Busworld 2015 showcases advancements in CO2 MAC technology

Konvekta is trialing its CO₂ MAC units in high ambient temperatures for the first time this year with French transport provider RTM. The ongoing trial will be key to the company’s, and the industry’s, adoption of CO₂ MAC throughout Europe – a hot topic at Busworld 2015, held 16-21 October, in Kortrijk.

At the event Konvekta Director Business for Bus AC, Reiner Boland outlined the positive trials of its CO₂ mobile air conditioning (MAC) system for Regie des transport de Marseille (RTM) and the release of the company’s second generation CO₂ heat pump for electric buses.

Konvekta has approximately 100 CO₂ buses throughout Europe (CO₂ MAC, and CO₂ heat pumps on electric buses), predominantly serving Germany, where the company is based, and neighbouring countries like Switzerland and Austria. Boland said Konvekta had fitted 40 buses in the past year 2014-2015 and expected that number to increase year by year.

The next frontier will be the hotter southern climates in Europe. In Marseille, where temperatures can reach between 35-40°C, the components in Konvekta’s units are forced to work much harder.

“For these temperatures we still have to improve our product and the implementation which means we need a much higher RPM for the compressor and this has to be implemented in the U.S. So the units in (Marseille) are not running trouble free but they are improving.”

“We are focused on testing in Marseille and our aim is to improve the performance there and then when they reach the next level we would like to test in other areas of Europe.”

Second generation CO₂ heat pumps

Konvekta's first generation of R744 heat pumps have covered more than 100,000km in recent months across 20 installations. The heat pump systems take over the entire thermo-management in electric busses - from air conditioning for passengers to the sensitive batteries.

“We’ve been working on the development of CO₂ solutions since 1994, and we are fully convinced about CO₂ and especially for battery buses. With the CO₂ heat pump you can work with temperatures as low as -10°C, which you can’t do with a conventional refrigerant.”

Taking the next step, Konvekta showcased its second generation heat pump, simplifying the design and integrating new components, from the compressor (to address RPM), to the expansions valve.

“One of the components was the compressor, other components are the expansion valve and valves in general. With the system itself we don’t have any problems – in regards to the heat exchanger and with the piping,” Boland said.

Policy landscape and component suppliers shaping future for CO₂ MAC

The phase down of HFC R134a by the start of 2017 for new passenger vehicles, will increase the cost of the refrigerant and in turn decrease the cost of CO_2,although this may have minimal effect on the bus industry for the time being. “If our competitors would increase the development of their units that would further (drive down cost), making it more attractive for our suppliers to develop more CO₂.”

“It’s not just an argument to say it’s environmentally friendly, but technically as a refrigerant CO₂ is outstanding. Of course, we have some challenges; we need more support from our suppliers because at the moment we have to make some of our own components, which we don’t like to do, but we have to because there are not adequate suppliers. We have seen that trend in the passenger car industry, and we hope that we do get access to more components in the future.”

Boland praised the work of the Deutsche Umwelt Hilfe (DUH) in Germany to facilitate the transition towards climate-friendly refrigerants like CO₂.

“We felt that the DUH was very strong. They were contacting end users and local manufacturers, they even took on a lot of responsibility, asking continually: ‘what are you doing with CO₂? The passenger industry is going in this direction, why isn’t the commercial bus industry going in this direction?’ So they were very helpful.”

Recently, the “Blauer Engel” (Blue Angel) label, designed by the German government to award environmentally friendly technology, implemented a new category for CO₂ air conditioners.

“This will give incentives to manufacturers and end users to (conduct) trials and tests. These financial incentives will help a lot, maybe to encourage trials of the systems for hybrid buses.”

Further encouragement is coming from companies like Bitzer, who were in attendance at Busworld showcasing their new propane MAC prototype, sending a clear message to the industry that this phase down of HFCs in Europe may be the last phase down.

“If we switch to CO₂ then it’s done. There is no need to have any phase down in the future because when we have CO₂ then it’s done all over the world and we should do it not for commercial aspects alone but for environmental reasons,” Boland said.