Volume 52

Experimental Study on the Design of a Refrigeration System Based on a Small-scale Centrifugal Compressor with Gas Foil Bearings Xiang Qiu, Jingyang Hua, Chenyi Qian, Jiaxuan Wang, Binbin Yu, Junye Shi, Jiangping Chen

Abstract

Small-scale centrifugal compressors have the potential to offer higher efficiency and operate without oil, compared to positive displacement compressors. With advancements in industrial design and manufacturing technology, the potential for replacing traditional positive displacement compressors with small-scale centrifugal compressors is increasing. While centrifugal compressors have traditionally been favored for large systems with cooling capacities of several
hundred kilowatts or more, their application in smaller refrigeration systems, with capacities in the tens of kilowatts, has not been thoroughly explored and remains under-researched. In this study, a 45 kW refrigeration system test bench was constructed using an R134a small-scale oil-free centrifugal compressor with gas foil bearings. The experiment investigated the impact of key design factors, including refrigerant charge amount and the settings of air-cooled condenser fan, on system performance. After optimization, the system achieved a maximum cooling capacity of 44.54 kW and a highest COP of 3.59 under design conditions (ambient temperature of 35°C). Additionally, control strategies for cooling service were designed and main control parameters were calibrated, with experimental results indicating that the system successfully performed cooling tasks and operated with stable parameters.

Keywords Vapor compression refrigeration cycle, Small-scale centrifugal compressor, System design, System performance, Air-cooled condenser, Control strategies