Absorption Chiller Heat Pump Patent Landscape 2026 | Patsnap Eureka
- 155 families, accelerating late. Filings fell to zero at the 2022 midpoint before climbing to a 2025 peak of 6 — growth is recent, not steady.
- Chemistry outweighs hardware. C09K materials claims (42 records) dwarf every equipment-integration subclass, showing fluid-pair and sorbent formulation is where the claim space is actually contested.
- Legacy assignees have gone quiet. Every assignee named in recent-year momentum, including major incumbents, shows zero filings in the latest year — current activity is coming from elsewhere.
Filing growth compares 2021 (2 records) with 2024 (0) — a three-year span. 2024 is the most recent year we treat as complete: publication lags filing by roughly 18 months, so 2025 onwards are still filling in and any growth rate that ends there would understate the field. Top-5 share is the combined record count of the five largest assignees divided by all 155 records in scope (CR5), not by the ranked leaders only.
What this landscape covers
Absorption chillers and absorption heat pumps use a heat-driven sorption cycle rather than mechanical vapour compression, and this landscape tracks the 155 patent families published between 2015 and the 2026 cut-off that combine absorption-cycle terminology with the core F25B refrigeration and heat-pump classifications. The scope spans working-fluid chemistry, multi-effect cycle staging, desiccant-assisted hybrids, and the heat-exchanger hardware that moves heat through the absorber, evaporator and condenser stages.
Filing offices cluster around the United States, Europe and Japan, with Australia, Canada and the United Kingdom forming a second tier — a spread that tracks where district-heating retrofits and industrial waste-heat recovery programmes are commercially active rather than where the underlying research originates.
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How the filing activity and technology mix have moved
Filing counts and IPC tags for absorption chiller and heat pump patents, drawn from the 155 families published between 2015 and the 2026 data cut-off.
Filings are accelerating after a flat middle period
Annual filings ran at 2 in 2017, dropped to 0 at the 2022 midpoint, and have climbed since — 2025 is the peak year so far at 6. Because publication lags filing by roughly 18 months, the 2026 figure is a partial count and will revise upward once the remaining applications publish.
F25B carries the field; C09K carries the chemistry
Every record in this set is tagged F25B (refrigeration and heat pumps), as expected from the search definition. C09K (materials for miscellaneous applications) is a distant second at 42 records — mostly working-fluid and sorbent chemistry — while F24F, F28D, F24H, B01D, C02F and F04B each sit in single or low-double digits, marking the equipment-integration side as comparatively open.
Shares are the percentage of the 155 records in scope. A patent can carry several IPC classes, so the shares add up to more than 100%.
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Try EurekaThe records that shape freedom to operate
WO2001018462A1 — hydrophilic-surface heat exchanger for absorption cycles
A shell and tube heat exchanger having heat transfer tubes which is surface modified by plasma polymerization to be hydrophilic and an absorption chiller and an absorption heat pump using the heat exchanger to enhance heat transfer in the field of an air conditioning and refrigerating and heat exchange accompanying out-of-tube condensation and evaporation, etc.. There is formed a plasma polymerized film of a receding contact angle of not more than 30 DEG on the heat transfer tubes. The plasma hydrophilic polymerized film is applicable to a bare tube or a mechanically machined tube of the condenser, the evaporator, and the absorber which comprising an absorption chiller and an absorption heat pump.Filed by Korea Institute of Science and Technology, published 2001-03-15 — the claim scope is tied to the plasma-polymerization process and contact-angle threshold, not to hydrophilic enhancement generally.
| # | Publication no. | Patent title | Citations |
|---|---|---|---|
| 1 | US5846450A | Vapor absorbent compositions comprising potassium formate | 101 |
| 2 | US4732008A | Triple effect absorption chiller utilizing two refrigeration circuits | 78 |
| 3 | US20080028777A1 | Novel Pairs Of Working Substances For Absorption Heat Pumps, Absorption Refrigeration Machines And Heat Trans… | 74 |
| 4 | US5943874A | Desiccant assisted air conditioning apparatus | 71 |
| 5 | US5546760A | Generator for absorption heat pumps | 69 |
| 6 | US4646541A | Absorption refrigeration and heat pump system | 48 |
| 7 | US5666818A | Solar driven ammonia-absorption cooling machine | 45 |
| 8 | US4827728A | Seven-effect absorption refrigeration | 45 |
| 9 | US4719767A | Absorption refrigeration and heat pump system | 43 |
| 10 | US4542629A | Variable effect desorber-resorber absorption cycle | 33 |
Ranked by citation count within the searched corpus; older records are structurally favoured, so treat this as an influence signal rather than a current-relevance ranking.
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Three readings worth pausing on before deciding where to file or who to watch.
Growth is compressed into the last few years
A flat or empty midpoint followed by a run-up to 6 filings in 2025 indicates the field only recently attracted renewed attention, likely tied to heat-pump decarbonisation programmes rather than a steady multi-year build.
Fluid and sorbent chemistry is the real battleground
With C09K appearing in 42 of 155 records against single digits for most equipment subclasses, differentiation is happening in what goes inside the cycle, not how the hardware is arranged around it.
Incumbents are not defending their positions actively
Every assignee listed in recent-year momentum data, spanning gas utilities, national labs and equipment makers, shows no filings in the most recent year, suggesting current filing activity is coming from newer or smaller entrants.
Influence is old, not necessarily current
The most-cited records date back to the 1990s and early 2000s formate-chemistry and multi-effect cycle work. High citation counts inside a search corpus favour older records structurally, so read them as markers of foundational influence rather than present-day relevance.
Eureka can read the same corpus for gaps instead of for coverage: under-claimed branches adjacent to absorption chiller heat pump, with the prior art for and against each one.
| Assignee | Co-assignee | Shared families |
|---|---|---|
| British Gas plc | IC GAS INTERNATIONAL LTD | 1 |
Only one co-assignee pair appears in the dataset, a single link between a UK gas utility and IC Gas International Ltd — collaboration on record is the exception here, not the norm.
Who is filing, and where the claim space is still open
Recent-year momentum shows established assignees, from gas utilities to national energy-research bodies, sitting at zero filings in the latest year, which points to a field currently being entered by newer players rather than defended by incumbents.
Incumbent gas and equipment makers have paused
Utilities and equipment assignees with historical depth in this space, including national energy-research centres, show no filings in the most recent year, which is consistent with a legacy claim position rather than active expansion.
Filers mostly go it alone
A single co-assignee pairing, between a UK gas utility and IC Gas International Ltd, is the only joint-filing relationship recorded across 155 families, suggesting most work here is filed by a single owner rather than through joint ventures or research consortia.
US, Europe and Japan carry most of the volume
The United States leads receiving offices, with Europe and Japan forming a clear second tier, and Australia, Canada and the UK trailing behind — a pattern that matches where absorption-cycle retrofit and waste-heat-recovery deployment is commercially active.
| Assignee | Recent year | YoY |
|---|---|---|
| COLUMBIA GAS SYSTEM SERVICE CORP | 0 | — |
| Bavarian Center for Applied Energy Research (ZAE Bayern) | 0 | — |
| ATKINSON STEPHEN | 0 | — |
| Carrier Corporation | 0 | — |
| THERMAX LTD (IN) | 0 | — |
| U.S. Department of Energy | 0 | — |
| King Fahd University of Petroleum and Minerals | 0 | -100% |
| BASF SE | 0 | — |
Where to take this landscape next
The filing data points to where claim density sits and where it doesn't — the next step is testing a specific claim or assignee against the full family set.
Check a draft claim against the fluid-chemistry cluster
C09K carries 42 of the 155 records here, so any working-fluid or sorbent claim should be checked against that cluster specifically before filing, not just against the F25B core.
Run a claim check in EurekaTrack which assignees resume filing after the 2022 gap
With the midpoint year at zero and 2025 the peak so far, watching which named assignees re-enter the field will show whether growth is incumbent-led or newcomer-led.
Set up assignee monitoring in EurekaScope the under-claimed adjacencies before a competitor does
Solution filtration, wastewater-linked absorption cooling and solution-pump integration each carry single-digit record counts against the 155-family core — narrow but currently open.
Explore white space in EurekaFrequently asked questions
The dataset covering 2015 through the 2026 cut-off contains 155 published patent families that combine absorption chiller, absorption refrigeration or absorption cooling terminology with absorption heat pump IPC classification (F25B15/00, F25B30/04, F25B27/00). This counts families rather than raw documents, which is the fairer unit because it neutralises duplicate filings across jurisdictions and continuation applications from the same invention. It is not a count of commercially deployed systems, only of patent protection sought.
Filing activity is accelerating, not shrinking. Annual filings were at 2 in 2017, fell to 0 at the 2022 midpoint, and have since risen to a peak of 6 in 2025. Because patent publication typically lags the filing date by around 18 months, the most recent year in any such trend is always undercounted, so the actual 2025-2026 filing volume is likely higher than currently visible.
F25B (refrigeration and heat pump machinery) anchors every record in this set by definition of the search. Beyond that core, C09K (materials for miscellaneous applications, largely working-fluid and sorbent chemistry) is the clear second subclass at 42 records, indicating that fluid-pair and sorbent formulation is where most technical differentiation is being claimed. Air conditioning integration (F24F), heat exchangers (F28D), water heating (F24H), separation processes (B01D), water treatment (C02F) and pump design (F04B) each account for single-digit to low-double-digit shares, marking those as narrower, less contested claim spaces.
WO2001018462A1, filed by the Korea Institute of Science and Technology, claims a shell-and-tube heat exchanger for absorption chillers and heat pumps whose tubes are made hydrophilic through plasma polymerization, with a receding contact angle of no more than 30 degrees. It matters as a reference point because it ties a specific surface-treatment process, rather than the general concept of hydrophilic heat-transfer enhancement, to condenser, evaporator and absorber components. Designs relying on other surface-modification methods, such as chemical etching or sol-gel coatings, sit outside its claim scope.
The densest prior art sits around working-fluid and sorbent-pair compositions and multi-effect cycle staging, evidenced by the highest-cited records in the set, including a potassium-formate absorbent composition and a triple-effect two-circuit cycle design. Filing narrow method-of-use or formulation claims that overlap those established compositions or staging arrangements is likely to run into dense, well-cited prior art. Under-claimed adjacencies — solution filtration, wastewater handling tied to absorption cycles, and solution-pump integration — carry far fewer records and represent comparatively open claim space.
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Disclaimer. This page is generated from Patsnap Eureka data drawn from a limited snapshot of global patent and scientific-literature records, and is provided for general information and reference only.
Patent data carries inherent limitations: recent filings (typically the most recent 18–24 months) are under-counted due to standard publication lag; counts may be reported at either a patent-family or a patent-record basis and are not always directly comparable; classification, applicant-name, and citation data may contain errors, duplicates, or omissions; and the underlying search query defines and constrains the scope shown. As a result, the analysis may be incomplete or inaccurate and may not reflect the full technology landscape.
Nothing on this page constitutes an exhaustive prior-art, novelty, freedom-to-operate, or validity search, nor does it constitute legal, financial, investment, or professional advice, and it should not be relied upon as such. Any patent, commercial, or strategic decision should be verified independently and reviewed with qualified patent, legal, and domain professionals. Patsnap makes no warranties, express or implied, as to the accuracy, completeness, or fitness for any particular purpose of the information presented.
Machine translation. Assignee and organisation names originally recorded in Chinese, Japanese or Korean have been rendered into English by an AI translation step so that the tables stay readable. These renderings are best-effort and may not match a company’s registered English name; the original name is what the underlying patent record carries, and it is what any Eureka query launched from this page uses.