Author: Erik Hansen
I recently completed a visit to a facility I have never been to before in Colorado. The end-user had hired a 3rd party engineering firm to perform an energy balance for their central ammonia refrigeration system. The end-user viewed the report and took at face value which is fine. I mean, that is what they are paid for right? While it is reasonable to assume that the content in the report reflected accurate numbers, it hardly considered piping practices and how it can have adverse effects to the catalog data they may have been referencing. Be sure to consult with a system designer like Carlson & Stewart Refrigeration when having a system audit being conducted so not only catalog data is considered but also good piping practices.
Specifically, the report suggested that the evaporative condensers had an approximate evaporator ton capacity of about 560TR. I am not discounting for one second that this is likely accurate and following manufacturer’s direction from their technical bulletin, and assuming no scaling or fouling, 560TR may indeed be correct. What isn’t accounted for though is the hydrostatic pressure required to allow for proper flow from the evaporative condenser (by gravity) to the High Pressure Receiver. The liquid legs were only about 4ft long and as such, it was highly suspect that the condenser was sacrificing some of its heat transfer area to providing enough hydrostatic pressure to allow for continuous flow.
Much care should be taken from system designers to account for this because if it isn’t, you might think you are short on condenser capacity when you are not (like this end-user). Consider hiring a designer (or a design/build contractor) that is well versed in proper piping of condensers. Specifically, those that are familiar with IIAR piping handbook recommendations should be given additional consideration. Carlson & Stewart Refrigeration, Inc. is very active in the IIAR and regularly implements industry sanctioned piping practices into its designs and installations. Hiring contractors or designers that follow these principles often will result in smooth installations, startups and continual operation for years to come.