The heat-pump fresh-air ventilator is a device that combines fresh-air ventilation with heat-pump technology. By recovering heat or cooling from indoor and outdoor air, it achieves efficient ventilation and energy savings. Its working principle is mainly based on the refrigeration/heating cycle of the heat pump and air heat-exchange technology. The detailed working principle is as follows:
1. Basic Components
A heat-pump fresh-air ventilator typically includes the following core components:
- Heat-pump system: Includes compressor, evaporator, condenser, expansion valve, and refrigerant for heat transfer.
- Total heat exchanger (or sensible heat exchanger): Used for heat and/or moisture exchange between indoor and outdoor air.
- Fresh-air and exhaust channels: Introduce outdoor fresh air and expel indoor stale air respectively.
- Fans: Drive air flow, usually including supply and exhaust fans.
- Filtration system: Purifies incoming fresh air, removing particles, pollutants, etc.
- Control system: Adjusts operating mode, temperature, airflow, and other parameters.
2. Working Principle
The operation of a heat-pump fresh-air ventilator can be divided into two main parts: ventilation and heat recovery/regulation:
(1) Ventilation
- Fresh-air intake: Outdoor fresh air is drawn in by the fan through the fresh-air channel, purified by the filter to remove dust, PM2.5, and other pollutants.
- Exhaust discharge: Indoor stale air (containing CO₂, odors, etc.) is expelled outdoors through the exhaust channel.
- These two air streams meet in the total heat exchanger but are separated by a partition to avoid direct mixing.
(2) Heat Recovery and Heat-Pump Regulation
The core of the heat-pump fresh-air ventilator lies in the efficient use of energy through the heat-pump system and heat exchanger, as follows:
- Total heat exchange (or sensible heat exchange):
- In the total heat exchanger, indoor exhaust and outdoor fresh air exchange heat and humidity.
- Summer: Indoor cold air (low temp, low humidity) exchanges with outdoor hot air (high temp, high humidity), pre-cooling the fresh air and reducing its temperature and humidity.
- Winter: Indoor warm air (high temp, low humidity) exchanges with outdoor cold air (low temp, high humidity), preheating the fresh air, raising its temperature and recovering some humidity.
- Exchange efficiency typically reaches 60%–80%, significantly reducing the temperature-difference load of fresh air.
- Heat-pump system regulation:
- The heat pump further regulates fresh-air temperature through the refrigerant cycle.
- Cooling mode (summer): The heat-pump evaporator absorbs heat from the fresh air; the refrigerant evaporates, is compressed, and releases heat to the exhaust or outdoors in the condenser; the cooled fresh air is sent indoors.
- Heating mode (winter): The heat pump runs in reverse, absorbing heat from the exhaust or outdoor air and releasing it in the condenser to heat the fresh air sent indoors.
- The heat-pump system achieves efficient heat transfer via the reverse Carnot cycle, with a typically high COP and significant energy-saving effect.
(3) Air Purification and Supply
- The fresh air, after heat exchange and heat-pump regulation, is further purified by the filtration system to ensure air quality.
- The purified fresh air is sent indoors by the supply fan, keeping indoor air fresh while maintaining positive pressure to prevent external pollutants from infiltrating.
3. Operating Modes
The heat-pump fresh-air ventilator can switch between different modes based on environment and demand:
- Total heat-exchange mode: Relies only on the heat exchanger for heat and humidity recovery; suitable for seasons with large temperature differences.
- Heat-pump assist mode: The heat-pump system starts to further regulate fresh-air temperature; suitable for extreme weather (such as severe heat or cold).
- Bypass mode: When the indoor-outdoor temperature difference is small (e.g., spring/autumn), fresh air can bypass the exchanger and be introduced directly, saving energy.
- Single-direction ventilation mode: Only supplies fresh air or exhausts; used for specific scenarios (such as rapid pollutant removal).
4. Energy Saving and Advantages
- High efficiency and energy saving: The heat exchanger recovers 70%–90% of heat/cooling; the heat-pump system further reduces consumption; overall efficiency far exceeds ordinary ventilation equipment.
- Comfort: Fresh-air temperature is close to indoor temperature, avoiding cold/hot air entering directly and keeping indoor temperature and humidity stable.
- Air quality: Continuously introduces fresh air, expels stale air, and filters pollutants, improving the indoor environment.
- Flexibility: The heat-pump system can cool or heat according to climate, adapting to year-round use.
5. Typical Application Scenarios
- Residences, offices, schools, and other places requiring high air quality.
- Energy-saving buildings or passive houses, combining airtight structure for ventilation and energy saving.
- Extreme-climate regions, using the heat pump to regulate fresh-air temperature.
Summary
The heat-pump fresh-air ventilator recovers heat and humidity from indoor and outdoor air through a total heat exchanger, combined with the heat-pump system's cooling/heating function, achieving efficient ventilation, energy savings, and air purification. Its working principle is based on heat transfer and air circulation, using the heat pump's reverse Carnot cycle and heat-exchange technology to adjust fresh-air temperature close to indoor levels while keeping the air fresh. This equipment offers significant advantages in energy saving, comfort, and air quality, and is widely used in modern building ventilation systems.