Conference Agenda

The suction valve is usually installed on the cylinder head of small reciprocating compressors. However, due to the current trend of miniaturizing compressors, an alternative is to install the suction valve on the piston head to increase the valve passage area. This article reports an analysis on the performance of suction valves placed on the cylinder head and piston for different compressor speeds. A validated numerical model was used to simulate the compressor for both configurations under different operating conditions. The results showed that the suction valve dynamics is very sensitive to changes in the compressor speed and can significantly affect the compressor performance. Furthermore, we found that valves with the same passage area and dynamic characteristics perform worse when installed on the piston head in comparison with the valve on the cylinder head. Despite significantly reducing the compressor volumetric efficiency, the suction gas superheating associated with the valve on the piston was not influenced by the compressor speed. The findings of this study provide valuable information for the design and optimization of variable-speed compressors as far as efficiency and reliability are concerned.

This paper presents an exploration of the development of a new compressor valve steel variant (Freeflex^® Versa) developed to elevate fatigue properties, catering to the rigorous demands of high-end household, commercial, and industrial segments within the refrigeration and freezer industry. The primary objective is to meet and exceed the performance requirements for compressors in the evolving landscape of HVACR applications, with a specific focus on energy efficiency.

Over the past decade, generic compressor valve steels have emerged to meet the latest energy efficiency standards across diverse HVACR applications. Our research presents Freeflex® Versa as a pioneering compressor valve steel, further improving mechanical properties, impact and bending fatigue resistance, residual stresses, and wear resistance. In the light of designs towards smaller and lighter compressors, the valve steel is not the only parameter to support this development but is essential to enable further pace and pressure with shorter, thinner and in general more complex valve geometries for future improvements in reliability and compressor Coefficient of Performance (COP). The importance of these developments has been discussed within the International Energy Association, IEA, and furthermore governmental directives on progress have been issued in several countries, with the aim to set future standards. While our company's previous version, launched in 2021, targeted the residential AC compressor market, the new version Freeflex^® Versa, has been developed and presented with an even higher fatigue resistance then it’s precursors which together with an elevated wear resistance offers unique conditions to manage future compressor demand of reliability and increased COP in the Refrigeration Industry. The benefits with smaller and shorter valves, higher deflection to mention a few parameters, is to enhance miniaturization of compressors alone or in combination with improving the performance which is crucial for better utilization of our world’s resources. A miniaturization can follow, if the flow of cooling media can be retained because of the reed valves better performance, despite a smaller sized compressor. In the paper, the purpose of segmentation, the unique steel alloy together with information of the developing process and the steel performance in terms of mechanical properties, microstructure, impact and bending fatigue, residual stresses and wear resistance will be discussed. The findings of this paper hold significance for manufacturers, engineers, and stakeholders involved in the continuous improvement of compressor technologies to meet the evolving market demands.