Effectiveness of orchard heaters effectivenessofo0723kepn Year: 1951 all represent the same fuel input to the plot (50 gallons of oil per hour, or an equivalent amount of coke). Figure 12 shows curves of heating effect in relation to temperature inversion for the different kinds of heaters tested. The experimental points representing in- dividual runs have been omitted from the graph. Each curve, however, is based upon at least 3 runs at different inver- sions. The results from 11 of the 55 nights were not used because of periods with wind or unsteady conditions during the tests. Of the 44 r
Effectiveness of orchard heaters effectivenessofo0723kepn Year: 1951 all represent the same fuel input to the plot (50 gallons of oil per hour, or an equivalent amount of coke). Figure 12 shows curves of heating effect in relation to temperature inversion for the different kinds of heaters tested. The experimental points representing in- dividual runs have been omitted from the graph. Each curve, however, is based upon at least 3 runs at different inver- sions. The results from 11 of the 55 nights were not used because of periods with wind or unsteady conditions during the tests. Of the 44 runs used in plotting these curves, only 4 were more than 10 per cent above or below the curves as drawn. The curves of figure 12 confirm field experience that regardless of the kind of heater, the response for a given fuel input is less for small inversions than for larger ones. When the inversion is large, there appears to be little choice as to type of heater, but at the smaller inversions there are definite differences in effectiveness. At 6° F inversion, for example, the re- sponse with Fugit heaters spaced one per 3 trees was only half as great as with coke heaters for the same heat input in the plot. Of the bowl-type heaters tested, the lazy- flame heaters were the least effective at small inversions, while the Jumbo Cone and 7-inch Exchange heaters appeared to be the best. At inversions smaller than those included on the curves, the differ- ences between heaters would undoubtedly be greater. If values of heating effect are taken from figure 12 for the various heaters at a small inversion (5° F), and values for radiant fractions to trees plus ground are taken from figure 4 for the appropriate burning rates, it can be shown that the effectiveness or response of the various heaters at this inversion was in almost direct proportion to the radiant fractions. Taking the extreme comparison of coke heaters with and without radiation shields, figure 12 indicates that even at an
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