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Enhanced vapor injection technology of air source heat pump

  • air source heat pump

    Last Updated on January 11, 2024 by Shawn Lee

    Principle of air source heat pump and enhanced vapor injection Technology
    Enhanced vapor injection technology is liked by foreign customers. Recently, I received many emails from customers asking me about this technology.
    Today, I’ll explain in depth the working principle and enhanced vapor injection technology of the air source heat pumps.

    If you know a lot about air source heat pumps, you can read the second paragraph directly and skip this paragraph. Because I’m going to explain the working principle of an air-powered heat pump.

    Working principle of air source heat pump:

    In most cases, in the natural environment, due to the gravity of the earth, water must flow downwards, and the flow of heat is the same as that of water, with high heat flowing towards low temperature.
    However, the normal operation of the air-powered heat pump requires that both the water source and the heat flow from the lower part to the higher part, which can be realized by means of the heat pump.
    The function of a heat pump is to absorb heat from the surrounding environment and transfer it to the heated object.

    air source heat pump
    air source heat pump

    Air-source heat pump = heating in winter+cooling in summer (meeting the requirements of both working conditions in winter and summer). Other heating equipment can only heat in winter, and air-conditioning equipment needs to be installed when cooling in summer.

    The four components of an air source heat pump include an evaporator, compressor, condenser, and expansion valve.

    Second, the air energy heat pump enhanced vapor injection technology.

    At first, the air-powered heat pump had many problems, such as too noisy operation, too large unit size, and low heating efficiency at low temperatures, which really affected the performance of the products. Many manufacturers began to tackle this problem, such as the “enhanced vapor injection” scheme.

    “enhanced vapor injection”: based on a complete system, which consists of an enhanced vapor injection compressor, hot water heat exchanger, evaporator, and other special components.

    But the compressor plays a central role in it?

    The following figure is a special compressor with “enhanced vapor injection” technology. An additional steam injection port is added to the compressor. The compressor receives the energy from the evaporator from the suction port and the steam from the other end of the pipeline from the steam injection port. The steam is used to cool the refrigerant (refrigerant) circulating in the pipeline. The essential meaning of this is to divide the original one-stage compression process into a quasi-two-stage compression process by using steam.

    To explain more clearly, we can analyze this process step by step:

    The first step: the compressor receives the heat A absorbed by the evaporator from the air and compresses it;

    Step 2: Open the air supply loop of the enhanced vapor injection, and let the steam enter the compressor;

    Step 3: The part of energy A being compressed by the compressor is mixed with the incoming steam. This process will continue until the working cavity of the compressor is separated from the air inlet. At this time, the steam is fully mixed with energy A and becomes a new energy B;

    Step 4: After the working cavity of the compressor is separated from the air inlet, energy B is subjected to “two-stage” compression, and finally, energy B enters the condenser for heat exchange with water.

    So where does the “qi” in tonifying qi come from?

    These gases are produced by the flash evaporator in the air source heat pump.

    The flash evaporator is connected to the compressor through a pipeline, along which steam passes from the flash evaporator to the compressor. Whether and when to supplement air is controlled by the on-off of an electromagnetic valve.

    Because the flash evaporator is actually located in the middle of the loop from the condenser to the evaporator.

    When the flash evaporator supplies air to the compressor, it actually increases the supercooling degree of the liquid refrigerant before throttling, so that the liquid refrigerant can better absorb the energy in the air in the evaporator. It is equivalent to indirectly increasing the energy A provided by the evaporator to the compressor.

    In addition, since the compressor is supplied with air, the amount of exhaust gas to the condenser is also increased, which increases the amount of refrigerant that exchanges heat with water in the condenser. It is these two factors that make the “enhanced vapor injection” scheme improve the heating capacity of the unit in a low-temperature environment.


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