December 10, 2012
When the ambient temperature is relatively high, the air source heat pump has good operating performance, but when the outdoor ambient temperature is low, there are problems such as large compressor pressure ratio, high compressor exhaust temperature, frequent overheating protection, severe heating capacity attenuation, low heat pump COP and evaporator frosting, which have always restricted the large-scale promotion and application of air source heat pumps in cold areas. The air source heat pump system with compressor jet enthalpy technology and economizer (referred to as jet enthalpy air source heat pump) is a better solution to this problem.
Principle of jet enthalpy technology
Jet enthalpy technology refers to the optimization of medium-pressure refrigerant injection technology based on jet enthalpy compressor. The principle is to inhale a part of the intermediate pressure gas through the intermediate pressure suction hole, mix it with the partially compressed refrigerant and then compress it, so as to achieve two-stage compression with a single heat pump compressor, increase the refrigerant flow in the condenser, and increase the enthalpy difference of the main circulation loop, thereby greatly improving the efficiency of the heat pump compressor.
The air source heat pump compressor adopts the jet enthalpy increase method, which effectively reduces the exhaust temperature and improves the heating capacity and COP of the air source heat pump. At the same time, because the compression process is a quasi-two-stage compression, the compression ratio is increased, which is more conducive to low-temperature operation.
The air source heat pump system using the jet enthalpy increase technology mainly has the following forms: a heat pump system with an economizer and a heat pump system with a flasher.
Advantages of the jet enthalpy increase air source heat pump technology
The existing common air source heat pump compressor can only operate in the evaporation temperature range greater than -10 ℃, and the low condensation temperature limits the outlet water temperature. The jet enthalpy increase air source heat pump compressor can operate under the condition of the lowest evaporation temperature of -25 ℃, at which time the condensation temperature can reach 65 ℃, which increases the outlet water temperature. At the same ambient temperature, the energy efficiency of the jet enthalpy increase heat pump system is significantly higher than that of the common heat pump system, especially at low ambient temperature, the energy saving effect is very significant. When the outdoor ambient temperature is -22 ℃, the heat pump COP can reach 2.22, which can meet the heating needs of my country's coldest areas.
Application of jet enthalpy air source heat pump
With the maturity of low-temperature air source heat pump technology, it has been applied for heating in Tibet, Shenyang and other places in my country. The average COP during the heating period has reached more than 2.5, with good results. The initial investment of using low-temperature air source heat pump to transform the heat source of existing buildings (excluding the terminal system) is about 100-120 yuan/m2. For new heating systems, when the terminal form is floor radiation heating, the initial investment is 150-180 yuan/m2, and when the terminal form is fan coil, the initial investment is 180-210 yuan/m2. In Shenyang, the operating cost of air source heat pump is equivalent to that of centralized heating, saving more than 15% compared with gas wall-mounted boilers and more than 60% compared with electric heating.
From the initial investment, environmental protection and energy saving, stable operation and other aspects, the use of low-temperature air source heat pump for heating is a green heating technology worthy of promotion to replace coal.
