The importance of leak-tight heat exchangers

Leak-tightness is one of three key parameters of recovery units, together with thermal efficiency and pressure drop. Heat exchanger tightness significantly affects the internal leakage of the recovery unit, and is also an important, monitored parameter in the system overall.

Leakage / tightness effects

The better a?heat exchanger’s tightness, the smaller the amount of air mixing between the individual branches (i.e. between exhaust air leaving the interior and fresh air coming in from outside), and thus less contamination of the supplied fresh air by undesirable substances.

The high leakage tightness also helps optimize the fan input and does not distort the unit’s efficiency values and pressure drops.

Leakage prevention

Leakage of plate heat exchangers mainly occurs in the areas where plates connect and around the plate blocks, i.e. in the areas where they are connected to the heat exchanger casing. At RECUTECH, we connect plates by double-folding, which improves their strength (especially with large heat exchangers) and thus the bond’s tightness.

The folded plate block is subsequently glued by a?special hotmelt adhesive to individual parts of the casing, and then the whole set is strengthened by rivets for better resistance during transport.

Testing

Leakage testing is carried out automatically at a?specialized measuring centre. Testing works by pressurizing one of the heat exchanger’s branches to a?specified pressure and then measuring its subsequent drop, i.e. the air leakage of that particular branch.

We guarantee our customers that the leakage of all delivered heat exchangers is within 0.5% of their nominal flow rate. The actual measured leakage value is declared in the nameplate of each heat exchanger in m3/h and in percent of the nominal flow rate. On average, our heat exchangers show leakages of less than 0.15% and are thus one of the tightest components for heat recovery in the market.