JIANGSU SUNCHI NEW ENERGY CO.,LTD.

What Exactly is Evi? Why Use EVI Air Source Heat Pumps in Cold Areas?

1. The air source heat pump EVI has become the main heating equipment


With the implementation of the policy, air source heat pumps EVI have gradually replaced coal-fired heating's "Leading Position" in cold regions due to its energy-saving, environmentally friendly, and efficient heating characteristics. In the face of the low temperature in winter in cold regions, why can air source heat pump EVI still show good heating effects and operate efficiently?


Why use EVI air source heat pumps in cold areas?


(1) The restriction of ultra-low temperature environment on the operation of air source

The compressor plays a role of "heat transfer" in the heat pump, and the electronic expansion valve throttling makes the refrigerant pressure drop and enters the evaporator cycle again. Once the system is placed in an environment with a temperature below -15°C, the ultra-low temperature air cannot release enough heat to satisfy the evaporation process of the liquid refrigerant in the evaporator. Insufficient evaporation makes the amount of low-temperature and low-pressure gaseous refrigerant entering the compressor insufficient, causing the compressor's exhaust temperature to be high, and it is easy to report a high-temperature exhaust failure.


(2) What is EVI?

We often hear a word——EVI. So what exactly is EVI? In fact, EVI is "jet enthalpy". Using this technology enables the ultra-low temperature air source to operate efficiently below -15°C to meet the heating needs of users.

The air source heat pump EVI loaded with the "jet-enhancing enthalpy" compressor can perform "quasi-secondary compression" on the low-temperature heat in the air, so that the air source heat pump compressor's exhaust content will increase, and in low-temperature conditions, the system will be stable and the heating efficiency will be improved at the same time.


2. The working principle of EVI  in the fluorine circuit


After passing through the condenser (tube) heat exchange, a part of the medium-temperature and high-pressure liquid refrigerant has the same energy as conventional air and returns to the evaporator after throttling and depressurization. Although the heat absorbed at the ultra-low temperature is insufficient, it is only a part of the refrigerant exchanges heat in the system, so the evaporation effect can be guaranteed.


The other part of the refrigerant enters the enthalpy plate exchange after throttling and depressurization and returns to the compressor after absorbing part of the heat. The use of this method increases the return air volume of the compressor (the volume of low-temperature and low-pressure gaseous refrigerant) and avoids the hidden danger of the compressor reporting high exhaust temperature. Moreover, a part of the refrigerant obtains heat from the enthalpy-increasing plate exchange, thereby ensuring the heating effect on the use side.


Therefore, the air source heat pump EVI can ensure efficient heating of the unit in an ultra-low temperature environment.

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