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Wikipedia

Heat pump

March 04, 2023

This article is about devices used to heat and potentially also cool a building using the refrigeration cycle. For cooling only, see air conditioner. For other uses, see Heat pump (disambiguation).

A heat pump is a device that can provide heat to a building by transferring thermal energy from the outside using a refrigeration cycle. Many heat pumps can also operate in the opposite direction, cooling the building by removing heat from the enclosed space and rejecting it outside. Units that only provide cooling are called air conditioners.

External heat exchanger of an air-source heat pump

When in heating mode, a refrigerant at outside temperature is being compressed. As a result, the refrigerant becomes hot. This thermal energy can be transferred to an indoor unit. After being moved outdoors again, the refrigerant is decompressed — evaporated. It has lost some of its thermal energy and returns colder than the environment. It can now take up the surrounding energy from the air or from the ground before the process repeats. Compressors, fans, and pumps run with electric energy.

Air source heat pumps are the most common models, while other types include ground source heat pumps, water source heat pumps and exhaust air heat pumps. Large-scale heat pumps are also used in district heating systems.[1]

The efficiency of a heat pump is expressed with a coefficient of performance (COP), or seasonal coefficient of performance (SCOP). The higher the number, the more efficient a heat pump is and the less energy it consumes. When used for space heating, heat pumps are typically much more energy efficient than simple electrical resistance heaters.

Because of their high efficiency and the increasing share of fossil-free sources in electrical grids, heat pumps can play a key role in climate change mitigation.[2][3] With 1 kWh of electricity, they can transfer 3 to 6 kWh of thermal energy into a building.[4] The carbon footprint of heat pumps depends on how electricity is generated, but they usually reduce emissions in mild climates.[5] Heat pumps could satisfy over 80% of global space and water heating needs with a lower carbon footprint than gas-fired condensing boilers: however, in 2021 they only met 10%.[6]

Principle of operation

Heat will flow spontaneously from a region of higher temperature to a region of lower temperature. Heat will not flow spontaneously from lower temperature to higher, but it can be made to flow in this direction if work is performed. The work required to transfer a given amount of heat is usually much less than the amount of heat; this is the motivation for using heat pumps in applications such as heating of water and the interior of buildings.[7]

The amount of work required to drive an amount of heat Q from a lower-temperature reservoir such as ambient air to a higher-temperature reservoir such as the interior of a building is:

 
where
  •   is the work performed on the working fluid by the heat pump's compressor.
  •   is the heat transferred from the lower-temperature reservoir to the higher-temperature reservoir.
  •   is the instantaneous coefficient of performance for the heat pump at the temperatures prevailing in the reservoirs at one instant.

The coefficient of performance of a heat pump is greater than unity so the work required is less than the heat transferred, making a heat pump a more efficient form of heating than electrical resistance heating. As the temperature of the higher-temperature reservoir increases in response to the heat flowing into it, the coefficient of performance decreases, causing an increasing amount of work to be required for each unit of heat being transferred.[7]

The coefficient of performance, and the work required, by a heat pump can be calculated easily by considering an ideal heat pump operating on the reversed Carnot cycle:

  • If the low-temperature reservoir is at a temperature of 270 K (−3 °C) and the interior of the building is at 280 K (7 °C) the relevant coefficient of performance is 27. This means only 1 joule of work is required to transfer 27 joules of heat from a reservoir at 270 K to another at 280 K. The one joule of work ultimately ends up as thermal energy in the interior of the building so for each 27 joules of heat that are removed from the low-temperature reservoir, 28 joules of heat are added to the building interior, making the heat pump even more attractive from an efficiency perspective.
  • As the temperature of the interior of the building rises progressively to 300 K (27 °C) the coefficient of performance falls progressively to 9. This means each joule of work is responsible for transferring 9 joules of heat out of the low-temperature reservoir and into the building. Again, the 1 joule of work ultimately ends up as thermal energy in the interior of the building so 10 joules of heat are added to the building interior.

History

Milestones:

1748
William Cullen demonstrates artificial refrigeration.
1834
Jacob Perkins builds a practical refrigerator with dimethyl ether.
1852
Lord Kelvin describes the theory underlying heat pumps.
1855–1857
Peter von Rittinger develops and builds the first heat pump.[8]
1877
In the period before 1875, heat pumps were for the time being pursued for vapour compression evaporation (open heat pump process) in salt works with their obvious advantages for saving wood and coal. In 1857, Peter von Rittinger was the first to try to implement the idea of vapor compression in a small pilot plant. Presumably inspired by Rittinger's experiments in Ebensee, Antoine-Paul Piccard from the University of Lausanne and the engineer J.H. Weibel from the Weibel–Briquet company in Geneva built the world's first really functioning vapor compression system with a two-stage piston compressor. In 1877 this first heat pump in Switzerland was installed in the Bex salt works.[9][10]
1928
Aurel Stodola constructs a closed-loop heat pump (water source from Lake Geneva) which provides heating for the Geneva city hall to this day.
1937–1945
During and after the First World War, Switzerland suffered from heavily difficult energy imports and subsequently expanded its hydropower plants. In the period before and especially during the Second World War, when neutral Switzerland was completely surrounded by fascist-ruled countries, the coal shortage became alarming again. Thanks to their leading position in energy technology, the Swiss companies Sulzer, Escher Wyss and Brown Boveri built and put in operation around 35 heat pumps between 1937 and 1945. The main heat sources were lake water, river water, groundwater, and waste heat. Particularly noteworthy are the six historic heat pumps from the city of Zurich with heat outputs from 100 kW to 6 MW. An international milestone is the heat pump built by Escher Wyss in 1937/38 to replace the wood stoves in the City Hall of Zurich. To avoid noise and vibrations, a recently developed rotary piston compressor was used. This historic heat pump heated the town hall for 63 years until 2001. Only then it was replaced by a new, more efficient heat pump,[11][9]
1945
John Sumner, City Electrical Engineer for Norwich, installs an experimental water-source heat pump fed central heating system, using a neighboring river to heat new Council administrative buildings. Seasonal efficiency ratio of 3.42. Average thermal delivery of 147 kW and peak output of 234 kW.[12]
1948
Robert C. Webber is credited as developing and building the first ground heat pump.[13]
1951
First large scale installation—the Royal Festival Hall in London is opened with a town gas-powered reversible water-source heat pump, fed by the Thames, for both winter heating and summer cooling needs.[12]

Types

Air-source heat pump

Main article: Air-source heat pump
 
Outdoor unit of air source heat pump operating in freezing conditions

Air-source heat pumps are used to move heat between two heat exchangers, one outside the building which is fitted with fins through which air is forced using a fan and the other which either directly heats the air inside the building or heats water which is then circulated around the building through radiators or underfloor heating which releases the heat to the building. These devices can also operate in a cooling mode where they extract heat via the internal heat exchanger and eject it into the ambient air using the external heat exchanger. Some can be used to heat water for washing which is stored in a domestic hot water tank.[14]

Air-source heat pumps are relatively easy and inexpensive to install and have therefore historically been the most widely used heat pump type. In mild weather, coefficient of performance (COP) may be around 4,[4] while at temperatures below around −7 °C (19 °F) an air-source heat pump may still achieve a COP of 3.

While older air-source heat pumps performed relatively poorly at low temperatures and were better suited for warm climates, newer models with variable-speed compressors remain highly efficient in freezing conditions allowing for wide adoption and cost savings in places like Minnesota and Maine.[15]

Ground-source heat pump

Main article: Ground-source heat pump

A ground-source heat pump draws heat from the soil or from groundwater which remains at a relatively constant temperature all year round below a depth of about 30 feet (9.1 m).[16] A well maintained ground-source heat pump will typically have a COP of 4.0 at the beginning of the heating season and a seasonal COP of around 3.0 as heat is drawn from the ground.[17] Ground-source heat pumps are more expensive to install due to the need for the drilling of boreholes for vertical placement of heat exchanger piping or the digging of trenches for horizontal placement of the piping that carries the heat-exchange fluid (water with a little antifreeze).

A ground-source heat pump can also be used to cool buildings during hot days, thereby transferring heat from the dwelling back into the soil via the ground loop. Solar thermal collectors or piping placed within the tarmac of a parking lot can also be used to replenish the heat underground.[citation needed]

Exhaust air heat pump

Main article: Exhaust air heat pump

Exhaust air heat pumps extract heat from the exhaust air of a building and require mechanical ventilation. Two classes exist:

  • Exhaust air-air heat pumps transfer heat to intake air.
  • Exhaust air-water heat pumps transfer heat to a heating circuit that includes a tank of domestic hot water.

Solar-assisted heat pump

See also: Solar-assisted heat pump

A solar-assisted heat pump either integrates a heat pump and thermal solar panels or photovoltaic solar power in a single system. In the case of thermal solar, typically these two technologies are used separately (or are operated in parallel) to produce hot water.[18] In this system the solar thermal panel is the low-temperature heat source, and the heat produced feeds the heat pump's evaporator.[19] The goal of this system is to get high COP and then produce energy in a more efficient and less expensive way.[citation needed]. In the case of photovoltaic solar heat pumps, or solar air conditioners, electricity to run the heat pump is generated from the sun. Either batteries can be used to store excess solar energy generated to run during cloudy or nighttime periods, or grid power can be used during these periods.

Water-source heat pump

 
Water-source heat-exchanger being installed

A water-source heat pump works in a similar manner to a ground-source heat pump, except that it takes heat from a body of water rather than the ground. The body of water does, however, need to be large enough to be able to withstand the cooling effect of the unit without freezing or creating an adverse effect for wildlife.[20]

Thermoacoustic heat pump

A heat pump that operates as a thermoacoustic heat engine without refrigerant but instead using a standing wave in a sealed chamber driven by a loudspeaker to achieve a temperature difference across the chamber. [21]

Applications

The International Energy Agency estimated that, as of 2021, heat pumps installed in buildings have a combined capacity of more than 1 000 GW. [6] They are used in climates with moderate heating, ventilation, and air conditioning (HVAC) needs and may also provide domestic hot water and tumble clothes drying functions.[22] The purchase costs are supported in various countries by consumer rebates.[23]

Space heating and sometimes also cooling

In HVAC applications, a heat pump is typically a vapor-compression refrigeration device that includes a reversing valve and optimized heat exchangers so that the direction of heat flow (thermal energy movement) may be reversed. The reversing valve switches the direction of refrigerant through the cycle and therefore the heat pump may deliver either heating or cooling to a building. In cooler climates, the default setting of the reversing valve is heating.

The default setting in warmer climates is cooling. Because the two heat exchangers, the condenser and evaporator, must swap functions, they are optimized to perform adequately in both modes. Therefore, the Seasonal Energy Efficiency Rating (SEER) of a reversible heat pump is typically slightly less than those of two separately optimized machines. For equipment to receive the Energy Star rating, it must have a rating of at least 14 SEER. Pumps with ratings of 18 SEER or above are considered highly efficient. The highest efficiency heat pumps manufactured are up to 24 SEER.[24]

Water heating

In water heating applications, a heat pump may be used to heat or preheat water for swimming pools or heating potable water for use by homes and industry. Usually heat is extracted from outdoor air and transferred to an indoor water tank, another variety extracts heat from indoor air to assist in cooling the space.[citation needed]

District heating

Main article: District heating

Heat pumps can also be used as heat supplier for district heating. In Europe, heat pumps account for a mere 1% of heat supply in district heating networks but several countries have targets to decarbonise their networks between 2030 and 2040. [1] Possible sources of heat for such applications are sewage water, ambient water (e.g. sea, lake and river water), industrial waste heat, geothermal energy, flue gas, waste heat from district cooling and heat from solar seasonal thermal energy storage. In Europe, more than 1500 MW of large-scale heat pumps were installed since the 1980s, of which about 1000 MW were in use in Sweden in 2017.[25] Large-scale heat pumps for district heating combined with thermal energy storage offer high flexibility for the integration of variable renewable energy. Therefore, they are regarded as a key technology for smart energy systems with high shares of renewable energy up to 100%, and advanced 4th generation district heating systems.[25][26][27] They are also a crucial element of cold district heating systems.[28]

Industrial heating

There is great potential to reduce the energy consumption and related greenhouse gas emissions in industry by application of industrial heat pumps. An international collaboration project completed in 2015 collected totally 39 examples of R&D-projects and 115 case studies worldwide.[29] The study shows that short payback periods of less than 2 years are possible, while achieving a high reduction of CO2 emissions (in some cases more than 50%).[30][31] Industrial heat pumps can heat up to 200°C, and can meet the heating demands of many light industries.[32][33] In Europe alone, 15 GW of heat pumps could be installed in 3 000 facilities in the paper, food and chemicals industries.[1]

[MYIE1]Quote IEA report https://www.iea.org/reports/the-future-of-heat-pumps

Performance

Main article: Coefficient of performance

When comparing the performance of heat pumps, the term performance is preferred to efficiency, with coefficient of performance (COP) being used to describe the ratio of useful heat movement per work input. An electrical resistance heater has a COP of 1.0, which is considerably lower than a well-designed heat pump which will typically be between COP of 3 to 5 with an external temperature of 10 °C and an internal temperature of 20 °C. A ground-source heat pump will typically have a higher performance than an air-source heat pump.

The "Seasonal Coefficient of Performance" (SCOP) is a measure of the aggregate energy efficiency measure over a period of one year which is very dependent on regional climate. One framework for this calculation is given by the Commission Regulation (EU) No. 813/2013:[34]

A heat pump's operating performance in cooling mode is characterized in the US by either its energy efficiency ratio (EER) or seasonal energy efficiency ratio (SEER), both of which have units of BTU/(h·W) (note that 1 BTU/(h·W) = 0.293 W/W) and larger values indicate better performance. Actual performance varies, and it depends on many factors such as installation details, temperature differences, site elevation, and maintenance.

COP variation with output temperature
Pump type and source Typical use 35 °C
(e.g. heated screed floor) 		45 °C
(e.g. heated screed floor) 		55 °C
(e.g. heated timber floor) 		65 °C
(e.g. radiator or DHW) 		75 °C
(e.g. radiator and DHW) 		85 °C
(e.g. radiator and DHW)
High-efficiency air-source heat pump (ASHP), air at −20 °C[35] 2.2 2.0 ‐ ‐ ‐ ‐
Two-stage ASHP, air at −20 °C[36] Low source temperature 2.4 2.2 1.9 ‐ ‐ ‐
High-efficiency ASHP, air at 0 °C[35] Low output temperature 3.8 2.8 2.2 2.0 ‐ ‐
Prototype transcritical CO
2 (R744) heat pump with tripartite gas cooler, source at 0 °C[37]		 High output temperature 3.3 ‐ ‐ 4.2 ‐ 3.0
Ground-source heat pump (GSHP), water at 0 °C[35] 5.0 3.7 2.9 2.4 ‐ ‐
GSHP, ground at 10 °C[35] Low output temperature 7.2 5.0 3.7 2.9 2.4 ‐
Theoretical Carnot cycle limit, source −20 °C 5.6 4.9 4.4 4.0 3.7 3.4
Theoretical Carnot cycle limit, source 0 °C 8.8 7.1 6.0 5.2 4.6 4.2
Theoretical Lorentzen cycle limit (CO
2 pump), return fluid 25 °C, source 0 °C[37]		 10.1 8.8 7.9 7.1 6.5 6.1
Theoretical Carnot cycle limit, source 10 °C 12.3 9.1 7.3 6.1 5.4 4.8

Carbon footprint

The carbon footprint of heat pumps depends on their individual efficiency and how electricity is produced. An increasing share of low-carbon energy sources such as wind and solar will lower the impact on the climate.

heating system emissions of energy source efficiency resulting emissions for thermal energy
heat pump with onshore wind power 11 gCO2/kWh[38] 400% (COP=4) 3 gCO2/kWh
heat pump with global electricity mix 458 gCO2/kWh[39] 400% (COP=4) 131 gCO2/kWh
natural-gas thermal (high efficiency) 201 gCO2/kWh[40] 90% 223 gCO2/kWh
heat pump
electricity by lignite (old power plant)
and low performance		 1221 gCO2/kWh[40] 300% (COP=3) 407 gCO2/kWh

In most settings, heat pumps will reduce CO2 emissions compared to heating systems powered by fossil fuels.[41] In regions accounting for 70% of world energy consumption, the emissions savings of heat pumps compared with a high-efficiency gas boiler are on average above 45% and reach 80% in countries with cleaner electricity mixes.[1] These values can be improved by 10 percentage points, respectively, with alternative refrigerants. In the United States, 70% of houses could reduce emissions by installing a heat pump. [42][1]The rising share of renewable electricity generation in many countries is set to increase the emissions savings from heat pumps over time.[1]

Heating systems powered by green hydrogen are also low-carbon and may become competitors, but are much less efficient due to the energy loss associated with hydrogen conversion, transport and use. In addition, not enough green hydrogen is expected to be available before the 2030s or 2040s.[43][44]

Operation

See also: Vapor-compression refrigeration
 
Figure 2: Temperature–entropy diagram of the vapor-compression cycle.
 
An internal view of the outdoor unit of an Ecodan air source heat pump

Vapor-compression uses a circulating refrigerant as the medium which absorbs heat from one space, compresses it thereby increasing its temperature before releasing it in another space. The system normally has 8 main components: a compressor, a reservoir, a reversing valve which selects between heating and cooling mode, two thermal expansion valves (one used when in heating mode and the other when used in cooling mode) and two heat exchangers, one associated with the external heat source/sink and the other with the interior. In heating mode the external heat exchanger is the evaporator and the internal one being the condenser; in cooling mode the roles are reversed.

Circulating refrigerant enters the compressor in the thermodynamic state known as a saturated vapor[45] and is compressed to a higher pressure, resulting in a higher temperature as well. The hot, compressed vapor is then in the thermodynamic state known as a superheated vapor and it is at a temperature and pressure at which it can be condensed with either cooling water or cooling air flowing across the coil or tubes. In heating mode this heat is used to heat the building using the internal heat exchanger, and in cooling mode this heat is rejected via the external heat exchanger.

The condensed, liquid refrigerant, in the thermodynamic state known as a saturated liquid, is next routed through an expansion valve where it undergoes an abrupt reduction in pressure. That pressure reduction results in the adiabatic flash evaporation of a part of the liquid refrigerant. The auto-refrigeration effect of the adiabatic flash evaporation lowers the temperature of the liquid and-

vapor refrigerant mixture to where it is colder than the temperature of the enclosed space to be refrigerated.

The cold mixture is then routed through the coil or tubes in the evaporator. A fan circulates the warm air in the enclosed space across the coil or tubes carrying the cold refrigerant liquid and vapor mixture. That warm air evaporates the liquid part of the cold refrigerant mixture. At the same time, the circulating air is cooled and thus lowers the temperature of the enclosed space to the desired temperature. The evaporator is where the circulating refrigerant absorbs and removes heat which is subsequently rejected in the condenser and transferred elsewhere by the water or air used in the condenser.

To complete the refrigeration cycle, the refrigerant vapor from the evaporator is again a saturated vapor and is routed back into the compressor.

Over time, the evaporator may collect ice or water from ambient humidity. The ice is melted through defrosting cycle. An internal heat exchanger is either used to heat/cool the interior air directly or to heat water that is then circulated through radiators or underfloor heating circuit to either heat of cool the buildings.

Improvement of coefficient of performance (COP) by subcooling

Main article: Subcooling

Heat input can be improved if the refrigerant enters the evaporator with a lower vapor content. This can be achieved by cooling the liquid refrigerant after condensation. The gaseous refrigerant condenses on the heat exchange surface of the condenser. To achieve a heat flow from the gaseous flow center to the wall of the condenser, the temperature of the liquid refrigerant must be lower than the condensation temperature.

Additional subcooling can be achieved by heat exchange between relatively warm liquid refrigerant leaving the condenser and the cooler refrigerant vapor emerging from the evaporator. The enthalpy difference required for the subcooling leads to the superheating of the vapor drawn into the compressor. When the increase in cooling, achieved by subcooling, is greater that the compressor drive input required to overcome the additional pressure losses, such a heat exchange improves the coefficient of performance. [46]

One disadvantage of the subcooling of liquids is that the difference between the condensing temperature and the heat-sink temperature must be larger. This leads to a moderately high pressure difference between condensing and evaporating pressure, whereby the compressor energy increases.

Refrigerant choice

Main article: Refrigerant

Pure refrigerants can be divided into organic substances (Hydrocarbons (HCs), Chlorofluorocarbons (CFCs), Hydrochlorofluorocarbons (HCFCs), Hydrofluorocarbons (HFCs), Hydrofluoroolefins (HFOs), and HCFOs), and inorganic substances (Ammonia (NH3), Carbon dioxide (CO₂), and Water (H₂O)).[47]

In the past 200 years, the standards and requirements for new refrigerants have changed. These standards that govern the selection of next-generation refrigerants include a requirement for low global warming potential (GWP), in addition to all the previous requirements for safety, practicality, material compatibility, appropriate atmospheric life, and compatibility with high-efficiency products. By 2022, devices using refrigerants with a very low global warming potential (GWP) still have a small market share but are expected to play an increasing role due to enforced regulations,[48] as most countries have now ratified the Kigali Amendment to ban HFCs.[49] Isobutane (R600A) and propane (R290) are far less harmful to the environment than conventional hydrofluorocarbons (HFC) and already being used in air-source heat pumps.[50] Ammonia (R717) and carbon dioxide (R744) also have a low GWP.

Until the 1990s, heat pumps, along with fridges and other related products used chlorofluorocarbons (CFCs) as refrigerants that caused major damage to the ozone layer when released into the atmosphere. Use of these chemicals was banned or severely restricted by the Montreal Protocol of August 1987.[51]

Replacements, including R-134a and R-410A, are hydrofluorocarbons (HFC) with similar thermodynamic properties with insignificant ozone depletion potential but had problematic global warming potential.[52] HFC is a powerful greenhouse gas which contributes to climate change.[53][54] Dimethyl ether (DME) also gained in popularity as a refrigerant in combination with R404a.[55] More recent refrigerators include difluoromethane (R32) with a reduced GWP still over 600.

refrigerant 20 year global warming potential (GWP)[56] 100 year GWP[56][57][58]
R-290 propane / R-600a isobutane 3.3
R-32 2430 677
R-410a > 2430 2088
R-134a 3790 1550
R-404a 3922

Government incentives

Financial incentives are currently available in over 30 countries around the world, covering more than 70% of global heating demand in 2021.[1]

Australia

Food processors, brewers, petfood producers and other industrial energy users are exploring whether it is feasible to use renewable energy to produce industrial-grade heat. Process heating accounts for the largest share of onsite energy use in Australian manufacturing, with lower-temperature operations like food production particularly well-suited to transition to renewables.

To help producers understand how they could benefit from making the switch, the Australian Renewable Energy Agency (ARENA) provided funding to the Australian Alliance for Energy Productivity (A2EP) to undertake pre-feasibility studies at a range of sites around Australia, with the most promising locations advancing to full feasibility studies.[59]

Canada

In 2022, the Canada Greener Homes Grant [60] provides up to $5000 for upgrades (including certain heat pumps), and $600 for energy efficiency evaluations.

United Kingdom

As of 2022: heat pumps have no VAT although in Northern Ireland they are taxed at the reduced rate of 5% instead of the usual level of VAT of 20% for most other products.[61] As of 2022 the installation cost of a heat pump is more than a gas boiler, but with the government grant and assuming electricity/gas costs remain similar their lifetime costs would be similar.[62]

United States

After the Inflation Reduction Act was passed by the United States Congress and signed into law by President Joe Biden on August 16, 2022, the High-efficiency Electric Home Rebate Program was created to award grants to State energy offices and Indian Tribes in order to establish state-wide high-efficiency electric-home rebates. Effective immediately, American households are eligible for a tax credit to cover the costs of buying and installing a heat pump, up to $2,000. Starting in 2023, low- and moderate-level income households will be eligible for a heat-pump rebate of up to $8,000.[63]

Some US states and municipalities have previously offered incentives for air-source heat pumps:

California
In 2022, the California Public Utilities Commission allocated an additional $40 million from the 2023 gas Cap-and-Trade allowance auction proceeds to the existing $44.7 million budget of the Self-Generation Incentive Program (SGIP) Heat Pump Water Heater (HPWH) program, in which single-family residential customers can receive an incentive of up to $3,800 to install a HPWH. Half of the incentive funds are reserved for low-income utility customers, who are eligible for a maximum incentive of $4,885.[64]
Maine
The Efficiency Maine Trust offers residential heat-pump rebates of up to $1,200, as well as heat-pump rebates for low and moderate income Mainers of $2,000 for their first eligible heat pump and up to $400 for a second eligible heat pump.[65][66]
Massachusetts
Mass Save, a collaborative initiative between Massachusetts’ natural gas and electric utilities and energy efficiency service providers, offers an air-source heat-pump rebate of up to $10,000, which covers the purchase price of the heat pump and installation costs.[67]
Minnesota
Minnesota Power offers an air-source heat-pump rebate of up to $1,200 if the pump is bought and installed by a Minnesota Power Participating Contractor. [68]
South Carolina
Dominion Energy South Carolina offers a $400–$500 rebate for purchasing and installing an ENERGY STAR certified heat pump or air-conditioning unit. [69]

See also

References

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  • IPCC (2018). Masson-Delmotte, V.; Zhai, P.; Pörtner, H.-O.; Roberts, D.; et al. (eds.). Global Warming of 1.5°C. An IPCC Special Report on the impacts of global warming of 1.5°C above pre-industrial levels and related global greenhouse gas emission pathways, in the context of strengthening the global response to the threat of climate change, sustainable development, and efforts to eradicate poverty (PDF). Intergovernmental Panel on Climate Change. https://www.ipcc.ch/sr15/.
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Other

  • "High GWP refrigerants". California Air Resources Board. Retrieved 13 February 2022.
  • "Tracking Power 2021". International Energy Agency. Retrieved 22 February 2022.
  • "The GWP value of refrigerants and its importance for operators". Infraserv höchst. Retrieved 20 February 2022.
  • Quaschning, Volker. "Specific Carbon Dioxide Emissions of Various Fuels". Retrieved 22 February 2022.

External links

  •   Media related to Heat pumps at Wikimedia Commons
  • IEA Technology Collaboration Programme on Heat Pumping Technologies
  • Carbon Brief guest post: How heat pump sales are starting to take off around the world

March 04, 2023
heat, pump, this, article, about, devices, used, heat, potentially, also, cool, building, using, refrigeration, cycle, cooling, only, conditioner, other, uses, disambiguation, heat, pump, device, that, provide, heat, building, transferring, thermal, energy, fr. This article is about devices used to heat and potentially also cool a building using the refrigeration cycle For cooling only see air conditioner For other uses see Heat pump disambiguation A heat pump is a device that can provide heat to a building by transferring thermal energy from the outside using a refrigeration cycle Many heat pumps can also operate in the opposite direction cooling the building by removing heat from the enclosed space and rejecting it outside Units that only provide cooling are called air conditioners External heat exchanger of an air source heat pump When in heating mode a refrigerant at outside temperature is being compressed As a result the refrigerant becomes hot This thermal energy can be transferred to an indoor unit After being moved outdoors again the refrigerant is decompressed evaporated It has lost some of its thermal energy and returns colder than the environment It can now take up the surrounding energy from the air or from the ground before the process repeats Compressors fans and pumps run with electric energy Air source heat pumps are the most common models while other types include ground source heat pumps water source heat pumps and exhaust air heat pumps Large scale heat pumps are also used in district heating systems 1 The efficiency of a heat pump is expressed with a coefficient of performance COP or seasonal coefficient of performance SCOP The higher the number the more efficient a heat pump is and the less energy it consumes When used for space heating heat pumps are typically much more energy efficient than simple electrical resistance heaters Because of their high efficiency and the increasing share of fossil free sources in electrical grids heat pumps can play a key role in climate change mitigation 2 3 With 1 kWh of electricity they can transfer 3 to 6 kWh of thermal energy into a building 4 The carbon footprint of heat pumps depends on how electricity is generated but they usually reduce emissions in mild climates 5 Heat pumps could satisfy over 80 of global space and water heating needs with a lower carbon footprint than gas fired condensing boilers however in 2021 they only met 10 6 Contents 1 Principle of operation 2 History 3 Types 3 1 Air source heat pump 3 2 Ground source heat pump 3 3 Exhaust air heat pump 3 4 Solar assisted heat pump 3 5 Water source heat pump 3 6 Thermoacoustic heat pump 4 Applications 4 1 Space heating and sometimes also cooling 4 2 Water heating 4 3 District heating 4 4 Industrial heating 5 Performance 5 1 Carbon footprint 6 Operation 6 1 Improvement of coefficient of performance COP by subcooling 6 2 Refrigerant choice 7 Government incentives 7 1 Australia 7 2 Canada 7 3 United Kingdom 7 4 United States 8 See also 9 References 9 1 Sources 9 1 1 IPCC reports 9 1 2 Other 10 External linksPrinciple of operation EditHeat will flow spontaneously from a region of higher temperature to a region of lower temperature Heat will not flow spontaneously from lower temperature to higher but it can be made to flow in this direction if work is performed The work required to transfer a given amount of heat is usually much less than the amount of heat this is the motivation for using heat pumps in applications such as heating of water and the interior of buildings 7 The amount of work required to drive an amount of heat Q from a lower temperature reservoir such as ambient air to a higher temperature reservoir such as the interior of a building is W Q C O P displaystyle W frac Q mathrm COP where W displaystyle W is the work performed on the working fluid by the heat pump s compressor Q displaystyle Q is the heat transferred from the lower temperature reservoir to the higher temperature reservoir C O P displaystyle mathrm COP is the instantaneous coefficient of performance for the heat pump at the temperatures prevailing in the reservoirs at one instant The coefficient of performance of a heat pump is greater than unity so the work required is less than the heat transferred making a heat pump a more efficient form of heating than electrical resistance heating As the temperature of the higher temperature reservoir increases in response to the heat flowing into it the coefficient of performance decreases causing an increasing amount of work to be required for each unit of heat being transferred 7 The coefficient of performance and the work required by a heat pump can be calculated easily by considering an ideal heat pump operating on the reversed Carnot cycle If the low temperature reservoir is at a temperature of 270 K 3 C and the interior of the building is at 280 K 7 C the relevant coefficient of performance is 27 This means only 1 joule of work is required to transfer 27 joules of heat from a reservoir at 270 K to another at 280 K The one joule of work ultimately ends up as thermal energy in the interior of the building so for each 27 joules of heat that are removed from the low temperature reservoir 28 joules of heat are added to the building interior making the heat pump even more attractive from an efficiency perspective As the temperature of the interior of the building rises progressively to 300 K 27 C the coefficient of performance falls progressively to 9 This means each joule of work is responsible for transferring 9 joules of heat out of the low temperature reservoir and into the building Again the 1 joule of work ultimately ends up as thermal energy in the interior of the building so 10 joules of heat are added to the building interior History EditThis section needs expansion You can help by adding to it June 2008 Milestones 1748 William Cullen demonstrates artificial refrigeration 1834 Jacob Perkins builds a practical refrigerator with dimethyl ether 1852 Lord Kelvin describes the theory underlying heat pumps 1855 1857 Peter von Rittinger develops and builds the first heat pump 8 1877 In the period before 1875 heat pumps were for the time being pursued for vapour compression evaporation open heat pump process in salt works with their obvious advantages for saving wood and coal In 1857 Peter von Rittinger was the first to try to implement the idea of vapor compression in a small pilot plant Presumably inspired by Rittinger s experiments in Ebensee Antoine Paul Piccard from the University of Lausanne and the engineer J H Weibel from the Weibel Briquet company in Geneva built the world s first really functioning vapor compression system with a two stage piston compressor In 1877 this first heat pump in Switzerland was installed in the Bex salt works 9 10 1928 Aurel Stodola constructs a closed loop heat pump water source from Lake Geneva which provides heating for the Geneva city hall to this day 1937 1945 During and after the First World War Switzerland suffered from heavily difficult energy imports and subsequently expanded its hydropower plants In the period before and especially during the Second World War when neutral Switzerland was completely surrounded by fascist ruled countries the coal shortage became alarming again Thanks to their leading position in energy technology the Swiss companies Sulzer Escher Wyss and Brown Boveri built and put in operation around 35 heat pumps between 1937 and 1945 The main heat sources were lake water river water groundwater and waste heat Particularly noteworthy are the six historic heat pumps from the city of Zurich with heat outputs from 100 kW to 6 MW An international milestone is the heat pump built by Escher Wyss in 1937 38 to replace the wood stoves in the City Hall of Zurich To avoid noise and vibrations a recently developed rotary piston compressor was used This historic heat pump heated the town hall for 63 years until 2001 Only then it was replaced by a new more efficient heat pump 11 9 1945 John Sumner City Electrical Engineer for Norwich installs an experimental water source heat pump fed central heating system using a neighboring river to heat new Council administrative buildings Seasonal efficiency ratio of 3 42 Average thermal delivery of 147 kW and peak output of 234 kW 12 1948 Robert C Webber is credited as developing and building the first ground heat pump 13 1951 First large scale installation the Royal Festival Hall in London is opened with a town gas powered reversible water source heat pump fed by the Thames for both winter heating and summer cooling needs 12 Types EditAir source heat pump Edit Main article Air source heat pump Outdoor unit of air source heat pump operating in freezing conditions Air source heat pumps are used to move heat between two heat exchangers one outside the building which is fitted with fins through which air is forced using a fan and the other which either directly heats the air inside the building or heats water which is then circulated around the building through radiators or underfloor heating which releases the heat to the building These devices can also operate in a cooling mode where they extract heat via the internal heat exchanger and eject it into the ambient air using the external heat exchanger Some can be used to heat water for washing which is stored in a domestic hot water tank 14 Air source heat pumps are relatively easy and inexpensive to install and have therefore historically been the most widely used heat pump type In mild weather coefficient of performance COP may be around 4 4 while at temperatures below around 7 C 19 F an air source heat pump may still achieve a COP of 3 While older air source heat pumps performed relatively poorly at low temperatures and were better suited for warm climates newer models with variable speed compressors remain highly efficient in freezing conditions allowing for wide adoption and cost savings in places like Minnesota and Maine 15 Ground source heat pump Edit Main article Ground source heat pump A ground source heat pump draws heat from the soil or from groundwater which remains at a relatively constant temperature all year round below a depth of about 30 feet 9 1 m 16 A well maintained ground source heat pump will typically have a COP of 4 0 at the beginning of the heating season and a seasonal COP of around 3 0 as heat is drawn from the ground 17 Ground source heat pumps are more expensive to install due to the need for the drilling of boreholes for vertical placement of heat exchanger piping or the digging of trenches for horizontal placement of the piping that carries the heat exchange fluid water with a little antifreeze A ground source heat pump can also be used to cool buildings during hot days thereby transferring heat from the dwelling back into the soil via the ground loop Solar thermal collectors or piping placed within the tarmac of a parking lot can also be used to replenish the heat underground citation needed Exhaust air heat pump Edit Main article Exhaust air heat pump Exhaust air heat pumps extract heat from the exhaust air of a building and require mechanical ventilation Two classes exist Exhaust air air heat pumps transfer heat to intake air Exhaust air water heat pumps transfer heat to a heating circuit that includes a tank of domestic hot water Solar assisted heat pump Edit See also Solar assisted heat pump A solar assisted heat pump either integrates a heat pump and thermal solar panels or photovoltaic solar power in a single system In the case of thermal solar typically these two technologies are used separately or are operated in parallel to produce hot water 18 In this system the solar thermal panel is the low temperature heat source and the heat produced feeds the heat pump s evaporator 19 The goal of this system is to get high COP and then produce energy in a more efficient and less expensive way citation needed In the case of photovoltaic solar heat pumps or solar air conditioners electricity to run the heat pump is generated from the sun Either batteries can be used to store excess solar energy generated to run during cloudy or nighttime periods or grid power can be used during these periods Water source heat pump Edit Water source heat exchanger being installed A water source heat pump works in a similar manner to a ground source heat pump except that it takes heat from a body of water rather than the ground The body of water does however need to be large enough to be able to withstand the cooling effect of the unit without freezing or creating an adverse effect for wildlife 20 Thermoacoustic heat pump Edit A heat pump that operates as a thermoacoustic heat engine without refrigerant but instead using a standing wave in a sealed chamber driven by a loudspeaker to achieve a temperature difference across the chamber 21 Applications EditThe International Energy Agency estimated that as of 2021 heat pumps installed in buildings have a combined capacity of more than 1 000 GW 6 They are used in climates with moderate heating ventilation and air conditioning HVAC needs and may also provide domestic hot water and tumble clothes drying functions 22 The purchase costs are supported in various countries by consumer rebates 23 Space heating and sometimes also cooling Edit In HVAC applications a heat pump is typically a vapor compression refrigeration device that includes a reversing valve and optimized heat exchangers so that the direction of heat flow thermal energy movement may be reversed The reversing valve switches the direction of refrigerant through the cycle and therefore the heat pump may deliver either heating or cooling to a building In cooler climates the default setting of the reversing valve is heating The default setting in warmer climates is cooling Because the two heat exchangers the condenser and evaporator must swap functions they are optimized to perform adequately in both modes Therefore the Seasonal Energy Efficiency Rating SEER of a reversible heat pump is typically slightly less than those of two separately optimized machines For equipment to receive the Energy Star rating it must have a rating of at least 14 SEER Pumps with ratings of 18 SEER or above are considered highly efficient The highest efficiency heat pumps manufactured are up to 24 SEER 24 Water heating Edit In water heating applications a heat pump may be used to heat or preheat water for swimming pools or heating potable water for use by homes and industry Usually heat is extracted from outdoor air and transferred to an indoor water tank another variety extracts heat from indoor air to assist in cooling the space citation needed District heating Edit Main article District heating Heat pumps can also be used as heat supplier for district heating In Europe heat pumps account for a mere 1 of heat supply in district heating networks but several countries have targets to decarbonise their networks between 2030 and 2040 1 Possible sources of heat for such applications are sewage water ambient water e g sea lake and river water industrial waste heat geothermal energy flue gas waste heat from district cooling and heat from solar seasonal thermal energy storage In Europe more than 1500 MW of large scale heat pumps were installed since the 1980s of which about 1000 MW were in use in Sweden in 2017 25 Large scale heat pumps for district heating combined with thermal energy storage offer high flexibility for the integration of variable renewable energy Therefore they are regarded as a key technology for smart energy systems with high shares of renewable energy up to 100 and advanced 4th generation district heating systems 25 26 27 They are also a crucial element of cold district heating systems 28 Industrial heating Edit There is great potential to reduce the energy consumption and related greenhouse gas emissions in industry by application of industrial heat pumps An international collaboration project completed in 2015 collected totally 39 examples of R amp D projects and 115 case studies worldwide 29 The study shows that short payback periods of less than 2 years are possible while achieving a high reduction of CO2 emissions in some cases more than 50 30 31 Industrial heat pumps can heat up to 200 C and can meet the heating demands of many light industries 32 33 In Europe alone 15 GW of heat pumps could be installed in 3 000 facilities in the paper food and chemicals industries 1 MYIE1 Quote IEA report https www iea org reports the future of heat pumpsPerformance EditMain article Coefficient of performance When comparing the performance of heat pumps the term performance is preferred to efficiency with coefficient of performance COP being used to describe the ratio of useful heat movement per work input An electrical resistance heater has a COP of 1 0 which is considerably lower than a well designed heat pump which will typically be between COP of 3 to 5 with an external temperature of 10 C and an internal temperature of 20 C A ground source heat pump will typically have a higher performance than an air source heat pump The Seasonal Coefficient of Performance SCOP is a measure of the aggregate energy efficiency measure over a period of one year which is very dependent on regional climate One framework for this calculation is given by the Commission Regulation EU No 813 2013 34 A heat pump s operating performance in cooling mode is characterized in the US by either its energy efficiency ratio EER or seasonal energy efficiency ratio SEER both of which have units of BTU h W note that 1 BTU h W 0 293 W W and larger values indicate better performance Actual performance varies and it depends on many factors such as installation details temperature differences site elevation and maintenance COP variation with output temperature Pump type and source Typical use 35 C e g heated screed floor 45 C e g heated screed floor 55 C e g heated timber floor 65 C e g radiator or DHW 75 C e g radiator and DHW 85 C e g radiator and DHW High efficiency air source heat pump ASHP air at 20 C 35 2 2 2 0 Two stage ASHP air at 20 C 36 Low source temperature 2 4 2 2 1 9 High efficiency ASHP air at 0 C 35 Low output temperature 3 8 2 8 2 2 2 0 Prototype transcritical CO2 R744 heat pump with tripartite gas cooler source at 0 C 37 High output temperature 3 3 4 2 3 0Ground source heat pump GSHP water at 0 C 35 5 0 3 7 2 9 2 4 GSHP ground at 10 C 35 Low output temperature 7 2 5 0 3 7 2 9 2 4 Theoretical Carnot cycle limit source 20 C 5 6 4 9 4 4 4 0 3 7 3 4Theoretical Carnot cycle limit source 0 C 8 8 7 1 6 0 5 2 4 6 4 2Theoretical Lorentzen cycle limit CO2 pump return fluid 25 C source 0 C 37 10 1 8 8 7 9 7 1 6 5 6 1Theoretical Carnot cycle limit source 10 C 12 3 9 1 7 3 6 1 5 4 4 8Carbon footprint Edit The carbon footprint of heat pumps depends on their individual efficiency and how electricity is produced An increasing share of low carbon energy sources such as wind and solar will lower the impact on the climate heating system emissions of energy source efficiency resulting emissions for thermal energyheat pump with onshore wind power 11 gCO2 kWh 38 400 COP 4 3 gCO2 kWhheat pump with global electricity mix 458 gCO2 kWh 39 400 COP 4 131 gCO2 kWhnatural gas thermal high efficiency 201 gCO2 kWh 40 90 223 gCO2 kWhheat pumpelectricity by lignite old power plant and low performance 1221 gCO2 kWh 40 300 COP 3 407 gCO2 kWhIn most settings heat pumps will reduce CO2 emissions compared to heating systems powered by fossil fuels 41 In regions accounting for 70 of world energy consumption the emissions savings of heat pumps compared with a high efficiency gas boiler are on average above 45 and reach 80 in countries with cleaner electricity mixes 1 These values can be improved by 10 percentage points respectively with alternative refrigerants In the United States 70 of houses could reduce emissions by installing a heat pump 42 1 The rising share of renewable electricity generation in many countries is set to increase the emissions savings from heat pumps over time 1 Heating systems powered by green hydrogen are also low carbon and may become competitors but are much less efficient due to the energy loss associated with hydrogen conversion transport and use In addition not enough green hydrogen is expected to be available before the 2030s or 2040s 43 44 Operation EditSee also Vapor compression refrigeration This section needs additional citations for verification Please help improve this article by adding citations to reliable sources Unsourced material may be challenged and removed May 2021 Learn how and when to remove this template message Figure 2 Temperature entropy diagram of the vapor compression cycle An internal view of the outdoor unit of an Ecodan air source heat pump Vapor compression uses a circulating refrigerant as the medium which absorbs heat from one space compresses it thereby increasing its temperature before releasing it in another space The system normally has 8 main components a compressor a reservoir a reversing valve which selects between heating and cooling mode two thermal expansion valves one used when in heating mode and the other when used in cooling mode and two heat exchangers one associated with the external heat source sink and the other with the interior In heating mode the external heat exchanger is the evaporator and the internal one being the condenser in cooling mode the roles are reversed Circulating refrigerant enters the compressor in the thermodynamic state known as a saturated vapor 45 and is compressed to a higher pressure resulting in a higher temperature as well The hot compressed vapor is then in the thermodynamic state known as a superheated vapor and it is at a temperature and pressure at which it can be condensed with either cooling water or cooling air flowing across the coil or tubes In heating mode this heat is used to heat the building using the internal heat exchanger and in cooling mode this heat is rejected via the external heat exchanger The condensed liquid refrigerant in the thermodynamic state known as a saturated liquid is next routed through an expansion valve where it undergoes an abrupt reduction in pressure That pressure reduction results in the adiabatic flash evaporation of a part of the liquid refrigerant The auto refrigeration effect of the adiabatic flash evaporation lowers the temperature of the liquid and vapor refrigerant mixture to where it is colder than the temperature of the enclosed space to be refrigerated The cold mixture is then routed through the coil or tubes in the evaporator A fan circulates the warm air in the enclosed space across the coil or tubes carrying the cold refrigerant liquid and vapor mixture That warm air evaporates the liquid part of the cold refrigerant mixture At the same time the circulating air is cooled and thus lowers the temperature of the enclosed space to the desired temperature The evaporator is where the circulating refrigerant absorbs and removes heat which is subsequently rejected in the condenser and transferred elsewhere by the water or air used in the condenser To complete the refrigeration cycle the refrigerant vapor from the evaporator is again a saturated vapor and is routed back into the compressor Over time the evaporator may collect ice or water from ambient humidity The ice is melted through defrosting cycle An internal heat exchanger is either used to heat cool the interior air directly or to heat water that is then circulated through radiators or underfloor heating circuit to either heat of cool the buildings Improvement of coefficient of performance COP by subcooling Edit Main article Subcooling Heat input can be improved if the refrigerant enters the evaporator with a lower vapor content This can be achieved by cooling the liquid refrigerant after condensation The gaseous refrigerant condenses on the heat exchange surface of the condenser To achieve a heat flow from the gaseous flow center to the wall of the condenser the temperature of the liquid refrigerant must be lower than the condensation temperature Additional subcooling can be achieved by heat exchange between relatively warm liquid refrigerant leaving the condenser and the cooler refrigerant vapor emerging from the evaporator The enthalpy difference required for the subcooling leads to the superheating of the vapor drawn into the compressor When the increase in cooling achieved by subcooling is greater that the compressor drive input required to overcome the additional pressure losses such a heat exchange improves the coefficient of performance 46 One disadvantage of the subcooling of liquids is that the difference between the condensing temperature and the heat sink temperature must be larger This leads to a moderately high pressure difference between condensing and evaporating pressure whereby the compressor energy increases Refrigerant choice Edit Main article Refrigerant Pure refrigerants can be divided into organic substances Hydrocarbons HCs Chlorofluorocarbons CFCs Hydrochlorofluorocarbons HCFCs Hydrofluorocarbons HFCs Hydrofluoroolefins HFOs and HCFOs and inorganic substances Ammonia NH3 Carbon dioxide CO and Water H O 47 In the past 200 years the standards and requirements for new refrigerants have changed These standards that govern the selection of next generation refrigerants include a requirement for low global warming potential GWP in addition to all the previous requirements for safety practicality material compatibility appropriate atmospheric life and compatibility with high efficiency products By 2022 devices using refrigerants with a very low global warming potential GWP still have a small market share but are expected to play an increasing role due to enforced regulations 48 as most countries have now ratified the Kigali Amendment to ban HFCs 49 Isobutane R600A and propane R290 are far less harmful to the environment than conventional hydrofluorocarbons HFC and already being used in air source heat pumps 50 Ammonia R717 and carbon dioxide R744 also have a low GWP Until the 1990s heat pumps along with fridges and other related products used chlorofluorocarbons CFCs as refrigerants that caused major damage to the ozone layer when released into the atmosphere Use of these chemicals was banned or severely restricted by the Montreal Protocol of August 1987 51 Replacements including R 134a and R 410A are hydrofluorocarbons HFC with similar thermodynamic properties with insignificant ozone depletion potential but had problematic global warming potential 52 HFC is a powerful greenhouse gas which contributes to climate change 53 54 Dimethyl ether DME also gained in popularity as a refrigerant in combination with R404a 55 More recent refrigerators include difluoromethane R32 with a reduced GWP still over 600 refrigerant 20 year global warming potential GWP 56 100 year GWP 56 57 58 R 290 propane R 600a isobutane 3 3R 32 2430 677R 410a gt 2430 2088R 134a 3790 1550R 404a 3922Government incentives EditThe examples and perspective in this section may not represent a worldwide view of the subject You may improve this section discuss the issue on the talk page or create a new section as appropriate June 2021 Learn how and when to remove this template message Financial incentives are currently available in over 30 countries around the world covering more than 70 of global heating demand in 2021 1 Australia Edit Food processors brewers petfood producers and other industrial energy users are exploring whether it is feasible to use renewable energy to produce industrial grade heat Process heating accounts for the largest share of onsite energy use in Australian manufacturing with lower temperature operations like food production particularly well suited to transition to renewables To help producers understand how they could benefit from making the switch the Australian Renewable Energy Agency ARENA provided funding to the Australian Alliance for Energy Productivity A2EP to undertake pre feasibility studies at a range of sites around Australia with the most promising locations advancing to full feasibility studies 59 Canada Edit In 2022 the Canada Greener Homes Grant 60 provides up to 5000 for upgrades including certain heat pumps and 600 for energy efficiency evaluations United Kingdom Edit As of 2022 heat pumps have no VAT although in Northern Ireland they are taxed at the reduced rate of 5 instead of the usual level of VAT of 20 for most other products 61 As of 2022 update the installation cost of a heat pump is more than a gas boiler but with the government grant and assuming electricity gas costs remain similar their lifetime costs would be similar 62 United States Edit After the Inflation Reduction Act was passed by the United States Congress and signed into law by President Joe Biden on August 16 2022 the High efficiency Electric Home Rebate Program was created to award grants to State energy offices and Indian Tribes in order to establish state wide high efficiency electric home rebates Effective immediately American households are eligible for a tax credit to cover the costs of buying and installing a heat pump up to 2 000 Starting in 2023 low and moderate level income households will be eligible for a heat pump rebate of up to 8 000 63 Some US states and municipalities have previously offered incentives for air source heat pumps California In 2022 the California Public Utilities Commission allocated an additional 40 million from the 2023 gas Cap and Trade allowance auction proceeds to the existing 44 7 million budget of the Self Generation Incentive Program SGIP Heat Pump Water Heater HPWH program in which single family residential customers can receive an incentive of up to 3 800 to install a HPWH Half of the incentive funds are reserved for low income utility customers who are eligible for a maximum incentive of 4 885 64 Maine The Efficiency Maine Trust offers residential heat pump rebates of up to 1 200 as well as heat pump rebates for low and moderate income Mainers of 2 000 for their first eligible heat pump and up to 400 for a second eligible heat pump 65 66 Massachusetts Mass Save a collaborative initiative between Massachusetts natural gas and electric utilities and energy efficiency service providers offers an air source heat pump rebate of up to 10 000 which covers the purchase price of the heat pump and installation costs 67 Minnesota Minnesota Power offers an air source heat pump rebate of up to 1 200 if the pump is bought and installed by a Minnesota Power Participating Contractor 68 South Carolina Dominion Energy South Carolina offers a 400 500 rebate for purchasing and installing an ENERGY STAR certified heat pump or air conditioning unit 69 See also EditEcoCuteReferences Edit a b c d e f g IEA 2022 The Future of Heat Pumps IEA Paris https www iea org reports the future of heat pumps License CC BY 4 0 IPCC AR6 WG3 Ch11 2022 Sec 11 3 4 1harvnb error no target CITEREFIPCC AR6 WG3 Ch112022 help IPCC SR15 Ch2 2018 p 142 a b Warmepumpen mit Pruf Effizienznachweis heat pumps with efficiency validation in German BAFA Federal Office for Economic Affairs and Export Control in Germany Retrieved 2022 02 20 Deetjen Thomas A Walsh Liam Vaishnav Parth 2021 07 28 US residential heat pumps the private economic potential and its emissions health and grid impacts Environmental Research Letters 16 8 084024 Bibcode 2021ERL 16h4024D doi 10 1088 1748 9326 ac10dc ISSN 1748 9326 S2CID 236486619 a b Heat Pumps Analysis IEA a b G F C Rogers and Y R Mayhew 1957 Engineering Thermodynamics Work and Heat Transfer Section 13 1 Longmans Green amp Co Ltd Banks David L 2008 05 06 An Introduction to Thermogeology Ground Source Heating and Cooling PDF Wiley Blackwell ISBN 978 1 4051 7061 1 Archived PDF from the original on 2016 12 20 Retrieved 2014 03 05 a b Zogg M History of Heat Pumps Swiss Contributions and International Milestones Swiss Federal Office of Energy Berne 2008 Archived 2021 11 23 at the Wayback Machine Wirth E Aus der Entwicklungsgeschichte der Warmepumpe Schweizerische Bauzeitung 1955 Vol 73 No 52 pp 647 650 in German Zogg M History of Heat Pumps Swiss Contributions and International Milestones Proceedings 9th International Energy Agency Heat Pump Conference Zurich 20 22 May 2008 Archived 2021 11 18 at the Wayback Machine a b Electricity supply in the United Kingdom a chronology from the beginnings of the industry to 31 December 1985 Electricity Council The Council 1987 ISBN 978 0851881058 OCLC 17343802 a href Template Cite book html title Template Cite book cite book a CS1 maint others link Banks David August 2012 An Introduction to Thermogeology Ground Source Heating and Cooling John Wiley amp Sons p 123 Lawrence Karen Air source heat pumps explained Which Retrieved 2022 10 04 Heat pumps do work in the cold Americans just don t know it yet Grist 2022 05 09 Retrieved 2022 05 09 Seasonal Temperature Cycles May 30 2013 Archived from the original on May 30 2013 Rob Andrushuk Phil Merkel June 2009 Performance of Ground Source Heat Pumps in Manitoba PDF Archived PDF from the original on 2013 12 03 Retrieved 2013 11 30 Solar assisted heat pumps Archived from the original on 28 February 2020 Retrieved 21 June 2016 Pompe di calore elio assistite in Italian Archived from the original on 7 January 2012 Retrieved 21 June 2016 Trust Energy Saving 2019 02 13 Could a water source heat pump work for you Energy Saving Trust Retrieved 2022 10 04 author fullName Heat pump uses a loudspeaker and wet strips of paper to cool air New Scientist Retrieved 2023 01 04 a href Template Cite web html title Template Cite web cite web a last has generic name help Heat Pump Systems U S Department of Energy Archived from the original on 2017 07 04 Retrieved 2016 02 05 Renewable Heat Incentive Domestic RHI paid over 7 years Ground Source Heat Pump Association Archived from the original on 2018 03 08 Retrieved 2017 03 12 Heat Pump Efficiency Heat Pump SEER Ratings Carrier Retrieved 2023 01 14 a b David Andrei et al 2017 Heat Roadmap Europe Large Scale Electric Heat Pumps in District Heating Systems Energies 10 4 578 doi 10 3390 en10040578 Lund Henrik et al 2014 4th Generation District Heating 4GDH Integrating smart thermal grids into future sustainable energy systems Energy 68 1 11 doi 10 1016 j energy 2014 02 089 Sayegh M A et al 2018 Heat pump placement connection and operational modes in European district heating Energy and Buildings 166 122 144 doi 10 1016 j enbuild 2018 02 006 Archived from the original on 2019 12 14 Retrieved 2019 07 10 Simone Buffa et al 2019 5th generation district heating and cooling systems A review of existing cases in Europe Renewable and Sustainable Energy Reviews in German vol 104 pp 504 522 doi 10 1016 j rser 2018 12 059 IEA HPT TCP Annex 35 Archived 2018 09 21 at the Wayback Machine IEA HPT TCP Annex 35 Publications Archived 2018 09 21 at the Wayback Machine IEA HPT TCP Annex 25 Summary Archived 2018 09 21 at the Wayback Machine Norwegian Researchers Develop World s Hottest Heat Pump Ammonia21 2021 08 05 Retrieved 2022 06 07 Heat pumps are key to helping industry turn electric World Business Council for Sustainable Development WBCSD Retrieved 2022 10 04 Ecodesign requirements for space heaters European Union Law Archived from the original on 2021 01 18 Retrieved 2021 01 31 a b c d The Canadian Renewable Energy Network Commercial Earth Energy Systems Figure 29 Archived 2011 05 11 at the Wayback Machine Retrieved December 8 2009 Technical Institute of Physics and Chemistry Chinese Academy of Sciences State of the Art of Air source Heat Pump for Cold Region Figure 5 Archived 2016 04 14 at the Wayback Machine Retrieved April 19 2008 a b SINTEF Energy Research Integrated CO2 Heat Pump Systems for Space Heating and DHW in low energy and passive houses J Steen Table 3 1 Table 3 3 Archived 2009 03 18 at the Wayback Machine Retrieved April 19 2008 IPCC AR5 2014 p 1335harvnb error no target CITEREFIPCC AR52014 help IEA 2021 a b Quaschning 2022 The UK is sabotaging its own plan to decarbonize heating Engadget Archived from the original on 2021 06 06 Retrieved 2021 06 06 Deetjen Thomas A Walsh Liam Vaishnav Parth 2021 07 28 US residential heat pumps the private economic potential and its emissions health and grid impacts Environmental Research Letters 16 8 084024 Bibcode 2021ERL 16h4024D doi 10 1088 1748 9326 ac10dc S2CID 236486619 Can the UK rely on hydrogen to save its gas boilers inews co uk 2021 05 21 Archived from the original on 2021 06 06 Retrieved 2021 06 06 IEA 2022 Global Hydrogen Review 2022 IEA Paris https www iea org reports global hydrogen review 2022 License CC BY 4 0 Saturated vapors and saturated liquids are vapors and liquids at their saturation temperature and saturation pressure A superheated vapor is at a temperature higher than the saturation temperature corresponding to its pressure Ludwig von Cube Hans 1981 Heat Pump Technology Butterworths pp 22 23 ISBN 0 408 00497 5 Wu Di 2021 Vapor compression heat pumps with pure Low GWP refrigerants Renewable and Sustainable Energy Reviews 138 110571 doi 10 1016 j rser 2020 110571 ISSN 1364 0321 S2CID 229455137 Miara Marek 2019 10 22 Heat Pumps with Climate Friendly Refrigerant Developed for Indoor Installation Fraunhofer ISE Rabe Barry G 2022 09 23 Pivoting from global climate laggard to leader Kigali and American HFC policy Brookings Retrieved 2022 10 04 Itteilag Richard L 2012 08 09 Green Electricity and Global Warming AuthorHouse p 77 ISBN 9781477217405 Archived from the original on 2021 11 23 Retrieved 2020 11 01 Handbook for the Montreal Protocol on Substances that Deplete the Ozone Layer 7th Edition United Nations Environment Programme Ozone Secretariat 2007 Archived from the original on 2016 05 30 Retrieved 2016 12 18 Refrigerants Environmental Properties The Engineering ToolBox Archived from the original on 2013 03 14 Retrieved 2016 09 12 R 410A Environmental effects Ecometrica com 27 June 2012 Calculation of green house gas potential of R 410A Archived from the original on 2015 07 13 Retrieved 2015 07 13 R404 and DME Refrigerant blend as a new solution to limit global warming potential PDF March 14 2012 Archived from the original PDF on March 14 2012 a b IPCC AR5 WG1 Ch8 2013 pp 714 731 737 ARB 2022 Infraserv 2022 Electrifying industrial processes with heat pumps 22 March 2022 Retrieved 2022 08 09 Canada Greener Homes Grant 17 March 2021 Retrieved 2022 01 17 HMCR rates for goods and services Archived from the original on 2022 07 22 Retrieved 2022 08 24 BBC Radio 4 Sliced Bread Air Source Heat Pumps BBC Retrieved 2022 04 30 H R 5376 Inflation Reduction Act of 2022 Congress gov U S Congress Retrieved 17 November 2022 CPUC Provides Additional Incentives and Framework for Electric Heat Pump Water Heater Program cpuc ca gov California Public Utilities Commission Retrieved 16 November 2022 Residential Heat Pump Rebates Efficiency Maine The Efficiency Maine Trust Retrieved 16 November 2022 Heat Pump Rebates for Low and Moderate Income Mainers Efficiency Maine The Efficiency Maine Trust Retrieved 16 November 2022 Air Source Heat Pump Rebates Mass Save Mass Save Retrieved 17 November 2022 ASHP Rebates Minnesota Power Retrieved 17 November 2022 Rebates for Heating amp Cooling System Replacements Dominion Energy Retrieved 1 December 2022 Sources Edit IPCC reports Edit IPCC 2013 Stocker T F Qin D Plattner G K Tignor M et al eds Climate Change 2013 The Physical Science Basis PDF Contribution of Working Group I to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change Cambridge United Kingdom and New York NY USA Cambridge University Press ISBN 978 1 107 05799 9 pb 978 1 107 66182 0 https archive ipcc ch report ar5 wg1 Myhre G Shindell D Breon F M Collins W et al 2013 Chapter 8 Anthropogenic and Natural Radiative Forcing PDF Climate Change 2013 The Physical Science Basis Contribution of Working Group I to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change pp 659 740 IPCC 2018 Masson Delmotte V Zhai P Portner H O Roberts D et al eds Global Warming of 1 5 C An IPCC Special Report on the impacts of global warming of 1 5 C above pre industrial levels and related global greenhouse gas emission pathways in the context of strengthening the global response to the threat of climate change sustainable development and efforts to eradicate poverty PDF Intergovernmental Panel on Climate Change https www ipcc ch sr15 Rogelj J Shindell D Jiang K Fifta S et al 2018 Chapter 2 Mitigation Pathways Compatible with 1 5 C in the Context of Sustainable Development PDF IPCC SR15 2018 pp 93 174 IPCC 2022 Shula P R Skea J Slade R Al Khourdajie A et al eds Climate Change 2022 Mitigation of Climate Change PDF Contribution of Working Group III to the Sixth Assessment Report of the Intergovernmental Panel on Climate Change Cambridge UK and New York NY USA Cambridge University Press In Press Other Edit High GWP refrigerants California Air Resources Board Retrieved 13 February 2022 Tracking Power 2021 International Energy Agency Retrieved 22 February 2022 The GWP value of refrigerants and its importance for operators Infraserv hochst Retrieved 20 February 2022 Quaschning Volker Specific Carbon Dioxide Emissions of Various Fuels Retrieved 22 February 2022 External links Edit Media related to Heat pumps at Wikimedia Commons U S Department of Energy Practical information on setting up geothermal heat pump systems at home IEA Technology Collaboration Programme on Heat Pumping Technologies Carbon Brief guest post How heat pump sales are starting to take off around the world Retrieved from https en wikipedia org w index php title Heat pump amp oldid 1142242094, wikipedia, wiki, book, books, library,

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