How does the Heat Pump defrost

2: Increase the thermal resistance of the heat exchanger and reduce the heat transfer capacity

3: Frequent defrosting, endless defrosting. The defrosting process is an air-conditioning operation process, which not only cannot make hot water, but also needs to consume the energy efficiency of the original hot water, and the discharged frozen water is flushed back into the thermal insulation water frost. cause the water temperature to drop further

4: The evaporation temperature decreases, the energy efficiency ratio decreases, and the operation performance of the heat pump deteriorates until it can not work normally

5: Because the unit cannot work normally, it directly causes economic losses to customers

 

During the low-temperature heating process of the heat pump, the evaporator will inevitably frost, and the thickness of the frost layer will gradually increase with the passage of time, and the gradual frost formation will reduce the energy exchange and the heating capacity of the heat pump.

 

Therefore, in order to maintain the heat exchange capacity of the air source heat pump water heater and improve the heat exchange efficiency of the heat exchanger, the heat pump should have a reliable defrosting method.

 

1. Natural defrosting

This is one of the simplest defrosting methods for the air source heat pump family. When the system needs defrosting, the system stops running for a period of time, and uses the heat of the surrounding environment to melt the frost layer on the surface of the heat exchanger. The crew will start working again

Natural defrosting is relatively simple, and does not require extra energy to defrost, but the disadvantage is that the longer the defrosting time, the greater the heat loss in the space, and its heating efficiency will decrease. , this defrosting method is not applicable

 

2. Water cream

This defrosting method is also relatively simple. It only needs to use a water spray device to spray water on the outer surface of the evaporator, so that the frost layer is melted and washed away by the heat of the water. This defrosting method is relatively waste water, and the scope of use is limited to air coolers with drainage pipes. In the colder places in the northern region, the remaining water after the unit is flushed needs to be removed in time after the water spray is completed, otherwise the water will be frozen on it, which will accelerate the rate of frost formation

 

3. Hot gas defrosting

The method of hot gas defrosting is to pass the exhaust port of the compressor into the evaporator, and use the heat of the exhaust port to melt the frost on the outer wall. In some cases excess heat is used, in more cases the hot gas is condensed in the evaporator, using its sensible and latent heat to defrost

The advantage of this defrosting method is that the frost layer melts from the inside to the outside. After the defrosting is completed, the hot air can be sent to the space immediately, but there are also problems of long defrosting time and high defrosting frequency.

 

4. Electric defrosting

The way of electric heating defrosting is to install electric heating wire outdoors and use electric heating to defrost. It is mainly used for finned tube air coolers, and the electric heating element is attached to the fins. During defrosting, the compressor stops working

The advantages of electric heating defrosting are: simple system operation and complete defrosting, which are mainly suitable for small equipment. However, what is missing is that part of the heat from electric heating and defrosting will be dissipated into the atmosphere, increasing the energy consumption problem, and the service life of the heating wire is also limited, which will also cause certain safety hazards.

Defrost is also an important technical issue for air source heat pump units, so when choosing to install an air source heat pump, be sure to find a well-known big brand manufacturer. In this way, both system maintenance and defrosting issues can be guaranteed. It operates efficiently while saving heat pump maintenance costs

 

5. Reverse cycle method

This method requires a device four-way valve. After the four-way valve is activated, the flow direction of the refrigerant is changed, so that the system switches from the air source heating mode to the cooling mode within a certain period of time. The high temperature gas discharged from the compressor directly enters the heat exchanger (evaporator) for defrosting

 

6. Hot gas bypass method

Using this method, the refrigerant flow does not change during defrosting. The heat pump will maintain the heating state, and the high-temperature gas discharged from the compressor will directly enter the box heater to defrost through the bypass pipe. The heat source for defrosting is the electrical energy consumed by the compressor and the heat storage capacity of the compressor casing

 

7. Energy storage defrosting method

Using this method, first the phase change material will store energy. When the evaporator freezes to a certain level and needs to be defrosted, the energy stored in the phase change material will be released to defrost.

 

Measures to prevent frost formation again

  

1: Avoiding power outages

When the winter temperature is very low, if the air source heat pump unit is powered off, the water temperature will freeze after cooling, causing the heat exchanger to freeze and crack. Especially when the fluorine system and water system freeze at the same time, when the compressor is powered on and restarted, the compressor will directly suck the water from the outer water circuit into the fluorine system, causing the entire unit to be scrapped. Therefore, when using air source heat pumps in winter, do not cut off the power supply. If the power supply must be cut off, the water in the unit, pipeline, and pump should also be drained.

2: Do a good job of pipeline insulation

Winter pipeline insulation is very important because the external temperature is too low. If there is no insulation, the hot water will instantly drop by many degrees after passing through the pipeline, making it difficult to reach the set temperature. In addition, when connecting the pipe sleeve to the pipe sleeve, insulation adhesive must be applied to the end face (circumferential seam) of the pipe sleeve. The longitudinal joints of the pipe sleeve should be staggered, and the longitudinal joints should not be vertically downwards. Seal the joint with glue in the middle.

3: Condensate should be cleaned regularly

When the air source heat pump is started, the condensate will be discharged. In winter, the outdoor temperature is very low, and the condensed water will freeze during discharge, thus freezing the drainage pipes. Therefore, if condensation water is found to be frozen and accumulated, it should be cleaned up in a timely manner. In addition, the host should not be too low off the ground. If the ice and snow are severe, it is advisable to use more than 50 centimeters.

4: Timely clean the snow around the air energy heat pump

Air source heat pumps mainly absorb heat from the air for heating. Maintaining ventilation is very important. Although the temperature is low in winter, there is also heat. If the air source heat pump unit is surrounded by snow, it will affect the heating effect and should be cleaned in a timely manner.