Storage of Thermal Energy by Means of an Absorption Cycle

摘要

The possibilities for storing thermal energy by means of an absorption cycle are described. In such a cycle two components of a mixture are separated by the supply of energy (heat or mechanical energy). The components can be stored at ambient temperature; consequently there is no heat loss during storage. At the moment of heat demand, both components are recombined to produce heat of absorption. This heat consists of the heat of mixing and the heat of condensation, provided that one of the components is gaseous. The required heat of evaporation is extracted from the environment. The energetic efficiency of such a cycle, related to the net heat production and the supplied primary energy, can theoretically be over 100%. The absorption cycle was investigated for three different storage alternatives. In the first alternative the components are separated by heat supply. The heat of condensation of the gaseous component is transferred to the environment. The energetic efficiency of this cycle is less than 100%. In the second storage alternative the heat of desorption is supplied by a heat pump that uses the heat of condensation as a heat source. In the third alternative the heat of condensation is produced at such a high temperature that this heat can be used directly for desorption. To achieve this higher temperature, the gaseous component is condensed at a higher pressure. A compressor is applied for this purpose.