Phase-Change Thermal Storage Heat Exchanger Patents: Trends 2026
- Filing activity peaked in 2020 at 40 records and has since flattened toward the 2022 midpoint of 21, suggesting the core plate-and-cavity architectures are largely staked out rather than still expanding.
- F28D heat-exchange apparatus carries half the corpus at 173 of 351 records, far ahead of F25B refrigeration (77) and F24F air conditioning (69), showing where claim density is heaviest.
- The most-cited prior art predates the current wave US5722482A and US6319599B1 both sit above 275 citations and were filed well before the 2020 filing peak, meaning newer entrants are building on decades-old foundational claims.
Filing growth compares 2021 (9 records) with 2024 (19) — 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 351 records in scope (CR5), not by the ranked leaders only.
What this patent set covers
This landscape tracks 351 patent families published between 2015 and mid-2026 that combine phase-change material claims with a heat-exchanger structure — plate, capsule or coil designs that store or release latent heat rather than sensible heat alone. The search string pairs PCM and latent-heat-storage language with explicit heat-exchanger terms, which excludes pure materials-chemistry filings that never specify an exchanger geometry. Publication lags filing by roughly 18 months, so the 2025-2026 counts in the trend chart understate actual filing activity for those years.
The dataset spans HVAC, refrigeration, vehicle climate control and solar thermal applications, reflecting how the same plate-cavity PCM exchanger geometry gets re-claimed across adjacent end uses. Receiving-office distribution — led by the United States, EPO and India — points to where applicants expect enforcement value rather than where the underlying research originates.
Filing trend and technology composition
Two views of the same 351-family corpus: how filing volume has moved year over year, and how that volume splits across IPC subclasses.
A peak in 2020, then a plateau
Filings rose from 16 in 2017 to a peak of 40 in 2020, then eased toward 21 at the 2022 midpoint. The flat-to-declining pattern through the visible years indicates the technology has moved past its first filing surge; the 2026 figure is a partial year and should not be read as a drop-off.
F28D dominates the classification spread
F28D (heat-exchange apparatus) accounts for 173 of 351 records, roughly half the corpus. F25B (refrigeration and heat pumps, 77) and F24F (air conditioning and ventilation, 69) form a second tier, with F24D domestic heating, B60H vehicle HVAC, F28F exchanger details, F24S solar collectors and C09K materials rounding out the remainder — evidence that the exchanger geometry itself, not any single end application, is the most heavily claimed layer.
Shares are the percentage of the 351 records in scope. A patent can carry several IPC classes, so the shares add up to more than 100%.
Go deeper on Phase-Change Thermal Storage Heat Exchanger with Eureka
This page is one run against one query. Ask Eureka your own question about phase-change thermal storage heat exchanger and every answer comes back with the patent numbers behind it.
Try EurekaRepresentative and most-cited filings
WO2012128611A1 — Latent heat storage heat exchanger
The invention relates to a latent heat storage heat exchanger for use in a climate control system. The exchanger comprises a plurality of plate-shaped elements positioned parallel at a predetermined distance to form a fluid channel between adjacent elements, each with a cavity filled with phase change material. A coupling structure joins the cavities of the plates into one coupled cavity filled with phase change material.Filed by AUTARKIS B.V., published 2012-09-27 — predates this dataset's window but its plate-and-coupled-cavity architecture recurs across later filings in the corpus.
| # | Publication no. | Patent title | Citations |
|---|---|---|---|
| 1 | US5722482A | Phase change thermal control materials, method and apparatus | 358 |
| 2 | US6855410B2 | Phase change material thermal capacitor clothing | 292 |
| 3 | US6319599B1 | Phase change thermal control materials, method and apparatus | 277 |
| 4 | US20120227926A1 | Energy storage systems | 245 |
| 5 | US6464672B1 | Multilayer composite material and method for evaporative cooling | 123 |
| 6 | US6909349B1 | Apparatus and method for cooling power transformers | 69 |
| 7 | WO2011058383A2 | Energy storage systems | 67 |
| 8 | WO1994002257A2 | Phase change thermal control materials, method and apparatuses | 65 |
| 9 | US9389007B1 | Transportation refrigeration system with integrated power generation and energy storage | 64 |
| 10 | US20150316301A1 | Method and system for charging a transport refrigeration system | 44 |
Citation counts favour older filings simply because they have had longer to accumulate references; treat the ranking as a map of influence, not of present-day relevance.
Each row carries its publication number; clicking a row searches Eureka by that number.
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Three signals stand out once filing trend, classification spread and citation data are read together.
Growth has flattened after the 2020 peak
The run-up from 16 filings in 2017 to 40 in 2020 looks like a first wave of applicants staking out plate-and-cavity PCM exchanger designs. The pullback to 21 by 2022 suggests that wave has largely broken; new entrants now face a denser prior-art field than the 2017 cohort did.
Heat-exchange apparatus claims dominate the corpus
Just under half of all records classify under F28D, well ahead of refrigeration (F25B) and air conditioning (F24F). Applicants are contesting the exchanger structure itself more than any single downstream use, which is where freedom-to-operate searches should concentrate first.
Foundational patents predate the current filing wave
The most-cited records in this set, including US5722482A and US6319599B1, were granted long before the 2020 filing peak. Recent applicants are building claim language on top of these older thermal-control-material patents rather than displacing them.
Co-filing is limited and concentrated
Only 10 co-assignee pairs appear across the corpus, and the strongest pairings — such as AUTARKIS with its named inventors — repeat just three times. Most applicants in this space file independently rather than through joint ventures or research partnerships.
Eureka can read the same corpus for gaps instead of for coverage: under-claimed branches adjacent to phase-change thermal storage heat exchanger, with the prior art for and against each one.
Who is filing, and where the gate sits
Recent-year momentum across the named assignees shows zero filings in the latest tracked year for every one of them, consistent with the flat-to-declining trend line and the 18-month publication lag rather than an actual stop in R&D.
No single assignee dominates the full corpus
With filings spread across 351 families and receiving offices split six ways, ownership of the plate-and-cavity PCM exchanger concept is fragmented rather than consolidated under one or two firms.
United States leads, India is a close third
The United States receives the most filings, but India's 49 sits close behind EPO's 50, an unusual pattern that signals applicants see enforcement or manufacturing value in the Indian market alongside the traditional US/EU pair.
Joint filing is rare and inventor-linked
The strongest co-assignee relationships pair a corporate applicant with named individual inventors rather than with another company, pointing to small in-house teams rather than cross-industry R&D alliances.
| Assignee | Recent year | YoY |
|---|---|---|
| Sunamp Limited | 0 | — |
| MG Innovations | 0 | — |
| Trixco LLC | 0 | — |
| University of Southern Denmark | 0 | — |
| Thermo King Corporation | 0 | — |
| STASH ENERGY INC | 0 | — |
| Raytheon Company | 0 | — |
| AUTARKIS | 0 | — |
Where to take this analysis
The trend and classification data point to specific next steps depending on whether the goal is freedom-to-operate, licensing, or new filing strategy.
Run a freedom-to-operate check on F28D claims
Given that half the corpus sits in F28D, any new plate or cavity exchanger design should be checked against this subclass first, not against the application-specific subclasses like F24F or B60H.
Explore F28D filings in Eureka →Map the co-assignee network before partnering
With only 10 co-assignee pairs recorded, a partnership or licensing search should look at inventor-level links, not just corporate assignees, to find who is actually collaborating.
Trace assignee networks in Eureka →Watch the under-claimed branches for early filing
Cascaded multi-PCM stacks and EV cabin thermal buffering show thinner coverage than the core exchanger geometry, making them candidates for earlier, narrower claims.
Search white-space branches in Eureka →Common questions about this patent landscape
It is a heat exchanger structure — plates, capsules, coils or panels — that incorporates a phase change material as the storage medium rather than relying purely on sensible heat in a fluid. Patent claims in this space typically specify both the PCM composition or encapsulation and the exchanger geometry that moves heat into and out of it. This dataset was built by requiring both elements together, which is why it excludes pure PCM materials patents that never define an exchanger structure.
The filing trend rose from 16 in 2017 to 40 in 2020 before easing to 21 by the 2022 midpoint, a pattern consistent with an initial wave of applicants staking out core plate-and-cavity designs. Once foundational geometries were claimed, later applicants faced denser prior art and narrower room to file broad claims. It is worth noting that publication lags filing by roughly 18 months, so the apparent drop in the most recent years is partly a reporting artefact rather than a real halt in R&D.
By IPC classification, F28D heat-exchange apparatus leads with 173 of 351 records, roughly half the corpus, ahead of F25B refrigeration and heat pumps at 77 and F24F air conditioning and ventilation at 69. This means the exchanger structure itself is more heavily claimed than any single end application such as vehicle HVAC or solar collection. Anyone designing a new exchanger should check F28D prior art first regardless of which end market they target.
Not necessarily. The highest-cited records, such as US5722482A at 358 citations and US6319599B1 at 277, were filed well before the 2020 filing peak in this dataset and function as foundational thermal-control-material references. High citation counts inside a searched corpus favour older documents simply because they have had more time to accumulate references, so they are a better signal of historical influence than of which claims currently constrain new filings.
The classification spread shows thinner coverage in branches adjacent to the dense F28D and F25B core, including cascaded multi-melting-point PCM stacks, EV cabin thermal buffering exchangers, and long-cycle fouling or degradation claims for encapsulated PCM units. These sit at the intersection of well-claimed subclasses rather than in an entirely unclaimed area, so a workable strategy is to combine an established exchanger geometry with a narrower, under-claimed function such as multi-stage melting control.
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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.