| 摘要 |
<p>A refrigerant circulated in a heat pump passes through an evaporator which has a large black absorber surface. When bright sunshine coincides with low air temperatures, the absorber is covered by a sheet of glass which is transparent to solar radiation but not to low temperature radiation. A suitable insulator prevents conduction or convection from the absorber surface to the atmosphere through the glass. At high ambient temperatures, a good conducting medium is introduced between the cover and the absorber so that the heat of the air is used to evaporate the refrigerant. The change from one heat source to the other is effected automatically in accordance with the ambient temperature.</p> |
