Investigation into the influence of the cooling water temperature on the operating conditions of the thermosyphon generators

The application of thermosyphon generators in small capacity ammonia/water absorption refrigerators is widespread and well known. This kind of generator - which supersedes the necessity of a mechanical solution pump – has several advantages, since the processes of refrigerant desorption and solution pumping is combined in one hermetical unit. Nevertheless the application of thermosyphon generators in absorption chillers of larger scale is limited. When analysing the part load characteristics of different commercial H2O/LiBr-absorption chillers with such generators a considerable (and negative) deviation is found as compared to systems using mechanical pumps. During the investigations into these effects it appeared that the cooling water temperature can be used quite advantageously for correlating and understanding the chillers part load performance. The reason for the complex internal behaviour and the impact on and by the external conditions will be discussed in this paper. In addition basic correlations for a new control strategy will be derived.