEX-2，以确定最大的氦气液化能力。然后将LHP50装置的性能与先前报道的BARC涡轮膨胀机的液化能力进行比较。选择性能最好的一种，并将其安装在LHP50上作为TEX-2，以确定最大的氦气液化能力。然后将LHP50装置的性能与先前报道的BARC涡轮膨胀机的液化能力进行比较。