Autor:Editor del sitio Hora de publicación: 2023-04-10 Origen:Sitio
As we all know, a major function of the energy recovery ventilation is energy recovery.
Energy recovery is divided into total heat recovery and sensible heat recovery.
So what's the difference?
Sensible heat recovery is abbreviated as HRV in English.
The full name is Heat Recovery Ventilation.
Total heat recovery is abbreviated as ERV in English.
The full name is Energy Recovery Ventilation.
The energy in the air includes sensible heat (temperature) and latent heat (humidity). It is obvious that the total heat exchanger can recover energy as a whole, while the sensible heat exchanger can only recover temperature heat, which is their essential difference.
Therefore, in terms of energy saving effect, the sensible heat exchanger is not as good as the total heat exchanger.
Total heat is sensible heat + latent heat, sensible heat is temperature, latent heat is the heat contained in water molecules, sensible heat + latent heat is called enthalpy.
We can understand that when you shake hands, you feel that the other party's hands are hot and cold, which is the most common heat conduction;
What about latent heat?
Why is there a greater temperature difference between day and night in inland areas than in coastal areas? Because the humidity is different。
Without sunlight in inland areas, the temperature drops; In the coastal area, the heat contained in the water molecules can keep the temperature drop small. Therefore, to ensure comfort and energy saving, a full heat exchanger is required.
The energy in the air includes sensible heat (temperature) and latent heat (humidity). Whereas a total heat exchanger can effectively recover both types of energy, a sensible heat exchanger can only capture the former. Thus, in terms of energy efficiency, a total heat exchanger is superior to a sensible one.
So what is the heat conduction principle of a total heat exchanger?
When it is running, the indoor exhaust air and outdoor fresh air flow across through the heat exchanger respectively. Due to the temperature difference and steam pressure difference between the two airstreams, heat and moisture transfer occurs across the plate, allowing for the fresh air to effectively obtain enthalpy value from the exhaust air. In this way, air is ventilated and energy is saved.
The heat exchange material depicted in the figure is equivalent to a heat conduction plate, allowing for the transmission of temperature from the higher-temperature indoor exhaust air to the lower-temperature outdoor fresh air. As shown in the figure, the water molecules in the exhaust air can also pass through this heat exchange material to the fresh air side. What is that principle?
Because this heat recovery material is a special kind of paper, its density is much higher than that of ordinary paper, and its gas mobility is very low (so as to ensure that there is no wind mixing), but this paper has openings, through which water molecules can pass. Thereby realizing the recovery of latent heat.
But there is another problem here - will the dirty substances in the exhaust air also return to the room through the opening? the answer is negative!
The exchange membrane adopts hydrophilic/hydrophobic bipolar composite membrane, which has excellent selective moisture permeability and mechanical strength. The surface layer of the composite membrane is generally a hydrophilic substance, which is conducive to the passage of water molecules, screening and isolating harmful gas molecules such as carbon dioxide, formaldehyde, benzene, xylene, and VOC, and avoiding cross-contamination of fresh air and exhaust air during heat transfer.
The total heat exchanger can adjust the indoor air humidity.
Let's take summer humidity in southern region as an example.
high outdoor temperature, high humidity (38 degrees, relative humidity 90%).
low indoor temperature, high humidity (use air conditioner, 26 degrees, relative humidity 90%).
When indoor and outdoor humidity is 90%, can the indoor air humidity be reduced through the fresh air system?
Sensible heat exchanger is definitely not possible.
Because aluminum is not permeable as an exchange medium, humidity cannot be exchanged.
So can a full heat exchanger do it?
First add a few knowledge points
1. The humidity we usually refer to is relative humidity. Under the same relative humidity, the amount of water molecules contained in air with higher temperatures is greater than that contained in air with lower temperatures.
2. Moisture in the air is transmitted through pressure. The side with high pressure is transmitted to the side with low pressure. The more water molecules, the greater the pressure.
At the same humidity, assuming that there are 3 drops of water in the fresh wind at 38 degrees outside, then there will be less than 3 drops of water in the indoor exhaust air at 26 degrees. Let's say two drops for this example.
When two streams of air meet within the heat exchanger, the outdoor fresh air with more water molecules and higher pressure will conduct some of its water molecules to the indoor exhaust side, thus reducing the amount of water molecules contained in the fresh air entering into room and decreasing its overall humidity.
Dpurat patented total heat exchanger
The mortise and tenon structure, and the air duct is reasonably planned.
Enhance air permeability, increase heat conduction area,
Unique reverse convection layout, extending heat transfer time,
The total heat recovery efficiency reaches 70%, much higher than the national standard.
The heat exchanger core is made of special ER paper,
Nano film thickness 25um,
Polymer materials are not hospitable to bacteria,
Long-lasting prominent performance antibacterial materials.
It can be washed many times without affecting the performance.
The service life is up to 10 years.
Using ER special paper, low dew point,
No risk of ice blockage when used at - 20°.
The heat exchanger is one of the core components of the two-way flow ventilation system.
It is a highly efficient and energy-saving heat recovery device.
A good solution to the contradiction between indoor air quality and energy saving.
At present, paper heat exchange cores account for the majority.
With its high heat exchange rate and humidity recovery rate,
Smooth surface with low air resistance,
properties such as extremely long service life,
Become the best choice for energy saving and environmental protection,
Play an irreplaceable role in the field of energy saving.