SAVING FUEL

Waikato Independent, Volume XLV, Issue 6234, 4 May 1949, Page 8

SAVING FUEL

USE OF HEAT PUMP METHOD ATTRACTS ATTENTION The growing shortage and increasing costs of fuel, both in New Zealand and overseas, has focussed attention upon the various methods of conservation and better utilisation of the many sources of energy. One method that is attracting considerable attention overseas, and which is being increasingly used m several countries (especially _ m applications requiring comparatively low-temperature heat), is the heat pump. This apparatus extracts heat from a low-temperature source (such as a river) and transfers it to the medium concerned at a higher temperature, in the same way as the domestic refrigerator extracts heajv from a space and rejects it into che room. The principle of the heat pump was enunciated by Lord Kelvin m 1852, but it has only recently come into prominence in the U.S.A., Britain, and Switzerland— especially in the latter country owing to the very serious shortage of fuel. The disadvantages of the heat pump, in spite of the manner in which it utilises heat, is the very high capital cost for che initial plant. Notwithstanding' this, the heat pump has proved itself in several fields, which include the air conditioning of large buildings, the heating of public baths and hot houses, the concentration of milk and of fruit juices, and the production of salt.

The Department of Scientific and Industrial Research, through the Dominion Physical Laboratory, besides following developments overseas and studying possible applications in New Zealand, are carrying out small-scale experiments on the practical application of the heat pump to industry. The fields that most easily lend themselves to this application in New' Zealand are the heating of buildings and swimming baths, and the concentration of fruit juices. The Department is contacting those firms who are contemplating the use of any industrial process requiring large quantities of low-temperature heat, and in particular those who are considering such heating or processing as mentioned above.

Of the outstanding installations overseas, one made by Messrs. Brown Boveri is used according to seasons for concentrating milk and unl'ermented fruit juices. Both products are evaporated at temperatures much below' normal boiling point, and the temperatures obtained by the heat pump adequately meets these requirements. Up to 6700 gallons of fruit juices are treated daily, and it is claimed that the consumption of electrical energy is only one ninth of that necessary with direct electrical heating. An installation of the Swiss Rhine Salt Works has a capacity of 40,000 tons per annum, and in the first year of operation showed a saving of 14,000 tons of coal. In the new workshops and offices of the Norwich Corporation Electrical Department the comparative annual costs for heating the building were £1045 for coal-fired boilers and £978 for heat-pump installation, the latter having the additional advantages of cleanliness and automatic operation.

The above examples are only a few' illustrations of the savings in fuel that can be obtained by the substitution of heat pumps for orthodox heating and drying methods.