Higher than ambient temperatures was measured at air cooler inlets in a LNG plant. The higher temperatures at the air cooler inlet can cause reductions in LNG production rate. Understanding the mechanism for the temperature rise is beneficial to better design the facility and understand the design margin.

The causes of the higher temperatures may be due to several factors: cross contamination from nearby heat sources, air cooler exhaust re-circulates to the inlet and/or other plant activities. The temperature rise also depends on wind condition. To study the effect of wind, recirculation and cross contamination, 25 temperature sensors were installed at various locations of the air cooler inlets. Measurement data together with weather data were collected every 15 minutes for a six month period. A CFD model was built to predict the air cooler inlet temperatures. The predictions were compared with measurements at the LNG plant. It was found that under wind directions parallel to the air cooler rack, CFD predictions agree reasonably well with measurement. Under cross wind directions, larger discrepancies can occur at some locations.