| 主权项 |
1. A defrostable heat exchanging apparatus comprising:
a heat exchanger configured to cool gas flowing there through by heating a liquid also passing there through; a blockage having a predefined, fixed width and positionable upstream of the heat exchanger with respect to the liquid so as to reduce flow of the liquid through a portion of the heat exchanger aligned with the blockage relative to the flow of the liquid through other portions of the heat exchanger; and a positioning mechanism for moving the blockage of the predefined, fixed width relative to the heat exchanger in order to block a plurality of different portions of the heat exchanger while the entire predefined, fixed width of the blockage overlies different portions of the heat exchanger, wherein the positioning mechanism comprises a pair of conveying mechanisms spaced apart from one another and defining respective endless paths of travel, wherein the blockage is enraged by, extends between and moves with the pair of conveying mechanisms, wherein the positioning mechanism is configured to move the blockage relative to the heat exchanger so as to sequentially uncover each portion of the heat exchanger that is configured to receive liquid in order to permit liquid to flow therethrough while another portion of the heat exchanger that would also be configured to receive liquid in an absence of the blockage is blocked, and wherein the positioning mechanism is further configured to move the blockage relative to the heat exchanger such that uncovering of one portion of the heat exchanger occurs simultaneously with blocking of another portion of the heat exchanger, wherein the positioning mechanism is configured to be actuated by the flow of liquid so as to move the blockage relative to the heat exchanger, and wherein pair of conveying mechanisms comprise a pair of chains and a plurality of sprockets about which the chains extend, wherein the blockage is engaged by and moves with the chains. |
