This year at Busworld Konvekta AG will once again be focussing on electric mobility. In Hall 5, Stand 516a, Konvekta is showcasing the fast-charging enabled, modular, heat storage concept HEAT2GO for electric city buses. This sets new benchmarks in terms of energy-saving and emission-free heating “to go”. More than one hour of continuous heat with a capacity of 10 kWh is available to electric buses and this is without having to put any burden on the batteries.
Moreover, at the stand in Hall 5, multiple variants of the product range of the Konvekta CO2 heat pump will be exhibited. With zero emissions and heat from the ambient air, these thermal systems reduce the annual energy consumption, which is regularly needed for cooling and heating, by more than 50%. Furthermore, the CO2 heat pumps – which are operated with the refrigerant CO2 – provide additional ecological benefits for both operators and the environment.
Emission-free and efficient heating of E-buses
When procuring electric buses, one has a choice between two variants. Option one features larger, expensive, heavy batteries, the capacity of which is also sufficient for heating. Meanwhile, option two involves a thermal Konvekta heating variant for temperature control, which reduces costs and energy consumption.
In city traffic, energy consumption plays a significant role regarding heating and cooling, since this has a considerable impact on the range and therefore the deployment of the omnibuses. If the energy required for thermal management is taken from the stock available with the batteries, this might lead to considerable restrictions in the deployment planning of the buses, both during summer and even more so in winter. Tests conducted of late have demonstrated that during the very cold or warm months, the vehicles sometimes require more energy for temperature control than for driving.
HEAT2GO – Low-cost heat “to go”
Konvekta – a pioneer in the development of alternative methods for mobile air conditioning – is presenting another idea for the energy-saving heating of electric buses that is distinct from the series manufactured heat pump variants. The research project HEAT2GO – a joint venture development of the Fraunhofer Institute for Traffic and Infrastructure systems – is a quick-charge enabled, modular latent heat storage system for electric city buses. This heat storage absorbs thermal energy fed to it in a small-time frame, by changing the unit state from solid to liquid. The thermal energy now saved is discharged continuously during the bus travel to the driver’s workplace, the passenger cabin, as well as to secondary consumers requiring a high temperature. For this purpose, the system needs no energy from the on-board batteries. Continuous heat for over one hour is available to the electric bus with a capacity of 10 kWh. And thanks to the modular design, the capacity can be adjusted to meet different requirements.
HEAT2GO is suitable for the OppCharger just as it is for a depot charger. With opportunity charging, not only are the batteries of the buses charged at the quick-charge points of the pantographs, but even the latent heat storage system is charged within a few minutes. In parallel, the thermal energy produced during charging is used, if required, directly for heating the interior cabin and the overall efficiency is further enhanced in this way.
The system also gets perfectly integrated in modern thermal management concepts such as, for example, the CO2 heat pump for depot chargers. In doing so, the HEAT2GO – heat storage system is an optimal supplement in order to intercept temperature peaks.
The battery size is rated according to the energy consumption peaks, which become reduced considerably with the HEAT2GO heat storage. This means that during a bus life cycle one can save up to EUR 36,500 in battery capacity. The battery storage has to be replaced at least once in the life cycle of a bus, whereas the service life of the latent heat storage is theoretically unlimited. Over and above this, even this system, and also the CO2 heat pump, is capable of 100% recycling.
Reliable and efficient – The Konvekta CO2 heat pump variants
These air conditioning systems, especially for electric buses, are characterised by sustainability as well as the economical and efficient utilisation of the limited energy. Following the successful start of series production in 2018, the product portfolio of the Konvekta CO2 heat pump was expanded. Konvekta CO2 heat pumps are air conditioning systems for electric buses, which offer optimal comfort for human beings and maximum energy efficiency for the vehicle. With zero emissions, the annual energy consumption for cooling and heating gets reduced by more than 50%. The system draws up to 75% (COP up to 4) of the required heating or cooling not from fossil fuel or electricity, but from Nature – from the ambient air – and it is therefore highly efficient.
Energy Collect
However, not only is the product range being expanded, but there is also a new supplementary module in order to save on energy costs – “Energy Collect”. In the process, for example, waste heat from the axles or from the battery is used in order to heat the vehicle passenger cabin. Following initial measurements, one can save approximately 15 – 20% of the heating energy required in a year. Indeed, in the course of the next year, even the module “Energy Collect” will be ready for series production.
Natural refrigerant CO2 – efficient and not combustible or toxic
In addition, the product range of the heat pumps solves the refrigerant problem. The CO2 refrigerant used in the CO2 heat pumps is not subject to any statutory restriction, and it is therefore not limited in the future, and it is also very low-cost when compared to chemical refrigerants. Moreover, CO2 has a 20% higher efficiency compared to conventional refrigerants; in other words, you need approximately 25% less fuel for the same cooling power.