| 摘要 |
A heated tank such as in a railroad tank car has a heat exchanger spaced from the bottom of the car to define a dead air space to insulate the heat exchanger from the bottom. The heat exchanger extends substantially longitudinally and transversely across the entire bottom of the car to provide a large heating transfer surface to the lading supported by the exchanger. A portion of the exchanger substantially encompasses a discharge valve of the tank car to provide heat transfer to the valve during unloading. The heat exchanger slopes toward the discharge valve to facilitate total removal of the lading. An inlet and an outlet associated with the heat exchanger are disposed adjacent the discharge valve for additional transfer of heat to the discharge valve. Baffles in the heat exchanger define a plurality of serpentine passages for conducting a heating medium. Feeder lines interconnect a central passage with outermost passages for introducing a portion of the heating medium in the outlying passages to obtain more uniform heating across the surface of the heat exchanger. The feeder lines serve to return a portion of the condensate to the central passage to avoid build-up of the condensate. A modified heat exchanger also includes a series of ports at a downwardly sloped end for purging condensate forming in the passages. The purged condensate is discharged through an outlet which is situated away from the inlet so as not to sap incoming heat.
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