F28D 21/0008
Air heaters
Official title: {Air heaters}
F28D21/0008 (Air heaters) appears on 126 US grants and 34 published applications in this corpus.
Search patents in F28D- Granted patents
- 126
- Published applications
- 34
- Assignees
- 40
- Inventors
- 177
- Latest grant
- 31 Mar 2026
Filings by year
| Year | Granted patents | Published applications |
|---|---|---|
| 1976 | 6 | 0 |
| 1977 | 2 | 0 |
| 1978 | 8 | 0 |
| 1979 | 8 | 0 |
| 1980 | 12 | 0 |
| 1981 | 14 | 0 |
| 1982 | 11 | 0 |
| 1983 | 7 | 0 |
| 1984 | 7 | 0 |
| 1985 | 5 | 0 |
| 1986 | 4 | 0 |
| 1987 | 5 | 0 |
| 1988 | 1 | 0 |
| 1989 | 1 | 0 |
| 1990 | 1 | 0 |
| 1991 | 2 | 0 |
| 1992 | 0 | 0 |
| 1993 | 1 | 0 |
| 1994 | 1 | 0 |
| 1995 | 3 | 0 |
| 1996 | 0 | 0 |
| 1997 | 0 | 0 |
| 1998 | 0 | 0 |
| 1999 | 1 | 0 |
| 2000 | 1 | 0 |
| 2001 | 0 | 0 |
| 2002 | 2 | 1 |
| 2003 | 0 | 0 |
| 2004 | 0 | 0 |
| 2005 | 0 | 0 |
| 2006 | 0 | 0 |
| 2007 | 0 | 0 |
| 2008 | 0 | 2 |
| 2009 | 0 | 0 |
| 2010 | 0 | 1 |
| 2011 | 0 | 2 |
| 2012 | 1 | 5 |
| 2013 | 2 | 1 |
| 2014 | 0 | 3 |
| 2015 | 0 | 2 |
| 2016 | 2 | 2 |
| 2017 | 1 | 1 |
| 2018 | 2 | 3 |
| 2019 | 4 | 4 |
| 2020 | 3 | 3 |
| 2021 | 1 | 1 |
| 2022 | 3 | 0 |
| 2023 | 0 | 1 |
| 2024 | 0 | 2 |
| 2025 | 3 | 0 |
| 2026 | 1 | 0 |
By publication year. Applications have been published since 2001. 2026 runs to 8 Oct.
Recent patents
- Air sterilisation apparatus31 Mar 2026US 12,589,178 B2
- Flue gas energy recovery system and method25 Nov 2025US 12,480,720 B2Carbon Cap Inc.
- Heat recovery system4 Nov 2025US 12,460,875 B1
- Method for manufacturing counter flow total heat exchanger10 Jun 2025US 12,326,303 B2Gaontech Co., Ltd.
- Heat recovery unit13 Sep 2022US 11,441,775 B2
- Air treatment device1 Feb 2024US 2024/0035681 A1Daikin Industries, Ltd.
- Air sterilisation apparatus25 Jan 2024US 2024/0024529 A1
- Method for manufacturing counter flow total heat exchanger13 Jul 2023US 2023/0221076 A1Gaontech Co., Ltd.
- Heat recovery unit28 Jan 2021US 2021/0025590 A1Inline Heat Recovery Inc.
- Exhaust Hood Energy Recovery Device23 Jul 2020US 2020/0232650 A1ProGress Industries LLC
Most cited
By later US patents