Rotary Wheel Purge Sector: How Wheels Reduce Carryover

What a purge sector is

A rotary energy wheel spins exhaust and supply airstreams through the same matrix, so a small amount of exhaust gas and moisture is inevitably carried into the supply. A purge sector is a slice of the wheel (typically 5-15 degrees) where a portion of the clean supply air is directed backwards through the matrix to flush out residual exhaust before that section re-enters the supply duct.

What it reduces

• Gas carryover: a few percent of exhaust volume can migrate to supply; purge cuts it.
• Moisture carryover: important in humid climates where enthalpy recovery is used.
• Particulate carryover: helps in mildly dirty exhaust.

Limits of purge

Purge lowers but does not eliminate carryover, and it costs a little recovered energy. For genuinely contaminated streams – labs, hospitals – isolation beats purge, so a separated plate or heat pipe is preferred over a wheel.

Frequently asked questions

Does purge waste energy? A small amount, but it protects supply air quality, which is usually worth more.

Is purge the same as bypass? No – bypass diverts flow around the wheel for free cooling; purge cleans the matrix in place.

Need help specifying the right air-to-air heat recovery for your project? Contact the QIYU engineering team – WhatsApp +86 157 5335 5505, or email kuns913@gmail.com.

常见问题

常见问题

What is the purge sector on a rotary wheel?

A portion of the wheel, often 5 to 15 percent, is purged with supply air to sweep residual exhaust out of the matrix before it re-enters the supply stream, reducing carryover.

Does purge eliminate cross-contamination?

It greatly reduces it but cannot eliminate it entirely; for truly separated streams, such as dirty or contaminated exhaust, a plate or run-around coil is safer.