In cold-climate ventilation, an exhaust-to-supply air-to-air plate exchanger can frost on the exhaust side when the supply outlet drops below the dew point of the humid exhaust. Frost narrows the channels, raises pressure drop and eventually blocks the core. Knowing when it forms — and which protection strategy to use — keeps the unit efficient through winter.
When frost actually forms
Frost needs two things: sub-freezing supply temperature and moisture in the exhaust. A typical case: exhaust at 20 °C and 40% RH, outdoor air at −10 °C. As the exhaust cools toward the supply outlet it can reach −5 °C, well below freezing, and the condensed moisture ices onto the plates.
- 深冷环境中超过约70%的效率会提高冻风险。
- 高室内湿度（泳池、实验室、厨房）会使其恶化。
- 霜冻首先出现在板束的冷角。
Four protection strategies
| 方法 | 工作原理 | 权衡 |
|---|---|---|
| 预热送风入口 | 在芯体前加热室外空气 | 最可靠；消耗能量 |
| 排风旁通／再循环 | 牺牲部分回收以保板片温暖 | 简单；降低季节效率 |
| 定期除霜（轮式） | 反转旋转或吹扫以融冰 | 不适于板片；短暂损失回收 |
| 热管辅助 | 热管在冷角附近预热送风 | 被动；增加成本与深度 |
关于 板式换热器，预热送风入口是标准解法，因为板片没有可反转的运动部件。 旋转轮 则可改用吹扫与定期除霜周期。
Sizing margin
Size the core for the design winter temperature, then add 10–15% face area so the bypass or preheat strategy has room to work without starving airflow. Our 选型设计指南 逐步讲解计算，且 厨房回收示例 在热侧负荷上展示相同逻辑。
Related reading
常见问题
Why does frost form on a plate heat exchanger?
Frost forms when the supply outlet temperature drops below the freezing point of the moisture in the humid exhaust, condensing and then freezing on the cold plates until the channels narrow or block.
What frost-protection strategies are used?
Common methods are preheating the incoming air, recirculating a portion of warm supply air, modulating or bypassing the exchanger at low outdoor temperatures, and using a defrost cycle on the exhaust side.
How should a unit be sized for cold climates?
Size the core and the frost-control strategy for the design winter condition, checking the supply outlet temperature against the exhaust dew point so the chosen method keeps channels clear.
Does frost protection hurt efficiency?
It trades a little recovered heat for reliability; a well-tuned bypass or preheat holds effectiveness high through most of the season while preventing blockage during the coldest hours.
常见问题
Why does frost form on a plate heat exchanger?
Frost forms when the supply outlet temperature drops below the freezing point of the moisture in the humid exhaust, condensing and then freezing on the cold plates until the channels narrow or block.
What frost-protection strategies are used?
Common methods are preheating the incoming air, recirculating a portion of warm supply air, modulating or bypassing the exchanger at low outdoor temperatures, and using a defrost cycle on the exhaust side.
How should a unit be sized for cold climates?
Size the core and the frost-control strategy for the design winter condition, checking the supply outlet temperature against the exhaust dew point so the chosen method keeps channels clear.
Does frost protection hurt efficiency?
It trades a little recovered heat for reliability; a well-tuned bypass or preheat holds effectiveness high through most of the season while preventing blockage during the coldest hours.
相关产品
面向暖通空调与通风的板式、旋转式或热管回收。
空气与液体用大表面积固定芯体。
大风量用高效能量回收。
用于洁净场合的被动、完全分离气流。