Research and Projects

charge balancing technology

Patented refrigerant charge balancing technology - Efficient heating and cooling of electric buses

Konvekta AG presents another innovation in heating technology for electric buses: „refrigerant charge balancing“ as the latest module of the CO2 heat pump. This advanced technology improves once more efficiency and range - it is another step towards sustainable urban mobility.

Electromobility is becoming increasingly important, especially in local public transport (LPT). Electric buses are an environmentally friendly alternative to conventional diesel buses, but the limited range and long charging time are still a challenge.

Manufacturers of electric buses are working on improving the energy efficiency of the vehicle as well as that of the secondary consumers.  The heating and air conditioning system offers great potential for saving energy.

By using heat pump concepts and an optimized control system, the overall efficiency of electric buses can be significantly improved. CO2 heat pumps do not draw most of their energy from the battery but from the ambient air. The ambient heat is freely available, therefore the heat pump saves a significant quantity of energy.
All year round CO2 heat pump systems provide both efficient cooling in summer and reliable heating in winter. This is a major challenge because of the optimal refrigerant charge, which can vary according to heat demand, outdoor temperature, or operating mode, and thus has a direct impact on the system performance. With the new „refrigerant charge balancing“ module, the refrigerant charge level is precisely controlled, ensuring that the optimal quantity of refrigerant is always available to the system.

This is made possible by the use of patented valve technology, the exclusive Konvekta heat exchanger design and the specially developed control technology that specifically controls the refrigerant.


The function

CO2 thermal management consists of two circuits - one for heating and one for cooling. For example, the energy-intensive heating operation increases the demand for refrigerant. The inactive circuit - the cooling circuit - now acts as a resource source and provides the active circuit with the missing quantity of refrigerant. The performance of the system is thus significantly optimized, so that efficiency is increased and energy consumption is reduced. This saves costs and conserves environmental resources.

Refrigerant CO2

Another advantage of the „refrigerant charge balancing“ is that the system always operates in an optimal range due to the targeted control of the filling level so that the load on the components in the overall system is reduced. This extends the life span of the system and reduces maintenance requirements.

CO2 thermal management also uses the natural refrigerant CO2. CO2 is a natural component of the earth's atmosphere and is obtained as a waste product from industrial processes. CO2 is not subject to any legal restrictions and is permanently available at low cost. The natural refrigerant has no ozone depletion potential and therefore it does not damage the ozone layer.


The Konvekta - refrigerant charge balancing technology is the consequent further development of a system which sets new standards in the field of air conditioning and heating of electric buses again and again, resulting in efficient and sustainable mobility.

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