UPDATE: Latest low-temperature hydrocarbon freezers available for laboratories

Concerns with carbon footprint are spurring innovations in ultra low-temperature (ULT) refrigeration, required by most laboratories to store samples, reagents, antibodies and enzymes. Several companies now offer zero ODP and low GWP hydrocarbon freezers. Below we look at some of the ULT hydrocarbon products on offer. UPDATE: The most energy efficient freezer on the market is the Eco VIP -86°C ultra-l

Ultra low-temperature (ULT) laboratory freezers can achieve temperatures of -40°C to -86°C, in contrast to domestic freezers, which operate to about -20°C. As well as reliably reaching and maintaining low temperatures, ULT freezers must be energy efficient. Hydrocarbon technology provides an excellent, environmentally friendly solution for this type of application.

Hydrocarbon ULT freezers available

Buyers can opt for a range of numerous hydrocarbon options when selecting a low-temperature laboratory freezer, some of which include:

Green U725-G Upright -86°C Lab Freezers by NBS: Launched in 2010, the New Brunswick Scientific (NBS) range offers a number of innovations: the combination of vacuum insulation panel technology; new and improved circulation and compressor systems and in 50 Hz models; the use of hydrocarbon based refrigerants has allowed these freezers to consume up to 65 percent less electricity than competitive units.

Telstar Igloo ultra-low-freezer: Telstar, a multinational group based in Spain recently entered into the field of ultra-low-freezing by developing upright and chest freezers, with a capacity of 370 to 830 litres and using ultra thin vacuum insulation panels. The hydrocarbon freezers are safety compliant according EN60335-2-24, and have lower power consumption and noise levels of around 50 dB(A).

Thermo Scientific TS586e Eco-Friendly Freezer: In order to reduce energy consumption and reduce the carbon footprint of the freezer, the CE-certified and WEEE directive-compliant TS586e has been carefully designed to use 100% hydrocarbon refrigerants that are non-ozone depleting, low greenhouse warming potential (CFC, HFC and HCFC-free) and employ water- blown, foam insulation.

Skadi Green Line freezers, by ilShin Europe: ilShin Europe have developed their own compressors in combination with their WhisperFreeze technology for the Skadi hydrocarbon green line freezer. Upright freezers are available from 276 liter up to 730 liters and chest freezers are available from 191 liter up to 593 liters.

Panasonic Eco VIP Series -86°C Ultra-low Freezers: The energy efficient 500 and 700 litre -86°C, hydrocarbon freezers yield up to 55% reduction in energy use and up to €5.000 savings on energy costs over 10 years compared to traditional models. A new patent-pending heat exchanger design provides greater surface area contact at critical points in the refrigeration system to enhance energy efficiency. Panasonic's VIP PLUS vacuum insulation panel technology reduces energy use and shrinks wall thickness by approximately one half and achieves up to 30% more storage capacity than a conventionally insulated freezer.

Development of hydrocarbon low-temperature freezing

In 2007 New Brunswick Scientific (NBS) was among the first to offer an eco-friendly and cost-saving “Green Freezer” line in which high GWP HFC refrigerants were replaced with hydrocarbons refrigerants. The new design significantly lowered energy consumption and operating costs. At the time these freezers were not available in the U.S., where use of hydrocarbon refrigerators was not yet permitted.

However, following the recent US EPA approval of three hydrocarbon refrigerants, it seems likely the market for ULT freezer technology is set to see greater interest in hydrocarbon technology.

How ULT freezers operate

Laboratory freezers generally apply vapour compression with a single compressor to reach the -40° to -50° C range. A second compressor is required to cool below that point. To achieve energy efficiency and extend the life of the compressors, the low-stage compressor turns off automatically when the set-point temperature is reached, while the high-stage compressor remains on continuously.

It is vital that ULT freezers maintain uniform temperature throughout the unit and recover quickly from openings. Opening the freezer door introduces warm, moist air that causes the device to work harder to retain its set-point temperature and causes condensation and freezing of water vapour inside the unit. The speed at which a freezer recovers from temperature excursions is a function of BTU reserve capacity.

New trends in ULT cooling mechanisms include liquid nitrogen technology that does not use a compressor.