In a certain drying line project, the process side requires an inlet-outlet air temperature difference of ≥25°C, and the equipment must operate continuously under ambient temperatures of -20 to +60°C and relative humidity <80%. For the selection of finned-tube heat exchangers under such working conditions, the core is to clarify the constraint relationships among heat transfer capacity, logarithmic mean temperature difference, allowable pressure drop, and frontal area, rather than looking at a single parameter alone. The GCH-58 model determines the number of tube rows and fin spacing according to this approach.
When handling dust-laden hot air as well, the plate-fin structure is compact and has a large heat transfer area per unit volume, but the fin channels are narrow, making cleaning difficult after dust accumulation and causing pressure drop to rise relatively quickly; the shell-and-tube type has good pressure resistance, but the air side requires additional fans and ductwork coordination, resulting in a relatively large system footprint. The GCH-58 model adopts a finned tube bundle plus frame structure, with relatively open air-side channels; the fin spacing can be adjusted according to the dust content of the medium, and purging is convenient during maintenance. For occasions with strict pressure drop requirements, the air-side flow velocity can be controlled by increasing the frontal area or reducing the number of tube rows, at the cost of increased equipment dimensions, so space needs to be reserved during the layout stage.
The medium composition directly determines the finned tube material and fin spacing. When hot water or steam is used as the heating medium, carbon steel can be selected for the base tube; when the medium contains corrosive components, stainless steel or appropriate surface treatment must be used instead, and this should be noted in the technical agreement. For dust-laden airflows, the fin spacing should be appropriately increased to reduce the risk of blockage. Flow rate and inlet/outlet temperatures are used to calculate the heat transfer capacity and logarithmic mean temperature difference, and are the basic data for determining the heat transfer area; the allowable pressure drop constrains the flow velocity values on the air side and the medium side, and both sides need to be calculated separately.
At the data submission stage, it is advisable to provide the medium composition, flow rate, inlet and outlet temperatures, allowable pressure drop, installation space, and interface orientation. Ambient temperature and humidity conditions affect the selection of materials and anti-corrosion schemes, and should also be stated. The technical parameters of the GCH-58 model are verified according to project data at the contract stage, avoiding direct application based on general catalogs.
