How to Choose a Heat Exchanger for Industrial Applications

Heat exchanger selection begins with the operating conditions: hot- and cold-side medium, inlet and outlet temperatures, flow rate, allowable pressure drop, design pressure and design temperature. These six parameters define the thermal duty and bound the construction options. Selecting from a catalogue first — and forcing the duty into a frame size — almost always leads to over-designed or under-performing units.

The sequence below is the order our engineering team works through an enquiry. Each step narrows the options for the next one, which is why working out of order tends to produce a selection that has to be revised.

Confirm the heat load first, either directly in kW or from flow rate and temperature change. Then characterise both fluids: composition, concentration, solids content, viscosity and any constituents that affect corrosion, such as chlorides, sulphur species or free oxygen. Non-water fluids should be described in enough detail for physical properties to be assigned; assuming water properties for glycol, oil or process liquids is a common source of undersizing.

Inlet and outlet temperatures on both sides fix the temperature approach, which in turn controls how much surface is needed. A close approach is achievable in plate constructions but increases area and pressure drop. State the allowable pressure drop for each side: it is a design constraint, not an output, and pumps or existing pipework usually set it. Where flow varies with season or load, give the range rather than a single figure.

Plate heat exchangers offer high efficiency, a compact footprint and serviceable gaskets for clean liquid-to-liquid duties. Shell-and-tube units cover broader pressure and temperature envelopes, a wider fluid range and fouling services. Brazed and welded plate constructions remove gaskets for refrigerants and aggressive media. Plate-and-block and spiral designs are chosen when fouling or maintenance access dominate. See the detailed comparison in our plate heat exchanger vs shell and tube guide before fixing the construction.

Stainless 316L is the usual starting point for plates; higher alloys such as 254 SMO, duplex, titanium or nickel alloys are considered when chlorides, seawater or aggressive chemistries are present. Tube material follows the same logic, with carbon steel used for clean utility services. Gasket compound must be matched to both the process fluid and the cleaning chemistry. The materials guide covers the decision in more detail.

Decide how the unit will be cleaned before the construction is fixed. Openable plate packs allow mechanical cleaning and gasket renewal; welded constructions rely on chemical cleaning; tubular units allow bundle access and retubing. Allow clearance for plate-pack opening or bundle withdrawal in the layout, and plan spare gasket sets or plates where the duty is known to foul.

Confirm the design code (ASME, PED, GB) and any third-party inspection requirement at the enquiry stage rather than after selection. Material certificates, pressure test reports and dimensional inspection records should be specified in the purchase order, because they affect fabrication route, inspection scope and schedule.

Provide a datasheet or P&ID where available. If only process conditions are known, an engineering-based selection from the manufacturer is usually faster than searching catalogues. For a first-pass check of duty, LMTD and preliminary area, run the sizing calculator and send the output with your enquiry. At Jiangxing, our engineering team returns a thermal selection and indicative pricing after engineering review; timing is confirmed for each enquiry.