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A heat pump type fresh air exchanger is a device that combines fresh air exchange and heat pump technology. It achieves efficient ventilation and energy saving by recovering heat or cold from indoor and outdoor air. Its working principle is mainly based on the heat pump's cooling/heating cycle and air heat exchange technology. The following is a detailed explanation of its working principle:
1. Basic components
Heat pump type fresh air exchangers typically include the following core components:
- Heat Pump SystemIt includes a compressor, evaporator, condenser, expansion valve, and refrigerant, and is used 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 ducts: To introduce fresh outdoor air and expel stale indoor air respectively.
- Fan: Driving airflow, typically including supply fans and exhaust fans.
- Filtration systemPurifies the fresh air entering the room, removing particulate matter, pollutants, etc.
- Control SystemAdjust operating mode, temperature, air volume and other parameters.
2. How it works
The working process of a heat pump type fresh air exchanger can be divided into:VentilationandHeat recovery/regulationTwo main parts:
(1) Ventilation
- Fresh air introductionOutdoor fresh air is drawn in by the fan through the fresh air duct, purified by the filter, and pollutants such as dust and PM2.5 are removed.
- ExhaustStale indoor air (containing carbon dioxide, odors, etc.) is exhausted outdoors through the exhaust duct.
- The two airflows meet in the total heat exchanger, but are separated by a baffle to avoid direct mixing.
(2) Heat recovery and heat pump regulation
The core of a heat pump type fresh air exchanger lies in achieving efficient energy utilization through a heat pump system and heat exchanger. The specific process is as follows:
- Total heat exchange (or sensible heat exchange):
- In a total heat exchanger, indoor exhaust air and outdoor fresh air exchange heat and humidity.
- summerThe system exchanges indoor cool air (low temperature and low humidity) with outdoor hot air (high temperature and high humidity), pre-cooling the fresh air and reducing its temperature and humidity.
- winterThe system exchanges indoor warm air (high temperature and low humidity) with outdoor cold air (low temperature and high humidity), preheats the fresh air, increases the temperature of the fresh air, and recovers some of the humidity.
- The exchange efficiency can typically reach 60%-80%, significantly reducing the temperature difference load of fresh air.
- Heat pump system regulation:
- Heat pumps further regulate the temperature of fresh air through refrigerant circulation.
- Cooling mode (summer)The evaporator of a heat pump absorbs heat from the fresh air, and the refrigerant evaporates and is compressed by the compressor. The heat is then released into the exhaust air or outdoors in the condenser, and the fresh air is cooled and sent into the room.
- Heating mode (winter)The heat pump operates in reverse, where the refrigerant absorbs heat from the exhaust air or outdoor air, releases the heat in the condenser to heat the fresh air, and then sends it into the room.
- Heat pump systems achieve efficient heat transfer through a reverse Carnot cycle, typically resulting in a high coefficient of performance (COP) and significant energy savings.
(3) Air purification and ventilation
- The fresh air, after undergoing heat exchange and heat pump regulation, is further purified by a filtration system to ensure air quality.
- The purified fresh air is delivered into the room by a blower to keep the indoor air fresh and maintain positive pressure to prevent external pollutants from seeping in.
3. Work mode
Heat pump type fresh air exchangers can switch between different modes according to the environment and needs:
- Total heat exchange modeIt relies solely on heat exchangers for heat and humidity recovery and is suitable for seasons with large temperature differences.
- Heat pump auxiliary modeThe heat pump system starts up and further regulates the fresh air temperature, making it suitable for extreme weather (such as extreme heat or cold).
- Bypass modeWhen the temperature difference between indoors and outdoors is small (such as in spring and autumn), fresh air can be introduced directly without the heat exchanger, saving energy.
- One-way ventilation modeIt only supplies fresh air or exhaust air, and is used in specific scenarios (such as rapid sewage discharge).
4. Energy saving and advantages
- High efficiency and energy savingThe heat pump system recovers heat/cooling energy from the 70%-90% via a heat exchanger, further reducing energy consumption and achieving overall energy efficiency far exceeding that of ordinary ventilation equipment.
- ComfortThe fresh air temperature is close to the indoor temperature to avoid cold/hot air from entering directly and to maintain stable indoor temperature and humidity.
- air qualityIt continuously introduces fresh air, expels stale air, and filters pollutants to improve the indoor environment.
- flexibilityHeat pump systems can cool or heat depending on climate conditions, making them suitable for year-round use.
5. Typical application scenarios
- Places that require high air quality, such as residences, offices, and schools.
- Energy-efficient buildings or passive houses, combined with a closed structure, achieve both ventilation and energy conservation.
- In regions with extreme climates, heat pumps are used to regulate the temperature of fresh air.
Summarize
Heat pump-type fresh air exchangers recover heat and humidity from indoor and outdoor air through a total heat exchanger. Combined with the cooling/heating functions of a heat pump system, they achieve efficient ventilation, energy saving, and air purification. Their working principle is based on heat transfer and air circulation. Utilizing the reverse Carnot cycle and heat exchange technology of the heat pump, the fresh air temperature is adjusted to near the indoor level while maintaining air freshness. This type of equipment has significant advantages in energy saving, comfort, and air quality, and is widely used in modern building ventilation systems.
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