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Life sciences | The Institute of Molecular Biology | water-cooled ULT Freezers

The Institute of Molecular Biology (IMB) in Mainz Germany

The Institute of Molecular Biology (IMB) is a centre of excellence in life sciences located in Mainz, Germany. It carries out academic research into developmental biology, epigenetics and DNA-repair towards deepening our understanding of how we develop, adapt to our environment, age and develop diseases, such as cancer. Its work is acknowledged globally.

Employing 160 people, including some of the world’s leading scientific experts in bioinformatics, cytometry, histology, high-end microscopy, microarray analysis and next generation DNA sequencing, the IMB is housed in a state-of-the-art laboratory complex, equipped with cutting-edge technologies. With top performance, sustainability and reduced operational costs amongst its priorities, the IMB chose to equip its core facilities with PHCbi’s ultra-low temperature -86ºC and -150ºC freezers, both with water-cooled condensers.

The IMB’s research involves a wide variety of different types of biological materials, including human cell lines, tissue samples and human protein clones. All these need to be stored at ultra-low temperatures, before nucleic acids and proteins are extracted for further research. With such crucial medical and research applications, the IMB required freezers that offered the highest levels of performance and reliability to securely store these valuable, often irreplaceable samples. The

facilities of the IMB were specifically-designed to minimise energy consumption and save resources. With this in mind, wherever possible, equipment such as freezers, centrifuges, laser systems and sterile work benches, are water-cooled, rather than relying on traditional air-cooling, therefore, reducing costs and enhancing efficiency. Equipment use is optimised further by sharing resources amongst multiple users from different research groups.

The IMB selected 25 PHCbi MDF-U74V -86ºC ultra-low temperature freezers and four PHCbi MDF-C2156VAN -150ºC Cryogenic freezers. All freezers were equipped with a water-cooled condenser option and utilise the IBM’s central water-cooling system. The 728-litre, space-saving, -86ºC ultra-low temperature freezers with improved energy efficiency are used to hold a collection of more than 25,000 different human protein-coding clones, whilst the large capacity (231 litres) -150ºC Cryogenic freezers store a large number of human cell lines, tumour cell lines and tissue samples.

“What we really love about the PHCbi freezers is that they provide a very stable, constant environment with no temperature fluctuation,” said Dr. Korn, former Director of Core Facilities and Technology at the IMB1. “The insulated inner doors reduce temperature change when the freezer is opened and there is enough space for large boxes. A wide choice of shelving arrangements provides the flexibility to accommodate the storage needs of our different research groups. The freezers are very easy to operate and we like the fact that the main power switch is on the side.

This means there is no danger of a unit being turned off accidentally – a recognised hazard if this switch is placed on the front panel.”

Advanced performance and reliability

PHCbi’s VIP insulation significantly reduces the overall footprint and maximises the energy efficiency of the freezers compared to freezers with conventional insulation, whilst providing excellent temperature uniformity.

PHCbi’s MDF-C2156VAN -150ºC freezers feature a specially-designed cascade refrigeration system with Cool Safe® compressors. These application-specific compressors employ innovative refrigerant feedback processes to rapidly reduce compressor temperature, minimise heat output and extend compressor lifetime, thereby increasing the durability of the freezers. Temperatures within the freezers are extremely uniform.

Seamless integration into an energy-saving system

Many of PHCbi’s ultra-low temperature freezers feature an advanced new capillary tube heat exchanger, which significantly increases overall efficiency. By optimising the available heat exchange areas, system reliability is also increased and energy consumption is cut. In addition, some models can be supplied with an optional water-cooled condenser that enables laboratories with a chilled re-circulating water system, like the IMB, to reduce their requirement for air conditioning within the freezer facility, re-use heat energy elsewhere and achieve even greater savings.

The process of achieving ultra-low temperatures requires a lot of heat exchange at various stages of refrigeration. The condenser, which is where hot, high pressure, refrigerant gas is cooled to the point that it becomes a liquid, is the most intensive component in the heat exchange equation. In an air-cooled ultra-low temperature freezer, all of the heat is then released into the surrounding air. This heat energy is lost to the environment and in most cases, has to be removed from the building using air conditioning, which requires input of a lot of additional energy. If the air conditioning system fails for any reason, the room could potentially heat up relatively quickly.

PHCbi’s water-cooled ultra-low temperature freezers incorporate a double plate heat-exchanger that maximises heat energy transfer from the refrigerant to a closed water circuit. As water is more efficient than air at removing heat, the compressor efficiency is improved, meaning that the power consumption of a water-cooled ultra-low temperature freezer can be reduced by 15-20% compared to an equivalent air-cooled model. As heat is removed through the water, there are much lower demands on the air conditioning system, resulting in additional savings. The energy removed by the water cooling system has the potential for use for other purposes within the facility, such as heating water for handwashing, or heating the building, reducing site-wide energy costs. As well as the environmental and financial benefits, a water-cooled system can also improve freezer performance and sample protection.

The greater cooling capacity of water leads to a reduction in pull-down time by up to 40%, meaning faster temperature recovery after door-opening and improved sample security. Should the air conditioning system in the freezer room fail, the room will heat up less quickly, as less heat is being released into the room, helping to maintain freezer operation and protect samples.

“With less heat dissipated in the freezer room, only ventilation is needed, rather than air-conditioning, which not only requires energy but wastes heat. Water is circulated at 18ºC and leaves the freezers at 23–24ºC. However, this heat energy is not wasted, as the warmed water is used to contribute to the central heating for the whole building,” explained Dr. Korn. “With more than 100 instruments throughout the IMB connected to the water-cooling system, only a very few laboratories and measurement rooms require active cooling. Therefore, the IMB is able to reduce energy costs and benefit the environment.” The IMB also runs instruments and equipment, such as freezers, at the limit of capacity to optimise efficiency. The PHcbi freezers are located together in a dedicated area to make use of a centralised monitoring and alarm system, which constantly checks the temperature, power supply and cooling water for all units.

“Although initially more expensive than equivalent air-cooled freezers, choosing the water-cooled condenser option enables the IMB to use less energy and make significant savings in the medium and long term. We believe this is the way to go for the future,” remarked Dr. Korn. “Installing the freezers was essentially a ‘plug-andplay’ experience for us - The freezers arrived, they were hooked up to the cooling water, switched on and they worked!

PHCbi has since introduced a hybrid water-cooling option for its Eco Series freezers (MDF-DU300H, MDF-DU500VH and MDF-DU700VH). This hybrid system offers even greater sample security by allowing the freezer to function via an air-cooled condenser, if for any reason, the water cooling system fails, therefore, ensuring samples are still protected under these exceptional circumstances.

Water-cooling is an ideal solution for any facility with a recirculating, cooled-water circuit, as it not only provides great energy savings and reduced environmental impact, but also offers even better performance and sample security.