TeTra

The efficiency of district heating networks depends on heat losses, which are influenced by system temperatures and annual network utilisation. The aim of the TeTra project is to develop an innovative district heating transfer station ("exergy transformer") based on absorption for use at the end consumer or as an area converter in larger district heating networks. The converter station enables the end customer to provide not only heat but also cooling and electrical energy. This allows the annual network utilisation to be increased. As an area converter, the converter station makes it possible to lower the temperature level on the primary side, which leads to a reduction in heat losses.

As part of the project, the "exergy transformer" is being developed and optimised on the basis of thermodynamic process simulations. Based on the basic principle proposed in the patent, variant calculations and parameter studies will be carried out with the aim of creating the necessary basis for further development as part of an industrial research project.

Using typical load profiles of a district heating network, the effects and repercussions of the "exergy transformer" on the network are analysed. The new technology is compared with conventional systems and an economic and ecological assessment is carried out.

Fig. 1 shows the basic concept of the "exergy transformer". This differs from conventional absorption machines in that, depending on the application, useful heat and/or cold can be decoupled and electrical energy can also be produced. The mixing ratio of the working fluid pair ammonia/water or water/lithium bromide can be adapted to the respective operating conditions during operation.

Literature:
Beckmann G. (2012): Method and device for generating cold and/or useful heat as well as mechanical or electrical energy by means of an absorption cycle. Austrian patent AT5118231B1.