Although the air source heat pump has many advantages, but the current air source heat pump in the application there are still some problems. Mainly as follows:
(1) the design of the lack of air heat pump in the actual operation of the heat supply and performance factor correction
As we all know, the air temperature, relative humidity and frost and defrost control mode on the air source heat pump heat and performance coefficient has a very big impact. The current standards and manufacturers of product samples to provide data, neither considered frost around the country, nor consider the reasonable control of defrost mode. So the designer can not according to the existing product performance data to correctly determine the actual operation of the unit heat and performance coefficient, can not accurately design selection. To this end, should be identified throughout the country due to frost and defrost caused by the heating basin and the coefficient of performance of the coefficient of correction in order to obtain the actual operation of the unit heat and performance coefficient, as the basis for design and operation adjustment.
(2) how to prevent or delay the air side of the heat exchanger frost and how to choose an effective defrost mode
Air heat pump in the winter operation, when the air side of the heat exchanger surface knot box, will reduce the heat transfer coefficient of heat exchanger, increase the air side of the flow resistance, reduce the unit's heating capacity. How to prevent or delay the air side of the heat exchanger frost and how to choose an effective defrost control mode is generally concerned about the problem. To this end, should study the unit in the frost and defrost conditions under the operating rules and performance.
(3) unit operation of the instability
Outdoor temperature between 5-0 ℃, fog or rain and snow weather is the air source heat pump the worst operating conditions. At this point, due to serious serious frost, evaporative pressure is too low, often the unit to stop running; serious frost, the refrigerant evaporative volume decreased sharply, too much liquid caused by the possibility of liquid greatly increased. These often cause the unit to run the instability, so that the unit operation often fails, and even downtime.
(4) air source heat pump defrost process reliability is poor
At present, the air source heat pump in the defrost process. There are often some problems affecting the normal defrosting operation, mainly: inhale, exhaust pressure changes violently, the impact of the compressor, the system refrigerant back to the liquid; And the condenser frequent conversion, destruction of the normal operation of the unit, so each time a total of a long process to defrost the unit to return to normal operation; four-way valve action frequently, affecting its life; defrost start stage There is a pressure attenuation process, and some systems will be due to attenuation to low voltage protection caused by downtime; defrosting process on the indoor temperature is very large and so on. These problems have seriously affected the decay to low voltage protection caused by downtime; defrosting process on the indoor temperature is very large and so on. These problems seriously affect the reliability of the unit defrosting operation.