| 摘要 |
This invention provides a full flow vaporizer for use in a refrigeration system employing hot gas from the compressor to periodically defrost the cooling coil, or coils where multiple coils are employed. The vaporizer usually consists of three concentric circular cross-section tubes, the inner tube receiving the fluid from the coil and being provided in its wall with a plurality of fine bores directing the fluid forcefully radially outwards against the inner wall of the middle tube, which is heated by the hot gas. The flow capacities of the passages and the bores are chosen to be in a specific range of flow capacities relative to one another, so that when not in use the vaporizer has no appreciable effect on the remainder of the system. An orifice or restriction is provided at the outlet for the hot gas from the third annular passage through which the hot gas passes and heat the tube wall to vaporise any liquid refrigerant, and increases the back-pressure applied to the compressor, rendering the device self-balancing to prevent compressor motor overload. The vaporizer may be of other configurations, for example three rectangular chambers having two walls in common (Figs 5-7). Each restrictor may be provided downstream with a respective expansion chamber to re-evaporate any liquid that passes through the restrictor and maintain gas flow velocity. In a multiple evaporator system each evaporator may be provided with a respective adjustable restrictor to permit equalisation of the pressure drops in the individual hot gas lines and consequent equalisation of the respective defrost requirements. |
