Cooking and Cooling
The operation of the absorption refrigerator depends on the surface and a (inert) chemical-physical process. Thus, from an industrial point of view it is a niche product. This thinking is often unjustly, since this technology offers interesting perspectives. The necessary resources are heat and cooling water and little bit of energy for the pumps.
An absorber is “heat transformer” – not a “heat consumer”!
The processes “absorption” and “adsorption” have to be defined separately: “A-d-sorption” describes the accumulation of one substance to another. Today, it is a niche application for smaller output. “A-b-sorption” describes the process of taking up the refrigerant by the another substance (the solvent). This technology is commercial and interesting for all types of output and temperatures. Absorption, therefore, works with a pair of substances. Established pairs of substances are:
LiBr – Absorption, Quelle: Johnson Controls
Lithiumbromide / Water
The plants are built in serial production with up to 5,000 kW and supply cold water of +4° C minimum. Recently, lower temperatures have become possible as well. Water is a refrigerant, Lithiumbromide is a solvent. A schematic diagram is shown below.
NH3/H2O – Absorption, Quelle: Mattes Engineering
Ammonia / Water
… for plants of any size, from -60°C and up. When planned accordingly, an absorption refrigerator can be integrated very efficiantly into an existing refrigeration plant. That way, efficiency and application time can be increased, and the absorber can take up other “duties” in the system.