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A plate heat exchanger is selected on four variables — airflow, core area, recovery type and material grade — and the fifth decision, whether to use a sensible or a total heat core, follows from whether latent load matters in your climate. ROTER supplies cross-flow, counter-flow and cross counter-flow arrangements, in corrosion-resistant Series F and high-temperature Series G construction rated to 300°C, with sensible cores using hydrophilic aluminium foil of 0.1–0.2 mm thickness.

First: which airflow arrangement?

Three arrangements are used in practice, and the difference is in how the two air streams are oriented relative to each other inside the core. All three keep the supply and exhaust air completely separated — that is a property of the plate itself, not of the arrangement.

Plate heat exchanger airflow arrangements

The reason counter-flow is worth specifying is the heat-transfer area it gives. As the two streams pass in opposite directions along the same channel, the driving temperature difference is maintained over a longer length, so more area is available for the same core footprint. That can translate into a smaller unit or a lower pressure drop for the same duty.

Second: sensible or total heat core?

This is the decision with the biggest cost and performance consequences.

Sensible vs total heat plate core

The mechanism of the total heat core is worth understanding, because it is what makes the technology safe in an occupied building. The paper is made of specialty fibres processed so that the gaps between them are extremely small: only small-diameter water vapour molecules can pass through, while larger harmful gas and odour molecules cannot. Both latent and sensible heat are transferred and no cross-contamination occurs between the two streams.

Third: material grade and operating temperature

Material options and temperature limits

The frame can also be specified independently of the core: galvanized sheet, galvalume sheet, aluminium sheet, painted steel sheet, painted galvanized sheet or stainless steel, with screw, snap-fit or flange connection methods. For most corrosive duties the epoxy-coated core in a painted or galvanized frame is sufficient; stainless framing is usually only justified where the environment demands it.

Fourth: core geometry and how it is built

Plate core geometry and manufacture

Two details in that table have practical consequences. The spiral corrugation giving roughly 10% more heat-transfer area is why the sensible core reaches higher efficiency than the total heat core at similar core area — a sensible core moves only temperature but does so very efficiently. And the stamped boss channel support is what allows the core to withstand fresh- and exhaust-air pressure without deforming.

Published performance for reference

The tables below are ROTER's published data and are the figures to select against.

ROTER CXH series — medium ceiling-mounted total heat recovery unit

Full 14-model range on the medium ceiling-mounted page. Test conditions (GB/T 21087): summer — outdoor dry bulb 33°C, RH 80%, indoor 26°C, RH 50%; winter — outdoor 0°C, RH 30%, indoor 20°C, RH 60%. Fresh airflow = exhaust airflow = rated airflow. For reference only.

ROTER CHX-L series — sensible and total efficiency published separately

The CHX-L table is the more useful one for core selection, because it shows the sensible-versus-total gap on the same unit. On the CHX-15L that gap is 17 percentage points — 75% sensible against 58% total. That gap is the measurable cost of not recovering moisture, and in a humid climate it is the number that decides whether a sensible core is really the cheaper option.

How to complete the selection

With the four variables decided, the remaining work is arithmetic — and it is worth having ROTER do it, because the efficiency depends on the conditions.

Airflow — supply and exhaust, m³/h

Static pressure — design point, Pa

Core type — sensible or total; if total, the target supply humidity

Material grade — standard, epoxy-coated, Series F or Series G

Arrangement — cross-flow, counter-flow or cross counter-flow

Conditions — outdoor and indoor design temperature and humidity, and the exhaust gas composition

Send those and ROTER returns the core area, the plate stack-up, the model selection, the efficiency computed at your actual conditions rather than the catalogue value, and a quotation — normally within 24 hours. For the wider selection picture across all core types, see the rotary versus heat pipe comparison.

Frequently asked questions

What is a plate heat exchanger and what are its advantages?

A plate heat exchanger is a device that transfers energy between two air streams through thermally conductive plates, using the energy contained in the exhaust air to pre-condition the incoming fresh air. The supply and exhaust air streams are completely separated by the plates, which prevents cross-contamination and keeps the fresh air clean. Plate heat exchangers are classified by airflow direction into cross-flow, counter-flow, and cross counter-flow types. They feature a compact structure, no moving parts, high reliability, and a long service life.

How do I choose between cross-flow and counter-flow?

Counter-flow increases the heat-transfer area, because the two streams enter the channels in opposite directions and so maintain a temperature difference over a longer length. Cross-flow is simpler and shorter for a given duty. ROTER supplies counter-flow with three airflow-direction options — LL, LU and UU — to match different duct arrangements. The choice is usually about installation geometry as much as performance.

What is the difference between a sensible and a total heat plate exchanger?

A sensible heat exchanger transfers temperature only, using hydrophilic aluminium foil of 0.1–0.2 mm thickness. A total heat exchanger also transfers moisture, using heat exchange paper made of specialty fibres with gaps so small that only small-diameter water vapour molecules pass through — larger harmful gases and odour molecules cannot. Total heat exchangers cost more per square metre but reduce the latent load that the air-conditioning system has to remove.

Does a plate heat exchanger allow cross-contamination?

No. The supply and exhaust air streams are completely separated by the plates, which prevents cross-contamination and keeps the incoming fresh air clean. In the total heat core the fibre gaps are so small that only water vapour molecules pass through.

What temperature can a plate heat exchanger handle?

It depends on the series. Series F, built from anti-corrosion aluminium sheet with a galvanized sheet casing, is rated to a maximum of 100°C and suits severely corrosive gas environments. Series G, built from stainless steel plates and casing sealed with special sealing material, reaches 300°C for special high-temperature gas applications.

What maintenance does a plate heat exchanger need?

There are no moving parts, so maintenance is limited to filter replacement and periodic inspection of the core for fouling. Dust and foreign matter on the heat exchanger elements can be removed with a vacuum cleaner. The element design allows the coil to be withdrawn from the unit for external maintenance.

How much does a plate heat exchanger cost?

Cost is dominated by core area, which is set by airflow and face velocity, then by core type, foil thickness and frame material. ROTER does not publish a fixed price list for this reason. Send us the airflow, static pressure and core type and a quotation comes back within 24 hours.