Defrosting start point judgment method and defrosting start point judgment system for multi-loop heat exchanger of air source heat pump

Abstract

The invention provides a defrosting start point judgment method for a multi-loop heat exchanger of an air source heat pump. The defrosting start point judgment method comprises the following steps: calculating a frosting critical value A according to an overall heat exchange amount of outdoor heat exchangers; acquiring a coil pipe temperature Ttube of the outdoor heat exchanger in each loop and the dry-bulb temperature Ta of outdoor air; calculating an EMF value of each outdoor heat exchanger according to the coil pipe temperature Ttube and the dry-bulb temperature Ta; and counting the amount of the outdoor heat exchangers of which the EMF values are smaller than or equal to the frosting critical value A, and starting a defrosting mode if the amount is larger than a half of the amount of all outdoor heat exchangers so that the indoor heat is reversely transmitted to the outdoor environment in order to remove the frost on the outdoor heat exchangers. In a normal running process, the heat exchange amount needs not to be calculated repeatedly, and only the index of temperature needs to be measured. The method disclosed by the invention has the advantages of fully considering the characteristics of the multi-loop heat exchanger, realizing accurate measurement results and avoiding waste of energy. The invention also provides a defrosting start point judgment system for the multi-loop heat exchanger of the air source heat pump, and the system can realize the same technical effects.

Description

technical field [0001] The present invention relates to the technical field of air source heat pumps, and more particularly relates to a method and system for judging the defrosting starting point of a multi-loop heat exchanger of an air source heat pump. Background technique [0002] A heat pump is an energy-saving device that uses high-level energy to make heat flow from a low-level heat source to a high-level heat source. It has a wide range of application scenarios and huge market value. Air source heat pump has many advantages such as convenient heat source acquisition, high efficiency, simple operation, and no pollution, and has been widely concerned and applied. [0003] When the air source heat pump is in heating operation in winter, the outdoor air side heat exchanger acts as an evaporator. Due to the low evaporation temperature, the temperature on the surface of the heat exchanger also drops, even lower than 0°C. When the outdoor air flows through When the heat ex...

AI Technical Summary

Problems solved by technology

When the EMF method is applied to non-uniform frosting conditions, it is actually difficult to accurately determine the frosting situation through the measurement and analysis of the overall inlet and outlet refrigerant temperature and air temperature of the outdoor heat exchanger

It is difficult to avoid false defrosting caused by non-uniform frosting in practical application of EMF method

However, the traditional time determination method and time-temperature determination method not only cannot solve the wrong defrosting phenomenon caused by uneven frosting of multi-loop heat exchangers, but also tend to start defrosting when there is no frost, and delay starting when there is frost. The misoperation of defrosting seriously affects the normal operation of the heat pump system, which in turn causes a lot of energy waste

Images