A small recirculating-chip test unit was developed and tested.   The characteristics of the test dryer could be evaluated by time-slice heat-and-material-balances from test runs (usually 1 each minute of test).  With the gas and bed temperatures known, the least accurate measurement is the relative-humidity (RH) of the off-gas. The RH is calculated for each time-slice. The accumulated water removal during the test could be compared to the before-and-after moisture content of the wood. This helps determine if the calculated RH values are reasonable.  The results agreed within less than 20%.