Session: 17-03 Gas Turbine and Compressor Technologies

Submission Number: 176847

Techno Economic Analysis for Centrifugal Compressors Using Oil-Free Technologies for Modern Refrigerant Fluids in 300 kW Refrigeration Systems 

This paper presents a techno-economic case study evaluating centrifugal compressors designed with oil-free technologies to deliver 300 kW of cooling capacity. The analysis focuses on modern, low-GWP refrigerant fluids, comparing the performance and cost implications of four refrigerants: R-1234ze (HFO), R-290 (Propane), R-717 (Ammonia), and R-744 (Carbon Dioxide). This paper explores how the selection of these various refrigerants impacts compressor design, taking into account practical considerations such as cost and reliability of the compressor.

First, the thermodynamic cycle is analyzed to make sure the same cooling capacity and range of temperatures are covered for all the refrigerants. Then the key requirements for the compressor design (mass flows and pressure ratios) are extracted and the design point is chosen.

The analysis is then followed by the preliminary design and off-design analysis which would meet the requirements for each refrigerant system design. In order to keep the evaluation equivalent, a number of assumptions were done such as: design all the compressors for the same specific speed (so, in theory, all would reach similar efficiency levels), same compressor layout (if multi-stage, two back to back impeller configuration) and same impeller material (so tip speed could be used as a proxy for mechanical loading and similar material prices can be assumed for all designs), etc.

The preliminary mechanical and aerodynamic design then allowed for further layout and a preliminary rotor dynamic evaluation. After some assumptions regarding mechanical design, initial choices can be made regarding the electric motor sizing and the type of bearing suitable for each design. The technical metrics of performance and mechanical integrity are then compared for the four compressor systems developed as a full system.

Finally, the study explores the qualitative differences in manufacturability and implications for capital expenditure (CAPEX), and operational expenditure (OPEX) beyond the technical metrics from a final customer perspective, including projected maintenance needs and performance degradation over time. The paper provides insights into the trade-offs involved in selecting refrigerants and compressor architectures at mid-scale cooling capacities, offering guidance for system developers, manufacturers, and end-users seeking efficient and future-ready refrigeration solutions.

Presenting Author: Thiago Ebel Concepts NREC

Presenting Author Biography: Thiago Ebel is the Director of Technology and Innovation at Concepts NREC. Thiago has over 10 years of experience working with turbomachinery, consultancy projects and fluid mechanics. His thesis won the 2016 Don Miller Award for Thermo-Fluid Design Excellence. Thiago has authored or co-authored over 10 peer-reviewed papers and holds 2 patents in turbomachinery and aero-acoustics. His expertise spans aerospace, energy, automotive, and white goods, with experience in turbomachinery, CFD, system modeling, and multi-disciplinary optimization.

Authors:

Thiago Ebel Concepts NREC
Thomas Gresham Concepts NREC
Mohammed Youbi Idrissi Solstice Advanced Materials
Amr Rizk Solstice Advanced Materials