Knowledge on heat pump

1. What is a heat pump?

Heat pump, also known as Leng Ji (Refrigerator) toenergy by low-temperature (Low-temperature thermal radiation field) to the high temperature (high temperature thermal radiation field) devices. Energy of the place and give it to a high temperature and is greater than the energy needed to run it.

 2. how heat pumps work
As a phenomenon of nature, from where the lower water, the heat always flows from the high temperature region at low temperature. But people can create machines, promoted from lower to higher ground and use the water pump, the heat pump can suck the heat from low temperature to high temperature. So the heat pump is essentially a thermal lift, heat pumps absorb heat from the surrounding environment, and passes it to the object being heated (hot objects), which has the same operating principle and refrigerator, are in accordance with the inverse Carnot cycle work, just a different temperature range is different.
Heat pump at work, which itself consumes some energy, medium energy mining storage environment, raise the temperature by heat transfer of refrigerant circulation system, and the entire heat pumps consume only a fraction of output power of the power and, therefore, can save a lot of high quality energy using heat pump technology.
Running, absorb heat from the surrounding environment evaporation heat transfer of evaporator refrigerant, refrigerant after the compactor, the steam temperature and pressure rise through the condenser for steam condensing into a liquid at high temperature, releasing heat to the water in the water reservoir. Condensation heat transfer of refrigerant through the expansion valve returns to the evaporator and then evaporated, so the circle.

Powerful tools–the waste heat recovery heat pump

Water flows from high to low, passes the heat from high temperature to low temperature objects, this is the law of nature. However, in real life, and for agricultural irrigation, domestic water needs, they pump water from the lower to the higher office. Similarly, in today’s increasingly tense energy, recovery is usually low-temperature heat emission into the atmosphere, discharge to rivers in the low-temperature heat from the hot water, heat pumps are used to cooler body heat transfer in high temperature objects and high-temperature objects to add hot water or heating, so that the heat is put to good use.

How heat pumps work and home air conditioners, refrigerators and work on basically the same principle through mobile media (formerly freon, now replaced by alternative freon) in the evaporator, compressor, condenser and expansion valve in the gas phase changes (boiling and condensation) circulating in the heat to a hotter to a cooler body. 

Specific work process is as follows: ① superheated liquid media within the evaporator to absorb heat from the cooler body and evaporates into a gas medium. ② evaporator compressor gas media through liquid compression, high temperature and high pressure gas media. ③ be reflected in high temperature and high pressure gas medium in the condenser heat release to give high temperature objects, at the same time itself becomes a high pressure liquid media. ④ vacuum high pressure liquid media in the expansion valve, and then becomes superheated liquid media, entering the evaporator, circulating initially in process.

Heat pump performance coefficient of performance (COP) to assess. Performance coefficient is defined as the low-temperature heat from the body to body heat and animal husbandry with the desired power. Coefficient of performance of the heat pump is usually around 3-4, that is, the heat pump itself can be 3 to 4 times times the energy required to transfer heat from a cooler body to a hotter. Europe, America and Japan are now racing to develop new types of heat pumps. Reported to a new type of heat pump performance coefficient can be 6 to 8. If this value were able to gain popularity, which means more efficient use of energy. Penetration of heat pumps will also be amazing improvement. Currently heat pump maximum output temperature is 110 degrees. Exceeding this temperature would likely make the media down danger.

Due to the Earth’s ozone damaging freon, in order to protect the eco-environment of the Earth, in addition to increase the coefficient of heat pumps, other than the efficient use of energy, and national scientific is also committed to the development of new refrigerating medium. There are now alternative freon used media.

Hosts system consists of heat pumps and heat pump hot water heat storage tanks in two parts. Heat pump hosts include air cooling, compressor and evaporator expansion valve; heat exchange coil storage water reservoir with built-in condensation box. Refrigerant (refrigerant) in the evaporation tubes absorbs heat from the ambient air, through the heat pump cycle by condensing coil in the tank to release heat, heating the water in the tank.
To figure out how heat pumps work, first of all to understand the principle of refrigeration system. Refrigeration system (compressor refrigeration) generally consists of four components: compressor, evaporator, condenser, throttling valve. The course of their work are: low temperature and low pressure liquid refrigerant (such as freon), first in the evaporator from low temperature heat sources (such as freezing water) and endothermic gasification. After gasification then pulls the evaporator, compressor refrigerant gases and compressed into a condenser, refrigerant gases, high temperature and high pressure gas. The high temperature and high pressure gas in the condenser high temperature heat sources (such as water) cooling condenses into a liquid, high temperature and high pressure liquid refrigerant. The throttle valve closure of low temperature and low pressure liquid refrigerant. A refrigeration cycle is completed.

One split heat pump for air conditioning, refrigeration condenser is placed in outdoor in the summer, and placed in the indoor evaporator. Runs conveying heat from indoor to outdoor. While the evaporator is placed outdoors in the winter, indoor condenser, thus conveying heat from outdoor to indoor. Of course we wouldn’t have to disassemble equipment season, but through the physical conversion valve to the evaporator and the condenser.

Heat pump with a four-way reversing valve. Under the condition of refrigeration, indoor heat exchanger is the evaporator, outdoor heat exchanger (whirring out the hot air out of that thing in the summer) is the condenser. When winter heating, four-way reversing valve switch, changing the refrigerant flow, in which case the indoor heat exchanger is a condenser, an outdoor heat exchanger (whirring out the winter cold of that thing) is the evaporator. Due to the out of the cold wind in the winter, heat exchanger with frosting, frosting to a certain extent, the four-way reversing valve switch, air conditioning, cooling conditions in the summer, outdoor heat exchangers are heat, defrost, defrost is complete, four-way valve before switching to hot. When defrosting, in order to prevent the Interior blows cold air, the indoor unit fan stopped running.

Heat pump condensation releases heat to heating and cooling systems, it is called “thermal multiplier”. Currently widespread in the market for household heating and air conditioner on, is already widely used heat pump heating, heating coefficient has reached more than 3. So, for producing hot water using heat pumps, consumption was obtained by hot water than ordinary electric water heaters consume three times gained more hot water, this is beyond traditional water heater.
There are many kinds of heat pump water heater on the market, mainly solar booster, water and air source in three series. Solar helps pushed type hot pump is hot pump and solar technology combines using of a hot pump technology; water hot pump is uses must temperature of water (20 ℃ above) as heat to refrigeration agent for media, will water in the of heat absorption Hou by compressor compression system hot, through hot Exchange players and cold water exchange heat to reached heating and system take hot of purpose, water hot pump must has must temperature and flow of water; air source hot pump to water hot pump similar method from air obtained heat to plus hot. Three types of heat pumps, air source heat pumps subject to conditionalities of the smallest, most development space, this paper focuses on an analysis of air source heat pump water heater discussion.
Fundamentals of heat pump water heater: it mainly consists of compressors, heat exchangers, axial flow fans, insulated water tanks, pumps, storage tanks, filters, electronic expansion valve and electronic automatic controller and other components. Connected power Hou, axis stream fan began running, outdoor air through evaporator for hot Exchange, temperature reduced Hou of air was fan discharge system, while, evaporator internal of workers mass endothermic vaporization was inhalation compressor, compressor will this low voltage workers mass gas compression into high temperature, and high pressure gas into condensation players, was pumps forced cycle of water also through condensation players, was workers mass heating Hou sent to for user using, and workers mass was cooling into liquid, the liquid by expansion valve throttle cooling Hou again inflow evaporator, so repeatedly cycle work, Thermal energy in the air is constantly “pump” into water, insulated tank water temperature is gradually increased, finally reaches 55 degrees Celsius or so, just right for bath, which is the basic working principle of air-source heat pump water heater.
Air-source heat pump is one of the world’s most advanced energy using products. With rapid economic development and the improvement of people’s quality of life, hot water have become necessities of life, however the conventional water heater (electric water heaters, gas water heaters, fuel) have disadvantages such as big, costly and polluting energy consumption; and energy-efficient solar water heater running are influenced by the meteorological conditions of the restriction. Air source heat pump heating principle distinct from the traditional solar water heaters, air-source heat pump for low temperature heat sources, such as air, water, solar, air source heat pumps driven by power from the low-temperature side learn from heat to heat domestic water, hot water by users directly into the circulatory system as the hot water supply or the use of small areas of fan-coil heating. Air-source heat pumps are by far the school hostel, hotel, bath Center, and other places of big, medium and small water supply system is the best solution.

3. efficiency
France engineers presented in 1824 Carnot efficiency can be used in the heat pump. Using the law of conservation of energy, we know that energy flowing into the heat pump (Qcold + w) is equal to the outflow of heat pumps for energy (Qhot). The efficiency of heat pumps (pump/heat input) coefficient (coefficient of performance), abbreviated C.O.P … As Carnot also turns out so we can get: the formula is predicated on heat pump used for heating, so when when the ambient temperature is relatively mild, heat pump more efficient. When heat pumps are used for cooling when the C.O.P. formula becomes:
The efficiency calculation only applies to ideal heat pump. Practice for heat pumps, C.O.P. typically between 2-6.


Heat pumps are widely used in air conditioners, refrigerators and other household appliances for refrigeration purposes. It can also be used in systems that use geothermal energy to heat the House (because some of the geothermal temperature is lower than the room temperature).

5. advantages/disadvantages
Advantages: heat pump makes the use of electricity became possible for housing heating and domestic water heating. Than using resistance heaters more efficient. Installing it is cheaper than using simple methods such as natural gas.
Disadvantages: it is in case of extreme cold, heat capacity decreases.