Unprecedented energy challenges are a global issue, with clearly discernible climate change, increased dependency on imports and concerns over supplies of fossil fuels worldwide. SWEP's CO2-based B9 heat exchanger can help protect the environment.

New gas cooler for CO2 in transcritical applications

The EU has established compulsory targets for reducing greenhouse gas emissions by 20 percent, ensuring 20 percent of renewable energy sources in the EU energy mix and planning to reduce EU global primary energy use by 20 percent by 2020.

To reach the EU's 2020 targets for renewable energy, heat pumps are an important tool. Heat pumps are used for residential and commercial space and water heating, cooling, refrigeration and in industrial processes. As heaters, they compete with fossil fuel-fired furnaces, boilers and direct electric heating.

Tomas Dahlberg, Innovation Manager at SWEP, says it is in line with SWEP's strategy to use CO2 as refrigerant. He adds that SWEP has developed a product – the B9 – that can be used as a gas cooler for CO2 in transcritical applications. It withstands extreme pressure, and has excellent thermal performance, he says.

“To meet the demands from the market, we had to deliver up to 140 bar working pressure, while also adhering to the legal requirements. In Europe, the European Pressure Directive (PED) requires five times the working pressure, so we need to achieve 700 to 800 bar burst pressure,” Dahlberg says. “The challenge  and success  in terms of innovation has been to achieve this pressure with a square heat exchanger design, while also delivering the required thermal performance.”

The new SWEP product satisfies the very tough Ecocute application requirements in Japan. The heat exchanger works as a high-pressure gas cooler in this application.

The Ecocute application for sanitary tap water has a heat pump driven by CO2 as a refrigerant. It is divided into a tank unit and a heat pump unit. On the tap water side, there is a tank and radiator. On the heat pump side, there is an evaporator, a compressor and a gas cooler.

“In Japan, many electric heaters have been replaced by Ecocute heat pumps, reducing energy consumption by up to four times,” Dahlberg says. “A double-wall unit that can handle 140 bar working pressure was required for Japan. It really was a challenge for us, and we also needed to consider a new plate-to-plate design to make it work.” The channel plate design utilizes SWEP's pioneering AsyMatrix technology.

“We can handle pressure drops and extreme pressures thanks to AsyMatrix and our heat exchanger design,” Dahlberg says. “The unit is also scalable in capacity – from 4.5 kW up to 10 kW  simply by adding plates. However, it still has the same design, which is cost-effective. We have also reduced the weight by 40 to 60 percent, and this is a huge step for transcritical gas coolers.”