Establishing criteria for the design of a combination parallel and cross-flaming covered burner

Abstract

A burner was designed and constructed to combine weed control practices of parallel and cross-flaming with the technology of covers and insulation. It involved two covers designed to be placed on the sides of a crop row. The flame under the covers was directed parallel to the crop row. Using uniquely designed vanes to divert heated air, the apparatus was designed to re-circulate a portion of heat emitted from the burners for increased fuel efficiency. The apparatus was evaluated by comparing it with the two open flame practices. This evaluation was performed by moving the burners over an area that would monitor the temperatures at specified heights and locations. Temperatures were measured using thermocouples placed at heights 7-mm, 150-mm, and 300-mm in the crop row and height 7-mm in the left and right furrows. Burners traveled at a designated speed (2, 3.5, or 5 km/h) and burner operating pressure combination (207, 276, or 345 kPa). Time versus temperature curves were generated with the data for the temperatures observed. The areas under the curve, above 100 degrees C and within an exposure time boundary were used to compute utilization factors. The utilization factors provided a relative comparison of burner efficiency and performance. At 300-mm in the row, temperatures never exceeded 100 degrees C. At 150-mm in the row, temperatures rarely exceeded 100 degrees C. Sometimes temperatures exceeded 100 degrees C for a brief time. These results were evidence the covered burner re-circulated some heat and excessive amounts of heat were not escaping into the crop canopy. The thermocouples at height 7-mm provided a good indication of temperature activity with the burners. With areas under the curve in the row at 7-mm, open cross-flaming showed higher temperatures for than the covered burner. However, the covered burner had higher utilization factors than open cross-flaming. The covered burner utilization factors were greater than open cross or parallel-flaming in the furrows.