## 3 Results
### Coupled Generation of Electricity and Cooling with or without Waste Heat Integration  
In Figure 21, the round trip utilization (RTU) is plotted against the round trip efficiency (RTE) for the coupled generation of electricity and cooling without waste heat integration.  
Figure 19: Lead concept CHP+WHI2 for coupled generation of electricity and heat with waste heat integration.  
Figure 20: Lead concept CHP+WHI3 for coupled generation of electricity and heat with waste heat integration.  
Each marker represents a physically feasible concept. Lighter markers represent the lower compressor discharge temperature (CDT) of 450 \({}^{\circ}\)C, while darker ones represent a CDT of 625 \({}^{\circ}\)C. Red-bordered markers represent concepts using CO\({}_{2}\) as the working fluid, and green-bordered ones represent concepts using Argon. Diamonds represent concepts with a recuperator in the charging line, while lying squares represent those with an additional recuperator in the discharging line.  
The calculated values for RTU range from 30% to 55%, which are lower compared to the coupled generation of electricity and heat, but the RTE ranges from 30% to 45%, which is significantly higher here. The number of solutions with a recuperator in the charging line as well as those with Argon as the working fluid seems to dominate, but there are also few physically feasible concepts based on air and without a recuperator. However, the concepts with two recuperators perform significantly worse than the rest.  
In the following diagrams, the results for RTU over the compressor pressure ratio (II) in the charging line are plotted: Figure 22 covers the full range of compressor pressure ratio, while Figure 23 restricts the range to 0 to 10.  
Figure 21: Coupled generation of electricity and cooling without waste heat integration: RTU over RTE.  
Figure 22: Coupled generation of electricity and cooling without waste heat integration: RTU over \(\Pi\) (complete solution area).  
It becomes clear that the dominance mentioned earlier is only apparent as the markers were directly overlapping there. In fact, there are approximately as many solutions for air as the working fluid even without the use of a recuperator. Furthermore, the concepts with a recuperator show significantly higher compressor pressure ratios, but the efficiencies are not higher.  
For future detailed investigations, the lead concepts for the coupled generation of power and cooling without heat integration are defined as those with CDT = 450 \({}^{\circ}\)C and CDT = 625 \({}^{\circ}\)C that exhibit the best combination of high RTU and high RTE, while remaining as simple as possible. In cases where similarly high values for both RTU and RTE are achieved, the simpler system is chosen, see Figure 21:  
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* CCP1: Working fluid air. Cooler before the turbine in the load path. Cooling provision after the turbine in the load path. Cooler before the compressor in the discharge path. \(\vartheta_{\max}\) = 625 \({}^{\circ}\)C; RTU = 53.2%; RTE = 42.4%; \(\Pi\) = 2.8. Flow scheme: Figure 24.
* CCP2: Working fluid air. Cooler before the turbine in the load path. Cooling provision before the compressor in the discharge path. \(\vartheta_{\max}\) = 450 \({}^{\circ}\)C; RTU = 51.7%; RTE = 38.3%; \(\Pi\) = 2.7. Flow scheme: Figure 25.  
Figure 23: Coupled generation of electricity and cooling without waste heat integration: RTU over \(\Pi\) (restricted solution area).  
Figure 24: Lead concept CCP1 for coupled generation of electricity and cooling without waste heat integration.  
The additional integration of waste heat leads to more physically possible solutions than without heat input. However, it is also evident that this does not result in significant improvements in terms of the RTU and RTE values. Therefore, it is not meaningful to discuss these results in detail. Accordingly, for future detailed investigations, no concepts with waste heat integration will be selected for the coupled generation of electricity and cooling.