LectureSouthwest Research Institute® (SwRI®), ACI Services, Inc. (ACI), and Libertine FPE Limited collaborated to design and build a Linear Motor Reciprocating Compressor (LMRC) via a DOE-funded project with ACI cost share. The advanced compression system utilizes a novel concept of driving a permanent magnet piston assembly inside a hermetically sealed compressor cylinder through electromagnetic windings. The LMRC design minimizes the mechanical part count and has no process gas leakage to atmosphere. The LMRC has no “rod,� rod packing, crankshaft, coupling, or separate motor/driver. In addition, the LMRC is able to improve the efficiency of the compression process by eliminating bearing losses and optimizing the piston speed profile to reduce fluid dynamic losses. The primary project objective was to meet the DOE goal of increasing the compression efficiency and reducing the cost of forecourt hydrogen compression; however, most of the associated technology developments can be applied to high-pressure natural gas, process gas, air, and other compressors. High pressures, electromagnetic fields, and a hydrogen environment (for the specific DOE vehicle refueling application) are the main design obstacles that had to be overcome to design a linear motor reciprocating compressor that can ultimately achieve a 12,700-psi final discharge pressure in the third stage. Manufacturing of the first stage LMRC (first of three stages) was completed and tested in early-to-mid 2020. Solid model images and a photo of the LMRC that was built and tested is presented in Figure 1. The first stage LMRC has design suction and discharge pressures of 290 and 1,035 psi, respectively. After a failure caused the testing to end prematurely, SwRI internal research and development (IR&D) funding was sought to rebuild the LMRC using the lessons-learned from the 2020 testing to improve some of the key components of the design. The key components that were the focus of the IR&D project are as follows: • Metal Coatings – Specifically, coatings for magnets. A new coating and process method was developed to protect magnets from hydrogen incursion. • Valve Design – Based on the identified design improvements, a new valve design with minimal leakage for hydrogen service was developed and built. • Motion Profile – Motion profile optimization efforts were performed with the rebuilt LMRC. Testing of the above-noted components of the LMRC was completed in early-to-mid 2022; therefore, test data is included in this lecture. In addition to those component developments, further advances in the hermetic actuator platform technology are expected to yield efficiency and durability benefits for subsequent phases of development ahead of commercial product launch. The paper will include discussions of design, manufacturing, and testing aspects of some of the individual components and of the entire LMRC. In addition to being highly relevant to the hydrogen gas economy, the LMRC is considered relevant and applicable to most gas compression industries
