Refrigerant maldistribution in brazed plate heat exchanger evaporators. Part A: Testing campaign and experimental results

The refrigerant distribution in a brazed plate heat exchanger evaporator with distributor has been studied with a thermographic camera working under different conditions of inlet vapor quality, superheat, and water temperature drop. The thermographies have shown a clear uneven thermal distribution except when superheat is null. In most of the cases, they show that a great part of the liquid accumulates at the end channels of the evaporator. The degradation of the evaporator performance is higher when the water temperature drop has a similar or higher value than the superheat. On the other hand, when the superheat is significantly higher than the water temperature drop, the evaporator performance is very similar to situations in which there is an even distribution of the refrigerant. The registered evaporation temperatures are much lower for the case of 13 K of water temperature drop, highlighting the importance of the influence of this parameter on the evaporator performance. This research is described in two parts, Part A (present paper) including the description of the experimental campaign, the obtained experimental results and the results discussion and Part B including an analysis of the degradation of the evaporation temperature due to the refrigerant maldistribution as well as a deeper analysis of the registered temperatures and of the causes for the great degradation observed when the water temperature drop is increased.