The sun as cooling agent: Solar refrigerator for medicine to manage without socket

Osnabrück. Medicine is a "sensitive plant”: it dislikes high temperatures. Vaccines are similarly sensitive. Both is difficult on longer transports in developing countries where electricity is not constantly available. Now the company va-Q-tec from Würzburg takes a first step towards solving the problem: developing a vacuum-insulated refrigerator for medicine using solar energy as cooling agent - supported by the Deutsche Bundesstiftung Umwelt DBU and in co-operation with the Baden-Württemberg company Phocos. Objective: A solar cooler that meets the demands of the World Health Organisation (WHO). "The safe transport of medicine is vital. This project goes a step further and combines health- and environmental protection", says DBU Secretary General Dr.-Ing. E. h. Fritz Brickwedde. The DBU promotes the project with 50.000 Euro.

The result: an ideal insulation

Basis of the new refrigerator is a very efficient insulation developed by va-Q-tec and working by means of a vacuum. "We use fine-porous quartz powder which is pressed to plates and then wrapped with an aluminium foil,” says the physicist Dr. Joachim Kuhn from va-Q-tec. "Finally all air is sucked out.” The result: an ideal insulation. Now, the fiddlers from va-O-tec and Phocos want to construct a cooler using that excellent insulation which can be supplied by solar energy.

"The cooler could be continuously operated with solar energy"

The researchers want to construct a solar refrigerator which needs on average less than 10W. "Then in regions without electricity the cooler could be continuously operated with solar energy,” expects Dr. Kuhn. A small photovoltaic conversion module is sufficient. At night and on cloudy days, a rechargeable battery or an integrated refrigeration store should maintain the operation.

The solar refrigerator does finally meet the demands of the WHO

In the next months, the engineers want to develop different prototypes which are afterwards subjected to long-term- and endurance tests. Objective of the researchers is that the solar refrigerator does finally meet the demands of the WHO for climate zones up to 32°C. Dr. Kuhn: "Afterwards we can work on constructing coolers that are suitable in the tropics as well.”