Global market and technology trends for copper tube heat exchanging technology in air conditioning, refrigeration and heat pumping | | Editor’s Note: Welcome to the very first issue of the SDCT Tech Newsletter! It’s hard to believe how far we’ve come since the International Copper Association first launched the MicroGroove Update newsletter fifteen years ago. Back then, small diameter copper tube technology was just beginning to make waves in the world of heat exchangers. Now, advantaged by hindsight, we’re excited to kick off this new chapter by looking at how SDCT has grown into a global game changer throughout the AC, Refrigeration and Heat Pump industries. | | SDCT Tech in ACRHP Goes Global | | |
Over the past decade, the adoption of SDCT technology has taken off—especially across Asia, where major OEMs continue to lead the charge in innovation and manufacturing excellence.
It is safe to say that Asian OEMs dominate AC appliance manufacturing. Chinese titans such as Gree, Haier, Hisense and Midea are potent forces. Japanese giants such as Daikin, Mitsubishi, Toshiba, Panasonic and Fujitsu are among the world’s largest OEMs in the ACRHP space. OEMs from South Korea including LG and Samsung are also forces to be reckoned with on the global stage. Finally, Bluestar is a rising star in AC manufacturing in South Asia, where the demand for AC is rapidly escalating. Other Asian countries play a role in the manufacturing infrastructure that supports the Asian ACRHP powerhouse.
| | The majority of heat exchangers for heat pumps harness round tubes and plate fins. Courtesy of CHPA and China IOL from "2024 Global Heat Pump Market Report." | | |
SDCT heat exchanger technology was in part an inevitable consequence of the intrinsic properties of copper, including its high thermal conductivity, durability and strength, and its resistance to corrosion. Historically, a consortium of Asian OEMs, tube fabricators and universities spearheaded the development of SDCT Technology.
Retooling was necessary to fabricate precision technical tubes with small diameters and enhanced inner surfaces and to bring the technology into OEM factories for the high-volume manufacture of AC appliances.
SDCT technology quickly advanced, matured and spread globally. SDCT coil makers today can be found throughout the United States, Europe and Asia. Large and small OEMs have availed themselves of this new technology in applications that go well beyond the original vision. SDCT with diameters of 7 mm are commonplace and 5 mm and a quarter inch are not unusual. Some manufacturers have introduced coils with 4 mm copper tubes.
But SDCT didn’t stop there. What started in residential AC systems quickly found its way into commercial and even industrial settings. Let’s take a look at how this technology is expanding its impact across applications and continents.
| | China exports heat pumps primarily to Asian and European countries. Courtesy of CHPA and China IOL from "2024 Global Heat Pump Market Report." | | |
Meanwhile, in North America, SDCT is gaining traction thanks to leading OEMs, innovative research collaborations, and major industry events. Here's how the region is embracing this forward-thinking approach.
SDCT technology has spread from residential (room) ACs and refrigerated cabinets for convenience stores to large capacity commercial systems for AC and refrigeration. Despite challenges relating to refrigerant flow, large commercial systems can also benefit from compact designs that use less refrigerant and less copper tubing. In many cases, the corrosion resistance of round copper tubes proves superior to any competing technology, including aluminum systems. Round copper tube systems with plate fins allow for easier drainage than flat aluminum tubes with serpentine fins brazed between ribbon-like microchannel tubes.
Other factors contribute to the success of SDCT in various applications. For example, the phase down of HFCs and the use of low-GWP refrigerants and refrigerant blends boosted the development of SDCT technology, especially in refrigeration applications. Small diameters and inner grooves increase the heat transfer coefficients (HTCs) of copper tubes. As a result, manufacturers can reduce the charge of flammable refrigerants to acceptable levels, opening the door to a whole new class of low-GWP refrigerated cabinets.
Natural refrigerants such as propane (R290) and CO2 (R744) obviate the release of atmosphere-wrecking HFCs. These systems became popular with refrigeration OEMs throughout the world from Japan to Europe to North America in the past decade. R290 is now viable for AC and HP systems that use SDCT technology, especially in cases where the heat exchanger can be situated outdoors.
By the middle of the last decade, it was becoming clear that there would be no stopping the use of SDCT Technology in ACRHP systems globally.
| | SDCT technology is especially compatible with natural refrigerants such as R290 and R744. Numerous slideshows are available within the ATMO.org event archive webpage. | | |
SDCT in the United States
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North America is under the auspices of the Copper Development Association with headquarters in Washington D.C. Major OEMs in North America include Carrier, Daikin-Goodman, Haier-GE Appliances and Johnson Controls as well as many OEMs of refrigeration equipment. A worldwide leader in thermal management, Modine Manufacturing Company has its corporate headquarters in Racine, Wisconsin.
North America is home to ASHRAE, AHRI, RSES and many other professional and trade associations in the ACRHP sector. The Copper Development Association (CDA) provided a summary report on the 2025 AHR Expo in a blog within HVAC&R section of its website. The CDA HVAC&R blog covers topics of special interest to North America, such as standards for refrigerants. Read CDA Blogs here.
For many years, CDA collaborated on research with Optimized Thermal Systems, whose CEO Dr. Vikrant Aute has more than fifteen years of experience in the research and development of simulation and optimization software for thermal systems. Dr. Aute currently serves as Director of the Modeling and Optimization Consortium within the Center for Environmental Energy Engineering (CEEE) at the University of Maryland, Department of Mechanical Engineering. OTS Partner Dr. Yunho Hwang currently serves as Chief Science Officer for OTS, providing technical guidance and support for critical projects. Case studies on SDCT technology were developed around CoilDesigner® software and the resulting reports are available online.
Oak Ridge National Laboratories (ORNL) and the U.S. Department of Energy have been active in research on heat pumps for nearly fifty years. The DOE/ORNL Heat Pump Design Model is a research tool for use in the steady-state design analysis of air-to-air heat pumps and air conditioners. Heat exchanger simulation software is reviewed in the newsletter article “Real Insights in the Age of Simulations” (MGU 11-2).
Major U.S. ACRHP Expositions and conferences include the annual AHR Expo as well as the biannual Purdue Conferences. The use of SDCT technology with natural refrigerants has been described at multiple ATMOsphere events in the USA and Europe. For more information, search “microgroove” in the ATMO.org event archive webpage.
Now let’s cross the Atlantic and check in with Europe—a region that’s buzzing with innovation in ACRHP technologies. From collaborative ventures to cutting-edge product development, the European market continues to push the envelope on what’s possible.
| | Advanced Technology Trends in Europe | | Europe is a hotbed for ACRHP product innovations. Major ACRHP OEMs can be found across the continent and in the United Kingdom. Europe is notable for its collaborations and partnerships with OEMs from other corners of the world. For example, Carrier acquired Viessmann Climate Solutions in a deal that officially closed on January 2, 2024. This acquisition positions Carrier as a leader in the sustainable climate solutions market, particularly in the growing heat pump sector. Other major OEMs include Alfa Laval, Armec, Swegon, TEKO, Valliant and many others. Europe also has a vibrant home-grown ACRHP manufacturing infrastructure which includes coil makers such as Eurocoils, Karyer, Kelvion, Lordan, LU-VE Group, Modine Eco, ProFroid, Sierra and many others. | | |
In Europe, Unilab (Padova, Italy) has developed a powerful suite of heat transfer software for simulating the performance of heat exchangers. A catalog of its software modules is available at www.unilab.eu.
Europe is home to the European Heat Pump Association (EHPA); the IEA Technology Collaboration Programme on Heat Pumping Technology (IEC TCP HPT); the International Institute of Refrigeration (IIR); and many world class ACRHP research laboratories.
Major trade shows in Europe include
and many regional conferences and expositions.
For an overview of tube suppliers, coil makers and ACRHP OEMs in Europe, see “Europe Turns Up the Heat on Heat Pumps” (MicroGroove Update 12- 2A and “MicroGroove Coils Span the Globe: Europe is Ecofriendly” (MGU 10-1).
While Europe brings its own ingenuity to the table, the beating heart of ACRHP manufacturing undeniably lies in Asia. Let’s take a deeper look at how China and its neighbors continue to set the pace for the global industry—and why all eyes are still turning eastward.
| | A paper on the “Principles of evaporator coil design for air source cold climate heat pumps” was presented at the International Congress on Refrigeration (E2, TS36. Paper 0191) ICR 2023. Read More: MGU 13-2. | | |
Asia is the undisputed leader in the manufacture of the whole gamut of ACRHP products.
As previously mentioned, major brands from China, Japan and South Korea dominate high volume AC manufacturing. All of these OEMs have broadly adopted SDCT Technology to improve the performance of their products. It is noteworthy that the next meeting of the International Conference on Refrigeration (ICR) from the International Institute of Refrigeration (IIR) https://iifiir.org/en/iir-presentation will be held in Seoul, South Korea, in 2027 https://www.icr2027.org/.
“ACREX” stands for the Air Conditioning, Heating, Ventilation, and Refrigeration Expo. ACREX India is South Asia's largest exhibition dedicated to these sectors. The Expo is organized by ISHRAE (Indian Society of Heating, Refrigerating and Air Conditioning Engineers). The next ACREX India will be held in Mumbai in March 2026.
Factually, China is a leader in the implementation of SDCT technology in the design of new products. In addition to the major brands, scores of smaller companies are designing and manufacturing innovative ACRHP products. For more about ACRHP development in China, see the article “Heat Pumps Gain Popularity in China." MGU 12-1
World class ACRHP research laboratories can be found within Chinese Universities such as Shanghai Jiao Tong University (SJTU) and University of Shanghai for Science and Technology (USST). See “In the Spotlight” column “USST Conducts Research on Heat Exchangers for Refrigerated Display Cabinets.” MGU 12-1 Spotlight
Major Industry Trade shows in China include the China Refrigeration Expo (CR Expo https://www.cr-expo.com/en/); and the Appliance & Electronics World Expo (AWE, https://www.awe.com.cn/).
Another key conference is the China Heat Pump Forum (CHPF), which is presented annually by the China Heat Pump Alliance (CHPA). The CHPF is the only international conference that is 100 percent dedicated to the heat pump sector. The CHPF is becoming a key annual event, which should be marked on the calendar of every executive, technologist or policy maker in the global heat pump industry. An important analysis on “The Future of Heat Pumps in China” was published in 2024 by the International Energy Agency.
| | More than 1,200 units of ASHPs were deployed as heating sources for large residential buildings in Zhao County. To avoid the cold island effect, frame structures keep the outdoor units at least 8 meters above the ground. Read More: MGU 13-1 Spotlight. | | Prognostication: What’s Next? | | |
The future looks bright for SDCT Technology within the global ACRHP industry. The transition to low GWP refrigerants will continue to develop, along with related trends toward the adoption of natural refrigerants such as R290 and R744 as the ultimate solution to lowering the GWP of refrigerants.
As average temperatures rise and purchasing power increases in low-income countries of the Global South, the demand for energy efficient AC systems using renewable energy will also rise. Similarly, Europe will demand more AC due to increasing temperatures.
The trend toward electrification with clean energy and decarbonization of heating is another major trend. China clearly dominates in technological know-how and manufacturing prowess for heat pumping technology. China will ramp up production of heat pumps to meet the demand of its domestic markets and position itself as a global supplier of air source, air-to-air (AS ATA) and air source, air-to-water (AS ATW) heat pumps for global export.
Asian countries are well positioned to take the lead in heat pump technology and manufacturing building on their existing expertise in the high-volume production of residential air conditioning systems and their global partnerships.
The Editors of the SDCT Update and regional ICA program managers look forward to continuing to provide vital information as SDCT technology advances and its deployment around the globe expands.
| | A new website sdct-tech.com will be launched in 2025 as microgoove.net is phased out. The sdct-tech.com website will cover global trends in ACRHP Technology, including updates from ICA Asia, ICA Europe and the Copper Development Association in North America. The sdct-tech.com website will include a Library of legacy newsletters and white papers as well as technical articles and slideshows. | | The 2024 Global Heat Pump Market Report is available for free download, thanks to the China Heat Pump Alliance (CHPA) and China Industry Online (ChinaIOL). | | |
White Papers
Harry Schmitz, "Copper Shines at AWE2025: How Copper is Driving the Low-Carbon Transformation in The Global Appliance Industry," Appliance & HVAC Report, Volume 7, Number 3, July 2025, Page 6.
Hengyi "Cooper" Zhao, Frank Gao, Harry Schmitz, “China Heat Pump Forum Heralds a Green Future,” Appliance & HVAC Report, Volume 6, Number 4, October 2024.
Frank Gao, Harry Schmitz, Yoram Shabtay, Kerry Song, “HVACR Engineers Focus on Cold-Climate Heat Pumps,” Appliance & HVAC Report, Volume 5, Number 4, October 2023, Page 22.
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