brazed plate heat exchangers, two-phase distribution, infrared thermography
When used as direct expansion (DX) evaporators, brazed plate heat exchangers (BPHEs) suffer from the maldistribution of the two-phase refrigerant among parallel plate channels. It is essential to accurately quantify the two-phase refrigerant distribution in BPHEs to evaluate the effect of the maldistribution on the heat exchangers and system performance. Considering the complex internal geometry of BPHEs and the potential influence of experimental measurements on the original flow field, the non-intrusive quantification of the two-phase flow distribution in BPHEs is preferred. This paper presents a method to quantify the two-phase refrigerant distribution in BPHEs from infrared images. Quantification is achieved by identifying the boundary between the two-phase and superheated region on the sidewall of BPHEs based on the infrared images and matching the identified boundary in a BPHE evaporator model to estimate the two-phase distribution. The proposed quantification method is validated by the experimental data. The results show that this non-intrusive method can effectively quantify the two-phase refrigerant distribution in the BPHE.