2016 ASHRAE Winter Conference

Brazing is a practical, fast and relatively low cost joining method.  Both aluminum and copper heat exchangers and many miscellaneous component connections are brazed.  In addition, field service repair often requires re-brazing that can take place under less-than-ideal conditions.  However, to achieve a reliable and leak-free braze joint, adequate surface preparation and proper control over heating parameters are required.  Unfortunately, if inadequate brazing techniques are used, thermal degradation at the interior surfaces of tubing can take place.  The degradation can lead to the formation of scale that may dislodge and cause contamination of bearings or valves in the HVAC&R system.

To guarantee long equipment life, the construction and assembly of heat exchangers, piping, valves and compressors requires metalworking fluids compatible with the refrigerant and lubricant without cleaning prior to final brazing or assembly. The movement of the industry to chemically unstable low GWP refrigerants and aluminum heat exchangers has necessitated the development of new metalworking lubricants and additive packages.  Continued interest in developing environmentally friendly materials with low VOC, no wax formation, and excellent compatibility when tested by ASHRAE Standards 86 and 97 continues to drive the manufacturing market to search for the next generation of sustainable metalworking fluids.

There is growing pressure on installation contractors to get refrigeration systems up and running with as little on-site work to keep projects within budget. Unfortunately, this trend can result in systems that meet the immediate need to keep the product cold but are not optimized to minimize life cycle operating costs, including energy usage and maintenance.  An installation plan that includes measures to correctly setup the refrigeration system can result in both significant energy savings as well as superior reliability.  This discussion will focus on several high priority areas that have historically proven to provide the most benefit.

More manufacturers are commercializing air conditioners and heat pumps using HFC32 refrigerant because of its environmental, energy efficiency and economic benefits. This presentation explains points to consider for installation and service practices when changing over from HCFC22 or R410A to HFC32. The presentation covers aspects such as the impact on tooling, refrigerant cylinders, working pressures, safety requirements as well as the impact on recovery and reuse. The information is intended for installers and service technicians but is also useful for training centers, associations and policymakers involved in training and certification schemes for people working on equipment containing a refrigerant circuit.