Potential benefits of smart refrigerant distributors. Final report.

The main goal of this study was to investigate the benefits for finned tube refrigerant evaporators when refrigerant distribution was precisely controlled to produce a desired equal superheat in each circuit. This goal was accomplished by examining three different finned-tube evaporators; a wavy fin, wavy-lanced fin, and a wavy-lanced fin evaporator with tube sheets separated. The effects of non-uniform airflow on capacity were also examined while superheat was controlled in each evaporator circuit. In parallel with the experimental effort, a modelling program was implemented and validated with the experimental results and then used to determine the savings in evaporator core volume possible if refrigerant distribution was controlled by a smart distributor. In extreme cases, the savings in core volume could be as much as 40%. Extract from the table of contents; background and literature review; laboratory experiment (evaporators selected for testing; test conditions and experimental procedure; experimental results); evaporator modelling and simulations (heat transfer and pressure drop correlations; modelling issues: refrigerant distribution, internal heat transfer in a finned tube evaporator; possible savings in heat transfer area due to optimized superheat). The report can be downloaded from the Web site: www.arti-21cr.org/research/completed/index.html.