What is a heat pump?

What is a heat pump?

Heat pump technology is a new energy technology that has attracted much attention worldwide in recent years. The familiar “pump” is a mechanical device that can increase potential energy. For example, a water pump mainly pumps water from a low position to a high position. The “heat pump” is a device that can obtain low-grade heat energy from natural air, water or soil, and provide high-grade heat energy that can be used by people through electric power.

How the heat pump works

As a natural phenomenon, just as water flows from high to low, heat always flows from high temperature to low temperature. But people can create machines, just like using water pumps to lift water from low to high, using heat pumps can pump heat from low to high temperatures. Therefore, the heat pump is essentially a heat lifting device. The function of the heat pump is to absorb heat from the surrounding environment and transfer it to the object to be heated (the object with a higher temperature). Its working principle is the same as that of a refrigerator. The work in reverse Carnot cycle, the only difference is that the operating temperature range is different.

When the heat pump is working, it consumes part of the energy itself, excavates the energy stored in the environmental medium, and uses it through the heat transfer working medium circulation system to increase the temperature, while the work consumed by the entire heat pump device is only a small part of the output work Therefore, the use of heat pump technology can save a lot of high-grade energy.

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In operation, the evaporator absorbs heat from the surrounding environment to evaporate the heat transfer working fluid. The working fluid vapor is compressed by the compressor and the temperature and pressure increase. When the high temperature vapor is condensed into liquid through the condenser, the heat released is transferred to the storage tank. Water in the water tank. The condensed heat transfer working medium returns to the evaporator through the expansion valve, and then is evaporated again, and so on. A powerful tool for waste heat utilization-heat pump Water flows from a high place to a low place, and the heat is transferred from high-temperature objects to low-temperature objects. This is a natural law. However, in real life, people use water pumps to send water from low places to high places for the needs of agricultural irrigation and domestic water. Similarly, in today’s increasingly scarce energy, in order to recover the heat from the low-temperature hot gas that is usually discharged into the atmosphere and the low-temperature hot water discharged into the rivers, heat pumps are used to transfer the heat energy in the low-temperature objects to the high-temperature objects, and then the high-temperature objects. Objects to heat water or heating, so that the heat can be fully utilized. The working principle of the heat pump is basically the same as that of household air conditioners and refrigerators. It is used in evaporators, compressors, condensers and expansion valves through mobile media (usually Freon in the past, but now replaced by Freon in the sky). The cycle of gas phase changes (boiling and condensation) transfers the heat of the low-temperature object to the high-temperature object

The specific working process is as follows:

① The overheated liquid medium absorbs the heat of the low temperature object in the evaporator and evaporates into a gas medium. ② The gas medium coming out of the evaporator is compressed by the liquid compressor to become a high temperature and high pressure gas medium. ③The high-temperature and high-pressure gas medium releases heat energy to the high-temperature object in the condenser, and at the same time turns itself into a high-pressure liquid medium. ④ The high-pressure liquid medium is decompressed in the expansion valve, and then becomes superheated liquid medium, enters the evaporator, and circulates the initial process. ?

The performance of heat pumps is generally evaluated by the coefficient of performance (COP). The performance coefficient is defined as the ratio of the heat transferred from the low-temperature object to the high-temperature pasture and the required power. Generally, the performance coefficient of a heat pump is about 3-4, that is to say, the heat pump can transfer 3 to 4 times the heat energy of its own required energy from a low-temperature object to a high-temperature object. Now Europe, America and Japan are racing to develop new heat pumps. It is reported that the performance coefficient of the new heat pump can be 6 to 8. If this value can be popularized, it means that energy will be used more efficiently. The penetration rate of heat pumps will also be amazingly improved. The current maximum output temperature of the heat pump is about 110 degrees. Exceeding this temperature may cause the danger of media decomposition.

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Because Freon has a destructive effect on the earth’s atmospheric ozone, in order to protect the earth’s ecological environment, in addition to improving the availability coefficient of heat pumps and effectively using energy, science in various countries is also committed to the development of new freezing media. At present, alternative Freon media have been used.

Heat pump technology is a new energy technology that has attracted much attention worldwide in recent years. The familiar “pump” is a mechanical device that can increase potential energy. For example, a water pump mainly pumps water from a low position to a high position. The “heat pump” is a device that can obtain low-grade heat energy from natural air, water or soil, and provide high-grade heat energy that can be used by people through electric power.


Post time: Aug-22-2020
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