2017 RETA Breeze Sept-Oct

oil is added than taken out through oil pots. If over a year there is a large gap between what has been added and what has been taken out, it most likely is still in the ammonia system somewhere. Does the system contain any evaporators that have had coil circuits pinched in the past? If so, the evaporator should be re-rated to show actual tonnage capacity. The basic energy balance can be difficult to put together if some of the equipment you own no longer has design data, or if the manufacturer no longer exists. It is the basis for evaluating if your system is sized correctly. It may show that you are short compressor capacity. This doesn’t necessarily mean that you should purchase another compressor. Processing facilities have fluctuating heat loads, the evaporator capacity may be greater than the compressor capacity on paper. Cows, pigs, turkeys, etc. cannot enter all cooler bays at once, it is a gradual heat load over time. A detailed energy balance should explain why a compressor capacity is lower than the evaporator capacity. One item we haven’t discussed is the heat load put onto the system. What is the total heat load that the refrigeration system has to absorb and reject? Lights, motors, people, wall and ceiling R-values, and infiltration loads need to be calculated to show that the evaporators are an appropriate size to handle the heat load. While an energy balance can be a daunting task to compile, it should not be just a check in the box for your PSM program, but a tool used to understand the actual performance.

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