Heat transfer fin and fin-tube type heat exchanger unit using the same

A heat exchanger unit comprising:

• a heat exchanger configured to receive heat generated by a combustion reaction and to heat heating water, the heat exchanger including a heat exchange pipe having an empty space formed therein in which the heating water flows and a heat transfer fin through which the heat exchange pipe passes;
• heat-insulating pipes disposed outside of the heat exchanger and adjacent to the heat exchanger with respect to a first direction and configured to receive the heating water and allow the heating water to flow through the heat-insulating pipes to thermally insulate the heat exchanger;
• and
• heat-insulating side plates located between opposite sides of the heat exchanger and the heat-insulating pipes with respect to the first direction,
• wherein the heat transfer fin includes:
• a fin body having a plate shape;
• a plurality of through-holes formed through the fin body and spaced apart from each other in the first direction so as to make a row, the heat exchange pipe being inserted into the plurality of through-holes;
• and
• two outer body portions protruding outward from at least partial areas of opposite ends of the fin body with respect to the first direction,
• wherein the outer body portions include:
• contact portions formed to make contact with the outer surfaces of the heat-insulating pipes make contact with the contact portions, with the heat-insulating side plates therebetween for transferring heat to the heat-insulating pipes through the heat-insulating side plates;
• and
• separated portions that are spaced apart from the heat-insulating side plates to form a gap,
• wherein the contact portions and the heat-insulating pipes are located in a range between two ends of the row of the plurality of through-holes with respect to a second direction which is a flow direction of combustion gas that is to flow along the fin body, and
• wherein parts of the separated portions are located at a downstream side of the contact portions and in the range with respect to the second direction.