Setup and characterisation of a multi-purpose test rig for R744 refrigerating cycles and equipment

Following a widespread trend in international research on R744 cooling applications, the authors have developed a test rig for investigating refrigerating cycles and equipment which operates with such refrigerant. The facility was designed aiming to a compact layout and to a high flexibility in terms of cycles and pieces of equipment to be tested. The test rig can operate stand-alone thanks to a passive load management system which works with water as secondary fluid. The paper gives some useful data, based on direct experience, for the realization and management of a multi-purpose test rig that allows the analysis of several cycle layouts over wide operating ranges. Some of the main critical issues related to proper plant and component design, a correct choice of the measurement equipment and a suitable system management are shown and discussed. The paper also includes experimental data obtained while testing a reciprocating compressor and a single-stage cycle layout both with and without using an internal heat exchanger.

► A multipurpose test rig for R744 cycles and components developed. ► Main issues for a good design and management of the system shown. ► A reciprocating semi-hermetic compressor characterised. ► A single stage transcritical cycle characterised. ► Influence of internal heat exchanger on cycle performance investigated.