From this R744.com site:
Belgium — 2008-03-26 — Konvekta’s new P-series for bus air conditioning features an innovative roof concept for city buses, intercity buses and coaches. Using aluminium heat exchangers and tube sets, as well as new plastic materials, the units achieve a substantial weight reduction. All systems can be equipped with re-usable metal air filters, a brushless evaporator and condenser fans. Due to its flexible, simple and time saving mounting, the P-series fits nearly all applications, while providing substantial lifecycle cost reductions. They are suitable for roof radii of 6,000 to 20,000 mm.

Konvekta P-Series Rooftop Bus A/C System

Type P 7744, to be used with the natural refrigerant CO2 (R744), features a cooling capacity of 33 kW, and a heating capacity of 38,000 Q 100. Since 1996, it has been running successfully in test fields with a German bus operator to prove its everyday suitability. The operational experience has shown that, compared to the current refrigerant R-134a, R744 is competitive in terms of efficiency and capacity due to a better compressor performance and heat transfer, as well as a lower effect in case of pressure losses. In addition, CO2 units in reversed circulation can be used for heating purposes, unlike R-134a. After more than 6,000 operating hours of the CO2 prototypes, Konvekta is now preparing for the serial production of its R744 cooling unit.

Basic Specifications
Main features of Konvekta’s CO2 bus air conditioning are:
Cooling capacity [kcal/h]: 28,400
Evaporator air capacity [m3/h]: 6.480
Current consumption at 26 V [A]: 104
Measures [length/width/height in mm]: 2680 / 2100 / 220
  
Konvekta – 15 years of CO2 innovations
Since the early 1990’s, Konvekta has invested in the development of CO2-based solutions for commercial vehicles. In 1994, the company presented the world’s first functional R744 bus air conditioning unit, starting first field tests only two years later. From that moment on, Konvekta focused on the development of other R744 innovations, including transport refrigeration and train air conditioning, and refined its bus system to optimize its performance for different vehicle types and climate conditions.

Konvekta has received several awards, among others "The Technology Award for Sustainable Development" by the European Commission in 2000. In October 2007, the company was awarded the prestigious "German Environment Award" for its work that helped demonstrate the efficiency of R744 in vehicle air conditioning.

About Konvekta
Konvekta was founded in 1957 to provide integral thermal solutions for commercial vehicles. The family-owned company is now established as a reliable partner for the commercial vehicle and rail industry in the field of air conditioning, refrigeration, and heating technology. Konvekta offers standardized solutions for a wide vehicle range as well as specialized solutions for non-standard applications.

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