Column 1 represents the drybulb bin range, Column 2 the mean temperature, [T.sub.mean,], of the bin, while Columns 3 and 4 represent the number of hours in a year that external hourly dry-bulb temperatures lie in that range and the mean corresponding wet-bulb temperature (MCWB) for that range.
Therefore, if the bin contains most of the dry-bulb data points towards the maximum limit of the bin, then the calculated MCWB value will also be towards the maximum limit of the bin, which is larger than the mean dry-bulb temperature of the bin.
Lastly, by taking the mean of all the dry-bulb temperature values in a bin rather than taking the mean of the bin endpoints makes the binning algorithm more robust since it is impossible for the MCWB temperature to be higher than the dry-bulb temperature.
Looking at the 120[degrees]F-115[degrees]F (49[degrees]C-46[degrees]C) bin in the chiller analysis, the Blue Book says that Phoenix spends an average of two hours per year in that temperature range, and that the mean coincident wet-bulb (MCWB
) temperature is 72[degrees]F (22[degrees]C).