| 摘要 |
An indirect heater for heating air to be used for drying, curing or heating having an enclosure housing a circulation fan, filter bank, heat exchanger module and a burner. The heat exchanger has a bundle of tubes received between a pair of spaced apart headers. A cylindrical burner tube extends through one header and the tube bundle and opens into the other header. The burner flame and gaseous combustion products are discharged into a replaceable sacrificial sleeve that is telescopically received in the burner tube. A fan recirculates the heated gases through the interior of the sleeve, burner tube and the tubes of the bundle to increase heat transfer to the exterior air. The enclosure has a base, two pairs of opposed sidewalls and a top wall overlying the sidewalls. Each sidewall has an inner skin, a framework of trusses, an outer skin and insulation between the skins. The inner skin consists of airtightly joined skin panels supported by the frame and which have expansion gaps between adjoining skin panels to permit thermal expansion and contraction. The outer skin has interlocking panels held in place without contacting directly the frame or inner skin for minimizing heat transmission through each sidewall.
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