German OEM Konvekta has joined some of the HVAC&R industry’s leading CO2 manufacturers as a bronze partner on R744.

Konvekta develops and manufactures mobile CO2 (R744) heat pumps systems for buses, construction and agricultural machinery, and rail. It also produces systems for transport refrigeration.

Konvekta has installed its CO2 heat pumps in more than 1,300 electric buses and rail vehicles since introducing them in 2018, with Germany as its main market. The CO2 heat pumps from Konvekta can switch from heating to cooling, and include  an air-to-air circuit and an air-to-water circuit.

The mobile CO2 heat pumps are energy efficient compared to traditional electric heaters in buses, said Konvekta. An articulated bus with two UltraLight 500 CO2 heat pumps from Konvekta has been running in Nuremberg, Germany, since the beginning of 2020. Studying data from the bus, Konvekta has found that the two heat pumps have reduced annual costs and emissions for the operator. 

Annual costs for heating and cooling using the CO2 heat pump have been slightly less than €1,500 (US$1,695). By comparison, the annual cost of running a heat pump with R134a refrigerant (plus electric heater) is slightly less than €3,000 (US$3,390). In addition, the CO2 heat pump produces just over 4,000kg (8,818.5lbs) of CO2e emissions, compared with more than 9,000kg (19,841.6lbs) of CO2e emissions for a heat pump featuring R134a plus electric heater.

The CO2 heat pumps can also increase the range of electric buses. In a February 2021 test, Konvekta compared two electric buses in Berlin, one with the Konvekta system installed, and one with a regular AC unit and an electrical heater. The bus with the Konvekta system used 0.38kWh/km (0.61kWh/mi) for the heating system, while the bus with the traditional system employed 0.9kWh/km (1.45kWh/mi).

For these two vehicles, the difference meant that the electric bus with the Konvekta unit had a range of 151km (94mi) on a charge, whereas the traditional bus managed a range of 114km (71mi).

The ambient-temperature range of the Konvekta units encompasses -20°C to 43°C (-4°F to 109.4°F).

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