TY - JOUR
T1 - Modeling of two-phase refrigerant distribution in brazed plate heat exchangers
AU - Li, Wenzhe
AU - Hrnjak, Pega
N1 - Publisher Copyright:
© 2022 Elsevier Ltd and IIR
PY - 2022/4
Y1 - 2022/4
N2 - This paper presents a mechanistic model that predicts two-phase refrigerant distribution in brazed plate heat exchangers. The modeling of two-phase distribution is based on the flow visualization in the inlet header, in which the flow regime is identified to be periodic and one cycle includes two or three flow stages, given a fully developed stratified/stratified-wavy flow is present at the heat exchanger entrance. To predict the vapor refrigerant distribution, this model considers two different flow stages in the inlet header: for the top corner vapor flow, the vapor refrigerant distribution is predicted by the balance between the suction force (radial pressure gradient) and the axial momentum of each phase; for the vapor jet flow, the vapor refrigerant is assumed to be distributed evenly among the channels. The time ratio of the two flow stages is estimated by assuming the irregular large-amplitude rolling waves in the feeding tube, which lead to the vapor jet flow in the header, to have the most dangerous wavelength and their traveling time can be related to the liquid slug frequency. The apparent vapor refrigerant distribution is the time average of the vapor distributions at the two stages. For the liquid refrigerant distribution, it is predicted by imposing an equal total pressure drop for each flow path. The proposed model is validated against the experimental results: quantified two-phase refrigerant distribution, heat exchanger capacities, pressure profiles in the headers, and surface temperature of the sidewalls.
AB - This paper presents a mechanistic model that predicts two-phase refrigerant distribution in brazed plate heat exchangers. The modeling of two-phase distribution is based on the flow visualization in the inlet header, in which the flow regime is identified to be periodic and one cycle includes two or three flow stages, given a fully developed stratified/stratified-wavy flow is present at the heat exchanger entrance. To predict the vapor refrigerant distribution, this model considers two different flow stages in the inlet header: for the top corner vapor flow, the vapor refrigerant distribution is predicted by the balance between the suction force (radial pressure gradient) and the axial momentum of each phase; for the vapor jet flow, the vapor refrigerant is assumed to be distributed evenly among the channels. The time ratio of the two flow stages is estimated by assuming the irregular large-amplitude rolling waves in the feeding tube, which lead to the vapor jet flow in the header, to have the most dangerous wavelength and their traveling time can be related to the liquid slug frequency. The apparent vapor refrigerant distribution is the time average of the vapor distributions at the two stages. For the liquid refrigerant distribution, it is predicted by imposing an equal total pressure drop for each flow path. The proposed model is validated against the experimental results: quantified two-phase refrigerant distribution, heat exchanger capacities, pressure profiles in the headers, and surface temperature of the sidewalls.
KW - Brazed plate heat exchanger
KW - Modeling
KW - Two-phase distribution
UR - http://www.scopus.com/inward/record.url?scp=85127914809&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=85127914809&partnerID=8YFLogxK
U2 - 10.1016/j.ijrefrig.2022.01.020
DO - 10.1016/j.ijrefrig.2022.01.020
M3 - Article
AN - SCOPUS:85127914809
SN - 0140-7007
VL - 136
SP - 172
EP - 183
JO - International Journal of Refrigeration
JF - International Journal of Refrigeration
ER -