Heat re-use with Chemistry building
As a part of PDC's ongoing work to reduce our environmental footprint, we have been engaging in heat re-use projects. Previously excess heat from the Cray XE6 supercomputer Lindgren was being used to heat a building used by the School of Chemistry Science and Engineering at the KTH campus.
The earlier Cray XE6 supercomputer Lindgren at PDC was one of the largest computers in northern Europe at the time and it consumed up to 640 kW of power. Prior to Lindgren, all of PDC's supercomputers had been cooled by the district cooling system available throughout Stockholm.
With the procurement of Lindgren, PDC started a project, together the KTH property owners Akademiska Hus, to re-use the energy from Lindgren on the KTH campus. With the start of the cool period in Sweden, the system was taken in full use.
Each rack of the Cray XE6 system had a fan which took in cool (16 °C) air from under the raised floor and the heated air (35-43 °C) was exhausted at the top of the rack. Ventilation hoods, specially designed for the project, lead the hot air into heat exchanger coils which transferred the energy into hot water (28-33 °C).
The hotter water was transferred to the Chemistry building where it was used to heat the air (20-22 °C) going in to the building. Due to the temperatures involved, no heat pumps were required. According to the project's calculations using heat pumps would have been too costly and the project would no longer have been economical. One additional idea to make the project economical was to use the existing pipes from the district cooling system between the buildings. When the cool season started, the flow in the pipes between the buildings was reversed. Some equipment still needing cooling in the affected part of the system could be adjusted to use the higher temperature for cooling.
Calculations show that between 60–70% of the energy from the Cray could be re-used during the cool season. This saved on district cooling costs at PDC and on district heating costs for the chemistry building. We expected to save around 1,300 MWh in district cooling and 600 MWh in district heating per year with an approximate value of 70,000 Euro.
For questions about the Lingren heat re-use project at PDC, please contact:
