Florian Entleitner and Florian Fuchs, the founders of Austrian start-up Lambda, had a ques­tion: How can heat pumps be made more effi­cient? Entleitner had the basic idea as part of his master’s thesis, which concerned the evap­o­ra­tion processes in tubular heat exchangers. This idea trig­gered the two men’s inven­tive­ness and in 2019 they used an inge­nious method to acquire an old heat pump. “Being country boys, we used a cattle truck to collect the enor­mous piece of equip­ment from the Steier­mark region,” explains Fuchs. “We cut it open and modi­fied it in line with our ideas.”

This proto­type earned them the neces­sary start-up funding from Austria Wirtschaftsser­vice and the Forschungs­förderungs­ge­sellschaft for deep-tech star­tups. Today, five years and one Euro­pean ­patent later, Lambda’s heat pumps are among the leaders in terms of effi­ciency and noise level – and Lambda is now a medium-sized enter­prise.

Inno­va­tion at Lambda Wärmepumpen is based on contin­uous further devel­op­ment. (Photo | Lambda Wärmepumpen)

Venti­lation in heat pumps is crucial because it supports effi­cient heat exchange by ensuring suffi­cient air circu­la­tion. (Photo | Lambda Wärmepumpen)

With AxiBlade fans, Lambda heat pumps can be precisely controlled via ModBus. This makes them partic­u­larly effi­cient. (Photo | Lambda Wärmepumpen)

The Lambda system

Circu­la­tion takes place in the air heat exchanger or evap­o­rator. Compared with a conven­tional heat pump, this increases the transfer of heat from the air to the cooling circuit by a factor of four to six. According to Fuchs, the biggest success was the design of the cooling circuit controller. As the design of their heat pump, the Eureka, is more complex, absolute preci­sion is essen­tial. This is achieved by the heat pump via a special controller for the expan­sion valve, which ensures that the flow of the propane refrig­erant is managed as precisely as possible. Fuchs does not want to disclose much more: “We have the patent on our special expan­sion valve controller.” And that’s not the last of the inno­va­tions. The controller works with the support of a virtual twin. It defines the math­e­mat­i­cally ideal vari­ables for the fan, compressor and valves, thus compen­sating the start phases and fluc­tu­a­tions in the Eureka.

(Graphic | Lamda Wärmepumpen)

With AxiBlade precise and quiet

Lambda not only prior­i­tizes preci­sion for its expan­sion valve. It is also the reason for choosing the AxiBlade 710 fan, which can be controlled precisely via Modbus. “That is already a signif­i­cant advan­tage for us because we can capture all the data and define the exact speed. In this way, we can accu­rately analyze the mass flow of the air.” This is impor­tant for the company. “When we were devel­oping the heat pump, low current consump­tion and a low noise level were the priority,” says Fuchs.

When we were devel­oping the heat pump, low current consump­tion and a low noise level were the priority.

Florian Fuchs, founder of Lambda Wärmepumpen GmbH

As well as using quiet fans, the engi­neers were inven­tive when it came to mini­mizing the noise level. In most heat pumps, the fan sucks the ambient air in through the evap­o­rator. “In our heat pump, the fan pushes the air through the evap­o­rator. This ensures addi­tional noise protec­tion for neigh­bors and that the heat pump doesn’t ice up as often,” says Fuchs, explaining the inno­va­tion of the fan design. However, just because a heat pump is quieter doesn’t make it a quiet heat pump. Even if the measured volume values are low, disrup­tive under­tones cannot be ruled out. That is why psychoa­coustics are just as impor­tant as volume. “We don’t just look at the measured value. We look at the pump on site and listen to estab­lish whether the noise is a distur­bance.”

The biggest devel­op­ment success was the cooling circuit controller.

Florian Entleitner, founder of Lambda Wärmepumpen GmbH

The fan pushing the air was devel­oped by ebm-papst for Lambda because, until now, air suction was the stan­dard for the AxiBlade. “They deliv­ered the first proto­type within a few weeks. This perfectly satis­fied our require­ment of creating maximum air flow while mini­mizing current consump­tion,” says Fuchs.

Thanks to its inno­v­a­tive heat pump, Lambda has moved from a carport to a 10,000-square-meter produc­tion building within just a short time. From here, the company can continue shaking up the Austrian market.