DAKTRis - Dynamic operational behaviour of absorption chillers in Trigeneration Systems
Trigeneration-systems provide significant potential to assure sustainable heat-, cold air- and electricity- supply to multifunctional buildings and urban settlements. Increasing the use of rejected heat from combined power (CHP) units leads to increased hours of operation and thus to higher electricity production and economic feasibility. The main challenge to accomplish such efficient systems is the adjustment of the main components and system arrangements.
Starting point / motivation
One possibility to provide multifunctional buildings and urban settlements with heat, cold air and electricity is the use of so called trigeneration systems. The first results of relevant projects (e.g. PolySMART) show a significant potential for small capacity systems and outline the necessary steps toward economical and primary energy efficiency. The main challenges are adjusting the main components, the combined heat and power unit (CHP) and the absorption chiller, as well as the design of the overall system (user profile, hydraulics, control strategy,...).
Contents and goals
Up to now trigeneration systems have been built up with standard absorption chillers. Most of these chillers are not designed for such operation conditions. When adapting the chiller with respect to higher generation temperatures and dynamic boundary conditions by means of the optimization of the internal circuit, the requirements for a successful and efficient system solution can be fulfilled. Increasing the use of rejected heat from the CHP unit (e.g. during summer time) results in increased hours of operation and thus in higher electricity production and economic feasibility.
Methods of treatment
By means of market, economic and primary energy considerations as well as dynamic system simulations, profiles for multifunctional buildings (residential and non-residential use) will be set up. Corresponding to these, profiles system configurations (with/without storage, choice of CHP Unit, ) including control strategies will be defined and analyzed in the project steps.
After the adaption of the chiller to the specific boundary conditions, the different system configurations will be analyzed in hardware-in-the-loop measurements. In these lab tests the system performance can be measured and mapped under realistic dynamic conditions. Using this method, early stage analyses of the systems can be carried out, leading to reduced costs and higher success rates in the implementation. Additionally statements concerning economic and primary energy efficiency can be determined and the systems can be optimized respectively.
Expected results / conclusions
Finally an economic and primary energy efficient operation can only be guaranteed with an adequate choice and adjustment of the single components. Thus, a significant contribution to the reduction or even avoidance (if using biomass-fired CHP units) of greenhouse gas emissions in the building sector can be achieved.
Unit for Energy Efficient Buildings / Institute of Structural Engineering and Material Sciences / University of Innsbruck