Similarity model for predicting the performance of an R718 compressor

Yong-Jin Son,Kyoung-Yong Lee,Joonyong Yoon,Hyeonmo Yang,Young-Seok Choi,Si-Woo Lee,Jun-Won Suh

doi:10.1177/16878140211050797

Abstract

A general compression refrigeration system consists of a compressor, condenser, pressure-reducing valve, and evaporator to induce phase changes in the refrigerant. The performance of the compression refrigeration system strongly depends on the type and characteristics of the refrigerant. However, synthetic refrigerants such as chlorofluorocarbon, hydrochloro-fluorocarbon, and hydrofluorocarbon directly affect the environment as greenhouse gases and indirectly affect the environment by generating substances as they decompose. Thus, researchers have been focusing on developing refrigerants with a low or zero global warming potential. R718 (i.e. water) is an ecofriendly refrigerant, but its specific volume rapidly changes between the liquid and gas phases. This requires making the components of the compression refrigeration system larger than normal to accommodate these volume changes, which is inefficient for manufacturing prototypes. In this study, an alternative refrigerant was applied to the design of a centrifugal compressor that uses R718 as the working fluid. To address the volume change of R718, a numerical analysis was conducted by using the similarity method, where the size of the impeller was reduced and the rotational speed was controlled. To ensure the reliability of the similarity model, its results were compared against the experimental data of the original model for verification.

Highlights

A compression refrigeration system takes heat from a target space or object by using external energy and is applicable to various industrial fields such as cooling buildings, freezing food, and industrial cooling
This study evaluated the feasibility of applying the similarity method to resolve the inefficient prototype manufacturing of centrifugal compressors using R718 as a refrigerant
The numerical analysis and experimental results showed that the maximum error between the similarity model using CO2 as a refrigerant and the original model using R718 as the refrigerant was about 7%

Summary

Introduction

A compression refrigeration system takes heat from a target space or object by using external energy and is applicable to various industrial fields such as cooling buildings, freezing food, and industrial cooling. A compression refrigeration system comprises a compressor, condenser, pressure-reducing valve, and evaporator to induce phase changes in the refrigerant. The compressor is a core component of a compression system and has three types: centrifugal, Roots, and screw. Centrifugal compressors are being continuously developed through conventional design methods, and recent studies have focused on optimizing the design by using computational fluid dynamics (CFD).[1,2] Many researchers have focused on improving the durability and aerodynamic performance and analyzing the characteristics of the internal flow field.[3,4,5]

Objectives

Results

Conclusion