After almost 40 years, the technology and building of the canteen on the Garching Campus exceeded its expected lifespan. Currently, around 17,000 students and about 7,000 employees are on campus every day – a number that is growing every year. To supply the largest Technical University of Munich (TUM) campus, a new building was constructed in which the Free State of Bavaria invested around EUR 44.5 million.
With a usable area of 5,300 m2, the new building is designed to provide a total capacity of around 7,300 meals and handle 5,400 guests a day. The dining room alone measures 2,200 m2 and has 1,500 seats. Since 11 September 2019, students have been able to enjoy a wide range of offerings: salad bars, a vegetable bar, a soup station, a pizza, pasta and wok counter and a barbecue, as well as vegetarian and vegan dishes. The meals are freshly prepared and served daily by the canteen staff.
“This new building means that even the canteen in Garching will be state-of-the-art,” explains Dr Ursula Wurzer-Faßnacht, the Managing Director of the Munich Student Union. “The university catering department of the Munich Student Union is excited to run this modern facility and provide high-quality food for its guests in a stylish and contemporary atmosphere.” 1)
The Garching canteen was in urgent need of modernising since the building had long been unable to meet the required standards of capacity, technology and energy efficiency. Because of the state-of-the-art technology used, the new canteen will not only consume significantly less energy but will also offer long-term, sustainable, future-proof cooling with the natural refrigerant CO2.
Refrigeration planning & equipment
The refrigeration equipment installation was designed by the engineering office Schmid+Partner from Erlangen and installed by K.E.D. Kälte- & Klimatechnik GmbH from Bischofsmais (both Germany). Beginning in 2022, a 40 kW limit will apply to chemical refrigerants, and Hendrik Schmid (engineering office) immediately realised that their only option was a refrigeration system that uses CO2 for this application.
“After we received the call for tenders from Schmid+Partner, we offered a ROXSTAsmart from TEKO – and were awarded the contract,” says Michael Kraus of K.E.D. “The only problem was the installation of the blast freezers. Blast chillers of that capacity aren’t available ready to simply plug-in. Although the blast freezer manufacturer offers separate cooling units, they must be placed within a distance of 15 metres from the blast chiller. Spatially that was not feasible for this project; therefore, an additional refrigeration unit using R 407F was included in the initial planning phase. At Chillventa 2018, Simon Ahlers, the CO2 Systems Product Manager at TEKO, learned of our project and presented a perfect complete solution using CO2.
The refrigeration equipment was then redesigned to incorporate TEKO’s ROXSTAindustrial CO2 solution. From our perspective as the installation company, we were happy with this and so was Schmid+Partner – so two birds were killed with one stone in the end.”
Installing the refrigeration technology
The whole job was carried out within a very short timeframe and was completed in November 2018. With a gross value of EUR 1 million, the project is one of the largest individual projects ever undertaken by K.E.D.
The 5,300 m² area required correspondingly long pipelines. In total, 1,750 metres of K65 pipes up to 1 5/8” in diameter and approximately 18.5 kilometres of electrical cabling were laid.
Installing the refrigeration system also presented challenges. The unit had to be brought into the building through an opening in the side wall of the second floor using a mobile construction crane. From there, it was transported about 30 metres via a ventilation control centre and a stairwell to its final location. The ROXSTA’s modular design meant that the unit and intermediate pressure station could be installed separately, which is an enormous advantage in an installation of this size. And as the machine room is not large, the two units were installed separately, which economised the use of the available space.
The waste heat from the refrigeration system is used to preheat the dishwasher water. The heat goes to two 500-litre DK storage tanks with an integrated legionella circuit via an intermediate circuit fitted with a pump. In the storage tanks, the water is heated up to as much as 80 °C, depending on the dwell time. If the capacity of the heat recovery unit is insufficient for a required temperature level, further heating is done inside the dishwashers.
This special heat recovery application made it possible for planners to combine the refrigeration and dishwashing maintenance groups very effectively.
Wurm control electronics
To provide the electronic controls in the Garching canteen, K.E.D. worked with our partner Wurm Systeme from Remscheid.
“TEKO and Wurm have been working closely together for many years. So we decided to rely on this synergy and use the proven FRIGOLINK solution from Wurm,” says Michael Kraus. “All in all, eight main modules with 56 refrigeration modules have been installed. These control medium temperature and low temperature cooling, as well as the blast freezers. The main HCO2 G4 CO2 module – jointly developed by TEKO and Wurm – is used to control the medium and high-pressure valves, gas cooler control, heat recovery requirement and parallel compression. We also rely on control electronics from Wurm for CO2 gas warning control and remote data transmission.”
“The last items in the package supplied by TEKO are a CO2 gas cooler and 13 WHITELINE CO2 wedge coolers,” says Dirk Niedenthal, the Heat Exchanger Product Manager. “Because the capacities of the refrigeration rooms vary widely, we gave each cold room an evaporator specifically adapted to the surroundings and the temperatures required. When designing the components, we always take the entire refrigeration system into account and offer our customers an optimally coordinated service package.”
Good to know!
The blast freezers are for cooling down pre-cooked food as quickly as possible (Cook&Chill). Food can then be gently reheated in other catering facilities within the Munich Student Union. This process preserves the dishes’ vitamins and nutritional values to the greatest possible extent.
Description of the system technology
Facts & figures
- Useable area of 5,300 m2
- 7,300 meals served daily
- 5,400 guests served daily
- Dining room of 2,200 m2
- 1,500 seats
Refrigeration rooms for specific foods – dairy, meat, vegetables, etc.
- 9 cold storage rooms – total area 185 m2
- 4 deep-freeze rooms – total area 105 m2
- 36 small refrigeration units – refrigerated display cases, tanks, refrigerators, refrigerated tables
- 4 blast chillers / blast freezers
- Refrigerant R 744 (CO2)
- Medium temperature cooling
117 kW (t0 -11 / tGC 37 °C)
5x Bitzer compressors (1st compressor with FC / inc. parallel compressor)
- Low temperature cooling
13 kW (t0 -32 / tC -11 °C)
6x Bitzer compressors (1st compressor with FC)
- Blast chiller / blast freezer (each with FC)
4x 12,4 kW (t0 -25 °C)
Wurm control electronics FRIGOLINK: Multi compressor system, medium- and high-pressure valves, gas cooler control, heat recovery unit
Max. capacity 161 kW (water inlet 30 °C / water outlet 65 °C)
- Parallel compression
- Heat recovery
- Suction-side gas heat exchanger for each suction pressure stage
- Frequency converter for each suction pressure stage (parallel compression, MT/LT)
- 5 different LT suction pressure stages
- WHITELINE gas cooler with 6 EC fans
- 310 kW (tamb 35 °C/tGC from 37 °C)
- 13x WHITELINE CO2 wedge coolers
(1) Source: www.tum.de/nc/die-tum/aktuelles/pressemitteilungen/details/35678