The Indoor Humidity Is Too High in Summer. How to Dehumidify? Can the Dehumidification Mode of the Air Conditioner Really Save Electricity and Money?

It's the plum rain season again. The moisture in the air seems to be about to drip out, and only by keeping the air conditioner on can we keep the indoor environment dry. Non - HVAC professionals may not understand how the air conditioner dehumidifies. Here is a popular science article that is easy to understand.
Research shows that the human body is most comfortable in an air environment with a humidity of 50% - 70%. When the humidity is higher than 70%, the human body's comfort level will decrease.

When the indoor humidity is too high, appropriate dehumidification methods can be used to adjust the humidity to make the human body feel comfortable.
Pt.1 How Does the Air Conditioner Dehumidify?
The air conditioner has a dehumidification function in two modes:
a) Cooling mode
This is a mode that any air conditioner has and is also the most basic function of an air conditioner. The process of air conditioner cooling is inevitably accompanied by dehumidification. When the humid air passes through the evaporator of the air conditioner, its temperature will drop significantly. The air humidity is in a supersaturated state, and the excess water vapor precipitates in the form of condensed water and condenses on the fins of the evaporator, which is called "condensation". When the cooling mode reaches a certain equilibrium state, the air humidity will also drop to a certain level.
Psychrometric chart
b) Independent dehumidification mode
This method is called constant temperature dehumidification by professionals in the industry.

Its basic principle is to reheat the air that has been cooled by the evaporator to its original temperature and then send it back into the room. In this way, the indoor environment remains relatively constant while the humidity decreases.
There are also two ways to heat the temperature of the air outlet: One is to use an electric heating component to heat the air after it passes through the evaporator. This type of air conditioner is equipped with an electric heating device in the indoor unit. After the air passes through the evaporator (with a low surface temperature) and precipitates condensed water, the electric heating device then heats this part of the cooled air, keeping the temperature of the air outlet of the air conditioner basically the same as that of the air inlet.
The other is to use the heat generated by the condenser to heat the dehumidified air. This type of air conditioner has two exchangers, a and b. In the independent dehumidification mode, they are respectively switched to the evaporator and the condenser. Similarly, the air passes through the evaporator a (with a low surface temperature) and precipitates condensed water, and then the condenser b (with a high surface temperature) replaces the function of the electric heating component in the first method, also keeping the temperature of the air outlet of the air conditioner basically the same as that of the air inlet. These two heating methods only differ in the heating device and the heating method, and the latter is a pure physical method.
Pt.2 It is often said that turning on the dehumidification function of the air conditioner can save electricity and money. Is it true?
In fact, the "dehumidification" of our household air conditioner is a special cooling mode. The cooling mode is a mode of normal air supply and continuous dehumidification, while the dehumidification mode reduces the air supply and continuously dehumidifies.
In the dehumidification mode, in order to achieve a better dehumidification effect, the air conditioner generally operates at a low air volume. At this time, the temperature of the heat exchanger of the indoor unit of the air conditioner is lower, which is more conducive to the condensation of water vapor in the air into water. In the dehumidification mode, the air conditioner will intermittently start the compressor, which is a "big power consumer", and at the same time, it will lower the indoor temperature. In the cooling mode, the compressor will keep running until the preset temperature is reached.
At first glance, it seems that dehumidification saves a lot more electricity. However, a large number of air conditioner energy efficiency tests show that when the compressor of the air conditioner runs stably and the indoor air output is the largest, the cooling efficiency is the highest, that is, our COP is higher. Relatively speaking, in the dehumidification mode, the compressor starts and stops intermittently, and with a lower air volume, its cooling efficiency is naturally greatly reduced.
To give a simple example, in the normal cooling mode, the air conditioner consumes 2 kilowatt - hours of electricity and generates 6 kilowatt - hours of cooling capacity. In the dehumidification mode, the air conditioner consumes 1 kilowatt - hour of electricity and generates 1.5 kilowatt - hours of cooling capacity. On the surface, the dehumidification mode uses 1 kilowatt - hour less electricity, but this is not the case. Think about it in reverse and you'll understand. If you need to maintain the room at a certain temperature and require 6 kilowatt - hours of cooling capacity, then the cooling mode only needs 2 kilowatt - hours of electricity, while the dehumidification mode requires 4 kilowatt - hours of electricity. The difference is immediately obvious.
Pt.3 Do these 7 correct usage methods when using the air conditioner for cooling to save electricity and be healthier.